WO2023002986A1 - Iron-based sintered alloy valve seat for internal combustion engine - Google Patents

Iron-based sintered alloy valve seat for internal combustion engine Download PDF

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Publication number
WO2023002986A1
WO2023002986A1 PCT/JP2022/028064 JP2022028064W WO2023002986A1 WO 2023002986 A1 WO2023002986 A1 WO 2023002986A1 JP 2022028064 W JP2022028064 W JP 2022028064W WO 2023002986 A1 WO2023002986 A1 WO 2023002986A1
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Prior art keywords
valve seat
phase
particles
iron
solid lubricant
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PCT/JP2022/028064
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French (fr)
Japanese (ja)
Inventor
祐二 永岡
聡史 池見
克明 佐藤
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日本ピストンリング株式会社
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Application filed by 日本ピストンリング株式会社 filed Critical 日本ピストンリング株式会社
Priority to JP2023506535A priority Critical patent/JP7331290B2/en
Priority to CN202280050508.5A priority patent/CN117677452A/en
Priority to KR1020247002605A priority patent/KR20240024986A/en
Publication of WO2023002986A1 publication Critical patent/WO2023002986A1/en
Priority to JP2023129438A priority patent/JP2023156411A/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/02—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
    • C22C27/04—Alloys based on tungsten or molybdenum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/02—Selecting particular materials for valve-members or valve-seats; Valve-members or valve-seats composed of two or more materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/02—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers
    • B22F7/04—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers with one or more layers not made from powder, e.g. made from solid metal
    • B22F2007/042—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers with one or more layers not made from powder, e.g. made from solid metal characterised by the layer forming method

Definitions

  • the present invention relates to a valve seat for an internal combustion engine, and more particularly to a valve seat made of an iron-based sintered alloy with excellent wear resistance.
  • valve seat is pressed into the cylinder head of the internal combustion engine and plays the role of sealing the combustion gas and cooling the valve.
  • Valves are hit by valves, worn by sliding, heated by combustion gas, and corroded by combustion products. It has been demanded that the opponent's aggression is low.
  • Patent Document 1 describes a sintered alloy valve seat for internal combustion engines that has excellent wear resistance.
  • the sintered alloy valve seat described in Patent Document 1 is an iron-based sintered alloy valve seat in which hard particles and solid lubricant particles are dispersed in the matrix phase, and the matrix phase has a particle size of 10 ⁇ m or less.
  • a fine carbide precipitate phase having a Vickers hardness of 550 HV or more, hard particles having a Vickers hardness of 650 to 1200 HV are dispersed in an area ratio of 20 to 40%, It has a structure in which solid phase lubricant particles are dispersed by an area ratio of 0 to 5%, a diffusion phase is formed by an area ratio of more than 0% and 5% or less, and solid lubricant particles are dispersed by an area ratio of 0 to 5%.
  • Patent Literature 2 describes a valve seat made of an iron-based sintered alloy.
  • the valve seat described in Patent Document 2 is a valve seat having a two-layer structure in which a valve seating side portion and a head seating side portion are integrally sintered.
  • the valve seat side has a porosity of 10-25% by volume and a density after sintering of 6.1-7.1 g/cm 3 , with hard particles dispersed in the matrix phase, the hard particles comprising C, Particles composed of one or more elements selected from Cr, Mo, Co, Si, Ni, S, and Fe, dispersed in an area ratio of 5 to 40%, and containing a matrix phase and hard particles
  • the composition of the base is, in mass %, Ni: 2.0-23.0%, Cr: 0.4-15.0%, Mo: 3.0-15.0%, Cu: 0.2-3.0%, Co: 3.0-15.0%, V: 0.1-0.5 %, Mn: 0.1-0.5%, W: 0.2-6.0%, C: 0.8-2.0%
  • Patent Document 2 Cr—Mo—Co intermetallic compound particles, Ni—Cr—Mo—Co intermetallic compound particles, Fe—Mo alloy particles, Fe—Ni—Mo— S-based alloy particles and Fe--Mo--Si based alloy particles are exemplified.
  • Patent Document 3 proposes a valve seat made of an iron-based sintered alloy.
  • the valve seat made of an iron-based sintered alloy described in Patent Document 3 hard particles are dispersed in the matrix phase, and the overall composition, in mass%, is Cr: 5.0 to 20.0%, Si: 0.4 to 2.0%, Ni: 2.0 to 6.0%, Mo: 5.0 to 25.0%, W: 0.1 to 5.0%, V: 0.5 to 5.0%, Nb: 1.0% or less, C: 0.5 to 1.5%, balance Fe and unavoidable impurities
  • Patent Document 4 proposes a hard particle dispersed iron-based sintered alloy.
  • the hard particle-dispersed iron-based sintered alloy described in Patent Document 4 has, in weight percentage, Si: 0.4 to 2%, Ni: 2 to 12%, Mo: 3 to 12%, Cr: 0.5 to 5%, Hard particles of 3-20% based on the whole alloy are dispersed in a matrix containing V: 0.6-4%, Nb: 0.1-3%, C: 0.5-2%, and the balance Fe, and sintered,
  • the hard particles are a hard particle dispersed iron-based sintered alloy containing Mo: 60-70%, B: 0.3-1%, C: 0.1% or less, and the balance being Fe.
  • B When B is added to ferromolybdenum-based hard particles, B improves the wettability of ferromolybdenum, prevents the hard particles from falling off from the matrix, improves the adhesion between the matrix and hard particles, and improves the properties of the sintered alloy. It is said that the thermal strength and mechanical strength can be improved.
  • the present invention provides an iron-based sintered alloy valve seat for an internal combustion engine that has a sintered body composition that does not contain Co, has excellent wear resistance, and has sufficient strength as a valve seat.
  • excellent in wear resistance means that the wear resistance is improved as compared with the conventional iron-based sintered alloy valve seat having a Co-containing sintered body composition.
  • the "sufficient strength as a valve seat” here refers to the strength that does not cause cracks or cracks during press fitting, etc., and can be determined based on radial crushing strength obtained in accordance with JIS Z 2507.
  • the present inventors first thoroughly studied the influence of the Co-free composition of the hard particles and the Co-free composition of the matrix phase on the wear resistance. As a result, even if the hard particles have a composition that does not contain Co, cracking and chipping of the hard particles are avoided, the hardness is secured, and adhesion of the hard particles and the matrix is avoided, resulting in a decrease in wear resistance. It was newly found that the wear resistance can be prevented and the wear resistance equivalent to or higher than that using the conventional Co-based hard particles can be secured.
  • the hard particles consist of 1.5 to 3.5% Si-7.0 to 9.0% Cr-35.0 to 45.0% Mo-5.0 to 20.0% Ni, with the balance being Fe and unavoidable impurities. It was found that it is preferable to use Si--Cr--Ni--Fe-based Mo-based intermetallic compound particles of the composition.
  • the iron-based powder for forming the base phase, the hard particle powder, the alloying element powder, and the solid lubricant powder were adjusted to the compounding amounts shown in Table 1 and mixed to obtain a mixed powder.
  • Iron-based powders No.a and No.b having compositions shown in Table 2 were used as the iron-based powders for forming the matrix phase.
  • Hard particle powders No. MA and No. MD having compositions shown in Table 3 were used as the hard particle powders.
  • Hard particle powder No. MA is a commonly used Co-based intermetallic compound particle powder
  • hard particle powder No. MD is a Co-free Mo-based intermetallic compound particle powder.
  • Table 3 also shows the Vickers hardness HV of each particle powder.
  • MnS particle powder was used as the solid lubricant particle powder.
  • 0.75 parts by mass of zinc stearate was blended in the mixed powder as a lubricant with respect to 100 parts by mass of the mixed powder.
  • the mixed powder thus obtained is then filled into a mold, formed into a powder compact having a predetermined valve seat shape by a powder molding machine, and further subjected to a dewaxing process, and then subjected to a reducing atmosphere at 1100°C to 1200°C for 0.5hr. was sintered to obtain a sintered body.
  • the obtained sintered body was further processed by cutting, polishing, etc. to obtain an iron-based sintered alloy valve seat with a predetermined size and shape (outer diameter: 32.1 mm ⁇ x inner diameter: 26.1 mm ⁇ x thickness 5.5 mm). .
  • a hard particle cracking resistance test and an abrasion test were carried out on the obtained valve seat (sintered body).
  • the test method was as follows. (1) Hard particle crack resistance test The cross section of the obtained valve seat (sintered body) was polished, and a Vickers hardness tester (test force: 0.98 N) was used to measure hard particles (20 An indentation was given so as to fit within a 10 mm), and the presence or absence of cracking in each particle to which the indentation was given was observed with an optical microscope. Cracking was determined to occur when cracks were generated outside the indentation, and the number of cracked particles (number of cracks) was investigated. Using the number of cracks generated in valve seat No.
  • valve seat (No.S4) uses the hard particle powder No.MD, which is a Mo-based intermetallic compound powder with a composition that does not contain Co, there is no cracking of the hard particles, and the Co-based intermetallic compound It is possible to obtain a valve seat having wear resistance equal to or higher than that obtained when the particles are used as hard particles (valve seat No. S1). That is, the present inventors have found that deterioration of wear resistance can be prevented by dispersing Si--Cr--Ni--Fe based Mo-based intermetallic compound particles having a composition that does not contain Co as hard particles in the matrix phase.
  • the present inventors have found that, in order to further improve wear resistance, in addition to dispersing hard particles having the composition described above, the proportion of fine carbide precipitates in the matrix phase is increased to improve wear resistance. It was found that the performance can be improved.
  • a valve seat press-fitted into a cylinder head of an internal combustion engine has a two-layer structure in which the functional member side layer and the support member side layer are integrally sintered,
  • the functional member-side layer has a base phase, and a structure in which hard particles with an area ratio of 10 to 40% and solid lubricant particles with an area ratio of 0 to 5% are dispersed in the base phase,
  • the hard particles have a Vickers hardness of 700 to 1300 HV, and the mass % is Si: 1.5 to 3.5%, Cr: 7.0 to 9.0%, Mo: 35.0 to 45.0%, Ni: 5.0 to 20.0%.
  • the support member side layer comprises a matrix phase, a structure in which solid lubricant particles with an area ratio of 0 to 5% and hardness improving particles with an area ratio of 0 to 5% are dispersed in the matrix phase, and
  • the base portion containing the base phase, the solid lubricant particles and the hardness improving particles contains, in % by mass, C: 0.3 to 1.3%, Ni
  • a valve seat press-fitted into a cylinder head of an internal combustion engine The valve seat has a single layer structure consisting of a functional member side layer, The functional member-side layer has a base phase, and a structure in which hard particles with an area ratio of 10 to 40% and solid lubricant particles with an area ratio of 0 to 5% are dispersed in the base phase, The hard particles have a Vickers hardness of 700 to 1300 HV, and the mass % is Si: 1.5 to 3.5%, Cr: 7.0 to 9.0%, Mo: 35.0 to 45.0%, Ni: 5.0 to 20.0%.
  • the matrix phase of the functional member-side layer comprises 10 to 90% fine carbide precipitate phase and 0 to 30% in area ratio, where the area of the matrix phase excluding the hard particles and the solid lubricant particles is 100%. % of the high alloy phase and the balance of pearlite.
  • the base phase of the functional member side layer has a high alloy phase of 0 to 15% and the balance is fine carbide, with an area ratio of 100% for the base phase area excluding the hard particles and the solid lubricant particles.
  • the base phase of the functional member-side layer has a high alloy phase of 0 to 25% and a bainite phase as the balance, with an area ratio of 100% for the base phase area excluding the hard particles and the solid lubricant particles.
  • the valve seat made of an iron-based sintered alloy for an internal combustion engine according to [1] or [2], characterized by having a structure consisting of: [6]
  • the base phase of the functional member side layer has an area ratio of 0 to 30% with the base phase area excluding the hard particles and the solid lubricant particles being 100%, and the balance is pearlite.
  • the valve seat made of an iron-based sintered alloy for an internal combustion engine according to [1] or [2], characterized by having a structure of [7]
  • the fine carbide precipitation phase is a phase in which fine carbides with a grain size of 10 ⁇ m or less are precipitated and have a Vickers hardness of 400 to 600 HV.
  • valve seats made of iron-based sintered alloy for internal combustion engines.
  • the solid lubricant particles according to any one of [1] to [7], wherein the solid lubricant particles are one or two selected from manganese sulfide MnS and molybdenum disulfide MoS2.
  • Valve seat made of iron-based sintered alloy.
  • the valve seat made of an iron-based sintered alloy according to [1], wherein the hardness improving particles are iron-molybdenum alloy particles.
  • valve seat having excellent wear resistance, with little cracking and chipping of hard particles and no adhesion even in a severe wear environment. It has a remarkable effect.
  • the valve seat of the present invention is made of an iron-based sintered alloy, and has a two-layer structure in which the functional member side layer on which the valve is seated and the support member side layer that is seated on the cylinder head and supports the functional member side layer are integrally sintered. or has a single layer structure with only the functional member side layer.
  • the iron-based sintered alloy material constituting the functional member side layer of the valve seat of the present invention has a structure in which hard particles or solid lubricant particles are dispersed in the matrix phase, and has excellent wear resistance properties. have.
  • excellent wear resistance means that the wear resistance is improved to the same level or more than that of the iron-based sintered alloy material with the conventional Co-containing sintered body composition. shall be
  • the hard particles dispersed in the base phase are Si-Cr-Ni-Fe based Mo-based intermetallic compound particles having a Vickers hardness of 700 to 1300 HV.
  • the hardness of the hard particles is less than 700HV, adhesion occurs in the hard particles themselves, and the effect of improving wear resistance is small. Invite. For this reason, the hardness of the hard particles dispersed in the matrix phase is limited to the range of 700 to 1300 HV in terms of Vickers hardness.
  • the hard particles dispersed in the matrix phase in the present invention preferably have the hardness described above and an average particle size of 10 to 150 ⁇ m. If the average particle size is less than 10 ⁇ m, it tends to diffuse during sintering. Therefore, it is preferable to limit the average particle diameter of the hard particles dispersed in the matrix phase to the range of 10 to 150 ⁇ m.
  • the term "average particle size" as used herein means the particle size D50 at which the cumulative distribution measured by the laser scattering method is 50%.
  • the hard particles having the hardness described above are dispersed in the base phase at an area ratio of 10 to 40%. If the amount of dispersed hard particles is less than 10%, the desired wear resistance cannot be ensured. On the other hand, when it exceeds 40%, the bonding strength with the matrix phase is lowered, and the wear resistance is lowered. For this reason, the amount of hard particles dispersed in the matrix phase is limited to a range of 10 to 40% in area ratio with respect to the entire matrix phase.
  • the Si—Cr—Ni—Fe-based Mo-based intermetallic compound particles dispersed in the matrix phase are, in mass %, Si: 1.5 to 3.5%, Cr: 7.0 to 9.0%, Mo: 35.0 to Mo-based intermetallic compound particles having a composition (hard particle composition) containing 45.0% Ni, 5.0 to 20.0% Ni, and the balance Fe and unavoidable impurities.
  • hard particles having the hard particle composition described above it is possible to obtain a valve seat containing hard particles having a structure in which an intermetallic compound is precipitated after sintering.
  • the Mo content in order to obtain hard particles that have a Vickers hardness of 700 HV or more, suppress the occurrence of cracks and chips, and have high hard particle crack resistance by precipitating intermetallic compounds, the Mo content must be It is important to keep it as high as 35.0-45.0%. Further, in order to obtain hard particles that have toughness and maintain desired hardness, it is important to set the Ni content within the range of 5.0 to 20.0%.
  • solid lubricant particles may be further dispersed in the base phase. Machinability and lubricity are improved by dispersing solid lubricant particles in the matrix phase. However, if the area ratio exceeds 5%, the mechanical properties are significantly lowered. For this reason, the area ratio of the solid lubricant particles is limited to the range of 0 to 5%.
  • the solid lubricant particles are preferably one or two selected from manganese sulfide MnS and molybdenum disulfide MoS 2 .
  • the base phase of the functional member side layer of the valve seat of the present invention is fine carbide having an area ratio of 10 to 90%, more preferably 10 to 85%, when the area of the base phase excluding hard particles and solid lubricant particles is 100%.
  • Precipitate phase 0-30% high alloy phase and balance pearlite structure, or 0-15% high alloy phase and balance fine carbide precipitate phase, or 0-25 % high alloy phase and the balance bainite phase.
  • the fine carbide precipitation phase is a hard phase in which fine carbides having a grain size of 10 ⁇ m or less are precipitated and have a Vickers hardness of 400 to 600 HV. The presence of such a hard fine carbide precipitate phase can strengthen the matrix and further improve the wear resistance.
  • the matrix phase excluding the hard particles and the solid lubricant particles may be composed of 0 to 30% of the high alloy phase and the balance of pearlite. Even if the matrix phase has such a structure, if the sintered body has a composition that does not contain Co, the abrasion resistance is improved compared to the sintered body that has a composition that contains Co at the same hardness level.
  • the high-alloy phase is a region in which alloy elements diffuse from the hard particles during sintering and the alloy content increases, and has the effect of preventing the hard particles from falling off.
  • a high alloy phase can be allowed up to 30% in area ratio when the base phase area excluding hard particles and solid lubricant particles is 100%.
  • a predetermined amount of hard particles having the composition, structure, and hardness described above and solid lubricant particles having the composition described above are dispersed in the base phase of the structure described above. have an organization;
  • the base phase in mass %, C: 0.5 to 2.0%, Si: 0.2 to 2.0%, Mn: 5 % or less, Cr: 0.5-15%, Mo: 3-20%, Ni: 1-10%, V: 0-5%, W: 0-10%, S: 0-2%, It has a matrix composition containing 0 to 5% of Cu, with the balance being Fe and unavoidable impurities.
  • C 0.5-2.0%
  • C is an element necessary for adjusting the matrix phase to a predetermined hardness and structure, or for forming carbides, and is contained in an amount of 0.5% or more.
  • the content exceeds 2.0%, the melting point is lowered and the sintering process becomes liquid phase sintering. Liquid-phase sintering results in an excessive amount of precipitated carbides, an increased number of pores, and reduced elongation characteristics and dimensional accuracy. Therefore, C is limited to the range of 0.5-2.0%. In addition, it is preferably 0.50 to 2.00%, more preferably 1.00 to 1.50%.
  • Si 0.2-2.0%
  • Si is an element that is mainly contained in hard particles and constitutes an intermetallic compound, and increases the hardness of the hard particles, increases the strength of the matrix, and improves wear resistance.
  • it is preferable to contain 0.2% or more.
  • Si is limited to the range of 0.2 to 2.0%. Incidentally, it is preferably 0.20 to 2.00%. More preferably 0.20 to 1.40%.
  • Mn 5% or less Mn is an element that increases the hardness of the matrix phase, and Mn is an element that is contained in the matrix due to solid lubricant particles and contributes to improving machinability. It is preferable to contain at least On the other hand, if the content exceeds 5%, the matrix phase hardness, toughness and ductility are lowered. Therefore, Mn is limited to a range of 5% or less. In addition, it is preferably 5.00% or less, more preferably 0.20 to 3.00%.
  • Cr 0.5-15% Cr forms a solid solution in the matrix phase and increases the hardness of the matrix phase by forming carbides. is preferably 0.5% or more. On the other hand, if it exceeds 15%, precipitation of Cr carbides in the matrix phase becomes excessive, and it becomes difficult to make the carbides in the matrix phase into fine carbides. Therefore, Cr is limited to the range of 0.5 to 15%. Incidentally, it is preferably 1.00 to 15.00%, more preferably 0.70 to 6.00%.
  • Mo 3-20% Mo dissolves in the matrix phase and precipitates as carbides to increase the hardness of the matrix phase.
  • Molybdenum is an element that contributes to increasing the hardness of hard particles as a constituent element of intermetallic compounds. It is preferable to contain 3% or more as On the other hand, when it exceeds 20%, it is difficult to increase the density at the time of powder compaction, and the compactibility is deteriorated. Therefore, Mo is limited to the range of 3 to 20%. Incidentally, it is preferably 4.00 to 20.00%, more preferably 4.00 to 19.00%.
  • Ni is an element that contributes to improving the strength and toughness of the matrix phase, and is an element that contributes to increasing the hardness of the hard particles as a constituent element of the intermetallic compound, and is contained in an amount of 1% or more. On the other hand, if the content exceeds 10%, it is difficult to increase the density during powder molding, and the moldability is lowered. Therefore, Ni is limited to the range of 1 to 10%. In addition, it is preferably 1.00 to 10.00%, more preferably 2.00 to 9.00%.
  • the above ingredients are the basic ingredients, but as optional elements, V: 0-5%, W: 0-10%, S: 0-2%, and Cu: 0-5% can be added.
  • V 0-5%
  • V is an element that precipitates as fine carbides, increases the hardness of the matrix phase, and improves wear resistance, and can be contained as necessary. When it is contained, it is preferably 0.5% or more. On the other hand, if the content exceeds 5%, the moldability is lowered. Therefore, it is preferable to limit V to a range of 0 to 5%. In addition, it is more preferably 5.00% or less, still more preferably 2.00% or less.
  • W 0-10% W is an element that precipitates as fine carbides, increases the hardness of the matrix phase, and improves wear resistance, and can be contained as necessary. When it is contained, it is preferably contained in an amount of 0.5% or more. On the other hand, if the content exceeds 10%, the formability is lowered. Therefore, it is preferable to limit W to the range of 0 to 10%. In addition, it is more preferably 10.00% or less, and still more preferably 5.00% or less.
  • S 0-2% S is an element contained in the solid lubricant particles, contained in the base portion, and contributing to the improvement of machinability, and can be contained as necessary. If the S content exceeds 2%, it leads to a decrease in toughness and ductility. Therefore, it is preferable to limit S to the range of 0 to 2%. More preferably, it is 2.00% or less.
  • Cu 0-5% Cu is an element that contributes to improving the strength and toughness of the matrix phase, and can be contained as necessary. A Cu content of more than 5% leads to a decrease in adhesion resistance. Therefore, Cu is preferably limited to the range of 0 to 5%. More preferably, it is 5.00% or less.
  • the balance other than the above components consists of Fe and unavoidable impurities.
  • P 0.1% or less is permissible as an unavoidable impurity.
  • the iron-based sintered alloy material constituting the support member side layer of the valve seat of the present invention includes a base phase, solid lubricant particles in the base phase at an area ratio of 0 to 5%, and hardness improving particles at an area ratio of 0 to 5%. 0-5% with a dispersed structure.
  • the base phase of the support member side layer of the valve seat of the present invention consists of 100% pearlite or 100% bainite phase in terms of area ratio when the area of the base phase excluding solid lubricant particles and hardness improving particles is 100%. Organization is preferable.
  • a high alloy phase with an area ratio of up to 5% is permissible when the area of the matrix phase excluding the solid lubricant particles is taken as 100%.
  • the hardness-improving particles are preferably iron-molybdenum alloy (also referred to as Fe—Mo alloy or ferromolybdenum alloy) particles.
  • the Fe—Mo alloy particles preferably contain, for example, 60% by mass of Mo, with the balance being Fe and unavoidable impurities.
  • the base portion containing the base phase, the solid lubricant particles and the hardness improving particles contains, by mass %, C: 0.3 to 1.3%, and Ni: 0 to 2.0. %, Mo: 0 to 2.0%, Cu: 0 to 5.0%, Cr: 0 to 5.0%, Mn: 0 to 5.0%, S: 0 to 2.0%, and the balance is Fe and unavoidable impurities.
  • the reasons for limiting the composition of the base portion of the supporting member side layer are as follows.
  • C 0.3-1.3%
  • C is an element necessary for adjusting the base phase of the support member side layer to a predetermined hardness and structure, or for forming carbide, and is contained in an amount of 0.3% or more.
  • the content exceeds 1.3%, the melting point is lowered and the sintering process becomes liquid phase sintering.
  • liquid phase sintering is used, the amount of precipitated carbide becomes too large, and the elongation characteristics and dimensional accuracy deteriorate. Therefore, C is limited to the range of 0.3-1.3%. In addition, it is preferably 0.30 to 1.30%, more preferably 0.80 to 1.20%.
  • Ni: 0-2.0%, Mo: 0-2.0%, Cu: 0-5.0%, Cr: 0-5.0% Ni, Mo, Cu, and Cr are all elements that increase the hardness of the matrix phase, and can be contained as necessary. In order to obtain such effects, it is desirable to contain Ni: 0.1% or more, Mo: 0.1% or more, Cu: 0.1% or more, and Cr: 0.1% or more. On the other hand, when Ni: 2.0%, Mo: 2.0%, Cu: 5.0%, and Cr: 5.0% are contained, respectively, the formability of the matrix phase deteriorates. Therefore, it is preferable to limit the range to Ni: 0 to 2.0%, Mo: 0 to 2.0%, Cu: 0 to 5.0%, and Cr: 0 to 5.0%. More preferably, Ni: 2.00% or less, Mo: 2.00% or less, Cu: 5.00% or less, and Cr: 5.00% or less.
  • Mn 0-5.0%
  • S 0-2.0%
  • Both Mn and S are elements that are contained in the matrix due to the inclusion of solid lubricant particles and contribute to the improvement of machinability, and can be included as necessary. Mn also contributes to increasing the hardness of the matrix phase. When S exceeds 2.0% and Mn exceeds 5.0%, the ductility decreases significantly. Therefore, it is preferable to limit S to 0 to 2.0% and Mn to 0 to 5.0%. More preferably, S: 2.00% or less and Mn: 5.00% or less.
  • the balance other than the above components consists of Fe and unavoidable impurities.
  • P 0.1% or less is permissible as an unavoidable impurity.
  • the raw material powder for the functional member side layer and the raw material powder for the support member side layer are each blended and mixed so as to obtain the base phase composition and structure and the base portion composition and structure described above, and the functional member side layer is obtained. and the mixed powder for the supporting member side layer.
  • the raw material powder for the functional member side layer the iron-based powder for forming the base phase, the alloying element powder, the hard particle powder, and the solid lubricant particle powder are mixed so as to have the above-described predetermined composition and structure. , to blend.
  • an iron-based powder for forming the base phase, graphite powder, or alloying element powder, solid lubricant particle powder, and hardness improving particle powder are combined in the above-described predetermined composition, Mix to form a texture.
  • the hard particle powder to be blended in the mixed powder is obtained by melting the molten metal having the above-described hard particle composition by a commonly used melting method, and using a commonly used atomizing method to produce a powder (hard particle powder). It is preferable to
  • the iron-based powder to be blended into the mixed powder is preferably atomized pure iron powder, reduced iron powder, or alloyed steel powder, or a mixture thereof.
  • the alloy steel powder it is preferable to use a powder having a high-speed tool steel composition specified in JIS G 4403 so as to form a fine carbide precipitate phase having the hardness described above as a matrix phase.
  • the high-speed tool steel it is preferable to use a Mo-based material such as SKH51.
  • the mixed powder includes pure iron powder, pure iron powder and alloy steel powder having the composition described above, alloy steel powder having the composition described above, graphite powder so as to have the base phase composition described above, and Needless to say, contains alloying element powders.
  • the mixed powder may contain a lubricant such as zinc stearate.
  • the obtained mixed powder is filled into a mold and molded by a powder molding machine or the like to obtain a valve seat-shaped powder compact with predetermined dimensions and shape.
  • the raw material powder for the supporting member side layer and the raw material powder for the functional member side layer are sequentially filled into the mold so as to form two layers.
  • the mold is filled with raw material powder for the functional member side layer.
  • the green compact obtained is subjected to a sintering treatment to obtain a sintered body.
  • the sintering treatment is preferably carried out in a reducing atmosphere such as ammonia decomposition gas or vacuum at a temperature range of 1100 to 1200° C. for 0.5 hours or longer.
  • the powder molding-sintering process may be performed once (1P1S), or may be performed multiple times (2P2S, etc.).
  • the resulting sintered body is processed by cutting, grinding, or the like to form a valve seat having desired dimensions and shape.
  • Example 1 a mixed powder for the functional member side layer and a mixed powder for the supporting member side layer were prepared.
  • the mixed powder for the functional member side layer contains the iron-based powder for forming the base phase, the graphite powder, the alloying element powder, the hard particle powder, and the solid lubricant particle powder (MnS powder) in the amounts shown in Table 7. and mixed to obtain a mixed powder.
  • the iron-based powders used were pure iron powder (atomized pure iron powder, reduced iron powder), high-speed steel powder, and alloyed steel powder having the compositions shown in Table 5.
  • hard particle powder having the composition shown in Table 6 was used as the hard particle powder.
  • the hard particle powder No. A is a commonly used Co-based intermetallic compound particle powder, and is used as a conventional example. Table 6 also shows the Vickers hardness HV before sintering and the average particle size D50 of each hard particle.
  • the mixed powder for the supporting member side layer contains the iron-based powder for forming the base phase, the graphite powder, the alloy element powder, the hardness improving particle powder, and the solid lubricant particle powder (MnS powder) as shown in Table 8. The amount was adjusted and mixed to obtain a mixed powder.
  • the iron-based powder used was a pure iron powder (atomized pure iron powder, reduced iron powder) having the composition shown in Table 5.
  • the hardness-improved particle powder used was an iron-molybdenum alloy particle powder having a composition containing 60% by mass of Mo with the balance being Fe and unavoidable impurities.
  • valve seat No. 17A was a single layer with only the layer on the functional member side.
  • the compact thus obtained was subjected to a degreasing process for removing the lubricant and a sintering treatment at 1100° C. to 1200° C. for 0.5 hours in an ammonia decomposition gas to obtain a sintered body.
  • a process (2P2S) of performing powder compaction and sintering treatment twice was employed.
  • the obtained sintered body was further processed by cutting, polishing, etc. to obtain an iron-based sintered alloy valve seat with a predetermined size and shape (outer diameter: 32.1 mm ⁇ x inner diameter: 26.1 mm ⁇ x thickness 5.5 mm). .
  • the composition of the base part of each part of the sintered body is analyzed, and the structure observation, hardness measurement, density measurement, hard particle cracking resistance test, wear test, radial crushing strength test are performed. Carried out.
  • the test method was as follows. (1) Observation of structure The cross section perpendicular to the axial direction of the obtained valve seat is polished, corroded (corrosive liquid: nital liquid, marble liquid) to expose the structure, and an optical microscope (magnification: 200 times) The organization of the basal phase was identified.
  • the reference valve seat No. 1A (conventional example) has a structure in which the functional member side layer has hard particles and solid lubricant particles dispersed in the matrix phase, It is an iron-based sintered alloy material with a Co-containing composition, and is used for valve seats on the exhaust side of a wide range of gasoline engines from general gasoline engines to high-performance gasoline engines. Items that affect wear resistance on the exhaust side and the intake side of the valve seat (for example, heat load, design values of the valve mechanism, etc.) have different degrees of influence, and generally the exhaust side is more severe as a usage environment. Also, the wear resistance of the valve seat is required to be higher than that of the intake side.
  • valve seats of the present invention do not contain Co, have excellent wear resistance equal to or superior to that of the conventional example (valve seat No. 1A), and have sufficient radial crushing strength as a valve seat. It has become.
  • the comparative example which is outside the scope of the present invention, has a higher wear ratio than the conventional example (valve seat No. 1A).
  • the mixed powder for the functional member side layer contains the iron-based powder for forming the base phase, the graphite powder, the alloying element powder, the hard particle powder, and the solid lubricant particle powder (MnS powder) in the amounts shown in Table 13. and mixed to obtain a mixed powder.
  • the iron-based powders used were pure iron powders (atomized pure iron powders, reduced iron powders) and alloyed iron powders (pre-alloyed powders) having compositions shown in Table 11.
  • the hard particle powder used was the hard particle powder having the composition shown in Table 12.
  • A is a commonly used Co-based intermetallic compound particle powder, and the mixed powder D1 containing the hard particle powder No. A is a conventional example.
  • Table 12 also shows the Vickers hardness HV before sintering and the average particle diameter D50 of each hard particle.
  • the mixed powder for the supporting member side layer is prepared by adjusting the blending amounts of the iron-based powder for forming the base phase, the graphite powder, the alloying element powder, and the hardness-improving particle powder so as to have the compounding amounts shown in Table 14, and mixing them. , and mixed powder.
  • the iron-based powder used was pure iron powder (atomized pure iron powder) No.a having the composition shown in Table 11.
  • the hardness-improved particle powder used was iron-molybdenum alloy particle powder Fe—Mo having a composition containing 60% by mass of Mo with the balance being Fe and unavoidable impurities. Also, no solid lubricant particle powder (MnS powder) was added.
  • the obtained mixed powder for the functional member side layer and the obtained mixed powder for the support member side layer are sequentially filled into a mold so as to form two layers, and a green compact having a predetermined valve seat shape is formed by a powder molding machine. Molded.
  • the obtained compact is subjected to a degreasing step for removing the lubricant and a step (1P1S) of performing sintering treatment at 1100 to 1200° C. for 0.5 hr in ammonia decomposition gas to obtain a sintered compact. and
  • the obtained sintered body was further processed by cutting, polishing, etc. to obtain an iron-based sintered alloy valve seat with a predetermined size and shape (outer diameter: 32.1 mm ⁇ x inner diameter: 26.1 mm ⁇ x thickness 5.5 mm). .
  • valve seat sintered body
  • the composition of the base part of each part of the sintered body is analyzed, and the structure observation, hardness measurement, density measurement, hard particle cracking resistance test, wear test, radial crushing strength test are performed. Carried out.
  • the test method was the same as in Example 1.
  • the standard valve seat No. 1B (conventional example) is a material used for valve seats on the intake side of general gasoline engines, and the functional member side layer is , an iron-based sintered alloy material having a Co-containing composition.
  • a valve seat used on the intake side is required to have lower wear resistance than a valve seat used on the exhaust side.
  • the structure of the matrix phase becomes a structure consisting of a high alloy phase and pearlite
  • it is equivalent to the sintered body (conventional example No. 1B) with the same hardness level and a composition containing Co.
  • It is a valve seat with excellent abrasion resistance and sufficient radial crushing strength.
  • it can be said to be sufficiently applicable to intake side valve seats, which require relatively low wear resistance.
  • valve seat 2 cylinder block equivalent material 3 heating means 4 valve

Abstract

Provided is an iron-based sintered alloy valve seat having excellent wear resistance.　The present invention provides an iron-based sintered alloy valve seat for an internal combustion engine, wherein: Si-Cr-Ni-Fe-based and Mo-based intermetallic compound particles that have a hardness of 700-1300 HV in terms of the Vickers hardness and that have a composition containing, in terms of mass%, 1.5-3.5% of Si, 7.0-9.0% of Cr, 35.0-45.0% of Mo, and 5.0-20.0% of Ni, with the remainder consists of Fe and inevitable impurities are dispersed in a base phase as hard particles; and a base part containing the base phase, the hard particles, solid lubricant particles, etc. has a composition containing, in terms of mass%, 0.5-2.0% of C, 0.2-2.0% of Si, 5% or less of Mn, 0.5-15% of Cr, 3-20% of Mo, and 1-10% of Ni and additionally containing 0-5% of V, 0-10% of W, 0-2% of S, and 0-5% of Cu, with the remainder consists of Fe and inevitable impurities. Accordingly, the occurrence of cracks and chips in the hard particles is avoided even with a composition that does not contain Co, and thus, it is possible to prevent wear resistance deterioration and to obtain a valve seat having wear resistance that is equivalent to or greater than the case in which a conventional Co-containing composition is employed.

Description

内燃機関用鉄基焼結合金製バルブシートIron-based sintered alloy valve seats for internal combustion engines
　本発明は、内燃機関用バルブシートに係り、とくに、耐摩耗性に優れた鉄基焼結合金製バルブシートに関する。 The present invention relates to a valve seat for an internal combustion engine, and more particularly to a valve seat made of an iron-based sintered alloy with excellent wear resistance.
　バルブシートは、内燃機関のシリンダーヘッドに圧入されて、燃焼ガスのシールとバルブを冷却する役割を担っている。バルブによる叩かれ、すべりによる摩耗、燃焼ガスによる加熱、燃焼生成物による腐食等に晒されるため、従来からバルブシートには、耐熱性、耐摩耗性に優れること、相手材であるバルブを摩耗させないように相手攻撃性が低いことなどが要求されてきた。 The valve seat is pressed into the cylinder head of the internal combustion engine and plays the role of sealing the combustion gas and cooling the valve. Valves are hit by valves, worn by sliding, heated by combustion gas, and corroded by combustion products. It has been demanded that the opponent's aggression is low.
　このような要求に対し、例えば、特許文献１には、耐摩耗性に優れた内燃機関用焼結合金製バルブシートが記載されている。特許文献１に記載された焼結合金製バルブシートは、基地相中に硬質粒子および固体潤滑剤粒子を分散させた鉄基焼結合金製バルブシートであり、基地相が、粒径：10μm以下の微細炭化物が析出し、ビッカース硬さで550HV以上の硬さを有する微細炭化物析出相であり、ビッカース硬さで650～1200HVの硬さを有する硬質粒子を面積率で20～40％分散させ、固相潤滑剤粒子を面積率で0～5％分散させた組織を有し、拡散相が面積率で0％超え5％以下形成し、固体潤滑剤粒子を面積率で0～5％分散させ、基地相と拡散相と硬質粒子と固体潤滑剤粒子とを含む基地部が、質量％で、C：0.5～2.0％、Si：0.5～2.0％、Mn：5％以下、Cr：2～15％、Mo：5～20％、Co：2～30％を含む組成を有するとしている。これにより、厳しい摩耗環境においても、バルブシートの耐摩耗性が向上するとしている。 In response to such demands, Patent Document 1, for example, describes a sintered alloy valve seat for internal combustion engines that has excellent wear resistance. The sintered alloy valve seat described in Patent Document 1 is an iron-based sintered alloy valve seat in which hard particles and solid lubricant particles are dispersed in the matrix phase, and the matrix phase has a particle size of 10 μm or less. of fine carbide precipitates, a fine carbide precipitate phase having a Vickers hardness of 550 HV or more, hard particles having a Vickers hardness of 650 to 1200 HV are dispersed in an area ratio of 20 to 40%, It has a structure in which solid phase lubricant particles are dispersed by an area ratio of 0 to 5%, a diffusion phase is formed by an area ratio of more than 0% and 5% or less, and solid lubricant particles are dispersed by an area ratio of 0 to 5%. , The base part containing the base phase, the diffusion phase, the hard particles and the solid lubricant particles, in mass %, C: 0.5 to 2.0%, Si: 0.5 to 2.0%, Mn: 5% or less, Cr: 2 to 15 %, Mo: 5-20%, Co: 2-30%. As a result, the wear resistance of the valve seat is improved even in severe wear environments.
　また、特許文献２には、鉄基焼結合金製バルブシートが記載されている。特許文献２に記載されたバルブシートは、バルブ着座側部とヘッド着座側部とが一体で焼結された二層構造を有するバルブシートである。バルブ着座側部は、体積率で10～25％の気孔率と6.1～7.1g/cm3の焼結後密度とを有し、基地相中に硬質粒子を分散させ、硬質粒子が、C、Cr、Mo、Co、Si、Ni、S、Feのうちから選ばれた１種または２種以上の元素からなる粒子であり、面積率で5～40％分散し、基地相と硬質粒子を含む基地部の組成が、質量％で、Ni：2.0～23.0％、Cr：0.4～15.0％、Mo：3.0～15.0％、Cu：0.2～3.0％、Co：3.0～15.0％、V：0.1～0.5％、Mn：0.1～0.5％、W：0.2～6.0％、C：0.8～2.0％、Si：0.1～1.0％、S：0.1～1.0％のうちから選ばれた１種または２種以上を合計で10.0～40.0％含有し、残部Feおよび不可避的不純物からなる組成を有する鉄基焼結合金材からなるとしている。なお、特許文献２には、上記した硬質粒子として、Cr－Mo－Co系金属間化合物粒子、Ni－Cr－Mo－Co系金属間化合物粒子、Fe－Mo合金粒子、Fe－Ni－Mo－S系合金粒子、Fe－Mo－Si系合金粒子が例示されている。 Further, Patent Literature 2 describes a valve seat made of an iron-based sintered alloy. The valve seat described in Patent Document 2 is a valve seat having a two-layer structure in which a valve seating side portion and a head seating side portion are integrally sintered. The valve seat side has a porosity of 10-25% by volume and a density after sintering of 6.1-7.1 g/cm 3 , with hard particles dispersed in the matrix phase, the hard particles comprising C, Particles composed of one or more elements selected from Cr, Mo, Co, Si, Ni, S, and Fe, dispersed in an area ratio of 5 to 40%, and containing a matrix phase and hard particles The composition of the base is, in mass %, Ni: 2.0-23.0%, Cr: 0.4-15.0%, Mo: 3.0-15.0%, Cu: 0.2-3.0%, Co: 3.0-15.0%, V: 0.1-0.5 %, Mn: 0.1-0.5%, W: 0.2-6.0%, C: 0.8-2.0%, Si: 0.1-1.0%, S: 0.1-1.0% It is made of an iron-based sintered alloy material having a composition of 10.0 to 40.0% in the balance, and the balance being Fe and unavoidable impurities. In Patent Document 2, Cr—Mo—Co intermetallic compound particles, Ni—Cr—Mo—Co intermetallic compound particles, Fe—Mo alloy particles, Fe—Ni—Mo— S-based alloy particles and Fe--Mo--Si based alloy particles are exemplified.
　特許文献１、２に記載されたバルブシートでは、基地相の高温強度や靭性の向上や、耐摩耗性の向上に寄与するとして、基地相や硬質粒子に多量のCoを含有させることが好ましいとしている。しかし、近年、Coは産出国の政治的不安定さや、リチウムイオン電池などの他の分野におけるCo使用量の増加に関連して、価格が高騰したり、入手が困難になったりする恐れが強くなっている。そのため、Coの使用を制限することが要望されている。 In the valve seats described in Patent Documents 1 and 2, it is preferable to add a large amount of Co to the matrix phase and hard particles because it contributes to the improvement of the high-temperature strength and toughness of the matrix phase and the improvement of wear resistance. there is However, in recent years, there is a strong fear that the price of Co will rise and that it will become difficult to obtain Co due to political instability in producing countries and an increase in Co usage in other fields such as lithium-ion batteries. It's becoming Therefore, it is desired to limit the use of Co.
　このような要望に対し、例えば、特許文献３には、鉄基焼結合金製バルブシートが提案されている。特許文献３に記載された鉄基焼結合金製バルブシートは、基地相中に硬質粒子が分散し、全体の組成が、質量％で、Cr：5.0～20.0％、Si：0.4～2.0％、Ni：2.0～6.0％、Mo：5.0～25.0％、W：0.1～5.0％、V：0.5～5.0％、Nb：1.0％以下、C：0.5～1.5％、を含み、残部Fe及び不可避的不純物からなる組成を有する鉄基焼結合金製バルブシートである。特許文献３に記載された鉄基焼結合金製バルブシートでは、硬質粒子として、質量％で、Mo：40.0～70.0％、Si：0.4～2.0％、C：0.1％以下を含み、残部Feおよび不可避的不純物からなるFe－Mo－Si合金粒子を用いることが好ましいとしている。 In response to such a demand, Patent Document 3, for example, proposes a valve seat made of an iron-based sintered alloy. In the valve seat made of an iron-based sintered alloy described in Patent Document 3, hard particles are dispersed in the matrix phase, and the overall composition, in mass%, is Cr: 5.0 to 20.0%, Si: 0.4 to 2.0%, Ni: 2.0 to 6.0%, Mo: 5.0 to 25.0%, W: 0.1 to 5.0%, V: 0.5 to 5.0%, Nb: 1.0% or less, C: 0.5 to 1.5%, balance Fe and unavoidable impurities An iron-based sintered alloy valve seat having a composition consisting of In the iron-based sintered alloy valve seat described in Patent Document 3, the hard particles include Mo: 40.0 to 70.0%, Si: 0.4 to 2.0%, C: 0.1% or less, and the balance is Fe and It is said that it is preferable to use Fe--Mo--Si alloy particles containing unavoidable impurities.
　また、特許文献４には、硬質粒子分散型鉄基焼結合金が提案されている。特許文献４に記載された硬質粒子分散型鉄基焼結合金は、重量百分率で、Si：0.4～2％、Ni：2～12％、Mo：3～12％、Cr：0.5～5％、V：0.6～4％、Nb：0.1～3％、C：0.5～2％、および残部Feを含む基地中に、合金全体を基準として3～20％の硬質粒子が分散されて焼結され、硬質粒子はMo：60～70％、B：0.3～1％、C：0.1％以下を含み、残部Feを含む硬質粒子分散型鉄基焼結合金である。フェロモリブデン系硬質粒子にBを添加すると、Bは、フェロモリブデンの濡れ性を向上し、硬質粒子の基地からの脱落を防止し、基地と硬質粒子との密着性が向上し、焼結合金の熱的強度、機械的強度を向上できるとしている。 In addition, Patent Document 4 proposes a hard particle dispersed iron-based sintered alloy. The hard particle-dispersed iron-based sintered alloy described in Patent Document 4 has, in weight percentage, Si: 0.4 to 2%, Ni: 2 to 12%, Mo: 3 to 12%, Cr: 0.5 to 5%, Hard particles of 3-20% based on the whole alloy are dispersed in a matrix containing V: 0.6-4%, Nb: 0.1-3%, C: 0.5-2%, and the balance Fe, and sintered, The hard particles are a hard particle dispersed iron-based sintered alloy containing Mo: 60-70%, B: 0.3-1%, C: 0.1% or less, and the balance being Fe. When B is added to ferromolybdenum-based hard particles, B improves the wettability of ferromolybdenum, prevents the hard particles from falling off from the matrix, improves the adhesion between the matrix and hard particles, and improves the properties of the sintered alloy. It is said that the thermal strength and mechanical strength can be improved.
特開2018－90900号公報Japanese Patent Application Laid-Open No. 2018-90900 特開2004－232088号公報Japanese Patent Application Laid-Open No. 2004-232088 特開2015－178650号公報Japanese Patent Application Laid-Open No. 2015-178650 特開2005－325436号公報Japanese Patent Application Laid-Open No. 2005-325436
　しかしながら、特許文献３、４に記載された技術では、分散させたCoを含有しない鉄基硬質粒子が、従来のCo基硬質粒子より割れ、欠けを生じやすく、基地相から硬質粒子が脱落し、とくに、近年の厳しいバルブシート使用環境下では、所望の耐摩耗性を確保できないという問題があることを知見した。また、常用のCoを含有しないNi基硬質粒子を分散させた場合には、硬さが低く、凝着が発生しやすいという問題があった。Coは、硬質粒子に含有される場合は基地への拡散、基地に含まれる場合は、基地の焼結の進行を促進させる等の効果に寄与し、バルブシートの強度向上に大きな役割を果たしているが、特許文献３、４に記載された技術では、Coを含有しないことにより硬質粒子から基地への合金元素の拡散や、基地の焼結を促進させる効果が乏しく、バルブシートとして十分な強度が得られないためであると考えた。 However, in the techniques described in Patent Documents 3 and 4, the dispersed iron-based hard particles containing no Co are more likely to crack and chip than conventional Co-based hard particles, and the hard particles fall off from the matrix phase. In particular, it has been found that the desired wear resistance cannot be ensured under the severe environment in which the valve seat is used in recent years. Moreover, when Ni-based hard particles not containing Co, which are commonly used, are dispersed, there is a problem that the hardness is low and adhesion is likely to occur. When Co is contained in hard particles, it diffuses into the matrix, and when contained in the matrix, Co contributes to effects such as promoting the progress of sintering of the matrix, and plays a major role in improving the strength of the valve seat. However, in the techniques described in Patent Documents 3 and 4, the diffusion of alloying elements from the hard particles to the matrix and the effect of promoting sintering of the matrix are poor due to the absence of Co, and sufficient strength as a valve seat is not obtained. I thought it was because I couldn't get it.
　本発明は、かかる従来技術の問題に鑑み、Coを含有しない焼結体組成を有し、耐摩耗性に優れ、かつバルブシートとして十分な強度を有する内燃機関用鉄基焼結合金製バルブシートを提供することを目的とする。なお、ここでいう「耐摩耗性に優れた」とは、従来のCo含有焼結体組成の鉄基焼結合金製バルブシートに比べて、耐摩耗性が向上した場合をいうものとする。なお、ここでいう「バルブシートとして十分な強度」とは、圧入時等に亀裂、割れが発生しない強度をいい、JIS Z 2507の規定に準拠して求めた圧環強さを基に判断できる。 In view of the problems of the prior art, the present invention provides an iron-based sintered alloy valve seat for an internal combustion engine that has a sintered body composition that does not contain Co, has excellent wear resistance, and has sufficient strength as a valve seat. intended to provide Here, the term "excellent in wear resistance" means that the wear resistance is improved as compared with the conventional iron-based sintered alloy valve seat having a Co-containing sintered body composition. The "sufficient strength as a valve seat" here refers to the strength that does not cause cracks or cracks during press fitting, etc., and can be determined based on radial crushing strength obtained in accordance with JIS Z 2507.
　本発明者らは、上記した目的を達成するため、まず、Coを含有しない組成の硬質粒子およびCoを含有しない組成の基地相の耐摩耗性に対する影響について、鋭意検討した。その結果、Coを含有しない組成の硬質粒子でも硬質粒子の割れ、欠けの発生を回避して、硬さを確保し、かつ硬質粒子および基地の凝着を回避することにより、耐摩耗性の低下を防止でき、従来のCo基硬質粒子を用いたと同等かそれ以上の耐摩耗性を確保できることを新規に知見した。 In order to achieve the above-mentioned objectives, the present inventors first thoroughly studied the influence of the Co-free composition of the hard particles and the Co-free composition of the matrix phase on the wear resistance. As a result, even if the hard particles have a composition that does not contain Co, cracking and chipping of the hard particles are avoided, the hardness is secured, and adhesion of the hard particles and the matrix is avoided, resulting in a decrease in wear resistance. It was newly found that the wear resistance can be prevented and the wear resistance equivalent to or higher than that using the conventional Co-based hard particles can be secured.
　そして、更なる検討の結果、硬質粒子としては、質量％で、1.5～3.5％Si－7.0～9.0％Cr－35.0～45.0％Mo－5.0～20.0％Niを含み残部Feおよび不可避的不純物からなる組成のSi－Cr－Ni－Fe系Mo基金属間化合物粒子とすることが好ましい、ことを見出した。 As a result of further investigation, the hard particles consist of 1.5 to 3.5% Si-7.0 to 9.0% Cr-35.0 to 45.0% Mo-5.0 to 20.0% Ni, with the balance being Fe and unavoidable impurities. It was found that it is preferable to use Si--Cr--Ni--Fe-based Mo-based intermetallic compound particles of the composition.
　まず、本発明の基礎となった実験結果について、説明する。
　基地相形成用の鉄基粉末と、硬質粒子粉末と、合金元素粉末と、固体潤滑剤粉末と、を表１に示す配合量となるように調整し、混合して、混合粉とした。使用した基地相形成用鉄基粉末は、表２に示す組成の鉄基粉末No.a、No.bとした。また、使用した硬質粒子粉末は、表３に示す組成の硬質粒子粉末No.MA、No.MDとした。硬質粒子粉末No.MAは、常用のCo基金属間化合物粒子粉であり、硬質粒子粉末No.MDは、Coを含有しないMo基金属間化合物粒子粉である。各粒子粉のビッカース硬さHVを表３に併記した。なお、固体潤滑剤粒子粉末はMnS粒子粉末を用いた。また、混合粉には、潤滑剤として、混合粉100質量部に対し、ステアリン酸亜鉛を0.75質量部配合した。 First, the experimental results that form the basis of the present invention will be described.
The iron-based powder for forming the base phase, the hard particle powder, the alloying element powder, and the solid lubricant powder were adjusted to the compounding amounts shown in Table 1 and mixed to obtain a mixed powder. Iron-based powders No.a and No.b having compositions shown in Table 2 were used as the iron-based powders for forming the matrix phase. Hard particle powders No. MA and No. MD having compositions shown in Table 3 were used as the hard particle powders. Hard particle powder No. MA is a commonly used Co-based intermetallic compound particle powder, and hard particle powder No. MD is a Co-free Mo-based intermetallic compound particle powder. Table 3 also shows the Vickers hardness HV of each particle powder. MnS particle powder was used as the solid lubricant particle powder. In addition, 0.75 parts by mass of zinc stearate was blended in the mixed powder as a lubricant with respect to 100 parts by mass of the mixed powder.
　得られた混合粉を、ついで、金型に充填し、粉末成形機で所定のバルブシート形状の圧粉体とし、さらに脱ワックス工程を経て、還元雰囲気中で、1100℃～1200℃×0.5hrの焼結処理を施し、焼結体とした。得られた焼結体に、さらに切削、研磨等の加工を施して、所定寸法形状（外径：32.1mmφ×内径：26.1mmφ×厚さ5.5mm）の鉄基焼結合金製バルブシートとした。 The mixed powder thus obtained is then filled into a mold, formed into a powder compact having a predetermined valve seat shape by a powder molding machine, and further subjected to a dewaxing process, and then subjected to a reducing atmosphere at 1100°C to 1200°C for 0.5hr. was sintered to obtain a sintered body. The obtained sintered body was further processed by cutting, polishing, etc. to obtain an iron-based sintered alloy valve seat with a predetermined size and shape (outer diameter: 32.1 mmφ x inner diameter: 26.1 mmφ x thickness 5.5 mm). .
　得られたバルブシート（焼結体）について、硬質粒子割れ耐性試験、摩耗試験を実施した。試験方法は次の通りとした。
（１）硬質粒子割れ耐性試験
　得られたバルブシート（焼結体）について、断面を研磨し、ビッカース硬さ計（試験力：0.98N）を用いて基地相中に分散した硬質粒子（各20個）内に収まるように圧痕を付与し、圧痕を付与した各粒子における割れ発生の有無を光学顕微鏡で観察した。圧痕から外に亀裂が発生している場合を割れが発生したと判断し、割れが発生した粒子数（割れ発生個数）を調査した。バルブシートNo.S1の割れ発生個数を基準（＝1.0）として、基準に対する当該バルブシートの硬質粒子の割れ発生個数比（割れ発生比）を算出した。
（２）摩耗試験
　得られたバルブシートについて、図１に示すリグ試験機を用いて、下記に示す試験条件で、摩耗試験を実施した。
　試験温度：200℃（シートフェース）、
　試験時間：8hr、
　カム回転数：3000rpm、
　バルブ回転数：10rpm、
　衝撃荷重(スプリング荷重)：780N、
　バルブ材質：NCF751相当材、
　リフト量：6mm
　試験後、試験片（バルブシート）の摩耗量を測定した。得られた摩耗量から、バルブシートNo.S1を基準（＝1.00）として、当該バルブシートの摩耗比を算出した。
（３）圧環強さ試験
　得られたバルブシート（機能部材側層のみ）について、JIS Z 2507の規定に準拠して、圧環強さを求めた。 A hard particle cracking resistance test and an abrasion test were carried out on the obtained valve seat (sintered body). The test method was as follows.
(1) Hard particle crack resistance test The cross section of the obtained valve seat (sintered body) was polished, and a Vickers hardness tester (test force: 0.98 N) was used to measure hard particles (20 An indentation was given so as to fit within a 10 mm), and the presence or absence of cracking in each particle to which the indentation was given was observed with an optical microscope. Cracking was determined to occur when cracks were generated outside the indentation, and the number of cracked particles (number of cracks) was investigated. Using the number of cracks generated in valve seat No. S1 as a reference (=1.0), the ratio of the number of cracks generated in the hard particles of the valve seat to the reference (crack generation ratio) was calculated.
(2) Abrasion test The obtained valve seat was subjected to an abrasion test using the rig tester shown in Fig. 1 under the test conditions shown below.
Test temperature: 200°C (seat face),
Exam time: 8hr,
Cam speed: 3000rpm,
Valve speed: 10rpm,
Impact load (spring load): 780N,
Valve material: NCF751 equivalent material,
Lift amount: 6mm
After the test, the wear amount of the test piece (valve seat) was measured. Using the valve seat No. S1 as a reference (=1.00), the wear ratio of the valve seat was calculated from the obtained wear amount.
(3) Radial crushing strength test The radial crushing strength of the obtained valve seat (only the functional member side layer) was determined according to JIS Z 2507 regulations.
　得られた結果を表４に示す。 Table 4 shows the results obtained.

Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　Coを含有しない組成のMo基金属間化合物粒子粉である硬質粒子粉末No.MDを用いたバルブシート（No.S4）であれば、硬質粒子の割れ等の発生もなく、Co基金属間化合物粒子を硬質粒子として使用した場合（バルブシートNo.S1）と同等以上の耐摩耗性を有するバルブシートを得ることができる。すなわち、Coを含有しない組成のSi－Cr－Ni－Fe系Mo基金属間化合物粒子を硬質粒子として基地相中に分散させることにより、耐摩耗性の低下を防止できるという知見を得た。 If the valve seat (No.S4) uses the hard particle powder No.MD, which is a Mo-based intermetallic compound powder with a composition that does not contain Co, there is no cracking of the hard particles, and the Co-based intermetallic compound It is possible to obtain a valve seat having wear resistance equal to or higher than that obtained when the particles are used as hard particles (valve seat No. S1). That is, the present inventors have found that deterioration of wear resistance can be prevented by dispersing Si--Cr--Ni--Fe based Mo-based intermetallic compound particles having a composition that does not contain Co as hard particles in the matrix phase.
　また、本発明者らは、更なる耐摩耗性の向上には、上記した組成の硬質粒子を分散させることに加えて、基地相において、微細炭化物析出相の割合を増加させることにより、耐摩耗性を向上させることができることを知見した。 Further, the present inventors have found that, in order to further improve wear resistance, in addition to dispersing hard particles having the composition described above, the proportion of fine carbide precipitates in the matrix phase is increased to improve wear resistance. It was found that the performance can be improved.
　本発明は、かかる知見に基づき、さらに検討を加えて完成したものである。すなわち、本発明の要旨はつぎのとおりである。
［１］内燃機関のシリンダーヘッドに圧入されるバルブシートであって、
該バルブシートが機能部材側層と支持部材側層とが一体で焼結された二層構造を有し、
前記機能部材側層が、基地相と、該基地相中に面積率で10～40％の硬質粒子とさらに面積率で0～5％の固体潤滑剤粒子を分散させてなる組織を有し、前記硬質粒子が、ビッカース硬さで700～1300HVの硬さを有し、質量％で、Si：1.5～3.5％、Cr：7.0～9.0％、Mo：35.0～45.0％、Ni：5.0～20.0％を含み残部Feおよび不可避的不純物からなる組成を有するSi－Cr－Ni－Fe系Mo基金属間化合物粒子であり、さらに前記基地相、前記硬質粒子および前記固体潤滑剤粒子を含む基地部が、質量％で、C：0.5～2.0％、Si：0.2～2.0％、Mn：5％以下、Cr：0.5～15％、Mo：3～20％、Ni：1～10％、を含み、さらに、V：0～5％、W：0～10％、S：0～2％、Cu：0～5％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有する鉄基焼結合金材からなり、
前記支持部材側層が、基地相と、該基地相中に面積率で0～5％の固体潤滑剤粒子および面積率で0～5％の硬度改善粒子を分散させてなる組織と、さらに前記基地相、前記固体潤滑剤粒子および前記硬度改善粒子を含む基地部が、質量％で、C：0.3～1.3％を含み、さらに、Ni：0～2.0％、Mo：0～2.0％、Cu：0～5.0％、Cr：0～5.0％、Mn：0～5.0％、S：0～2.0％を含有し、残部Feおよび不可避的不純物からなる組成と、を有する鉄基焼結合金材からなり、
前記バルブシートの密度が6.70～7.20g/cm3であることを特徴とする内燃機関用鉄基焼結合金製バルブシート。
［２］内燃機関のシリンダーヘッドに圧入されるバルブシートであって、
該バルブシートが機能部材側層からなる単層構造を有し、
前記機能部材側層が、基地相と、該基地相中に面積率で10～40％の硬質粒子とさらに面積率で0～5％の固体潤滑剤粒子を分散させてなる組織を有し、前記硬質粒子が、ビッカース硬さで700～1300HVの硬さを有し、質量％で、Si：1.5～3.5％、Cr：7.0～9.0％、Mo：35.0～45.0％、Ni：5.0～20.0％を含み残部Feおよび不可避的不純物からなる組成を有するSi－Cr－Ni－Fe系Mo基金属間化合物粒子であり、さらに前記基地相、前記硬質粒子および前記固体潤滑剤粒子を含む基地部が、質量％で、C：0.5～2.0％、Si：0.2～2.0％、Mn：5％以下、Cr：0.5～15％、Mo：3～20％、Ni：1～10％、を含み、さらに、V：0～5％、W：0～10％、S：0～2％、Cu：0～5％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有する鉄基焼結合金材からなり、
前記バルブシートの密度が6.70～7.20g/cm3であることを特徴とする内燃機関用鉄基焼結合金製バルブシート。
[３]前記機能部材側層の前記基地相が、前記硬質粒子および前記固体潤滑剤粒子を除く基地相面積を100％とする面積率で、10～90％の微細炭化物析出相と0～30％の高合金相と残部がパーライトからなる組織を有することを特徴とする［１］または［２］に記載の内燃機関用鉄基焼結合金製バルブシート。
［４］前記機能部材側層の前記基地相が、前記硬質粒子および前記固体潤滑剤粒子を除く基地相面積を100％とする面積率で、0～15％の高合金相と残部が微細炭化物析出相からなる組織を有することを特徴とする［１］または［２］に記載の内燃機関用鉄基焼結合金製バルブシート。
［５］前記機能部材側層の前記基地相が、前記硬質粒子および前記固体潤滑剤粒子を除く基地相面積を100％とする面積率で、0～25％の高合金相と残部がベイナイト相からなる組織を有することを特徴とする［１］または［２］に記載の内燃機関用鉄基焼結合金製バルブシート。
［６］前記機能部材側層の前記基地相が、前記硬質粒子および前記固体潤滑剤粒子を除く基地相面積を100％とする面積率で、0～30％の高合金相と残部がパーライトからなる組織を有することを特徴とする［１］または［２］に記載の内燃機関用鉄基焼結合金製バルブシート。
［７］前記微細炭化物析出相は、粒径10μm以下の微細炭化物が析出し、ビッカース硬さで400～600HVの硬さを有する相であることを特徴とする［３］または［４］に記載の内燃機関用鉄基焼結合金製バルブシート。
［８］前記固体潤滑剤粒子が、硫化マンガンMnS、二硫化モリブデンMoS2のうちから選ばれた１種または２種であることを特徴とする［１］ないし［７］のいずれかに記載の鉄基焼結合金製バルブシート。
［９］前記硬度改善粒子が、鉄―モリブデン合金粒子であることを特徴とする［１］に記載の鉄基焼結合金製バルブシート。 The present invention has been completed based on these findings and further studies. That is, the gist of the present invention is as follows.
[1] A valve seat press-fitted into a cylinder head of an internal combustion engine,
The valve seat has a two-layer structure in which the functional member side layer and the support member side layer are integrally sintered,
The functional member-side layer has a base phase, and a structure in which hard particles with an area ratio of 10 to 40% and solid lubricant particles with an area ratio of 0 to 5% are dispersed in the base phase, The hard particles have a Vickers hardness of 700 to 1300 HV, and the mass % is Si: 1.5 to 3.5%, Cr: 7.0 to 9.0%, Mo: 35.0 to 45.0%, Ni: 5.0 to 20.0%. Si—Cr—Ni—Fe-based Mo-based intermetallic compound particles having a composition containing Fe and inevitable impurities, and a base portion containing the base phase, the hard particles, and the solid lubricant particles, In mass%, C: 0.5-2.0%, Si: 0.2-2.0%, Mn: 5% or less, Cr: 0.5-15%, Mo: 3-20%, Ni: 1-10%, and further, Iron-based sintered alloy material containing V: 0-5%, W: 0-10%, S: 0-2%, Cu: 0-5%, with the balance being Fe and unavoidable impurities consists of
The support member side layer comprises a matrix phase, a structure in which solid lubricant particles with an area ratio of 0 to 5% and hardness improving particles with an area ratio of 0 to 5% are dispersed in the matrix phase, and The base portion containing the base phase, the solid lubricant particles and the hardness improving particles contains, in % by mass, C: 0.3 to 1.3%, Ni: 0 to 2.0%, Mo: 0 to 2.0%, and Cu: 0-5.0%, Cr: 0-5.0%, Mn: 0-5.0%, S: 0-2.0%, and the balance consisting of Fe and unavoidable impurities. ,
A valve seat made of an iron-based sintered alloy for an internal combustion engine, wherein the valve seat has a density of 6.70 to 7.20 g/cm 3 .
[2] A valve seat press-fitted into a cylinder head of an internal combustion engine,
The valve seat has a single layer structure consisting of a functional member side layer,
The functional member-side layer has a base phase, and a structure in which hard particles with an area ratio of 10 to 40% and solid lubricant particles with an area ratio of 0 to 5% are dispersed in the base phase, The hard particles have a Vickers hardness of 700 to 1300 HV, and the mass % is Si: 1.5 to 3.5%, Cr: 7.0 to 9.0%, Mo: 35.0 to 45.0%, Ni: 5.0 to 20.0%. Si—Cr—Ni—Fe-based Mo-based intermetallic compound particles having a composition containing Fe and inevitable impurities, and a base portion containing the base phase, the hard particles, and the solid lubricant particles, In mass%, C: 0.5-2.0%, Si: 0.2-2.0%, Mn: 5% or less, Cr: 0.5-15%, Mo: 3-20%, Ni: 1-10%, and further, Iron-based sintered alloy material containing V: 0-5%, W: 0-10%, S: 0-2%, Cu: 0-5%, with the balance being Fe and unavoidable impurities consists of
A valve seat made of an iron-based sintered alloy for an internal combustion engine, wherein the valve seat has a density of 6.70 to 7.20 g/cm 3 .
[3] The matrix phase of the functional member-side layer comprises 10 to 90% fine carbide precipitate phase and 0 to 30% in area ratio, where the area of the matrix phase excluding the hard particles and the solid lubricant particles is 100%. % of the high alloy phase and the balance of pearlite.
[4] The base phase of the functional member side layer has a high alloy phase of 0 to 15% and the balance is fine carbide, with an area ratio of 100% for the base phase area excluding the hard particles and the solid lubricant particles. A valve seat made of an iron-based sintered alloy for an internal combustion engine according to [1] or [2], characterized by having a structure composed of a precipitate phase.
[5] The base phase of the functional member-side layer has a high alloy phase of 0 to 25% and a bainite phase as the balance, with an area ratio of 100% for the base phase area excluding the hard particles and the solid lubricant particles. The valve seat made of an iron-based sintered alloy for an internal combustion engine according to [1] or [2], characterized by having a structure consisting of:
[6] The base phase of the functional member side layer has an area ratio of 0 to 30% with the base phase area excluding the hard particles and the solid lubricant particles being 100%, and the balance is pearlite. The valve seat made of an iron-based sintered alloy for an internal combustion engine according to [1] or [2], characterized by having a structure of
[7] The fine carbide precipitation phase is a phase in which fine carbides with a grain size of 10 μm or less are precipitated and have a Vickers hardness of 400 to 600 HV. valve seats made of iron-based sintered alloy for internal combustion engines.
[8] The solid lubricant particles according to any one of [1] to [7], wherein the solid lubricant particles are one or two selected from manganese sulfide MnS and molybdenum disulfide MoS2. Valve seat made of iron-based sintered alloy.
[9] The valve seat made of an iron-based sintered alloy according to [1], wherein the hardness improving particles are iron-molybdenum alloy particles.
　本発明によれば、厳しい摩耗環境下においても、硬質粒子の割れ、欠けの発生が少なく、また、凝着の発生もなく、優れた耐摩耗性を有するバルブシートを得ることができ、産業上格段の効果を奏する。 According to the present invention, it is possible to obtain a valve seat having excellent wear resistance, with little cracking and chipping of hard particles and no adhesion even in a severe wear environment. It has a remarkable effect.
リグ試験機の概要を示す説明図である。It is an explanatory view showing an outline of a rig testing machine.
　本発明のバルブシートは、鉄基焼結合金製で、バルブが着座する機能部材側層とシリンダーヘッドに着座し機能部材側層を支える支持部材側層とが一体で焼結された二層構造を有するか、あるいは機能部材側層のみの単層構造を有する。 The valve seat of the present invention is made of an iron-based sintered alloy, and has a two-layer structure in which the functional member side layer on which the valve is seated and the support member side layer that is seated on the cylinder head and supports the functional member side layer are integrally sintered. or has a single layer structure with only the functional member side layer.
　本発明バルブシートの機能部材側層を構成する鉄基焼結合金材は、基地相中に硬質粒子、あるいは更に固体潤滑剤粒子を分散させた組織を有し、耐摩耗性に優れた特性を有する。なお、ここでいう「耐摩耗性に優れた」とは、従来のCo含有焼結体組成の鉄基焼結合金材に比べて、同等またはそれ以上に、耐摩耗性が向上した場合をいうものとする。 The iron-based sintered alloy material constituting the functional member side layer of the valve seat of the present invention has a structure in which hard particles or solid lubricant particles are dispersed in the matrix phase, and has excellent wear resistance properties. have. Here, "excellent wear resistance" means that the wear resistance is improved to the same level or more than that of the iron-based sintered alloy material with the conventional Co-containing sintered body composition. shall be
　本発明バルブシートの機能部材側層で、基地相中に分散させる硬質粒子は、ビッカース硬さで700～1300HVの硬さを有するSi－Cr－Ni－Fe系Mo基金属間化合物粒子とする。 In the functional member side layer of the valve seat of the present invention, the hard particles dispersed in the base phase are Si-Cr-Ni-Fe based Mo-based intermetallic compound particles having a Vickers hardness of 700 to 1300 HV.
　硬質粒子の硬さが、700HV未満では、硬質粒子自体に凝着が発生し、耐摩耗性の向上効果が少なく、また1300HVを超えて高くなると、硬質粒子の靭性低下および被削性の低下を招く。このようなことから、基地相中に分散させる硬質粒子の硬さをビッカース硬さで700～1300HVの範囲に限定した。 If the hardness of the hard particles is less than 700HV, adhesion occurs in the hard particles themselves, and the effect of improving wear resistance is small. Invite. For this reason, the hardness of the hard particles dispersed in the matrix phase is limited to the range of 700 to 1300 HV in terms of Vickers hardness.
　なお、本発明で基地相中に分散させる硬質粒子は、上記硬さを有し、平均粒径：10～150μmの粒子とすることが好ましい。平均粒径が10μm未満では、焼結時に拡散しやすく、一方、150μmを超えて大きくなると、基地との結合力が低下し、耐摩耗性が低下する。このため、基地相中に分散させる硬質粒子の平均粒径は10～150μmの範囲に限定することが好ましい。なお、ここでいう「平均粒径」は、レーザ散乱法で測定した累積分布が50％となる粒径D50を意味する。 It should be noted that the hard particles dispersed in the matrix phase in the present invention preferably have the hardness described above and an average particle size of 10 to 150 μm. If the average particle size is less than 10 µm, it tends to diffuse during sintering. Therefore, it is preferable to limit the average particle diameter of the hard particles dispersed in the matrix phase to the range of 10 to 150 μm. The term "average particle size" as used herein means the particle size D50 at which the cumulative distribution measured by the laser scattering method is 50%.
　また、本発明では、上記した硬さの硬質粒子を基地相中に面積率で10～40％分散させる。硬質粒子の分散量が10％未満では、所望の耐摩耗性を確保できない。一方、40％を超えると、基地相との結合力が低下し、耐摩耗性が低下する。このため、基地相中に分散させる硬質粒子の分散量は基地相全体に対する面積率で10～40％の範囲に限定した。 In addition, in the present invention, the hard particles having the hardness described above are dispersed in the base phase at an area ratio of 10 to 40%. If the amount of dispersed hard particles is less than 10%, the desired wear resistance cannot be ensured. On the other hand, when it exceeds 40%, the bonding strength with the matrix phase is lowered, and the wear resistance is lowered. For this reason, the amount of hard particles dispersed in the matrix phase is limited to a range of 10 to 40% in area ratio with respect to the entire matrix phase.
　そして、本発明で、基地相中に分散させるSi－Cr－Ni－Fe系Mo基金属間化合物粒子は、質量％で、Si：1.5～3.5％、Cr：7.0～9.0％、Mo：35.0～45.0％、Ni：5.0～20.0％を含み、残部Feおよび不可避的不純物からなる組成（硬質粒子組成）を有するMo基金属間化合物粒子とする。 In the present invention, the Si—Cr—Ni—Fe-based Mo-based intermetallic compound particles dispersed in the matrix phase are, in mass %, Si: 1.5 to 3.5%, Cr: 7.0 to 9.0%, Mo: 35.0 to Mo-based intermetallic compound particles having a composition (hard particle composition) containing 45.0% Ni, 5.0 to 20.0% Ni, and the balance Fe and unavoidable impurities.
　上記した硬質粒子組成の硬質粒子とすることにより、焼結後、金属間化合物が析出した組織の硬質粒子を含むバルブシートを得ることができる。また、ビッカース硬さで700HV以上の硬さを有し、割れ、欠け等の発生が抑制され、硬質粒子割れ耐性が高い金属間化合物を析出させた硬質粒子とするためには、Mo含有量を35.0～45.0％と高く維持することが重要である。また、さらに靭性を有し、所望の硬さを維持する硬質粒子とするためには、Ni含有量を5.0～20.0％の範囲とすることが重要となる。 By using hard particles having the hard particle composition described above, it is possible to obtain a valve seat containing hard particles having a structure in which an intermetallic compound is precipitated after sintering. In addition, in order to obtain hard particles that have a Vickers hardness of 700 HV or more, suppress the occurrence of cracks and chips, and have high hard particle crack resistance by precipitating intermetallic compounds, the Mo content must be It is important to keep it as high as 35.0-45.0%. Further, in order to obtain hard particles that have toughness and maintain desired hardness, it is important to set the Ni content within the range of 5.0 to 20.0%.
　また、本発明バルブシートの機能部材側層では、さらに基地相中に固体潤滑剤粒子を分散させてもよい。基地相中に固体潤滑剤粒子を分散させることにより、被削性、潤滑性が向上する。しかし、面積率で5％を超えて分散させると、機械的特性の低下が著しくなる。このため、固体潤滑剤粒子は面積率で0～5％の範囲に限定した。なお、固体潤滑剤粒子は、硫化マンガンMnS、二硫化モリブデンMoS2のうちから選ばれた１種または２種とすることが好ましい。 Further, in the functional member side layer of the valve seat of the present invention, solid lubricant particles may be further dispersed in the base phase. Machinability and lubricity are improved by dispersing solid lubricant particles in the matrix phase. However, if the area ratio exceeds 5%, the mechanical properties are significantly lowered. For this reason, the area ratio of the solid lubricant particles is limited to the range of 0 to 5%. The solid lubricant particles are preferably one or two selected from manganese sulfide MnS and molybdenum disulfide MoS 2 .
　本発明バルブシートの機能部材側層の基地相は、硬質粒子、固体潤滑剤粒子を除く基地相面積を100％とする面積率で、10～90％、より好ましくは10～85％の微細炭化物析出相と、0～30％の高合金相と残部がパーライトからなる組織を有するか、あるいは0～15％の高合金相と残部が微細炭化物析出相からなる組織を有するか、あるいは0～25％の高合金相と残部がベイナイト相からなる組織を有することが好ましい。微細炭化物析出相は、粒径10μm以下の微細炭化物が析出し、ビッカース硬さで400～600HVの硬さを有する硬質な相とする。このような硬質の微細炭化物析出相の存在により、基地が強化でき、耐摩耗性がより向上する。なお、本発明バルブシートの機能部材側層では、硬質粒子、固体潤滑剤粒子を除く基地相を、0～30％の高合金相と残部がパーライトからなる組織としてもよい。このような組織の基地相でも、Coを含有しない組成の焼結体であれば、Coを含有する組成の焼結体に比べて同一硬さレベルで比較して耐摩耗性は向上する。 The base phase of the functional member side layer of the valve seat of the present invention is fine carbide having an area ratio of 10 to 90%, more preferably 10 to 85%, when the area of the base phase excluding hard particles and solid lubricant particles is 100%. Precipitate phase, 0-30% high alloy phase and balance pearlite structure, or 0-15% high alloy phase and balance fine carbide precipitate phase, or 0-25 % high alloy phase and the balance bainite phase. The fine carbide precipitation phase is a hard phase in which fine carbides having a grain size of 10 μm or less are precipitated and have a Vickers hardness of 400 to 600 HV. The presence of such a hard fine carbide precipitate phase can strengthen the matrix and further improve the wear resistance. In addition, in the functional member side layer of the valve seat of the present invention, the matrix phase excluding the hard particles and the solid lubricant particles may be composed of 0 to 30% of the high alloy phase and the balance of pearlite. Even if the matrix phase has such a structure, if the sintered body has a composition that does not contain Co, the abrasion resistance is improved compared to the sintered body that has a composition that contains Co at the same hardness level.
　なお、高合金相は、焼結時に硬質粒子から合金元素が拡散し合金量が高くなった領域であり、硬質粒子の脱落を防止する作用を有する。機能部材側層では、硬質粒子、固体潤滑剤粒子を除く基地相面積を100％としたときの面積率で、30％まで高合金相を許容できる。 The high-alloy phase is a region in which alloy elements diffuse from the hard particles during sintering and the alloy content increases, and has the effect of preventing the hard particles from falling off. In the functional member side layer, a high alloy phase can be allowed up to 30% in area ratio when the base phase area excluding hard particles and solid lubricant particles is 100%.
　このように、本発明バルブシートの機能部材側層は、上記した組織の基地相中に、上記した組成、組織、硬さの硬質粒子、上記した組成の固体潤滑剤粒子を所定量分散させた組織を有する。 Thus, in the functional member side layer of the valve seat of the present invention, a predetermined amount of hard particles having the composition, structure, and hardness described above and solid lubricant particles having the composition described above are dispersed in the base phase of the structure described above. have an organization;
　そして、本発明バルブシートの機能部材側層では、基地相、硬質粒子および固体潤滑剤粒子を含む基地部は、質量％で、C：0.5～2.0％、Si：0.2～2.0％、Mn：5％以下、Cr：0.5～15％、Mo：3～20％、Ni：1～10％、を含み、さらに、V：0～5％、W：0～10％、S：0～2％、Cu：0～5％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有する。 In addition, in the functional member side layer of the valve seat of the present invention, the base phase, the base portion containing the hard particles and the solid lubricant particles, in mass %, C: 0.5 to 2.0%, Si: 0.2 to 2.0%, Mn: 5 % or less, Cr: 0.5-15%, Mo: 3-20%, Ni: 1-10%, V: 0-5%, W: 0-10%, S: 0-2%, It has a matrix composition containing 0 to 5% of Cu, with the balance being Fe and unavoidable impurities.
　つぎに、機能部材側層の基地部組成における限定理由について説明する。なお、以下、組成における質量％は、単に％で記す。 Next, the reasons for limiting the composition of the base portion of the functional member side layer will be explained. In addition, hereinafter, the mass% in the composition is simply described as %.
　C：0.5～2.0％
　Cは、基地相を所定の硬さ、組織に調整するため、あるいは炭化物を形成するために必要な元素であり、0.5％以上含有させる。一方、2.0％を超えて含有すると、融点が低下し、焼結処理が液相焼結となる。液相焼結となると、析出炭化物量が多くなりすぎ、また、空孔の数が増加し、伸び特性、寸法精度が低下する。このため、Cは0.5～2.0％の範囲に限定した。なお、好ましくは0.50～2.00％、より好ましくは1.00～1.50％である。 C: 0.5-2.0%
C is an element necessary for adjusting the matrix phase to a predetermined hardness and structure, or for forming carbides, and is contained in an amount of 0.5% or more. On the other hand, when the content exceeds 2.0%, the melting point is lowered and the sintering process becomes liquid phase sintering. Liquid-phase sintering results in an excessive amount of precipitated carbides, an increased number of pores, and reduced elongation characteristics and dimensional accuracy. Therefore, C is limited to the range of 0.5-2.0%. In addition, it is preferably 0.50 to 2.00%, more preferably 1.00 to 1.50%.
　Si：0.2～2.0％
　Siは、主として硬質粒子に含まれ、金属間化合物を構成する元素で、硬質粒子の硬さを増加させるとともに、基地強度を増加させ耐摩耗性を向上させる。このためには、0.2％以上含有することが好ましい。一方、2.0％を超えて含有すると、相手攻撃性が増加する。このようなことから、Siは0.2～2.0％の範囲に限定した。なお、好ましくは0.20～2.00％である。より好ましくは0.20～1.40％である。 Si: 0.2-2.0%
Si is an element that is mainly contained in hard particles and constitutes an intermetallic compound, and increases the hardness of the hard particles, increases the strength of the matrix, and improves wear resistance. For this purpose, it is preferable to contain 0.2% or more. On the other hand, if the content exceeds 2.0%, the opponent's aggression increases. For these reasons, Si is limited to the range of 0.2 to 2.0%. Incidentally, it is preferably 0.20 to 2.00%. More preferably 0.20 to 1.40%.
　Mn：5％以下
　Mnは、基地相の硬さを増加させる元素であり、またMnは固体潤滑剤粒子に起因して基地部に含まれ、被削性向上に寄与する元素であり、0.05％以上含有することが好ましい。一方、5％を超えて含有すると基地相硬さ、靭性、延性が低下する。このため、Mnは5％以下の範囲に限定した。なお、好ましくは5.00％以下、より好ましくは0.20～3.00％である。 Mn: 5% or less Mn is an element that increases the hardness of the matrix phase, and Mn is an element that is contained in the matrix due to solid lubricant particles and contributes to improving machinability. It is preferable to contain at least On the other hand, if the content exceeds 5%, the matrix phase hardness, toughness and ductility are lowered. Therefore, Mn is limited to a range of 5% or less. In addition, it is preferably 5.00% or less, more preferably 0.20 to 3.00%.
　Cr：0.5～15％
　Crは、基地相に固溶し、また炭化物を形成して基地相の硬さを増加させるとともに、Crは金属間化合物の構成元素として硬質粒子の硬さ増加に寄与する元素であり、基地部として0.5％以上含有することが好ましい。一方、15％を超えると、基地相中にCr炭化物の析出が過多となり、基地相中の炭化物を微細な炭化物とすることが難しくなる。このため、Crは0.5～15％の範囲に限定した。なお、好ましくは1.00～15.00％、より好ましくは0.70～6.00％である。 Cr: 0.5-15%
Cr forms a solid solution in the matrix phase and increases the hardness of the matrix phase by forming carbides. is preferably 0.5% or more. On the other hand, if it exceeds 15%, precipitation of Cr carbides in the matrix phase becomes excessive, and it becomes difficult to make the carbides in the matrix phase into fine carbides. Therefore, Cr is limited to the range of 0.5 to 15%. Incidentally, it is preferably 1.00 to 15.00%, more preferably 0.70 to 6.00%.
　Mo：3～20％
　Moは、基地相に固溶して、また炭化物として析出して基地相硬さを増加させ、さらにMoは金属間化合物の構成元素として硬質粒子の硬さ増加に寄与する元素であり、基地部として3％以上含有することが好ましい。一方、20％を超えると、粉末成形時の密度が増加しにくく、成形性が低下する。このため、Moは3～20％の範囲に限定した。なお、好ましくは4.00～20.00％、より好ましくは4.00～19.00％である。 Mo: 3-20%
Mo dissolves in the matrix phase and precipitates as carbides to increase the hardness of the matrix phase.Molybdenum is an element that contributes to increasing the hardness of hard particles as a constituent element of intermetallic compounds. It is preferable to contain 3% or more as On the other hand, when it exceeds 20%, it is difficult to increase the density at the time of powder compaction, and the compactibility is deteriorated. Therefore, Mo is limited to the range of 3 to 20%. Incidentally, it is preferably 4.00 to 20.00%, more preferably 4.00 to 19.00%.
　Ni：1～10％
　Niは、基地相の強度、靭性の向上に寄与する元素であり、また、Niは金属間化合物の構成元素として硬質粒子の硬さ増加に寄与する元素であり、1％以上含有する。一方、10％を超える含有は、粉末成形時の密度が増加しにくく、成形性を低下させる。このため、Niは1～10％の範囲に限定した。なお、好ましくは1.00～10.00％、より好ましくは2.00～9.00％である。 Ni: 1-10%
Ni is an element that contributes to improving the strength and toughness of the matrix phase, and is an element that contributes to increasing the hardness of the hard particles as a constituent element of the intermetallic compound, and is contained in an amount of 1% or more. On the other hand, if the content exceeds 10%, it is difficult to increase the density during powder molding, and the moldability is lowered. Therefore, Ni is limited to the range of 1 to 10%. In addition, it is preferably 1.00 to 10.00%, more preferably 2.00 to 9.00%.
　上記した成分が基本の成分であるが、更に選択元素として、V：0～5％、W：0～10％、S：0～2％、Cu：0～5％を含有できる。 The above ingredients are the basic ingredients, but as optional elements, V: 0-5%, W: 0-10%, S: 0-2%, and Cu: 0-5% can be added.
　V：0～5％
　Vは、微細炭化物として析出し、基地相の硬さを増加させて、耐摩耗性を向上させる元素であり、必要に応じて含有できる。含有する場合には0.5％以上とすることが好ましい。一方、5％を超える含有は、成形性を低下させる。このため、Vは0～5％の範囲に限定することが好ましい。なお、より好ましくは5.00％以下、さらに好ましくは2.00％以下である。 V: 0-5%
V is an element that precipitates as fine carbides, increases the hardness of the matrix phase, and improves wear resistance, and can be contained as necessary. When it is contained, it is preferably 0.5% or more. On the other hand, if the content exceeds 5%, the moldability is lowered. Therefore, it is preferable to limit V to a range of 0 to 5%. In addition, it is more preferably 5.00% or less, still more preferably 2.00% or less.
　W：0～10％
　Wは、微細炭化物として析出し、基地相の硬さを増加させて、耐摩耗性を向上させる元素であり、必要に応じて含有できる。含有する場合には、0.5％以上含有することが好ましい。一方、10％を超える含有は、成形性を低下させる。このため、Wは0～10％の範囲に限定することが好ましい。なお、より好ましくは10.00％以下、さらに好ましくは5.00％以下である。 W: 0-10%
W is an element that precipitates as fine carbides, increases the hardness of the matrix phase, and improves wear resistance, and can be contained as necessary. When it is contained, it is preferably contained in an amount of 0.5% or more. On the other hand, if the content exceeds 10%, the formability is lowered. Therefore, it is preferable to limit W to the range of 0 to 10%. In addition, it is more preferably 10.00% or less, and still more preferably 5.00% or less.
　S：0～2％
　Sは、固体潤滑剤粒子に含有され、基地部に含まれ、被削性向上に寄与する元素であり、必要に応じて含有できる。Sが2％を超えて含有されると、靭性、延性の低下に繋がる。このため、Sは0～2％の範囲に限定することが好ましい。より好ましくは2.00％以下である。 S: 0-2%
S is an element contained in the solid lubricant particles, contained in the base portion, and contributing to the improvement of machinability, and can be contained as necessary. If the S content exceeds 2%, it leads to a decrease in toughness and ductility. Therefore, it is preferable to limit S to the range of 0 to 2%. More preferably, it is 2.00% or less.
　Cu：0～5％
　Cuは、基地相の強度、靭性の向上に寄与する元素であり、必要に応じて含有できる。Cuが、5％を超えて含有されると、耐凝着性の低下に繋がる。このため、Cuは0～5％の範囲に限定することが好ましい。より好ましくは5.00％以下である。 Cu: 0-5%
Cu is an element that contributes to improving the strength and toughness of the matrix phase, and can be contained as necessary. A Cu content of more than 5% leads to a decrease in adhesion resistance. Therefore, Cu is preferably limited to the range of 0 to 5%. More preferably, it is 5.00% or less.
　上記した成分以外の残部は、Feおよび不可避的不純物からなる。なお、不可避的不純物としては、P：0.1％以下が許容できる。 The balance other than the above components consists of Fe and unavoidable impurities. Incidentally, P: 0.1% or less is permissible as an unavoidable impurity.
　また、本発明バルブシートの支持部材側層を構成する鉄基焼結合金材は、基地相と、該基地相中に固体潤滑剤粒子を面積率で0～5％、硬度改善粒子を面積率で0～5％、分散させてなる組織を有する。本発明バルブシートの支持部材側層の基地相は、固体潤滑剤粒子、硬度改善粒子を除く基地相面積を100％としたときの面積率で、100％のパーライトまたは100％のベイナイト相からなる組織とすることが好ましい。なお、基地相には、固体潤滑剤粒子を除く基地相面積を100％としたときの面積率で5％までの高合金相は許容できる。なお、硬度改善粒子は、鉄―モリブデン合金（Fe－Mo合金、フェロモリブデン合金ともいう）粒子とすることが好ましい。Fe－Mo合金粒子は、例えば60質量％Moを含み、残部がFeおよび不可避的不純物からなる組成の粒子とすることが好ましい。 Further, the iron-based sintered alloy material constituting the support member side layer of the valve seat of the present invention includes a base phase, solid lubricant particles in the base phase at an area ratio of 0 to 5%, and hardness improving particles at an area ratio of 0 to 5%. 0-5% with a dispersed structure. The base phase of the support member side layer of the valve seat of the present invention consists of 100% pearlite or 100% bainite phase in terms of area ratio when the area of the base phase excluding solid lubricant particles and hardness improving particles is 100%. Organization is preferable. In the matrix phase, a high alloy phase with an area ratio of up to 5% is permissible when the area of the matrix phase excluding the solid lubricant particles is taken as 100%. The hardness-improving particles are preferably iron-molybdenum alloy (also referred to as Fe—Mo alloy or ferromolybdenum alloy) particles. The Fe—Mo alloy particles preferably contain, for example, 60% by mass of Mo, with the balance being Fe and unavoidable impurities.
　そして、本発明バルブシートの支持部材側層では、基地相、固体潤滑剤粒子および硬度改善粒子を含む基地部が、質量％で、C：0.3～1.3％を含み、さらに、Ni：0～2.0％、Mo：0～2.0％、Cu：0～5.0％、Cr：0～5.0％、Mn：0～5.0％、S：0～2.0％を含有し、残部Feおよび不可避的不純物からなる組成を有する。
　なお、支持部材側層の基地部組成の限定理由は、以下のとおりである。 In the support member side layer of the valve seat of the present invention, the base portion containing the base phase, the solid lubricant particles and the hardness improving particles contains, by mass %, C: 0.3 to 1.3%, and Ni: 0 to 2.0. %, Mo: 0 to 2.0%, Cu: 0 to 5.0%, Cr: 0 to 5.0%, Mn: 0 to 5.0%, S: 0 to 2.0%, and the balance is Fe and unavoidable impurities. have.
The reasons for limiting the composition of the base portion of the supporting member side layer are as follows.
　C：0.3～1.3％
　Cは、支持部材側層の基地相を所定の硬さ、組織に調整するため、あるいは炭化物を形成するために必要な元素であり、0.3％以上含有させる。一方、1.3％を超えて含有すると、融点が低下し、焼結処理が液相焼結となる。液相焼結となると、析出炭化物量が多くなりすぎ、伸び特性、寸法精度が低下する。このため、Cは0.3～1.3％の範囲に限定した。なお、好ましくは0.30～1.30％、より好ましくは0.80～1.20％である。 C: 0.3-1.3%
C is an element necessary for adjusting the base phase of the support member side layer to a predetermined hardness and structure, or for forming carbide, and is contained in an amount of 0.3% or more. On the other hand, when the content exceeds 1.3%, the melting point is lowered and the sintering process becomes liquid phase sintering. When liquid phase sintering is used, the amount of precipitated carbide becomes too large, and the elongation characteristics and dimensional accuracy deteriorate. Therefore, C is limited to the range of 0.3-1.3%. In addition, it is preferably 0.30 to 1.30%, more preferably 0.80 to 1.20%.
　Ni：0～2.0％、Mo：0～2.0％、Cu：0～5.0％、Cr：0～5.0％
　Ni、Mo、Cu、Crは、いずれも基地相の硬さを増加させる元素であり、必要に応じて含有できる。このような効果を得るためには、Ni：0.1％以上、Mo：0.1％以上、Cu：0.1％以上、Cr：0.1％以上含有することが望ましい。一方、Ni：2.0％、Mo：2.0％、Cu：5.0％、Cr：5.0％をそれぞれ超えて含有すると、基地相の成形性が低下する。このため、Ni：0～2.0％、Mo：0～2.0％、Cu：0～5.0％、Cr：0～5.0％の範囲に限定することが好ましい。より好ましくはNi：2.00％以下、Mo：2.00％以下、Cu：5.00％以下、Cr：5.00％以下である。 Ni: 0-2.0%, Mo: 0-2.0%, Cu: 0-5.0%, Cr: 0-5.0%
Ni, Mo, Cu, and Cr are all elements that increase the hardness of the matrix phase, and can be contained as necessary. In order to obtain such effects, it is desirable to contain Ni: 0.1% or more, Mo: 0.1% or more, Cu: 0.1% or more, and Cr: 0.1% or more. On the other hand, when Ni: 2.0%, Mo: 2.0%, Cu: 5.0%, and Cr: 5.0% are contained, respectively, the formability of the matrix phase deteriorates. Therefore, it is preferable to limit the range to Ni: 0 to 2.0%, Mo: 0 to 2.0%, Cu: 0 to 5.0%, and Cr: 0 to 5.0%. More preferably, Ni: 2.00% or less, Mo: 2.00% or less, Cu: 5.00% or less, and Cr: 5.00% or less.
　Mn：0～5.0％、S：0～2.0％
　Mn、Sは、いずれも固体潤滑剤粒子の含有に起因して基地部に含まれ、被削性向上に寄与する元素であり、必要に応じて含有できる。なお、Mnは基地相の硬さ増加にも寄与する。Sが2.0％、Mnが5.0％を超えて超えると、延性の低下が著しくなる。このため、S：0～2.0％、Mn：0～5.0％に限定することが好ましい。より好ましくはS：2.00％以下、Mn：5.00％以下である。 Mn: 0-5.0%, S: 0-2.0%
Both Mn and S are elements that are contained in the matrix due to the inclusion of solid lubricant particles and contribute to the improvement of machinability, and can be included as necessary. Mn also contributes to increasing the hardness of the matrix phase. When S exceeds 2.0% and Mn exceeds 5.0%, the ductility decreases significantly. Therefore, it is preferable to limit S to 0 to 2.0% and Mn to 0 to 5.0%. More preferably, S: 2.00% or less and Mn: 5.00% or less.
　支持部材側層では、上記した成分以外の残部は、Feおよび不可避的不純物からなる。なお、不可避的不純物としては、P：0.1％以下が許容できる。 In the supporting member side layer, the balance other than the above components consists of Fe and unavoidable impurities. Incidentally, P: 0.1% or less is permissible as an unavoidable impurity.
　次に、本発明バルブシートの好ましい製造方法について説明する。
　まず、上記した基地相組成および組織、基地部組成および組織となるように、機能部材側層用の原料粉、支持部材側層用の原料粉を、それぞれ配合し混合して、機能部材側層用の混合粉および支持部材側層用混合粉とする。機能部材側層用の原料粉としては、基地相形成用の鉄基粉末に、合金元素粉末と、硬質粒子粉末と、固体潤滑剤粒子粉末とを、上記した所定の組成、組織となるように、配合する。また、支持部材側層用の原料粉としては、基地相形成用の鉄基粉末に、黒鉛粉末、あるいはさらに合金元素粉と固体潤滑剤粒子粉末と硬度改善粒子粉末を、上記した所定の組成、組織となるように、配合する。なお、原料粉として、混合粉に配合する硬質粒子粉末は、上記した硬質粒子組成を有する溶湯を、常用の溶製方法で溶製し、常用のアトマイズ法を用いて粉末（硬質粒子用粉末）とすることが好ましい。 Next, a preferred method for manufacturing the valve seat of the present invention will be described.
First, the raw material powder for the functional member side layer and the raw material powder for the support member side layer are each blended and mixed so as to obtain the base phase composition and structure and the base portion composition and structure described above, and the functional member side layer is obtained. and the mixed powder for the supporting member side layer. As the raw material powder for the functional member side layer, the iron-based powder for forming the base phase, the alloying element powder, the hard particle powder, and the solid lubricant particle powder are mixed so as to have the above-described predetermined composition and structure. , to blend. As raw material powders for the supporting member side layer, an iron-based powder for forming the base phase, graphite powder, or alloying element powder, solid lubricant particle powder, and hardness improving particle powder are combined in the above-described predetermined composition, Mix to form a texture. As the raw material powder, the hard particle powder to be blended in the mixed powder is obtained by melting the molten metal having the above-described hard particle composition by a commonly used melting method, and using a commonly used atomizing method to produce a powder (hard particle powder). It is preferable to
　なお、混合粉に配合する鉄基粉末は、アトマイズ純鉄粉、還元鉄粉、合金鋼粉末のいずれか、あるいはそれらの混合とすることが好ましい。合金鋼粉末としては、基地相として、上記した硬さを有する微細炭化物析出相を形成できるように、JIS G 4403に規定される高速度工具鋼組成の粉末とすることが好ましい。高速度工具鋼としてはSKH51等のMo系とすることが好ましい。高速度工具鋼組成以外にも、上記した硬さを有し、微細炭化物析出相あるいはベイナイト相となることができる組成の合金鋼を用いてもなんら問題はない。なお、混合粉には、純鉄粉に、あるいは純鉄粉と上記した組成の合金鋼粉末に、あるいは上記した組成の合金鋼粉末に、上記した基地相組成となるように、黒鉛粉末、さらには合金元素粉末を配合することは言うまでもない。なお、混合粉には、ステアリン酸亜鉛等の潤滑剤を配合してもよい。 The iron-based powder to be blended into the mixed powder is preferably atomized pure iron powder, reduced iron powder, or alloyed steel powder, or a mixture thereof. As the alloy steel powder, it is preferable to use a powder having a high-speed tool steel composition specified in JIS G 4403 so as to form a fine carbide precipitate phase having the hardness described above as a matrix phase. As the high-speed tool steel, it is preferable to use a Mo-based material such as SKH51. In addition to the high-speed tool steel composition, there is no problem in using an alloy steel having a composition that has the hardness described above and can form a fine carbide precipitate phase or a bainite phase. The mixed powder includes pure iron powder, pure iron powder and alloy steel powder having the composition described above, alloy steel powder having the composition described above, graphite powder so as to have the base phase composition described above, and Needless to say, contains alloying element powders. The mixed powder may contain a lubricant such as zinc stearate.
　ついで、得られた混合粉を、金型に充填し、粉末成形機等で成型加工を施して、所定寸法形状のバルブシート形状の圧粉体とする。なお、二層構造の場合には、支持部材側層用原料粉と機能部材側層用原料粉とを、二層となるように順次金型に充填する。一方、単層構造の場合には、機能部材側層用原料粉を金型に充填する。 Next, the obtained mixed powder is filled into a mold and molded by a powder molding machine or the like to obtain a valve seat-shaped powder compact with predetermined dimensions and shape. In the case of a two-layer structure, the raw material powder for the supporting member side layer and the raw material powder for the functional member side layer are sequentially filled into the mold so as to form two layers. On the other hand, in the case of a single layer structure, the mold is filled with raw material powder for the functional member side layer.
　ついで、得られた圧粉体に焼結処理を施して、焼結体とする。
　焼結処理は、アンモニア分解ガス、真空等の還元雰囲気中で、加熱温度：1100～1200℃の温度範囲で、0.5hr以上保持する処理とすることが好ましい。なお、粉末成形―焼結処理を１回施す工程（１Ｐ１Ｓ）としても、あるいは複数回繰返す工程（２Ｐ２Ｓ等）を施してもよいことは言うまでもない。
　得られた焼結体を、切削、研削等の加工により、所望の寸法形状のバルブシートとする。 Next, the green compact obtained is subjected to a sintering treatment to obtain a sintered body.
The sintering treatment is preferably carried out in a reducing atmosphere such as ammonia decomposition gas or vacuum at a temperature range of 1100 to 1200° C. for 0.5 hours or longer. Needless to say, the powder molding-sintering process may be performed once (1P1S), or may be performed multiple times (2P2S, etc.).
The resulting sintered body is processed by cutting, grinding, or the like to form a valve seat having desired dimensions and shape.
　以下、実施例に基づき、さらに本発明について説明する。 The present invention will be further described below based on examples.
（実施例１）
　まず、機能部材側層用混合粉と支持部材側層用混合粉を用意した。
　機能部材側層用混合粉は、基地相形成用の鉄基粉末と、黒鉛粉末、合金元素粉末と、硬質粒子粉末と、固体潤滑剤粒子粉末（MnS粉末）と、を表７に示す配合量となるように調整し、混合して、混合粉とした。なお、使用した鉄基粉末は、表５に示す組成の純鉄粉（アトマイズ純鉄粉、還元鉄粉）、高速度鋼粉、合金鋼粉とした。また、使用した硬質粒子粉末は、表６に示す組成の硬質粒子粉末とした。なお、硬質粒子粉末No.Aは、常用のCo基金属間化合物粒子粉末であり、従来例とした。また、表６には、各硬質粒子の焼結前のビッカース硬さHV、平均粒子径D50を併記した。 (Example 1)
First, a mixed powder for the functional member side layer and a mixed powder for the supporting member side layer were prepared.
The mixed powder for the functional member side layer contains the iron-based powder for forming the base phase, the graphite powder, the alloying element powder, the hard particle powder, and the solid lubricant particle powder (MnS powder) in the amounts shown in Table 7. and mixed to obtain a mixed powder. The iron-based powders used were pure iron powder (atomized pure iron powder, reduced iron powder), high-speed steel powder, and alloyed steel powder having the compositions shown in Table 5. Further, hard particle powder having the composition shown in Table 6 was used as the hard particle powder. The hard particle powder No. A is a commonly used Co-based intermetallic compound particle powder, and is used as a conventional example. Table 6 also shows the Vickers hardness HV before sintering and the average particle size D50 of each hard particle.
　支持部材側層用混合粉は、基地相形成用の鉄基粉末と、黒鉛粉末、合金元素粉末と、硬度改善粒子粉末と、固体潤滑剤粒子粉末（MnS粉末）と、を表８に示す配合量となるように調整し、混合して、混合粉とした。なお、使用した鉄基粉末は、表５に示す組成の純鉄粉（アトマイズ純鉄粉、還元鉄粉）とした。また、使用した硬度改善粒子粉末は、Mo：60質量％を含み残部Feおよび不可避的不純物からなる組成の鉄―モリブデン合金粒子粉末とした。 The mixed powder for the supporting member side layer contains the iron-based powder for forming the base phase, the graphite powder, the alloy element powder, the hardness improving particle powder, and the solid lubricant particle powder (MnS powder) as shown in Table 8. The amount was adjusted and mixed to obtain a mixed powder. The iron-based powder used was a pure iron powder (atomized pure iron powder, reduced iron powder) having the composition shown in Table 5. The hardness-improved particle powder used was an iron-molybdenum alloy particle powder having a composition containing 60% by mass of Mo with the balance being Fe and unavoidable impurities.
　なお、混合粉には、潤滑剤として、混合粉100質量部に対し、ステアリン酸亜鉛を0.75質量部配合した。 In addition, 0.75 parts by mass of zinc stearate was blended in the mixed powder as a lubricant with respect to 100 parts by mass of the mixed powder.
　ついで、得られた機能部材側層用混合粉と支持部材側層用混合粉を、二層となるように、順次金型に充填し、粉末成形機で所定のバルブシート形状の圧粉体を成形した。なお、バルブシートNo.17Aは機能部材側層のみの単層とした。 Next, the obtained mixed powder for the functional member side layer and the obtained mixed powder for the support member side layer are sequentially filled into a mold so as to form two layers, and a green compact having a predetermined valve seat shape is formed by a powder molding machine. Molded. In addition, valve seat No. 17A was a single layer with only the layer on the functional member side.
　ついで、得られた圧粉体に、さらに潤滑材を除去する脱脂工程と、アンモニア分解ガス中で、1100℃～1200℃×0.5hrの焼結処理とを施し、焼結体とした。
　なお、一部では、粉末成形―焼結処理を２回施す工程（２Ｐ２Ｓ）とした。 Next, the compact thus obtained was subjected to a degreasing process for removing the lubricant and a sintering treatment at 1100° C. to 1200° C. for 0.5 hours in an ammonia decomposition gas to obtain a sintered body.
In some cases, a process (2P2S) of performing powder compaction and sintering treatment twice was employed.
　得られた焼結体に、さらに切削、研磨等の加工を施して、所定寸法形状（外径：32.1mmφ×内径：26.1mmφ×厚さ5.5mm）の鉄基焼結合金製バルブシートとした。 The obtained sintered body was further processed by cutting, polishing, etc. to obtain an iron-based sintered alloy valve seat with a predetermined size and shape (outer diameter: 32.1 mmφ x inner diameter: 26.1 mmφ x thickness 5.5 mm). .
　得られたバルブシート（焼結体）について、焼結体各部位の基地部組成を分析し、さらに組織観察、硬さ測定、密度測定、硬質粒子割れ耐性試験、摩耗試験、圧環強さ試験を実施した。試験方法は次の通りとした。
（１）組織観察
　得られたバルブシートについて、軸方向に垂直な断面を研磨し、腐食（腐食液：ナイタール液、マーブル液）して組織を現出し、光学顕微鏡（倍率：200倍）で、基地相の組織を特定した。また、走査型電子顕微鏡（倍率：2000倍）を用いて、基地相中に析出した炭化物の粒径を測定し、炭化物の粒径（長辺長さ）が最大で10μm以下であることを確認し、炭化物が析出した相が微細炭化物析出相であることを確認した。炭化物の粒径（長辺長さ）が最大で10μmを超える場合は炭化物析出相とした。
（２）硬さ試験
　得られたバルブシートについて、断面を研磨し、腐食（腐食液：ナイタール液、マーブル液）して組織を現出し、ビッカース硬さ計（試験力：0.98N）を用いて基地相の硬さを測定した。なお、基地相が二相の場合にはそれぞれ別々に測定した。
（３）密度試験
　得られたバルブシートについて、アルキメデス法を用いて、バルブシートの密度を測定した。
（４）硬質粒子割れ耐性試験
　得られたバルブシートについて、断面を研磨し、ビッカース硬さ計（試験力：0.98N）を用いて基地相中に分散した硬質粒子（各20個）に圧痕を付与し、圧痕を付与した各粒子における割れ発生の有無を観察し、割れ発生個数を調査した。なお、倍率500倍で観察し付与した圧痕より外側に亀裂が進展していれば割れ発生と判断した。そして、従来例であるバルブシートNo.1Aの割れ発生個数を基準（＝1.0）として、基準に対する当該バルブシートの硬質粒子の割れ発生個数比（割れ発生比）を算出した。得られた結果から、割れ発生比が1.0未満である場合を〇（割れ耐性あり）、1.0以上である場合を×（割れ耐性なし）と評価した。
（５）摩耗試験
　得られたバルブシートについて、図１に示すリグ試験機を用いて、下記に示す試験条件で、摩耗試験を実施した。
　試験温度：200℃（シートフェース）、
　試験時間：8hr、
　カム回転数：3000rpm、
　バルブ回転数：10rpm、
　衝撃荷重(スプリング荷重)：780N、
　バルブ材質：NCF751相当材、
　リフト量：6mm
　試験後、試験片（バルブシート）の摩耗量を測定した。得られた摩耗量から、従来例であるバルブシートNo.1Aを基準（＝1.00）として、当該バルブシートの摩耗比を算出した。
（６）圧環強さ
　得られたバルブシート（機能部材側層のみ）について、JIS Z 2507の規定に準拠して、圧環強さ（kg/mm2）を求めた。なお、圧環強さが40kg/mm2以上であれば、バルブシート圧入時に割れ、欠けの発生のない、バルブシートとして十分な強度を有することを確認している。 For the obtained valve seat (sintered body), the composition of the base part of each part of the sintered body is analyzed, and the structure observation, hardness measurement, density measurement, hard particle cracking resistance test, wear test, radial crushing strength test are performed. Carried out. The test method was as follows.
(1) Observation of structure The cross section perpendicular to the axial direction of the obtained valve seat is polished, corroded (corrosive liquid: nital liquid, marble liquid) to expose the structure, and an optical microscope (magnification: 200 times) The organization of the basal phase was identified. In addition, using a scanning electron microscope (magnification: 2000 times), the grain size of carbides precipitated in the matrix phase was measured, and it was confirmed that the maximum grain size (long side length) of carbides was 10 μm or less. It was confirmed that the phase in which carbide precipitated was a fine carbide precipitate phase. When the grain size (long side length) of carbide exceeds 10 μm at maximum, it is defined as a carbide precipitate phase.
(2) Hardness test The cross section of the obtained valve seat is polished, corroded (corrosive liquid: nital liquid, marble liquid) to expose the structure, and a Vickers hardness tester (test force: 0.98 N) is used. The hardness of the matrix phase was measured. In addition, when the base phase was two phases, each measurement was performed separately.
(3) Density test The density of the obtained valve seat was measured using the Archimedes method.
(4) Hard particle cracking resistance test The cross section of the obtained valve seat was polished, and indentations were made on the hard particles (20 each) dispersed in the matrix phase using a Vickers hardness tester (test force: 0.98 N). The presence or absence of cracks in each particle to which the impression was given and the indentation was given was observed, and the number of cracks was investigated. In addition, when the crack was observed at a magnification of 500 times and the crack progressed to the outside of the given indentation, it was determined that the crack had occurred. Then, using the number of cracks generated in valve seat No. 1A, which is a conventional example, as a reference (=1.0), the crack generation number ratio (crack generation ratio) of the hard particles of the valve seat with respect to the reference was calculated. From the obtained results, the case where the crack generation ratio was less than 1.0 was evaluated as ◯ (with crack resistance), and the case with 1.0 or more was evaluated as × (no crack resistance).
(5) Abrasion test The obtained valve seat was subjected to an abrasion test using the rig tester shown in Fig. 1 under the test conditions shown below.
Test temperature: 200°C (seat face),
Exam time: 8hr,
Cam speed: 3000rpm,
Valve speed: 10rpm,
Impact load (spring load): 780N,
Valve material: NCF751 equivalent material,
Lift amount: 6mm
After the test, the wear amount of the test piece (valve seat) was measured. Based on the obtained wear amount, the wear ratio of the valve seat was calculated based on the conventional valve seat No. 1A (=1.00).
(6) Radial crushing strength The radial crushing strength (kg/mm 2 ) of the obtained valve seat (only the functional member side layer) was determined in accordance with JIS Z 2507. It has been confirmed that if the radial crushing strength is 40 kg/mm 2 or more, the valve seat has sufficient strength without cracking or chipping when the valve seat is press-fitted.
　なお、硬質粒子割れ耐性試験、摩耗試験で、基準としたバルブシートNo.1A（従来例）は、機能部材側層が、基地相中に硬質粒子、固体潤滑剤粒子を分散させた組織と、Co含有組成とを有する鉄基焼結合金材であり、一般的なガソリンエンジンから高性能ガソリンエンジンまで幅広い範囲の排気側向けバルブシートに使用される材料である。バルブシートは排気側と吸気側で耐摩耗性に影響を及ぼす項目（例えば、熱負荷・動弁機構の設計値など）の影響度合いが異なり、一般的には排気側の方が使用環境として厳しく、バルブシートの耐摩耗性としても吸気側以上の性能が要求される。 In the hard particle cracking resistance test and wear test, the reference valve seat No. 1A (conventional example) has a structure in which the functional member side layer has hard particles and solid lubricant particles dispersed in the matrix phase, It is an iron-based sintered alloy material with a Co-containing composition, and is used for valve seats on the exhaust side of a wide range of gasoline engines from general gasoline engines to high-performance gasoline engines. Items that affect wear resistance on the exhaust side and the intake side of the valve seat (for example, heat load, design values of the valve mechanism, etc.) have different degrees of influence, and generally the exhaust side is more severe as a usage environment. Also, the wear resistance of the valve seat is required to be higher than that of the intake side.
　得られた結果を表９、１０に示す。 The obtained results are shown in Tables 9 and 10.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005

Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006

Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007

Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008

Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009

Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
　本発明例はいずれもCoを含有せずに、従来例（バルブシートNo.1A）と同等かそれ以上の優れた耐摩耗性を有し、かつバルブシートとして十分な圧環強さを有するバルブシートとなっている。一方、本発明の範囲を外れる比較例は、従来例（バルブシートNo.1A）に比べて、摩耗比が高くなっている。 All of the valve seats of the present invention do not contain Co, have excellent wear resistance equal to or superior to that of the conventional example (valve seat No. 1A), and have sufficient radial crushing strength as a valve seat. It has become. On the other hand, the comparative example, which is outside the scope of the present invention, has a higher wear ratio than the conventional example (valve seat No. 1A).
（実施例２）
　まず、機能部材側層用混合粉と支持部材側層用混合粉を用意した。
　機能部材側層用混合粉は、基地相形成用の鉄基粉末と、黒鉛粉末、合金元素粉末と、硬質粒子粉末と、固体潤滑剤粒子粉末（MnS粉末）と、を表１３に示す配合量となるように調整し、混合して、混合粉とした。使用した鉄基粉末は、表１１に示す組成の純鉄粉（アトマイズ純鉄粉、還元鉄粉）、合金鉄粉（プレアロイ粉）とした。また、使用した硬質粒子粉末は、表１２に示す組成の硬質粒子粉末とした。なお、硬質粒子粉末No.Aは、常用のCo基金属間化合物粒子粉末であり、硬質粒子粉末No.Aを配合した混合粉D1は従来例とした。また、表１２には、各硬質粒子の焼結前のビッカース硬さHV、平均粒子径D50を併記した。 (Example 2)
First, a mixed powder for the functional member side layer and a mixed powder for the supporting member side layer were prepared.
The mixed powder for the functional member side layer contains the iron-based powder for forming the base phase, the graphite powder, the alloying element powder, the hard particle powder, and the solid lubricant particle powder (MnS powder) in the amounts shown in Table 13. and mixed to obtain a mixed powder. The iron-based powders used were pure iron powders (atomized pure iron powders, reduced iron powders) and alloyed iron powders (pre-alloyed powders) having compositions shown in Table 11. The hard particle powder used was the hard particle powder having the composition shown in Table 12. The hard particle powder No. A is a commonly used Co-based intermetallic compound particle powder, and the mixed powder D1 containing the hard particle powder No. A is a conventional example. Table 12 also shows the Vickers hardness HV before sintering and the average particle diameter D50 of each hard particle.
　支持部材側層用混合粉は、基地相形成用の鉄基粉末と、黒鉛粉末、合金元素粉末と、硬度改善粒子粉末と、を表１４に示す配合量となるように調整し、混合して、混合粉とした。なお、使用した鉄基粉末は、表１１に示す組成の純鉄粉（アトマイズ純鉄粉）No.aとした。また、使用した硬度改善粒子粉末は、Mo：60質量％を含み残部Feおよび不可避的不純物からなる組成の鉄―モリブデン合金粒子粉末Fe－Moとした。また、固体潤滑剤粒子粉末（MnS粉末）は添加しなかった。 The mixed powder for the supporting member side layer is prepared by adjusting the blending amounts of the iron-based powder for forming the base phase, the graphite powder, the alloying element powder, and the hardness-improving particle powder so as to have the compounding amounts shown in Table 14, and mixing them. , and mixed powder. The iron-based powder used was pure iron powder (atomized pure iron powder) No.a having the composition shown in Table 11. The hardness-improved particle powder used was iron-molybdenum alloy particle powder Fe—Mo having a composition containing 60% by mass of Mo with the balance being Fe and unavoidable impurities. Also, no solid lubricant particle powder (MnS powder) was added.
　なお、混合粉には、潤滑剤として、混合粉100質量部に対し、ステアリン酸亜鉛を0.75質量部配合した。 In addition, 0.75 parts by mass of zinc stearate was blended in the mixed powder as a lubricant with respect to 100 parts by mass of the mixed powder.
　ついで、得られた機能部材側層用混合粉と支持部材側層用混合粉を、二層となるように、順次金型に充填し、粉末成形機で所定のバルブシート形状の圧粉体を成形した。ついで、得られた圧粉体に、さらに潤滑材を除去する脱脂工程と、アンモニア分解ガス中で、1100～1200℃×0.5hrの焼結処理とを施す工程（１Ｐ１Ｓ）を行い、焼結体とした。 Next, the obtained mixed powder for the functional member side layer and the obtained mixed powder for the support member side layer are sequentially filled into a mold so as to form two layers, and a green compact having a predetermined valve seat shape is formed by a powder molding machine. Molded. Next, the obtained compact is subjected to a degreasing step for removing the lubricant and a step (1P1S) of performing sintering treatment at 1100 to 1200° C. for 0.5 hr in ammonia decomposition gas to obtain a sintered compact. and
　得られた焼結体に、さらに切削、研磨等の加工を施して、所定寸法形状（外径：32.1mmφ×内径：26.1mmφ×厚さ5.5mm）の鉄基焼結合金製バルブシートとした。 The obtained sintered body was further processed by cutting, polishing, etc. to obtain an iron-based sintered alloy valve seat with a predetermined size and shape (outer diameter: 32.1 mmφ x inner diameter: 26.1 mmφ x thickness 5.5 mm). .
　得られたバルブシート（焼結体）について、焼結体各部位の基地部組成を分析し、さらに組織観察、硬さ測定、密度測定、硬質粒子割れ耐性試験、摩耗試験、圧環強さ試験を実施した。試験方法は実施例１と同様とした。なお、硬質粒子割れ耐性試験では、バルブシートNo.1Bの割れ発生個数を基準（＝1.0）として、基準に対する当該バルブシートの硬質粒子の割れ発生個数比（割れ発生比）を算出した。また、摩耗試験では、バルブシートNo.1Bを基準（＝1.00）として、当該バルブシートの摩耗比を算出した。 For the obtained valve seat (sintered body), the composition of the base part of each part of the sintered body is analyzed, and the structure observation, hardness measurement, density measurement, hard particle cracking resistance test, wear test, radial crushing strength test are performed. Carried out. The test method was the same as in Example 1. In the hard particle cracking resistance test, the number of cracks generated in the valve seat No. 1B was used as a reference (=1.0), and the crack generation number ratio (crack generation ratio) of the hard particles of the valve seat was calculated. In the wear test, the wear ratio of the valve seat was calculated with the valve seat No. 1B as the reference (=1.00).
　なお、硬質粒子割れ耐性試験、摩耗試験で、基準としたバルブシートNo.1B（従来例）は、一般的なガソリンエンジンの吸気側向けバルブシートに使用される材料であり、機能部材側層が、Co含有組成を有する鉄基焼結合金材である。吸気側で使用されるバルブシートは、排気側で使用されるバルブシートに比べ、要求される耐摩耗性は低い。 In the hard particle cracking resistance test and wear test, the standard valve seat No. 1B (conventional example) is a material used for valve seats on the intake side of general gasoline engines, and the functional member side layer is , an iron-based sintered alloy material having a Co-containing composition. A valve seat used on the intake side is required to have lower wear resistance than a valve seat used on the exhaust side.
　得られた結果を表１５、表１６に示す。 The obtained results are shown in Tables 15 and 16.
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000012

Figure JPOXMLDOC01-appb-T000013
Figure JPOXMLDOC01-appb-T000013
Figure JPOXMLDOC01-appb-T000014
Figure JPOXMLDOC01-appb-T000014

Figure JPOXMLDOC01-appb-T000015
Figure JPOXMLDOC01-appb-T000015
Figure JPOXMLDOC01-appb-T000016
Figure JPOXMLDOC01-appb-T000016
　本発明例は、基地相の組織が高合金相とパーライトからなる組織となっても、同一硬さレベルであるCoを含有する組成の焼結体（従来例No.1B）に比べて、同等かそれ以上の優れた耐摩耗性と、十分な圧環強さを有するバルブシートとなっている。例えば、耐摩耗性要求の比較的低い、吸気側バルブシートに十分に適用可能といえる。 In the present invention example, even if the structure of the matrix phase becomes a structure consisting of a high alloy phase and pearlite, it is equivalent to the sintered body (conventional example No. 1B) with the same hardness level and a composition containing Co. It is a valve seat with excellent abrasion resistance and sufficient radial crushing strength. For example, it can be said to be sufficiently applicable to intake side valve seats, which require relatively low wear resistance.
１　　バルブシート
２　　シリンダーブロック相当材
３　　加熱手段
４　　バルブ 1 valve seat 2 cylinder block equivalent material 3 heating means 4 valve

Claims (9)

  1. 　内燃機関のシリンダーヘッドに圧入されるバルブシートであって、
    該バルブシートが機能部材側層と支持部材側層とが一体で焼結された二層構造を有し、
    前記機能部材側層が、基地相と、該基地相中に面積率で10～40％の硬質粒子とさらに面積率で0～5％の固体潤滑剤粒子を分散させてなる組織を有し、前記硬質粒子が、ビッカース硬さで700～1300HVの硬さを有し、質量％で、Si：1.5～3.5％、Cr：7.0～9.0％、Mo：35.0～45.0％、Ni：5.0～20.0％を含み残部Feおよび不可避的不純物からなる組成を有するSi－Cr－Ni－Fe系Mo基金属間化合物粒子であり、さらに前記基地相、前記硬質粒子および前記固体潤滑剤粒子を含む基地部が、質量％で、C：0.5～2.0％、Si：0.2～2.0％、Mn：5％以下、Cr：0.5～15％、Mo：3～20％、Ni：1～10％、を含み、さらに、V：0～5％、W：0～10％、S：0～2％、Cu：0～5％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有する鉄基焼結合金材からなり、
    前記支持部材側層が、基地相と、該基地相中に面積率で0～5％の固体潤滑剤粒子および面積率で0～5％の硬度改善粒子を分散させてなる組織と、さらに前記基地相、前記固体潤滑剤粒子および前記硬度改善粒子を含む基地部が、質量％で、C：0.3～1.3％を含み、さらに、Ni：0～2.0％、Mo：0～2.0％、Cu：0～5.0％、Cr：0～5.0％、Mn：0～5.0％、S：0～2.0％を含有し、残部Feおよび不可避的不純物からなる組成と、を有する鉄基焼結合金材からなり、
    前記バルブシートの密度が6.70～7.20g/cm3であることを特徴とする内燃機関用鉄基焼結合金製バルブシート。     A valve seat press-fitted into a cylinder head of an internal combustion engine,
    The valve seat has a two-layer structure in which the functional member side layer and the support member side layer are integrally sintered,
    The functional member-side layer has a base phase, and a structure in which hard particles with an area ratio of 10 to 40% and solid lubricant particles with an area ratio of 0 to 5% are dispersed in the base phase, The hard particles have a Vickers hardness of 700 to 1300 HV, and the mass % is Si: 1.5 to 3.5%, Cr: 7.0 to 9.0%, Mo: 35.0 to 45.0%, Ni: 5.0 to 20.0%. Si—Cr—Ni—Fe-based Mo-based intermetallic compound particles having a composition containing Fe and inevitable impurities, and a base portion containing the base phase, the hard particles, and the solid lubricant particles, In mass%, C: 0.5-2.0%, Si: 0.2-2.0%, Mn: 5% or less, Cr: 0.5-15%, Mo: 3-20%, Ni: 1-10%, and further, Iron-based sintered alloy material containing V: 0-5%, W: 0-10%, S: 0-2%, Cu: 0-5%, with the balance being Fe and unavoidable impurities consists of
    The support member side layer comprises a matrix phase, a structure in which solid lubricant particles with an area ratio of 0 to 5% and hardness improving particles with an area ratio of 0 to 5% are dispersed in the matrix phase, and The base portion containing the base phase, the solid lubricant particles and the hardness improving particles contains, in % by mass, C: 0.3 to 1.3%, Ni: 0 to 2.0%, Mo: 0 to 2.0%, and Cu: 0-5.0%, Cr: 0-5.0%, Mn: 0-5.0%, S: 0-2.0%, and the balance consisting of Fe and unavoidable impurities. ,
    A valve seat made of an iron-based sintered alloy for an internal combustion engine, wherein the valve seat has a density of 6.70 to 7.20 g/cm 3 .
  2. 　内燃機関のシリンダーヘッドに圧入されるバルブシートであって、
    該バルブシートが機能部材側層からなる単層構造を有し、
    前記機能部材側層が、基地相と、該基地相中に面積率で10～40％の硬質粒子とさらに面積率で0～5％の固体潤滑剤粒子を分散させてなる組織を有し、前記硬質粒子が、ビッカース硬さで700～1300HVの硬さを有し、質量％で、Si：1.5～3.5％、Cr：7.0～9.0％、Mo：35.0～45.0％、Ni：5.0～20.0％を含み残部Feおよび不可避的不純物からなる組成を有するSi－Cr－Ni－Fe系Mo基金属間化合物粒子であり、さらに前記基地相、前記硬質粒子および前記固体潤滑剤粒子を含む基地部が、質量％で、C：0.5～2.0％、Si：0.2～2.0％、Mn：5％以下、Cr：0.5～15％、Mo：3～20％、Ni：1～10％、を含み、さらに、V：0～5％、W：0～10％、S：0～2％、Cu：0～5％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有する鉄基焼結合金材からなり、
    前記バルブシートの密度が6.70～7.20g/cm3であることを特徴とする内燃機関用鉄基焼結合金製バルブシート。     A valve seat press-fitted into a cylinder head of an internal combustion engine,
    The valve seat has a single layer structure consisting of a functional member side layer,
    The functional member-side layer has a base phase, and a structure in which hard particles with an area ratio of 10 to 40% and solid lubricant particles with an area ratio of 0 to 5% are dispersed in the base phase, The hard particles have a Vickers hardness of 700 to 1300 HV, and the mass % is Si: 1.5 to 3.5%, Cr: 7.0 to 9.0%, Mo: 35.0 to 45.0%, Ni: 5.0 to 20.0%. Si—Cr—Ni—Fe-based Mo-based intermetallic compound particles having a composition containing Fe and inevitable impurities, and a base portion containing the base phase, the hard particles, and the solid lubricant particles, In mass%, C: 0.5-2.0%, Si: 0.2-2.0%, Mn: 5% or less, Cr: 0.5-15%, Mo: 3-20%, Ni: 1-10%, and further, Iron-based sintered alloy material containing V: 0-5%, W: 0-10%, S: 0-2%, Cu: 0-5%, with the balance being Fe and unavoidable impurities consists of
    A valve seat made of an iron-based sintered alloy for an internal combustion engine, wherein the valve seat has a density of 6.70 to 7.20 g/cm 3 .
  3. 　前記機能部材側層の前記基地相が、前記硬質粒子および前記固体潤滑剤粒子を除く基地相面積を100％とする面積率で、10～90％の微細炭化物析出相と0～30％の高合金相と残部がパーライトからなる組織を有することを特徴とする請求項１または２に記載の内燃機関用鉄基焼結合金製バルブシート。 The base phase of the functional member side layer has a fine carbide precipitate phase of 10 to 90% and a high 3. A valve seat made of an iron-based sintered alloy for an internal combustion engine according to claim 1 or 2, characterized in that it has a structure in which the alloy phase and the balance consist of pearlite.
  4. 　前記機能部材側層の前記基地相が、前記硬質粒子および前記固体潤滑剤粒子を除く基地相面積を100％とする面積率で、0～15％の高合金相と残部が微細炭化物析出相からなる組織を有することを特徴とする請求項１または２に記載の内燃機関用鉄基焼結合金製バルブシート。 The base phase of the functional member side layer is composed of 0 to 15% of the high alloy phase and the balance of the fine carbide precipitate phase, with the area ratio of the base phase excluding the hard particles and the solid lubricant particles being 100%. 3. The valve seat made of an iron-based sintered alloy for an internal combustion engine according to claim 1 or 2, characterized in that it has a structure of
  5. 　前記機能部材側層の前記基地相が、前記硬質粒子および前記固体潤滑剤粒子を除く基地相面積を100％とする面積率で、0～25％の高合金相と残部がベイナイト相からなる組織を有することを特徴とする請求項１または２に記載の内燃機関用鉄基焼結合金製バルブシート。 A structure in which the base phase of the functional member-side layer is composed of 0 to 25% of the high alloy phase and the balance of the bainite phase, with the area ratio of the base phase excluding the hard particles and the solid lubricant particles being 100%. The valve seat made of an iron-based sintered alloy for an internal combustion engine according to claim 1 or 2, characterized by comprising:
  6. 　前記機能部材側層の前記基地相が、前記硬質粒子および前記固体潤滑剤粒子を除く基地相面積を100％とする面積率で、0～30％の高合金相と残部がパーライトからなる組織を有することを特徴とする請求項１または２に記載の内燃機関用鉄基焼結合金製バルブシート。 The base phase of the functional member side layer has a structure consisting of 0 to 30% high alloy phase and the balance pearlite, with an area ratio of 100% for the base phase area excluding the hard particles and the solid lubricant particles. 3. The valve seat made of an iron-based sintered alloy for an internal combustion engine according to claim 1 or 2, characterized by comprising:
  7. 　前記微細炭化物析出相は、粒径10μm以下の微細炭化物が析出し、ビッカース硬さで400～600HVの硬さを有する相であることを特徴とする請求項３または４に記載の内燃機関用鉄基焼結合金製バルブシート。 The iron for an internal combustion engine according to claim 3 or 4, wherein the fine carbide precipitation phase is a phase in which fine carbides having a particle size of 10 µm or less are precipitated and have a Vickers hardness of 400 to 600 HV. Base sintered alloy valve seat.
  8. 　前記固体潤滑剤粒子が、硫化マンガンMnS、二硫化モリブデンMoS2のうちから選ばれた１種または２種であることを特徴とする請求項１ないし７のいずれかに記載の鉄基焼結合金製バルブシート。 8. An iron-based sintered alloy according to any one of claims 1 to 7, wherein said solid lubricant particles are one or two selected from manganese sulfide MnS and molybdenum disulfide MoS2. valve seat.
  9. 　前記硬度改善粒子が、鉄―モリブデン合金粒子であることを特徴とする請求項１に記載の鉄基焼結合金製バルブシート。 The valve seat made of an iron-based sintered alloy according to claim 1, wherein the hardness improving particles are iron-molybdenum alloy particles.
PCT/JP2022/028064 2021-07-20 2022-07-19 Iron-based sintered alloy valve seat for internal combustion engine WO2023002986A1 (en)

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CN202280050508.5A CN117677452A (en) 2021-07-20 2022-07-19 Iron-base sintered alloy valve seat for internal combustion engine
KR1020247002605A KR20240024986A (en) 2021-07-20 2022-07-19 Iron sintered alloy valve seat for internal combustion engines
JP2023129438A JP2023156411A (en) 2021-07-20 2023-08-08 Valve seat constituted of iron-based sintered alloy for internal combustion engine

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JP2003119542A (en) * 2001-08-06 2003-04-23 Hitachi Powdered Metals Co Ltd Abrasion resistant sintered member and manufacturing method therefor
JP2016060922A (en) * 2014-09-16 2016-04-25 株式会社リケン Cu-BASED SINTERED ALLOY AND MANUFACTURING METHOD THEREFOR
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JP3926320B2 (en) 2003-01-10 2007-06-06 日本ピストンリング株式会社 Iron-based sintered alloy valve seat and method for manufacturing the same
JP4368245B2 (en) 2004-05-17 2009-11-18 株式会社リケン Hard particle dispersion type iron-based sintered alloy
JP5887374B2 (en) 2014-03-19 2016-03-16 株式会社リケン Ferrous sintered alloy valve seat
JP6736227B2 (en) 2016-11-28 2020-08-05 日本ピストンリング株式会社 Valve seat made of iron-based sintered alloy for internal combustion engine with excellent wear resistance and combination of valve seat and valve

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JP2003119542A (en) * 2001-08-06 2003-04-23 Hitachi Powdered Metals Co Ltd Abrasion resistant sintered member and manufacturing method therefor
JP2016060922A (en) * 2014-09-16 2016-04-25 株式会社リケン Cu-BASED SINTERED ALLOY AND MANUFACTURING METHOD THEREFOR
JP2016216762A (en) * 2015-05-15 2016-12-22 山陽特殊製鋼株式会社 Alloy powder

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