WO2024096134A1 - Lightweight hard alloy and lightweight hard alloy member - Google Patents

Lightweight hard alloy and lightweight hard alloy member Download PDF

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Publication number
WO2024096134A1
WO2024096134A1 PCT/JP2023/039776 JP2023039776W WO2024096134A1 WO 2024096134 A1 WO2024096134 A1 WO 2024096134A1 JP 2023039776 W JP2023039776 W JP 2023039776W WO 2024096134 A1 WO2024096134 A1 WO 2024096134A1
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Prior art keywords
hard alloy
lightweight
mass
less
powder
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PCT/JP2023/039776
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French (fr)
Japanese (ja)
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僚太 佐藤
勉 小椋
隆行 庄司
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冨士ダイス株式会社
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Publication of WO2024096134A1 publication Critical patent/WO2024096134A1/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
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • 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
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/05—Mixtures of metal powder with non-metallic powder
    • C22C1/051—Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
    • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
    • C22C29/04—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbonitrides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
    • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
    • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
    • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
    • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
    • C22C29/10—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds based on titanium carbide
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ

Definitions

  • the present invention relates to a lightweight hard alloy and a lightweight hard alloy component using the same.
  • cemented carbide are often used for wear-resistant components that rotate at high speeds and are large in size, such as screws and crushing blades used to crush, mix, or knead resins and magnetic materials.
  • cemented carbide has high toughness, the specific gravity of WC is high at 15.6, so components such as large screws and crushing blades are heavy, which can cause deflection in cantilevered components, and makes it difficult to increase the rotation speed.
  • ceramics are lightweight but have low toughness, and the problem is that they are prone to chipping due to interference between wear-resistant components. For this reason, when attempting to add metal components to increase toughness, there are limitations to obtaining a material with both strength and toughness, as the ceramic particles and metal components have poor wettability and low sinterability.
  • Patent Document 1 discloses a highly tough cermet in which needle-shaped precipitates containing W as one of the component elements are dispersed in a matrix containing 5-25% by weight of TiC, 25-50% by weight of WC, and 5-40% by weight of Ni+Co. However, because it contains a large amount of WC, 25-50% by weight, it also becomes a heavy tool component.
  • Patent Document 2 discloses a cermet obtained by press-molding a mixed powder having a composition of 25-50% by weight of TiN, 10-30% by weight of TiC, 5-25% by weight of one or more of carbides of Ta, Nb, and Zr, 10-25% by weight of one or more of WC and Mo2C , and 5-25% by weight of one or more of Co and Ni, and sintering the resulting green compact.
  • a cermet obtained by press-molding a mixed powder having a composition of 25-50% by weight of TiN, 10-30% by weight of TiC, 5-25% by weight of one or more of carbides of Ta, Nb, and Zr, 10-25% by weight of one or more of WC and Mo2C , and 5-25% by weight of one or more of Co and Ni, and sintering the resulting green compact.
  • it contains a large amount of titanium nitride, the grindability is poor, and the productivity decreases in wear-resistant tools with a large grinding
  • Cermets made primarily of Ti compounds such as TiC and Ti(C,N) are materials that combine the toughness of cemented carbide with the lightweight properties of ceramics.
  • TiC and Ti(C,N) have relatively good wettability with Ni and Co, allowing dense sintered bodies to be obtained, and because they contain a metallic bonding phase, they have higher fracture toughness than ceramics.
  • TiC and Ti(C,N) also have a lower specific gravity than WC, making cermets lighter than cemented carbide.
  • existing cermets do not meet the toughness required for wear-resistant components, and there have been problems with chipping during use. In addition, cracks are prone to occur during sintering, making it difficult to obtain relatively large sintered bodies.
  • Non-Patent Document 1 discloses TiC-based and Ti(C, N ) -based cermets with compositions of TiC-, Ti( C0.7N0.3 )-, Ti( C0.5N0.5 )-19% by mass Mo2C-24% by mass Ni, using commercially available TiC (average particle size by FSSS method: 1.4 ⁇ m), Ti( C0.7N0.3 ) ( 1.4 ⁇ m), Ti( C0.5N0.5 ) (1.4 ⁇ m), Mo2C ( 3.6 ⁇ m), and Ni (2.5 ⁇ m).
  • Ti(C,N)-based cermets have the problem that they tend to generate fine powder when mixed with the powder, and tend to crack when sintering thick-walled products.
  • the object of the present invention is therefore to provide a lightweight hard alloy that is both lightweight and tough, and that is less likely to crack during sintering even in thick-walled products and has excellent grindability, as well as a lightweight hard alloy part that uses the same.
  • the titanium compound powder which is the main component
  • Ti(C,N) powder produced by the heated carbonitriding method has been widely used.
  • fine powder is likely to be generated when the powder is pulverized and classified after carbonitriding to adjust to the specified particle size, so there is a lot of fine powder at the raw powder stage used to produce the alloy, and the fine powder increases when the powder is mixed because it is further pulverized.
  • the generation of this fine powder generates a lot of fine hard phases in the sintered body structure, while hard phases with relatively large particle sizes tend to grow even more easily. As a result, it was found that the hard phase/hard phase adhesive interface increases, cracks are more likely to progress, and hardness decreases.
  • a lightweight hard alloy obtained by sintering a mixed powder having a carbon-containing titanium compound as the main component, hard phase constituent particles containing 5 to 33 mass% WC and/or Mo2C , and binder phase constituent particles containing 5 to 40 mass% Ni and/or Co by setting the BET value x theoretical specific gravity of the mixed powder to 38 or less, a lightweight hard alloy can be obtained in which the average particle size of the hard phase is 1 to 3.5 ⁇ m, which achieves both light weight and high toughness, and which is less likely to crack during sintering and has excellent grindability, and thus arrived at the present invention.
  • a lightweight hard alloy according to one embodiment of the present invention is a lightweight hard alloy obtained by sintering a mixed powder having a carbon-containing titanium compound as its main component, hard phase constituent particles containing 5 to 33 mass% WC and/or Mo2C , and binder phase constituent particles containing 5 to 40 mass% Ni and/or Co, and is characterized in that the BET value x theoretical specific gravity of the mixed powder is 38 or less, and the average particle size of the hard phase is 1 to 3.5 ⁇ m.
  • the particle amount A is expressed by the following formula (1) relative to the content X (volume %) of Ni and/or Co contained in the mixed powder: A ⁇ -1.3X +53.4 ... (1) or is preferably 20 volume % or less.
  • the titanium compound preferably includes at least one compound selected from the group consisting of titanium carbide and titanium carbonitride.
  • the titanium compound preferably contains titanium carbonitride, and the nitrogen content of the titanium carbonitride is preferably less than 8 mass%.
  • the Co content in the entire mixed powder is preferably 9.5 mass% or less.
  • the hard phase particles preferably further contain 5 mass % or less of Cr3C2 .
  • the lightweight hard alloy component according to one embodiment of the present invention is characterized by using the lightweight hard alloy described above.
  • the present invention provides a lightweight hard alloy that is both lightweight and highly tough, and is less likely to crack during sintering even in thick-walled products, and has excellent grindability. This makes it ideal for use in wear-resistant parts that are large in size and rotate at high speeds, such as screws and crushing blades, and can dramatically improve production efficiency in crushing, mixing, and kneading. For example, it is suitable for use as tools and crushing blades for crushing, mixing, and kneading resins and magnetic materials. Also, because it has similar characteristics, it is suitable for use as peripheral parts for molds and lens molding.
  • the lightweight hard alloy according to one embodiment of the present invention is a lightweight hard alloy obtained by sintering a mixed powder having a carbon-containing titanium compound as a main component, hard phase constituent particles containing 5 to 33 mass% WC and/or Mo2C , and binder phase constituent particles containing 5 to 40 mass% Ni and/or Co, in which the BET value x theoretical specific gravity of the mixed powder is 38 or less, and the average grain size of the hard phase is 1 to 3.5 ⁇ m.
  • the titanium compound constituting the main component of the hard phase constituent particles is a titanium compound containing carbon, and specifically, it is preferably at least one compound selected from the group consisting of titanium carbide and titanium carbonitride. Furthermore, titanium nitride may be contained in an amount of up to 5 mass% of the total amount of the titanium compound. Since carbon-containing titanium compounds have high hardness and excellent wear resistance, when they are included as the main component of the hard phase constituent particles, a lightweight hard alloy with excellent wear resistance can be obtained.
  • the mixed powder contains 5 to 33 mass% of WC and/or Mo2C as hard phase constituent particles. If this content is less than 5 mass%, the surrounding structure may not be sufficiently formed in the hard phase of the lightweight hard alloy, making it difficult to control the grain size and resulting in insufficient strength. On the other hand, if it exceeds 33 mass%, the hardness of the lightweight hard alloy may be too high and the toughness may decrease.
  • the content of WC and Mo2C contained in the hard phase constituent particles is preferably 7 to 30 mass%, more preferably 10 to 26 mass%.
  • the mixed powder preferably further contains Cr as a hard phase constituent particle in an amount of 5% by mass or less calculated as Cr3C2 . This can improve the corrosion resistance of the lightweight hard alloy. If the Cr content exceeds 5% by mass calculated as Cr3C2 , the toughness may decrease. Cr may be added in the form of carbide or nitride, or may be added as an alloy of Ni or Cr. The Cr content is more preferably 0.1 to 2.0% by mass calculated as Cr3C2 , and even more preferably 0.25 to 3.0% by mass.
  • the carbon-containing titanium compound is the "main component" means that the content of the carbon-containing titanium compound is greater than the total content of WC, Mo2C , and Cr3C2 in terms of mass ratio.
  • the content of the carbon-containing titanium compound is preferably 1.5 to 5 times, more preferably 2 to 4 times , the total content of WC, Mo2C , and Cr3C2 in terms of mass ratio.
  • At least a part of WC, Mo2C , and Cr3C2 may be added as a solid solution with a Ti compound.
  • compounds of Group 4 to 6 elements other than Ti, W, Mo, and Cr may be included up to 5 mass% in terms of compound of the total amount of the mixed powder.
  • Group 4 to 6 elements other than Ti, W, Mo, and Cr may be added as a solid solution with a Ti compound.
  • the hard phase forms a core-rim structure with the titanium compound as the main component of the core and the peripheral structure around it. Some of them also form a solid solution in the binder phase.
  • the nitrogen content of the titanium carbonitride is less than 8 mass%. If the nitrogen content of the titanium carbonitride is 8 mass% or more, it is effective in improving wear resistance by leaving the core phase of titanium carbonitride and improving strength and alloy hardness by suppressing grain growth of the hard phase, but it also causes problems such as reduced productivity and increased costs due to poor grindability and increased processing time for wear-resistant components.
  • the mixed powder contains 5-40 mass% Ni and/or Co as binder phase constituent particles. If this content is less than 5 mass%, the necessary strength of the lightweight hard alloy cannot be maintained, and if it exceeds 40 mass%, the necessary wear resistance cannot be maintained.
  • the Ni and Co content is preferably 10-38 mass%, and more preferably 16-36 mass%.
  • a portion of the binder phase constituent particles may be replaced with Fe. The amount of Fe substituted is preferably 10-30 mass% of the total Ni and Co content.
  • the Co content of the entire mixed powder is preferably 9.5 mass% or less. If the Co content exceeds 9.5 mass%, the wettability with the hard phase decreases, which may reduce sinterability, or the interfacial strength may decrease, making cracks more likely to develop. It is more preferable that the Co content of the entire mixed powder is 9 mass% or less.
  • the product of the BET value and the theoretical specific gravity of the mixed powder is 38 or less.
  • the BET value is the total surface area per unit weight (1 g) of the mixed powder measured by the BET method, expressed in square meters, and corresponds to the specific surface area ( m2 /g) of the mixed powder.
  • the theoretical specific gravity of the mixed powder is calculated from the specific gravity and composition ratio of each raw material powder used.
  • the product of the BET value and the theoretical specific gravity of the mixed powder is a dimensionless number.
  • the mixed powder of the lightweight hard alloy of the present invention contains a titanium compound containing carbon as the main component of the hard phase constituent particles, and contains WC and/or Mo2C .
  • the specific gravity of WC is 15.6, the specific gravity of Mo2C is 9.18, while the specific gravity of TiC is 4.92, for example, and there is a large difference in the specific gravity of each component, so the specific gravity of the mixed powder changes greatly depending on the content ratio of those.
  • the amount of powder per unit weight (1 g) also changes, so the BET value cannot fully express the characteristics of the mixed powder. Therefore, by multiplying the BET value by the theoretical specific gravity of the mixed powder, the specific surface area of the powder per volume when the mixed powder is considered as a dense body is used as an index.
  • the BET value x theoretical specific gravity of the mixed powder exceeds 38, the specific surface area per volume of the mixed powder becomes too large, resulting in a large amount of fine powder in the mixed powder or an excessively small average particle size of the mixed powder. This makes it easier for fine hard phases to form in the lightweight hard alloy, and the fine powder dissolves and reprecipitates, making it easier for the surrounding structure (rim phase) of the hard phase to form.
  • the surrounding structure has low strength, and the adhesion of the hard phase increases with the formation of the surrounding structure, so fracture toughness decreases, and sufficient strength is not obtained and chipping is likely to occur.
  • the BET value x theoretical specific gravity of the mixed powder is preferably 38 or less, more preferably 36 or less, and even more preferably 35 or less.
  • the particle amount A is expressed by the following formula (1) relative to the content X (volume %) of Ni and/or Co contained in the mixed powder: A ⁇ -1.3X +53.4 ... (1) or is preferably 20% by volume or less.
  • the particle size distribution of the mixed powder may be measured by a laser diffraction type particle size distribution measuring device. From the particle size distribution of the obtained mixed powder, the amount A of particles having a particle size of 0.8 ⁇ m or less is calculated in terms of volume ratio.
  • the particle amount A satisfies A ⁇ -1.3X+53.4 or is 20% by volume or less, fine hard phases are unlikely to be formed in the lightweight hard alloy structure, and since the amount of fine powder is small, peripheral structures are unlikely to be formed due to dissolution and reprecipitation during sintering. It is more preferable that the particle amount A satisfies A ⁇ -1.3X+53.4, and it is even more preferable that the particle amount A is A ⁇ -X+41.3.
  • the particle amount A may be A ⁇ -1.3X+53.4 or may be 20% by volume or less of the entire mixed powder. The particle amount A may also be 20% by volume or less of the entire mixed powder.
  • the average grain size of the hard phase is 1 to 3.5 ⁇ m.
  • the average grain size of the hard phase is determined by the Fulman formula based on the SEM structure of any cross section of the lightweight hard alloy. If the average grain size of the hard phase is less than 1 ⁇ m, the wear resistance may be slightly inferior depending on the usage conditions. If the average grain size of the hard phase is more than 3.5 ⁇ m, the strength may be insufficient.
  • the average grain size of the hard phase is preferably 1.0 to 3.0 ⁇ m, more preferably 1.2 to 2.8 ⁇ m, and even more preferably 1.3 to 2.6 ⁇ m.
  • Manufacturing method of the lightweight hard alloy is a method in which powders of the above-mentioned hard phase constituent particles and binder phase constituent particles are blended, wet mixed and ground in an organic solvent, dried, and then the powder to which a binder such as paraffin has been added is pressed to form a green body, and the green body is sintered to obtain the lightweight hard alloy.
  • the mixed powder compact may be press-molded to a state close to the finished product (near net shape), or it may be machined to give it a desired shape. It may also be machined after preliminary sintering to give it a desired shape.
  • the atmosphere during sintering may be a vacuum or an inert gas.
  • a compact made of mixed powder containing nitrogen nitrogen or a mixed gas containing nitrogen may be used, or CO gas may be used.
  • the introduction temperature and gas pressure of these atmospheric gases may be varied depending on the purpose.
  • the heating rate, sintering temperature and holding time, as well as the temperature holding time and gas pressure on the way thereto, can be selected as desired depending on the purpose, such as degreasing, improving sinterability, or improving surface properties.
  • Titanium compounds are often made using metallic titanium, titanium hydride, titanium oxide, etc. as the main raw materials, and the finished titanium compounds, such as TiC produced by the Menstrum process and Ti(C,N) produced by the heated carbonitriding process, are crushed and classified to control the particle size within a specified range.
  • the crushing process produces powder that is finer than the desired particle size. It has been found that the presence of a certain amount of this fine powder in titanium compound powder is one of the causes of the low toughness of lightweight hard alloys. To increase the toughness of lightweight hard alloys that use this titanium compound powder, it is necessary to reduce the amount of fine powder contained in the mixed powder before sintering.
  • mixing conditions that do not easily generate fine powder. It is necessary to set conditions that can obtain a specified average particle size even if the mixing time is shortened.
  • mixing conditions such as the ball mill rotation speed, powder amount, solvent amount, ball amount, ball diameter, and mixing and grinding time can be set, and it was found that any of the parameters can be changed, and it is essential that the value obtained by multiplying the specific surface area ( m2 /g) of the mixed powder by the theoretical specific gravity is 38 or less.
  • some raw material powders contain fine powder at the raw material powder stage as mentioned above, and that the fine powder can be removed by various methods, or that the same effect can be obtained by using a titanium compound powder that contains less fine powder.
  • the sintering temperature is preferably 1330-1450°C so as not to cause the surrounding structure of the hard phase to grow too much.
  • sintering may be performed using sinter-HIP, or a normally sintered sintered body may be subjected to HIP treatment.
  • Sintering may be performed by hot press sintering or electromagnetic energy assisted sintering such as electric current sintering or SPS sintering.
  • the lightweight hard alloy of the present invention is suitable for use in wear-resistant parts that are large in size and rotate at high speed, such as screws and crushing blades. Therefore, the lightweight hard alloy parts using the lightweight hard alloy of the present invention can exhibit excellent performance, for example, when used as crushing, mixing or kneading parts.
  • the lightweight hard alloy of the present invention is not limited to these applications, and can be used for punching punches, room temperature, warm and hot forming dies, extrusion dies, dies and forging punches because it is difficult to crack when using the tool, and is also effective for use in lens molding peripheral parts such as barrel dies for special lenses with a large thermal expansion coefficient because it is difficult to chip or crack when handling the parts.
  • Examples 1 to 15 and Comparative Examples 1 to 9 The raw powders prepared were TiC powder (1.4 ⁇ m, 2.1 ⁇ m, 2.9 ⁇ m, 3.5 ⁇ m), Ti(C0.7N0.3 ) powder (1.4 ⁇ m), (Ti,Mo)(C,N) powder (1.5 ⁇ m), WC powder (0.6 ⁇ m), Mo2C powder (3.2 ⁇ m), Cr3C2 powder ( 1.3 ⁇ m ), Ni powder (2.4 ⁇ m), and Co powder (1.9 ⁇ m) (numbers in parentheses are average particle sizes measured by Fischer particle size measurement method (FSSS method)).
  • FSSS method Fischer particle size measurement method
  • the (Ti,Mo)(C,N) powder was prepared by preparing a mixed powder with the composition Ti( C0.7N0.3 )-25 mass% Mo2C , heat treating it in nitrogen , crushing and classifying it.
  • inventive product 6 used 2.1 ⁇ m TiC powder
  • inventive product 9 used 2.9 ⁇ m TiC powder
  • comparative product 9 used 3.5 ⁇ m TiC powder
  • the rest used 1.4 ⁇ m TiC powder.
  • the measured powders were mixed and wet mixed and ground using a ball mill.
  • the mixed and ground conditions were adjusted while taking into consideration the amount of fine powder contained in the titanium compound raw powder so that the BET value x theoretical specific gravity of the invented product was 38 or less and the average particle size of the hard phase of the resulting sintered body was 1 to 3.5 ⁇ m.
  • the grinding level of the grinding strength was rated as "2" when it was normal strength, "1" when it was weaker, "3" when it was stronger, and "4" when it was stronger than grinding level “3”.
  • Table 2 also shows the volume ratios of the Ni amount, Co amount, and (Ni+Co) amount in the mixed powder, and the upper limit A' of the volume ratio of particles with a particle size of 0.8 ⁇ m or less contained in the mixed powder.
  • the powder after grinding and mixing was dried using a vacuum dryer, and a binder was added to produce a mixed powder.
  • a binder was added to produce a mixed powder.
  • the particle size distribution of the mixed powder was measured using an MT3300EXII (Microtrack Bell Co., Ltd.), and the amount A of particles with a particle size of 0.8 ⁇ m or less was calculated as a volume ratio. The results are shown in Table 3.
  • the BET value of the mixed powder was measured using a TriStar II 3020 (Micromeritics).
  • the theoretical specific gravity of the mixed powder was calculated from the specific gravity and composition ratio of the raw powder of each sample.
  • the BET value x theoretical specific gravity of each sample is shown in Table 3.
  • the obtained mixed powder was pressed into a cylinder of ⁇ 20 ⁇ H20 (mm) at a pressure of 98 N/ mm2 , and then sintered at a sintering temperature of 1400°C for one hour to produce invention products 1 to 15 and comparison products 1 to 9.
  • Test pieces for the transverse strength test were also prepared in the same manner after being pressed into a rectangular parallelepiped of 6 ⁇ 11 ⁇ 31 (mm).
  • the transverse strength of each sample was measured by a three-point bending test based on JIS R 1601.
  • the fracture toughness value K IC of each sample was also measured and calculated based on JIS R 1607. The results are shown in Table 3.
  • a diamond wheel grinding stone (#140) was used to perform surface grinding at a cutting depth of 5 ⁇ m, and a sharp edge of 20° was processed.
  • the size of the chipping at the tip of the sharp edge of each sample was evaluated from 0 to 5.
  • chipping width was 0.9 times or more but less than 1.1 times the width of the chipping of invention product 4, it was rated as "4", if it was less than 0.9 times, it was rated as "5", if it was 1.1 times or more but less than 1.2 times, it was rated as "3", if it was 1.2 times or more but less than 1.3 times, it was rated as "2”, if it was 1.3 times or more but less than 1.4 times, it was rated as "1”, and if it was rated as 1.4 times or more, it was rated as "0". If the chipping resistance did not meet the rating of "1" in this evaluation, that is, if it was rated as "0", the wear resistance was not evaluated.
  • inventive products 1, 3, 4, 6, 11, 12, 14 and 15 the amount of fine powder in the mixed powder is small because the Ti compound powder with less fine powder was used. Therefore, the alloy is unlikely to form a relatively fine hard phase and the peripheral structure of the hard phase (rim phase) is also unlikely to form, so that it has both wear resistance and chipping resistance.
  • inventive products 2 and 5 even when raw material powder with a lot of fine powder is used, the amount of fine powder in the mixed powder is kept low by weakening the grinding conditions, so that the fine hard phase is unlikely to form and the rim phase is also unlikely to form, so that it has both wear resistance and chipping resistance.
  • Inventive products 7 and 8 are both high-hardness alloys with a small amount of binder phase, but the powder particle amount A and the BET value x theoretical specific gravity are within the specified range, so that both have minimum chipping resistance and extremely high wear resistance.
  • Inventive products 9 and 10 are high-toughness alloys with a large amount of binder phase, so that they have extremely high chipping resistance while having minimum wear resistance.
  • Invention product 13 uses (Ti,Mo)(C,N) solid solution powder, and has a smaller particle amount A and a smaller BET value x theoretical specific gravity than Invention product 2 , which has the same alloy composition but uses Ti( C0.7N0.3 ) powder and Mo2C powder. Therefore, while having roughly the same wear resistance, it tends to have better chipping resistance.
  • Comparative Product 1 In contrast, the total amount of WC and/or Mo2C in Comparative Product 1 is small, and the formation of the peripheral structure (rim phase) is insufficient. Therefore, the bending strength is low, and both the wear resistance and chipping resistance are low. Comparative Product 2 has too much total amount of WC and/or Mo2C , so the ratio of the rim phase increases and the hardness decreases, and the wear resistance is also low. Similarly, the chipping resistance is low because the ratio of the rim phase increases. Comparative Product 3 uses raw powder with little fine powder, but the grinding conditions are strong, so the BET value x theoretical specific gravity is large at 62, and for the same reason, the chipping resistance is low.
  • Comparative Product 4 uses raw powder with a lot of fine powder, even under normal grinding conditions, so the BET value x theoretical specific gravity is large at 60, and there is a large amount of fine powder in the mixed powder, and many fine hard phases are generated in the alloy structure, and the rim phase is also large, so the chipping resistance is low. Comparative Product 5 does not meet the minimum chipping resistance of "1" because the (Ni + Co) amount is small at 3.0 mass%.
  • the powder containing a large amount of fine powder was strongly crushed, so the BET value x theoretical specific gravity was large at 71, the hard phase grain size was small, the peripheral structure ratio was high, and the fracture toughness was reduced, so it did not meet the minimum chipping resistance of "1".

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Abstract

[Problem] To provide: a lightweight hard alloy that achieves both light weight and high toughness and has excellent machinability and low susceptibility to cracking during sintering even in a thick-walled product; and a lightweight hard alloy member that uses the same. [Solution] A lightweight hard alloy according to the present invention comprises, as the main component thereof, a titanium compound containing carbon, and is formed by sintering a mixed powder having hard phase constituent particles containing WC and/or Mo2C at 5 to 33 mass%, and binding phase constituent particles containing Ni and/or Co at 5 to 40 mass%, wherein the product of a BET value and the theoretical specific gravity of the mixed powder is 38 or less, and the average particle diameter of the hard phase is 1 to 3.5 μm.

Description

軽量硬質合金及び軽量硬質合金部材Lightweight hard alloys and lightweight hard alloy components
　本発明は、軽量硬質合金、及びそれを用いた軽量硬質合金部材に関する。 The present invention relates to a lightweight hard alloy and a lightweight hard alloy component using the same.
　近年、樹脂や磁性体材料を粉砕、混合又は混錬するためのスクリューや粉砕刃などのサイズが大きく高速回転を伴う耐摩耗部材にはセラミックスや超硬合金が用いられることが多い。超硬合金は高靭性ではあるがWCの比重が15.6と大きいため、サイズが大きいスクリューや粉砕刃などの部材は重量が大きくなってしまい、片持ちのものではたわみの原因になったり、回転速度を上げられないという問題がある。 In recent years, ceramics and cemented carbide are often used for wear-resistant components that rotate at high speeds and are large in size, such as screws and crushing blades used to crush, mix, or knead resins and magnetic materials. Although cemented carbide has high toughness, the specific gravity of WC is high at 15.6, so components such as large screws and crushing blades are heavy, which can cause deflection in cantilevered components, and makes it difficult to increase the rotation speed.
　一方、セラミックスは軽量であるが靭性が低く、耐摩耗部材同士の干渉により欠けやすいという問題がある。このため靭性を高めるために金属成分を添加しようとするとセラミックス粒子と金属成分は濡れ性が悪く焼結性が低いため、強度・靭性を有する材料を得るには限界がある。 On the other hand, ceramics are lightweight but have low toughness, and the problem is that they are prone to chipping due to interference between wear-resistant components. For this reason, when attempting to add metal components to increase toughness, there are limitations to obtaining a material with both strength and toughness, as the ceramic particles and metal components have poor wettability and low sinterability.
　特許文献１は、TiC：５～25重量％、WC：25～50重量％及びNi+Co：５～40重量％を含むマトッリクス中に、Ｗを成分元素の一部として含む針状析出物を分散した高靱性サーメットを開示している。しかし、WCを25～50重量％と多量に含むため、工具部材としても重い工具となってしまう。 Patent Document 1 discloses a highly tough cermet in which needle-shaped precipitates containing W as one of the component elements are dispersed in a matrix containing 5-25% by weight of TiC, 25-50% by weight of WC, and 5-40% by weight of Ni+Co. However, because it contains a large amount of WC, 25-50% by weight, it also becomes a heavy tool component.
　特許文献２は、TiN：25～50重量％、TiC：10～30重量％、Ta、Nb及びZrの炭化物のうちの１種又は２種以上：５～25重量％、WC及びMo2Cのうちの１種又は２種：10～25重量%、及びCo及びNiのうちの１種又は２種：５～25重量％の配合組成からなる混合粉末をプレス成形し、得られた圧粉体を焼結してなるサーメットを開示している。しかし、窒化チタンを多く含むため研削性が悪く、研削しろが多い耐摩耗工具では生産性が低下する。 Patent Document 2 discloses a cermet obtained by press-molding a mixed powder having a composition of 25-50% by weight of TiN, 10-30% by weight of TiC, 5-25% by weight of one or more of carbides of Ta, Nb, and Zr, 10-25% by weight of one or more of WC and Mo2C , and 5-25% by weight of one or more of Co and Ni, and sintering the resulting green compact. However, since it contains a large amount of titanium nitride, the grindability is poor, and the productivity decreases in wear-resistant tools with a large grinding allowance.
　超硬合金の靭性とセラミックスの軽量性の両方の特徴を併せ持った材料としてTiC、Ti(C,N)等のTi化合物を主成分としたサーメットがある。TiCやTi(C,N)はNiやCoとの濡れ性が比較的優れることから緻密な焼結体が得られ、さらに金属結合相を含むためセラミックスよりも破壊靭性が高い。またTiCやTi(C,N)はWCよりも比重は小さいためサーメットの重さは超硬合金よりも軽量である。しかし、既存のサーメットは超硬合金と比べて耐摩耗部材として必要とされる靭性を満たさず、使用中の欠け等の点で問題があった。また、焼結時に割れが生じやすく比較的大きい焼結体を得られない場合があった。 Cermets made primarily of Ti compounds such as TiC and Ti(C,N) are materials that combine the toughness of cemented carbide with the lightweight properties of ceramics. TiC and Ti(C,N) have relatively good wettability with Ni and Co, allowing dense sintered bodies to be obtained, and because they contain a metallic bonding phase, they have higher fracture toughness than ceramics. TiC and Ti(C,N) also have a lower specific gravity than WC, making cermets lighter than cemented carbide. However, compared to cemented carbide, existing cermets do not meet the toughness required for wear-resistant components, and there have been problems with chipping during use. In addition, cracks are prone to occur during sintering, making it difficult to obtain relatively large sintered bodies.
　非特許文献１は、市販TiC（FSSS法による平均粒度：1.4μm），Ti(C0.7N0.3)（1.4μm），Ti(C0.5N0.5)（1.4μm），Mo2C（3.6μm），Ni（2,5μm）を用いて、TiC-，Ti(C0.7N0.3)-，Ti(C0.5N0.5)-19質量％Mo2C-24質量％Ni組成のTiC基及びTi(C,N)基サーメットを開示している。しかし、Ti(C,N)基サーメットは粉末混合時に微粉を生じやすく、肉厚品を焼結する際に割れを生じやすいという問題がある。 Non-Patent Document 1 discloses TiC-based and Ti(C, N ) -based cermets with compositions of TiC-, Ti( C0.7N0.3 )-, Ti( C0.5N0.5 )-19% by mass Mo2C-24% by mass Ni, using commercially available TiC (average particle size by FSSS method: 1.4 μm), Ti( C0.7N0.3 ) ( 1.4 μm), Ti( C0.5N0.5 ) (1.4 μm), Mo2C ( 3.6 μm), and Ni (2.5 μm). However, Ti(C,N)-based cermets have the problem that they tend to generate fine powder when mixed with the powder, and tend to crack when sintering thick-walled products.
特開平3-281752号公報Japanese Patent Application Laid-Open No. 3-281752 特開昭59-229431号公報Japanese Patent Publication No. 59-229431
　従って、本発明の目的は、軽量化と高靭性化を両立させ、かつ肉厚品でも焼結時の割れが生じにくく被研削性にも優れる軽量硬質合金、及びそれを用いた軽量硬質合金部材を提供することである。 The object of the present invention is therefore to provide a lightweight hard alloy that is both lightweight and tough, and that is less likely to crack during sintering even in thick-walled products and has excellent grindability, as well as a lightweight hard alloy part that uses the same.
　前記課題を解決するため、TiC基及びTi(C,N)基サーメットの靭性が低い原因を調べ、求められる因子を見つけて合金設計することによって、同一硬さにおける靭性を向上させることを試みた。 To solve the above problem, we investigated the causes of the low toughness of TiC-based and Ti(C,N)-based cermets, and attempted to improve toughness at the same hardness by identifying the desired factors and designing the alloy.
　まず、主成分であるチタン化合物粉末を見直した。従来、例えばTi(C,N)粉末は加熱炭窒化法により作製されたものが広く用いられる。しかし、炭窒化後に粉砕し分級して所定の粒度に調整する際に微粉が発生しやすいことから合金作製に用いる原料粉末の段階で微粉が多く、また混合時にはさらに粉砕されるため微粉が増加する。この微粉の発生により焼結体組織には微粒な硬質相が多く発生する一方、相対的に粒径が大きい硬質相はさらに粒成長しやすくなる。その結果、硬質相／硬質相接着界面が増加してクラックは進展しやすくなり、硬さも低下することが分かった。 First, the titanium compound powder, which is the main component, was reviewed. Conventionally, for example, Ti(C,N) powder produced by the heated carbonitriding method has been widely used. However, fine powder is likely to be generated when the powder is pulverized and classified after carbonitriding to adjust to the specified particle size, so there is a lot of fine powder at the raw powder stage used to produce the alloy, and the fine powder increases when the powder is mixed because it is further pulverized. The generation of this fine powder generates a lot of fine hard phases in the sintered body structure, while hard phases with relatively large particle sizes tend to grow even more easily. As a result, it was found that the hard phase/hard phase adhesive interface increases, cracks are more likely to progress, and hardness decreases.
　これらを解決するため種々検討した結果、本発明者らは、炭素を含むチタン化合物を主成分とし、WC及び／又はMo2Cを５～33質量％を含む硬質相構成粒子と、Ni及び／又はCoを５～40質量％含む結合相構成粒子とを有する混合粉末を焼結してなる軽量硬質合金において、混合粉末のBET値×理論比重を38以下とすることにより、硬質相の平均粒径が１～3.5μmであって、軽量化と高靭性化を両立させ、かつ焼結時に割れにくく被研削性にも優れる軽量硬質合金が得られることを発見し、本発明に想到した。 As a result of various investigations to solve these problems, the inventors discovered that in a lightweight hard alloy obtained by sintering a mixed powder having a carbon-containing titanium compound as the main component, hard phase constituent particles containing 5 to 33 mass% WC and/or Mo2C , and binder phase constituent particles containing 5 to 40 mass% Ni and/or Co, by setting the BET value x theoretical specific gravity of the mixed powder to 38 or less, a lightweight hard alloy can be obtained in which the average particle size of the hard phase is 1 to 3.5 μm, which achieves both light weight and high toughness, and which is less likely to crack during sintering and has excellent grindability, and thus arrived at the present invention.
　即ち、本発明の一実施態様による軽量硬質合金は、炭素を含むチタン化合物を主成分とし、WC及び／又はMo2Cを５～33質量％を含む硬質相構成粒子と、Ni及び／又はCoを５～40質量％含む結合相構成粒子とを有する混合粉末を焼結してなる軽量硬質合金であって、前記混合粉末のBET値×理論比重が38以下であり、硬質相の平均粒径が１～3.5μmであることを特徴とする。 That is, a lightweight hard alloy according to one embodiment of the present invention is a lightweight hard alloy obtained by sintering a mixed powder having a carbon-containing titanium compound as its main component, hard phase constituent particles containing 5 to 33 mass% WC and/or Mo2C , and binder phase constituent particles containing 5 to 40 mass% Ni and/or Co, and is characterized in that the BET value x theoretical specific gravity of the mixed powder is 38 or less, and the average particle size of the hard phase is 1 to 3.5 μm.
　前記混合粉末に含まれる粒径が0.8μm以下の粒子の量をA（体積％）としたとき、粒子量Aが、前記混合粉末に含まれるNi及び／又はCoの含有量X（体積％）に対し、下記式(1)：
A＜-1.3X+53.4                      ・・・(1)
を満たすか、又は20体積％以下であるのが好ましい。 When the amount of particles having a particle size of 0.8 μm or less contained in the mixed powder is A (volume %), the particle amount A is expressed by the following formula (1) relative to the content X (volume %) of Ni and/or Co contained in the mixed powder:
A < -1.3X +53.4 ... (1)
or is preferably 20 volume % or less.
　前記チタン化合物は、炭化チタン及び炭窒化チタンからなる群から選ばれる少なくとも一つの化合物を含むのが好ましい。 The titanium compound preferably includes at least one compound selected from the group consisting of titanium carbide and titanium carbonitride.
　前記チタン化合物は炭窒化チタンを含み、前記炭窒化チタンの窒素含有量が８質量％未満であるのが好ましい。 The titanium compound preferably contains titanium carbonitride, and the nitrogen content of the titanium carbonitride is preferably less than 8 mass%.
　前記混合粉末全体に対するCoの含有量は9.5質量％以下であるのが好ましい。 The Co content in the entire mixed powder is preferably 9.5 mass% or less.
　前記硬質相構成粒子はさらにCr3C2を５質量％以下含むのが好ましい。 The hard phase particles preferably further contain 5 mass % or less of Cr3C2 .
　本発明の一実施態様による軽量硬質合金部材は、上述の軽量硬質合金を用いることを特徴とする。 The lightweight hard alloy component according to one embodiment of the present invention is characterized by using the lightweight hard alloy described above.
　本発明によれば、軽量化と高靭性化を両立させ、かつ肉厚品でも焼結時の割れが生じにくく被研削性にも優れる軽量硬質合金が得られる。これにより、スクリューや粉砕刃などサイズが大きく高速回転を伴う耐摩耗部材に好適に用いられ、粉砕、混合、混錬における生産効率が飛躍的に向上できる。例えば、樹脂や磁性体材料の粉砕、混合、混錬するための工具、粉砕刃などの用途に適する。また同様の特徴を有するため、金型やレンズ成形用周辺部材にも適する。 The present invention provides a lightweight hard alloy that is both lightweight and highly tough, and is less likely to crack during sintering even in thick-walled products, and has excellent grindability. This makes it ideal for use in wear-resistant parts that are large in size and rotate at high speeds, such as screws and crushing blades, and can dramatically improve production efficiency in crushing, mixing, and kneading. For example, it is suitable for use as tools and crushing blades for crushing, mixing, and kneading resins and magnetic materials. Also, because it has similar characteristics, it is suitable for use as peripheral parts for molds and lens molding.
[1] 軽量硬質合金
　本発明の一実施態様による軽量硬質合金は、炭素を含むチタン化合物を主成分とし、WC及び／又はMo2Cを５～33質量％を含む硬質相構成粒子と、Ni及び／又はCoを５～40質量％含む結合相構成粒子とを有する混合粉末を焼結してなる軽量硬質合金であって、混合粉末のBET値×理論比重が38以下であり、硬質相の平均粒径が１～3.5μmである。 [1] Lightweight hard alloy The lightweight hard alloy according to one embodiment of the present invention is a lightweight hard alloy obtained by sintering a mixed powder having a carbon-containing titanium compound as a main component, hard phase constituent particles containing 5 to 33 mass% WC and/or Mo2C , and binder phase constituent particles containing 5 to 40 mass% Ni and/or Co, in which the BET value x theoretical specific gravity of the mixed powder is 38 or less, and the average grain size of the hard phase is 1 to 3.5 μm.
　硬質相構成粒子の主成分を構成するチタン化合物は炭素を含むチタン化合物であり、具体的には、炭化チタン及び炭窒化チタンからなる群から選ばれる少なくとも一つの化合物であるのが好ましい。またチタン化合物の総量のうち５質量％まで窒化チタンを含んでもよい。炭素を含むチタン化合物は高硬度かつ耐摩耗性に優れるので、硬質相構成粒子の主成分として含むと耐摩耗性に優れた軽量硬質合金が得られる。 The titanium compound constituting the main component of the hard phase constituent particles is a titanium compound containing carbon, and specifically, it is preferably at least one compound selected from the group consisting of titanium carbide and titanium carbonitride. Furthermore, titanium nitride may be contained in an amount of up to 5 mass% of the total amount of the titanium compound. Since carbon-containing titanium compounds have high hardness and excellent wear resistance, when they are included as the main component of the hard phase constituent particles, a lightweight hard alloy with excellent wear resistance can be obtained.
　混合粉末は、硬質相構成粒子としてWC及び／又はMo2Cを５～33質量％を含む。この含有量が５質量％未満であると、軽量硬質合金の硬質相に周辺組織が十分に形成されない場合があり粒度の制御がしにくく、十分な強度が得られない。一方、33質量％超であると、軽量硬質合金の硬さが高すぎて靭性が低下する恐れがある。硬質相構成粒子に含まれるWC及びMo2Cの含有量は７～30質量％であるのが好ましく、10～26質量％であるのがより好ましい。 The mixed powder contains 5 to 33 mass% of WC and/or Mo2C as hard phase constituent particles. If this content is less than 5 mass%, the surrounding structure may not be sufficiently formed in the hard phase of the lightweight hard alloy, making it difficult to control the grain size and resulting in insufficient strength. On the other hand, if it exceeds 33 mass%, the hardness of the lightweight hard alloy may be too high and the toughness may decrease. The content of WC and Mo2C contained in the hard phase constituent particles is preferably 7 to 30 mass%, more preferably 10 to 26 mass%.
　混合粉末は、硬質相構成粒子としてさらにCrをCr3C2換算で５質量％以下含むのが好ましい。それにより、軽量硬質合金の耐食性を高めることができる。Crの含有量がCr3C2換算で５質量％超であると靭性が低下する恐れがある。Crの添加形態は炭化物でも窒化物良く、NiやCrなどの合金として添加しても良い。Crの含有量がCr3C2換算で0.1～2.0質量％であるのがより好ましく、0.25～3.0質量％であるのがより好ましい。 The mixed powder preferably further contains Cr as a hard phase constituent particle in an amount of 5% by mass or less calculated as Cr3C2 . This can improve the corrosion resistance of the lightweight hard alloy. If the Cr content exceeds 5% by mass calculated as Cr3C2 , the toughness may decrease. Cr may be added in the form of carbide or nitride, or may be added as an alloy of Ni or Cr. The Cr content is more preferably 0.1 to 2.0% by mass calculated as Cr3C2 , and even more preferably 0.25 to 3.0% by mass.
　ここで、炭素を含むチタン化合物を「主成分」とするとは、炭素を含むチタン化合物の含有量が、質量比率でWC、Mo2C及びCr3C2の合計の含有量よりも多いことを意味する。炭素を含むチタン化合物の含有量が質量比でWC、Mo2C及びCr3C2の合計の含有量の1.5～５倍であるのが好ましく、２～４倍であるのがより好ましい。WC、Mo2C及びCr3C2の少なくとも一部をTi化合物との固溶体として添加しても良い。またTi、W、Mo、Cr以外の４～６族元素の化合物を、混合粉末の総量のうち化合物換算で５質量％まで含んでも良い。Ti、W、Mo、Cr以外の４～６族元素はTi化合物との固溶体として添加しても良い。 Here, the carbon-containing titanium compound is the "main component" means that the content of the carbon-containing titanium compound is greater than the total content of WC, Mo2C , and Cr3C2 in terms of mass ratio. The content of the carbon-containing titanium compound is preferably 1.5 to 5 times, more preferably 2 to 4 times , the total content of WC, Mo2C , and Cr3C2 in terms of mass ratio. At least a part of WC, Mo2C , and Cr3C2 may be added as a solid solution with a Ti compound. In addition , compounds of Group 4 to 6 elements other than Ti, W, Mo, and Cr may be included up to 5 mass% in terms of compound of the total amount of the mixed powder. Group 4 to 6 elements other than Ti, W, Mo, and Cr may be added as a solid solution with a Ti compound.
　WC、Mo2C及びCr3C2のW、Mo及びCrの一部は炭素を含むチタン化合物との固溶体として硬質相の周辺組織を形成する。すなわち、硬質相はチタン化合物を主成分とするコアとして周囲に周辺組織を有するコアリム構造を形成する。また一部は結合相に固溶する。 In WC, Mo2C and Cr3C2 , some of the W, Mo and Cr form a solid solution with the titanium compound containing carbon to form the peripheral structure of the hard phase. In other words, the hard phase forms a core-rim structure with the titanium compound as the main component of the core and the peripheral structure around it. Some of them also form a solid solution in the binder phase.
　硬質相構成粒子のチタン化合物が炭窒化チタンを含む場合、炭窒化チタンの窒素含有量が８質量％未満であるのが好ましい。炭窒化チタンの窒素含有量が８質量％以上であると、炭窒化チタンのコア相残存による耐摩耗性向上や硬質相の粒成長抑制による強度および合金硬さの向上に効果がある一方、研削性が悪化し耐摩耗部材の加工時間が増加するため生産性低下やコスト上昇という問題が生じる。 When the titanium compound of the hard phase constituent particles contains titanium carbonitride, it is preferable that the nitrogen content of the titanium carbonitride is less than 8 mass%. If the nitrogen content of the titanium carbonitride is 8 mass% or more, it is effective in improving wear resistance by leaving the core phase of titanium carbonitride and improving strength and alloy hardness by suppressing grain growth of the hard phase, but it also causes problems such as reduced productivity and increased costs due to poor grindability and increased processing time for wear-resistant components.
　混合粉末は、結合相構成粒子として、Ni及び／又はCoを５～40質量％含む。この含有量が５質量％未満であると、軽量硬質合金の必要な強度を保つことができず、40質量％超であると、必要な耐摩耗性を維持することができない。Ni及びCoの含有量は10～38質量％であるのが好ましく、16～36質量％であるのがより好ましい。結合相構成粒子の一部をFeと置き換えてもよい。Feの置換量はNi及びCoの合計含有量に対して10～30質量％であるのが好ましい。 The mixed powder contains 5-40 mass% Ni and/or Co as binder phase constituent particles. If this content is less than 5 mass%, the necessary strength of the lightweight hard alloy cannot be maintained, and if it exceeds 40 mass%, the necessary wear resistance cannot be maintained. The Ni and Co content is preferably 10-38 mass%, and more preferably 16-36 mass%. A portion of the binder phase constituent particles may be replaced with Fe. The amount of Fe substituted is preferably 10-30 mass% of the total Ni and Co content.
　混合粉末全体に対して、Coの含有量は9.5質量％以下であるのが好ましい。Coの含有量は9.5質量％超であると、硬質相との濡れ性が低下することにより焼結性が低下したり、界面強度の減少によりクラックが進展しやすくなる恐れがある。混合粉末全体に対して、Coの含有量は９質量％以下であるのがより好ましい。 The Co content of the entire mixed powder is preferably 9.5 mass% or less. If the Co content exceeds 9.5 mass%, the wettability with the hard phase decreases, which may reduce sinterability, or the interfacial strength may decrease, making cracks more likely to develop. It is more preferable that the Co content of the entire mixed powder is 9 mass% or less.
　混合粉末のBET値×理論比重が38以下である。BET値はBET法により測定した混合粉末の単位重量（１g）当たりの表面積を合計して平方メートル単位で表したものであり、混合粉末の比表面積（m2/g）に相当する。混合粉末の理論比重は、使用する各原料粉末の比重と組成比から算出する。混合粉末のBET値×理論比重は無次元数とする。 The product of the BET value and the theoretical specific gravity of the mixed powder is 38 or less. The BET value is the total surface area per unit weight (1 g) of the mixed powder measured by the BET method, expressed in square meters, and corresponds to the specific surface area ( m2 /g) of the mixed powder. The theoretical specific gravity of the mixed powder is calculated from the specific gravity and composition ratio of each raw material powder used. The product of the BET value and the theoretical specific gravity of the mixed powder is a dimensionless number.
　ここで、BET値×理論比重のパラメータとしての意義について説明する。本発明の軽量硬質合金の混合粉末は、硬質相構成粒子の主成分として炭素を含むチタン化合物を含み、WC及び／又はMo2Cを含んでいる。WCの比重が15.6であり、Mo2Cの比重が9.18であるのに対し、例えばTiCの比重は4.92であり、各成分の比重に大きな差があるため、それらの含有比によって混合粉末の比重が大きく変化する。その結果、単位重量（１g）当たりの粉末量も変化してしまうため、BET値では混合粉末の特性を十分に表すことができない。そのため、BET値に混合粉末の理論比重を乗じることにより、混合粉末を緻密体と考えたときの体積当たりの粉末の比表面積を指標としている。 Here, the significance of the BET value x theoretical specific gravity as a parameter will be explained. The mixed powder of the lightweight hard alloy of the present invention contains a titanium compound containing carbon as the main component of the hard phase constituent particles, and contains WC and/or Mo2C . The specific gravity of WC is 15.6, the specific gravity of Mo2C is 9.18, while the specific gravity of TiC is 4.92, for example, and there is a large difference in the specific gravity of each component, so the specific gravity of the mixed powder changes greatly depending on the content ratio of those. As a result, the amount of powder per unit weight (1 g) also changes, so the BET value cannot fully express the characteristics of the mixed powder. Therefore, by multiplying the BET value by the theoretical specific gravity of the mixed powder, the specific surface area of the powder per volume when the mixed powder is considered as a dense body is used as an index.
　混合粉末のBET値×理論比重が38超であると、混合粉末の体積当たりの比表面積が大きくなりすぎ、混合粉末中に微細な粉末が多量に存在したり、混合粉末の平均粒径が小さくなりすぎる状態になる。これにより軽量硬質合金において微細な硬質相が形成されやすくなるとともに、微細な粉末が溶解・再析出することで硬質相の周辺組織（リム相）も形成されやすくなる。周辺組織は強度も低く、また周辺組織形成に伴い硬質相の接着度も高くなるため破壊靭性も低下し、十分な強度が得られず欠けを生じやすい。混合粉末のBET値×理論比重は38以下であるのが好ましく、36以下であるのがより好ましく、35以下であるのがさらに好ましい。これにより強度の低い周辺組織の形成や硬質相の接着度上昇を抑制することができ、その結果、強度が高く耐摩耗性に優れるTi化合物相のコア相が多く残留した合金となり、工具として使用したときに優れた耐摩耗性と耐欠け性を備えた軽量硬質合金を得ることができる。軽量硬質合金の焼結体を構成する硬質相の平均粒径が3.5μmを超えないような混合粉末が得られれば、BET値×理論比重の下限に制限はない。 If the BET value x theoretical specific gravity of the mixed powder exceeds 38, the specific surface area per volume of the mixed powder becomes too large, resulting in a large amount of fine powder in the mixed powder or an excessively small average particle size of the mixed powder. This makes it easier for fine hard phases to form in the lightweight hard alloy, and the fine powder dissolves and reprecipitates, making it easier for the surrounding structure (rim phase) of the hard phase to form. The surrounding structure has low strength, and the adhesion of the hard phase increases with the formation of the surrounding structure, so fracture toughness decreases, and sufficient strength is not obtained and chipping is likely to occur. The BET value x theoretical specific gravity of the mixed powder is preferably 38 or less, more preferably 36 or less, and even more preferably 35 or less. This makes it possible to suppress the formation of a surrounding structure with low strength and an increase in the adhesion of the hard phase, resulting in an alloy in which a large amount of the core phase of the Ti compound phase, which is strong and has excellent wear resistance, remains, and a lightweight hard alloy with excellent wear resistance and chipping resistance can be obtained when used as a tool. If a mixed powder is obtained in which the average grain size of the hard phase that makes up the sintered lightweight hard alloy does not exceed 3.5 μm, there is no lower limit to the BET value x theoretical specific gravity.
　混合粉末に含まれる粒径が0.8μm以下の粒子の量をA（体積％）としたとき（混合粉末全体を100体積％とする。）、粒子量Aが、混合粉末に含まれるNi及び／又はCoの含有量X（体積％）に対し、下記式(1)：
A＜-1.3X+53.4                      ・・・(1)
を満たすか、又は20体積％以下であるのが好ましい。混合粉末の粒度分布は、レーザー回折式の粒度分布測定器で測定しても良い。得られた混合粉末の粒度分布から、粒径が0.8μm以下の粒子の量Aを体積比率で算出する。粒子量AがA＜-1.3X+53.4を満たすか、又は20体積％以下であると、軽量硬質合金組織中に微細な硬質相が形成されにくくなるとともに、微細な粉末が少量であることから焼結時に溶解・再析出による周辺組織が形成されにくい。粒子量AがA＜-1.3X+53.4を満たすのがより好ましく、粒子量AはA≦-X+41.3であるのがさらに好ましい。粒子量AがA＜-1.3X+53.4を満たすか、混合粉末全体の20体積％以下であっても良い。また粒子量Aは混合粉末全体の20体積％以下であっても良い。 When the amount of particles having a particle size of 0.8 μm or less contained in the mixed powder is A (volume %) (the entire mixed powder is taken as 100 volume %), the particle amount A is expressed by the following formula (1) relative to the content X (volume %) of Ni and/or Co contained in the mixed powder:
A < -1.3X +53.4 ... (1)
or is preferably 20% by volume or less. The particle size distribution of the mixed powder may be measured by a laser diffraction type particle size distribution measuring device. From the particle size distribution of the obtained mixed powder, the amount A of particles having a particle size of 0.8 μm or less is calculated in terms of volume ratio. If the particle amount A satisfies A<-1.3X+53.4 or is 20% by volume or less, fine hard phases are unlikely to be formed in the lightweight hard alloy structure, and since the amount of fine powder is small, peripheral structures are unlikely to be formed due to dissolution and reprecipitation during sintering. It is more preferable that the particle amount A satisfies A<-1.3X+53.4, and it is even more preferable that the particle amount A is A≦-X+41.3. The particle amount A may be A<-1.3X+53.4 or may be 20% by volume or less of the entire mixed powder. The particle amount A may also be 20% by volume or less of the entire mixed powder.
　硬質相の平均粒径が１～3.5μmである。硬質相の平均粒径は、軽量硬質合金の任意の断面のSEM組織をもとにフルマンの式により求められる。硬質相の平均粒径が１μm未満であると、使用状況によっては耐摩耗性が若干劣る。硬質相の平均粒径が3.5μm超であると、強度が不足する。硬質相の平均粒径は1.0～3.0μmであるのが好ましく、1.2～2.8μmであるのがより好ましく、1.3～2.6μmであるのがさらに好ましい。 The average grain size of the hard phase is 1 to 3.5 μm. The average grain size of the hard phase is determined by the Fulman formula based on the SEM structure of any cross section of the lightweight hard alloy. If the average grain size of the hard phase is less than 1 μm, the wear resistance may be slightly inferior depending on the usage conditions. If the average grain size of the hard phase is more than 3.5 μm, the strength may be insufficient. The average grain size of the hard phase is preferably 1.0 to 3.0 μm, more preferably 1.2 to 2.8 μm, and even more preferably 1.3 to 2.6 μm.
[2] 軽量硬質合金の製造方法
　本発明の軽量硬質合金の製造方法の一例として、上述の硬質相構成粒子及び結合相構成粒子の粉末を配合し、有機溶媒中で湿式混合粉砕し、乾燥した後、パラフィン等結合剤を添加した粉末を加圧成形して成形体を形成し、成形体を焼結することにより軽量硬質合金を得る方法が挙げられる。 [2] Manufacturing method of the lightweight hard alloy One example of the manufacturing method of the lightweight hard alloy of the present invention is a method in which powders of the above-mentioned hard phase constituent particles and binder phase constituent particles are blended, wet mixed and ground in an organic solvent, dried, and then the powder to which a binder such as paraffin has been added is pressed to form a green body, and the green body is sintered to obtain the lightweight hard alloy.
　混合粉末の成形体は、プレス成形により完成品に近い状態（ニアネットシェイプ）に成形しても良く、さらにそれを機械加工して所定の形状を付与したものでも良い。また仮焼結後に機械加工して所定の形状を付与しても良い。 The mixed powder compact may be press-molded to a state close to the finished product (near net shape), or it may be machined to give it a desired shape. It may also be machined after preliminary sintering to give it a desired shape.
　焼結時の雰囲気は真空でも良いし、不活性ガス中でも良い。窒素を含む混合粉末の成形体を焼結する場合は窒素又は窒素を含む混合ガスを使用しても良いし、COガス等を用いても良い。またそれらの雰囲気ガスの導入温度やガス圧力は目的により種々変化させて良い。昇温速度、焼結温度やその保持時間、またそれに至る途中での温度保持及びガス圧力は脱脂や焼結性向上また表面性状の改善など目的により任意に選定できる。 The atmosphere during sintering may be a vacuum or an inert gas. When sintering a compact made of mixed powder containing nitrogen, nitrogen or a mixed gas containing nitrogen may be used, or CO gas may be used. The introduction temperature and gas pressure of these atmospheric gases may be varied depending on the purpose. The heating rate, sintering temperature and holding time, as well as the temperature holding time and gas pressure on the way thereto, can be selected as desired depending on the purpose, such as degreasing, improving sinterability, or improving surface properties.
　チタン化合物は、金属チタンやチタン水素化物、チタン酸化物等を主原料として、メンストラム法によるTiCや加熱炭窒化法によるTi(C,N)など、完成したチタン化合物を粉砕し分級することで所定の粒度範囲に制御している場合が多い。この際の粉砕により狙いの粒度の粉末よりも微細な粉末が発生する。チタン化合物粉末にこの微粉が所定量含まれることが軽量硬質合金の靭性が低い原因のひとつであることが分かった。このチタン化合物粉末を用いた軽量硬質合金の靭性を高めるには、焼結前の混合粉末に含まれる微粉を少なくすれば良い。 Titanium compounds are often made using metallic titanium, titanium hydride, titanium oxide, etc. as the main raw materials, and the finished titanium compounds, such as TiC produced by the Menstrum process and Ti(C,N) produced by the heated carbonitriding process, are crushed and classified to control the particle size within a specified range. The crushing process produces powder that is finer than the desired particle size. It has been found that the presence of a certain amount of this fine powder in titanium compound powder is one of the causes of the low toughness of lightweight hard alloys. To increase the toughness of lightweight hard alloys that use this titanium compound powder, it is necessary to reduce the amount of fine powder contained in the mixed powder before sintering.
　このため微粉が発生しにくい混合条件を選定することが必要である。混合時間を短くしても所定の平均粒度が得られるような条件とする必要があり、例えばボールミルによる混合粉砕であれば、ボールミル回転数、粉末量、溶媒量、ボール量、ボール径などと混合粉砕時間などの混合条件を設定することができるが、いずれのパラメータを変化させてもよく、混合粉末の比表面積（m2/ｇ）に理論比重を乗じた値が38以下とすることが肝要であることが分かった。さらにこれを調べる過程で、原料粉末には前述したように原料粉末の時点で微粉を含むものもあり、種々の方法で微粉を除いてもよいし、微粉が少ないチタン化合物粉末を使用しても同様の効果が得られることが分かった。 For this reason, it is necessary to select mixing conditions that do not easily generate fine powder. It is necessary to set conditions that can obtain a specified average particle size even if the mixing time is shortened. For example, in the case of mixing and grinding using a ball mill, mixing conditions such as the ball mill rotation speed, powder amount, solvent amount, ball amount, ball diameter, and mixing and grinding time can be set, and it was found that any of the parameters can be changed, and it is essential that the value obtained by multiplying the specific surface area ( m2 /g) of the mixed powder by the theoretical specific gravity is 38 or less. In the course of investigating this, it was found that some raw material powders contain fine powder at the raw material powder stage as mentioned above, and that the fine powder can be removed by various methods, or that the same effect can be obtained by using a titanium compound powder that contains less fine powder.
　焼結温度は、硬質相の周辺組織をあまり成長させないように1330～1450℃とするのが好ましい。また、用途に応じてsinter-HIPで焼結しても良いし、普通焼結した焼結体をHIP処理しても良い。焼結は、ホットプレス焼結により行っても良いし、通電焼結、SPS焼結等の電磁エネルギー支援焼結により行っても良い。 The sintering temperature is preferably 1330-1450°C so as not to cause the surrounding structure of the hard phase to grow too much. Depending on the application, sintering may be performed using sinter-HIP, or a normally sintered sintered body may be subjected to HIP treatment. Sintering may be performed by hot press sintering or electromagnetic energy assisted sintering such as electric current sintering or SPS sintering.
[3] 軽量硬質合金部材
　本発明の軽量硬質合金はスクリューや粉砕刃などサイズが大きく高速回転を伴う耐摩耗部材に好適に用いられる。そのため本発明の軽量硬質合金を用いた軽量硬質合金部材は、例えば、粉砕、混合又は混練用部材に用いることで優れた性能を発揮することができる。また本発明の軽量硬質合金は、これらの用途に限らず、工具使用時に割れ等が発生しにくいため打抜きパンチや室温、温間及び熱間の成形型、押出型、金型及び鍛造パンチに用いることができ、また部材の取扱い時に欠けや割れが生じにくいため熱膨張係数が大きい特殊レンズ用の胴型などのレンズ成形用周辺部材に用いることは有効である。 [3] Lightweight hard alloy parts The lightweight hard alloy of the present invention is suitable for use in wear-resistant parts that are large in size and rotate at high speed, such as screws and crushing blades. Therefore, the lightweight hard alloy parts using the lightweight hard alloy of the present invention can exhibit excellent performance, for example, when used as crushing, mixing or kneading parts. In addition, the lightweight hard alloy of the present invention is not limited to these applications, and can be used for punching punches, room temperature, warm and hot forming dies, extrusion dies, dies and forging punches because it is difficult to crack when using the tool, and is also effective for use in lens molding peripheral parts such as barrel dies for special lenses with a large thermal expansion coefficient because it is difficult to chip or crack when handling the parts.
　本発明を実施例によりさらに詳細に説明するが、本発明はそれらに限定されるものではない。 The present invention will be explained in more detail using examples, but the present invention is not limited thereto.
実施例１～15及び比較例１～９
　原料粉末として、TiC粉末（1.4μm、2.1μm、2.9μm、3.5μm）、Ti(C0.7N0.3)粉末（1.4μm）、(Ti,Mo)(C,N)粉末（1.5μｍ）、WC粉末（0.6μm）、Mo2C粉末（3.2μm）、Cr3C2粉末（1.3μm）、Ni粉末（2.4μｍ）、Co粉末（1.9μm）を準備した［カッコ内の数値はフィッシャー粒度測定法（FSSS法）により測定した平均粒度］。(Ti,Mo)(C,N)粉末は組成Ti(C0.7N0.3)-25質量%Mo2Cとなるように混合粉末を作製し、窒素中で熱処理を行い粉砕・分級を行い、作製した。TiC粉末を用いた発明品及び比較品のうち、発明品６は2.1μmのTiC粉末、発明品９は2.9μmのTiC粉末、比較品９は3.5μmのTiC粉末をそれぞれ用い、それ以外は1.4μmのTiC粉末を用いた。これらの原料粉末を焼結体が表１に示す各試料の組成になるように計量した。 Examples 1 to 15 and Comparative Examples 1 to 9
The raw powders prepared were TiC powder (1.4μm, 2.1μm, 2.9μm, 3.5μm), Ti(C0.7N0.3 ) powder (1.4μm), (Ti,Mo)(C,N) powder (1.5μm), WC powder (0.6μm), Mo2C powder (3.2μm), Cr3C2 powder ( 1.3μm ), Ni powder (2.4μm), and Co powder (1.9μm) (numbers in parentheses are average particle sizes measured by Fischer particle size measurement method (FSSS method)). The (Ti,Mo)(C,N) powder was prepared by preparing a mixed powder with the composition Ti( C0.7N0.3 )-25 mass% Mo2C , heat treating it in nitrogen , crushing and classifying it. Among the inventive and comparative products using TiC powder, inventive product 6 used 2.1 μm TiC powder, inventive product 9 used 2.9 μm TiC powder, comparative product 9 used 3.5 μm TiC powder, and the rest used 1.4 μm TiC powder. These raw material powders were weighed so that the sintered bodies had the compositions shown in Table 1 for each sample.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　各試料のTiC粉末、Ti(C0.7N0.3)粉末及び(Ti,Mo)(C,N)粉末のチタン化合物原料粉末のSEM観察を行い、微粉末が比較的少ないものを「少」、また粉砕処理したと思われ、微粉末が比較的多いものを「多」とした。得られた結果を表２に示す。 The titanium compound raw powders of TiC powder, Ti( C0.7N0.3 ) powder, and (Ti,Mo)(C,N) powder for each sample were observed under an SEM, and those with relatively little fine powder were rated as "few," and those with relatively much fine powder, which were probably pulverized, were rated as "much." The results are shown in Table 2.
　計量した粉末を混合し、ボールミルを用いて湿式混合粉砕した。発明品はBET値×理論比重が38以下及び得られる焼結体の硬質相の平均粒径が1～3.5μmになるように、チタン化合物原料粉末に含まれる微粉量を考慮しつつ混合粉砕条件を調節した。粉砕強度の粉砕レベルを通常の強度とするときを「２」とし、それより弱いときを「１」とし、それより強いときを「３」とし、粉砕レベル「３」よりも強いときを「４」とした。得られた結果を表２に示す。併せて混合粉末中のNi量、Co量及び(Ni+Co)量の体積率、及び混合粉末に含まれる粒径0.8μm以下の粒子の体積率上限値A’を表2に示す。 The measured powders were mixed and wet mixed and ground using a ball mill. The mixed and ground conditions were adjusted while taking into consideration the amount of fine powder contained in the titanium compound raw powder so that the BET value x theoretical specific gravity of the invented product was 38 or less and the average particle size of the hard phase of the resulting sintered body was 1 to 3.5 μm. The grinding level of the grinding strength was rated as "2" when it was normal strength, "1" when it was weaker, "3" when it was stronger, and "4" when it was stronger than grinding level "3". The results are shown in Table 2. Table 2 also shows the volume ratios of the Ni amount, Co amount, and (Ni+Co) amount in the mixed powder, and the upper limit A' of the volume ratio of particles with a particle size of 0.8 μm or less contained in the mixed powder.
Figure JPOXMLDOC01-appb-T000002
 注：(1) 混合粉末に含まれる粒径が0.8μｍ以下の粒子の体積率の上限値（Ni+Coの体積率をxとしたとき、A’＝-1.3X+53.4を満たす。）
 
Figure JPOXMLDOC01-appb-T000002
 Note: (1) The upper limit of the volume fraction of particles with a particle size of 0.8 μm or less contained in the mixed powder (where x is the volume fraction of Ni+Co, A' = -1.3X + 53.4 is satisfied).
　粉砕混合後の粉末を真空乾燥器を用いて乾燥させ、結合剤を添加して混合粉末を作製した。このとき結合剤を添加する前に混合粉末の粒度分布をMT3300EXII（マイクロトラック・ベル株式会社製）により測定し、粒径が0.8μm以下の粒子の量Aを体積比率で算出した。得られた結果を表３に示す。 The powder after grinding and mixing was dried using a vacuum dryer, and a binder was added to produce a mixed powder. Before adding the binder, the particle size distribution of the mixed powder was measured using an MT3300EXII (Microtrack Bell Co., Ltd.), and the amount A of particles with a particle size of 0.8 μm or less was calculated as a volume ratio. The results are shown in Table 3.
　混合粉末のBET値をTriStarII3020（マイクロメリティクス社製）を用いて測定した。また混合粉末の理論比重を、各試料の原料粉末の比重と組成比から算出した。各試料のBET値×理論比重を表３に示す。 The BET value of the mixed powder was measured using a TriStar II 3020 (Micromeritics). The theoretical specific gravity of the mixed powder was calculated from the specific gravity and composition ratio of the raw powder of each sample. The BET value x theoretical specific gravity of each sample is shown in Table 3.
　得られた混合粉末を98 N/mm2の圧力でφ20×20 H(mm)の円柱に圧粉成形した後、1400℃の焼結温度で１時間焼結し、発明品１～15及び比較品１～９を作製した。また抗折力試験用の試験片は6×11×31(mm)の直方体に圧粉成形した後、同様の方法で作製した。 The obtained mixed powder was pressed into a cylinder of φ20×H20 (mm) at a pressure of 98 N/ mm2 , and then sintered at a sintering temperature of 1400°C for one hour to produce invention products 1 to 15 and comparison products 1 to 9. Test pieces for the transverse strength test were also prepared in the same manner after being pressed into a rectangular parallelepiped of 6×11×31 (mm).
　各試料のビッカース硬さをビッカース硬度計HV (294N)を用いて計測した。得られた結果を表３に示す。 The Vickers hardness of each sample was measured using a Vickers hardness tester HV (294N). The results are shown in Table 3.
　各試料の焼結体を切断し、その断面を鏡面研磨したのち、Regulus8100（株式会社日立ハイテク製）により研磨断面を示すSEM写真（観察倍率：8,000倍）を撮影した。SEM写真を用いて、硬質相の平均粒径を求めた。硬質相の粒径はフルマンの式で求めた。得られた結果を表３に示す。 Each sintered sample was cut and its cross section was mirror-polished, after which SEM photographs (magnification: 8,000x) of the polished cross section were taken using a Regulus8100 (Hitachi High-Tech Corporation). The average grain size of the hard phase was determined using the SEM photographs. The grain size of the hard phase was determined using the Fullman formula. The results are shown in Table 3.
　各試料の抗折力を、JISR 1601に基づいて３点曲げ試験により測定した。また各試料の破壊靭性値KICをJISR 1607に基づいて測定、算出した。得られた結果を表３に示す。 The transverse strength of each sample was measured by a three-point bending test based on JIS R 1601. The fracture toughness value K IC of each sample was also measured and calculated based on JIS R 1607. The results are shown in Table 3.
　各試料の耐摩耗性（工具としての摩耗のしにくさ）を評価するために、ブラスト装置を用いて、SiCの粉体（粒度：♯500）を、投射角度30°、投射圧力0.6 MPa及び投射時間90秒の条件で各試料に衝突させた。ブラスト処理後の各試料の摩耗の大きさを0～５で評価した。発明品4の摩耗量の0.9倍以上1.1倍未満のときを「４」、0.9倍未満のときを「５」、1.1倍以上1.5倍未満のときを「３」、1.5倍以上1.9倍未満のときを「２」、1.9倍以上2.3倍未満のときを「１」、2.3倍以上のときを「０」とした。得られた結果を表３に示す。 In order to evaluate the wear resistance of each sample (resistance to wear as a tool), a blasting device was used to collide SiC powder (grain size: #500) with each sample at a projection angle of 30°, projection pressure of 0.6 MPa, and projection time of 90 seconds. The degree of wear of each sample after blasting was rated from 0 to 5. When the amount of wear of invention 4 was between 0.9 and 1.1 times, it was rated as "4", when it was less than 0.9 times, when it was between 1.1 and 1.5 times, it was rated as "3", when it was between 1.5 and 1.9 times, it was rated as "2", when it was between 1.9 and 2.3 times, it was rated as "1", and when it was 2.3 times or more, it was rated as "0". The results are shown in Table 3.
　各試料の耐欠け性（工具としての欠けにくさ；靱性）を評価するために、ダイヤモンドホイール砥石（#140）を用いて、切込み量５μmの条件で平面研削を行い、20°のシャープエッジに加工した。そのときの各試料のシャープエッジの先端の欠けの大きさを0～５で評価した。発明品4の欠け幅の0.9倍以上1.1倍未満のときを「４」、0.9倍未満のときを「５」、1.1倍以上1.2倍未満のときを「３」、1.2倍以上1.3倍未満のときを「２」、1.3倍以上1.4倍未満のときを「１」、1.4倍以上のときを「０」とした。なおこの評価で耐欠け性が評価「１」を満たさない、つまり評価「０」である場合には耐摩耗性の評価は行わなかった。耐摩耗性と耐欠け性のいずれかの評価が「０」の場合は工具として使用できない。いずれも評価が「１」以上で合計が「５」以上であれば使用する用途により靭性または耐摩耗性いずれかを重視した合金、またはバランスのよい靭性・耐摩耗性を有する合金を選択することができる。得られた結果を表３に示す。 In order to evaluate the chipping resistance of each sample (resistance to chipping as a tool; toughness), a diamond wheel grinding stone (#140) was used to perform surface grinding at a cutting depth of 5 μm, and a sharp edge of 20° was processed. The size of the chipping at the tip of the sharp edge of each sample was evaluated from 0 to 5. If the chipping width was 0.9 times or more but less than 1.1 times the width of the chipping of invention product 4, it was rated as "4", if it was less than 0.9 times, it was rated as "5", if it was 1.1 times or more but less than 1.2 times, it was rated as "3", if it was 1.2 times or more but less than 1.3 times, it was rated as "2", if it was 1.3 times or more but less than 1.4 times, it was rated as "1", and if it was rated as 1.4 times or more, it was rated as "0". If the chipping resistance did not meet the rating of "1" in this evaluation, that is, if it was rated as "0", the wear resistance was not evaluated. If either the wear resistance or the chipping resistance was rated as "0", it cannot be used as a tool. If all the ratings are "1" or higher and the total is "5" or higher, an alloy that emphasizes either toughness or wear resistance, depending on the application, or an alloy with a good balance of toughness and wear resistance can be selected. The results are shown in Table 3.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表３に示すように、発明品１、３、４、６、11、12、14及び15は、微粉が少ないTi化合物粉末を用いたため混合粉末中の微粉量は少ない。そのため合金には相対的に微粒な硬質相が形成されにくく、硬質相の周辺組織（リム相）も形成されにくいため、耐摩耗性と耐欠け性の両方を兼ね備えた。発明品２及び５は、微粉が多い原料粉末を用いた場合でも粉砕条件を弱くすることによって、混合粉末中の微粉量を少なく抑えたため、微粒な硬質相が形成されにくく、リム相も形成されにくくなり、耐摩耗性と耐欠け性の両方を兼ね備えた。発明品7及び８はともに結合相量が少ない高硬度の合金であるが粉末粒子量A及びBET値×理論比重が所定範囲内であるため、いずれも最低限の耐欠け性を持ちつつ、耐摩耗性が極めて高かった。発明品９及び10は最低限の耐摩耗性を持ちつつ、結合相量が多い高靭性合金であるため耐欠け性が極めて高かった。発明品13は(Ti,Mo)(C,N)固溶体粉末を用い、同じ合金組成でTi(C0.7N0.3)粉末とMo2C粉末を使用した発明品2よりも粒子量Aが少なくBET値×理論比重が小さいため、ほぼ同等の耐摩耗性を持ちつつ、耐欠け性はより優れる傾向にある。 As shown in Table 3, inventive products 1, 3, 4, 6, 11, 12, 14 and 15, the amount of fine powder in the mixed powder is small because the Ti compound powder with less fine powder was used. Therefore, the alloy is unlikely to form a relatively fine hard phase and the peripheral structure of the hard phase (rim phase) is also unlikely to form, so that it has both wear resistance and chipping resistance. Inventive products 2 and 5, even when raw material powder with a lot of fine powder is used, the amount of fine powder in the mixed powder is kept low by weakening the grinding conditions, so that the fine hard phase is unlikely to form and the rim phase is also unlikely to form, so that it has both wear resistance and chipping resistance. Inventive products 7 and 8 are both high-hardness alloys with a small amount of binder phase, but the powder particle amount A and the BET value x theoretical specific gravity are within the specified range, so that both have minimum chipping resistance and extremely high wear resistance. Inventive products 9 and 10 are high-toughness alloys with a large amount of binder phase, so that they have extremely high chipping resistance while having minimum wear resistance. Invention product 13 uses (Ti,Mo)(C,N) solid solution powder, and has a smaller particle amount A and a smaller BET value x theoretical specific gravity than Invention product 2 , which has the same alloy composition but uses Ti( C0.7N0.3 ) powder and Mo2C powder. Therefore, while having roughly the same wear resistance, it tends to have better chipping resistance.
　それに対し、比較品１はWC及び／又はMo2Cの合計量が少なく、周辺組織（リム相）の形成が十分でない。そのため、抗折力は低く、耐摩耗性と耐欠け性がいずれも低かった。比較品２はWC及び／又はMo2Cの合計量が多すぎるためリム相の比率が増加して硬さも減少するため耐摩耗性も低めであった。また同様にリム相比率が増加するため耐欠け性が低かった。比較品３は微粉が少ない原料粉末を用いているが、粉砕条件が強いため、BET値×理論比重が62と大きく、同様の理由で耐欠け性が低かった。比較品４は通常の粉砕条件であっても、微粉が多い原料粉末を用いたため、BET値×理論比重が60と大きく、混合粉末中に微細粉が多量に存在し、合金組織中には微粒な硬質相が多く発生しリム相も多めで耐欠け性が低かった。比較品５は(Ni+Co)量が3.0質量％と少ないため、最低限の耐欠け性である「１」を満たさなかった。比較品６は微粉が多い粉末を強粉砕しているためBET値×理論比重が71と大きく硬質相粒径も小さく周辺組織比率が高いため破壊靭性も低下し最低限の耐欠け性である「１」を満たさなかった。また比較品６のφ20×20 H(mm)の円柱試料を焼結した際に焼結時に割れが発生した形跡が認められたため、その部分を除いて使用して評価した。比較品７は(Ni+Co)量が40質量％で破壊靭性も高いため耐欠け性は優れていたが、結合相が多いことに加えBET値×理論比重が48と大きく強粉砕粉末であるためリム相比率が高く、その結果耐摩耗性が優れるTi化合物相（コア相）比率が小となり耐摩耗性は著しく低かった。比較品８は(Ni+Co)量が40質量％より多く耐摩耗性が著しく劣った。比較品9は合金粒度が4.1μmと大きすぎたため抗折力が低く、最低限の耐欠け性を満たさなかった。 In contrast, the total amount of WC and/or Mo2C in Comparative Product 1 is small, and the formation of the peripheral structure (rim phase) is insufficient. Therefore, the bending strength is low, and both the wear resistance and chipping resistance are low. Comparative Product 2 has too much total amount of WC and/or Mo2C , so the ratio of the rim phase increases and the hardness decreases, and the wear resistance is also low. Similarly, the chipping resistance is low because the ratio of the rim phase increases. Comparative Product 3 uses raw powder with little fine powder, but the grinding conditions are strong, so the BET value x theoretical specific gravity is large at 62, and for the same reason, the chipping resistance is low. Comparative Product 4 uses raw powder with a lot of fine powder, even under normal grinding conditions, so the BET value x theoretical specific gravity is large at 60, and there is a large amount of fine powder in the mixed powder, and many fine hard phases are generated in the alloy structure, and the rim phase is also large, so the chipping resistance is low. Comparative Product 5 does not meet the minimum chipping resistance of "1" because the (Ni + Co) amount is small at 3.0 mass%. For comparative product 6, the powder containing a large amount of fine powder was strongly crushed, so the BET value x theoretical specific gravity was large at 71, the hard phase grain size was small, the peripheral structure ratio was high, and the fracture toughness was reduced, so it did not meet the minimum chipping resistance of "1". In addition, when a cylindrical sample of comparative product 6 with a diameter of 20 x height of 20 mm was sintered, evidence of cracking during sintering was observed, so this part was removed and used for evaluation. For comparative product 7, the amount of (Ni+Co) was 40 mass% and the fracture toughness was high, so the chipping resistance was excellent, but in addition to the large amount of bonding phase, the BET value x theoretical specific gravity was large at 48, so the powder was strongly crushed, and the rim phase ratio was high, resulting in a small ratio of the Ti compound phase (core phase) which has excellent wear resistance, and the wear resistance was extremely low. For comparative product 8, the amount of (Ni+Co) was more than 40 mass%, so the wear resistance was extremely poor. For comparative product 9, the alloy grain size was too large at 4.1 μm, so the flexural strength was low and the minimum chipping resistance was not met.

Claims (10)

  1. 　炭素を含むチタン化合物を主成分とし、WC及び／又はMo2Cを５～33質量％を含む硬質相構成粒子と、Ni及び／又はCoを５～40質量％含む結合相構成粒子とを有する混合粉末を焼結してなる軽量硬質合金であって、
    　前記混合粉末のBET値×理論比重が38以下であり、
    　硬質相の平均粒径が１～3.5μmであることを特徴とする軽量硬質合金。     A lightweight hard alloy obtained by sintering a mixed powder having hard phase constituent particles containing a carbon-containing titanium compound as a main component, WC and/or Mo2C in an amount of 5 to 33 mass%, and binder phase constituent particles containing Ni and/or Co in an amount of 5 to 40 mass%,
    The BET value x theoretical specific gravity of the mixed powder is 38 or less,
    A lightweight hard alloy characterized in that the average grain size of the hard phase is 1 to 3.5 μm.
  2. 　前記混合粉末に含まれる粒径が0.8μm以下の粒子の量をA（体積％）としたとき、粒子量Aが、前記混合粉末に含まれるNi及び／又はCoの含有量X（体積％）に対し、下記式(1)：
    A＜-1.3X+53.4                      ・・・(1)
    を満たすか、又は20体積％以下であることを特徴とする請求項１に記載の軽量硬質合金。     When the amount of particles having a particle size of 0.8 μm or less contained in the mixed powder is A (volume %), the particle amount A is expressed by the following formula (1) relative to the content X (volume %) of Ni and/or Co contained in the mixed powder:
    A < -1.3X +53.4 ... (1)
    2. The lightweight hard alloy according to claim 1, characterized in that the content of C2 satisfies the above or is 20 volume % or less.
  3. 　前記チタン化合物は、炭化チタン及び炭窒化チタンからなる群から選ばれる少なくとも一つの化合物を含むことを特徴とする請求項１に記載の軽量硬質合金。 The lightweight hard alloy according to claim 1, characterized in that the titanium compound contains at least one compound selected from the group consisting of titanium carbide and titanium carbonitride.
  4. 　前記チタン化合物は、炭化チタン及び炭窒化チタンからなる群から選ばれる少なくとも一つの化合物を含むことを特徴とする請求項２に記載の軽量硬質合金。 The lightweight hard alloy according to claim 2, characterized in that the titanium compound contains at least one compound selected from the group consisting of titanium carbide and titanium carbonitride.
  5. 　前記チタン化合物は炭窒化チタンを含み、前記炭窒化チタンの窒素含有量が８質量％未満であることを特徴とする請求項１～４のいずれかに記載の軽量硬質合金。 The lightweight hard alloy according to any one of claims 1 to 4, characterized in that the titanium compound contains titanium carbonitride, and the nitrogen content of the titanium carbonitride is less than 8 mass%.
  6. 　前記混合粉末全体に対するCoの含有量は9.5質量％以下であることを特徴とする請求項１～４のいずれかに記載の軽量硬質合金。 The lightweight hard alloy according to any one of claims 1 to 4, characterized in that the Co content in the entire mixed powder is 9.5 mass% or less.
  7. 　前記硬質相構成粒子はさらにCrをCr3C2換算で５質量％以下含むことを特徴とする請求項１～４のいずれかに記載の軽量硬質合金。 5. The lightweight, hard alloy according to claim 1, wherein the hard phase particles further contain 5 mass % or less of Cr calculated as Cr 3 C 2 .
  8. 　前記硬質相構成粒子はさらにCrをCr3C2換算で５質量％以下含むことを特徴とする請求項５に記載の軽量硬質合金。 6. The lightweight, hard alloy according to claim 5, wherein the hard phase constituent particles further contain 5 mass % or less of Cr in terms of Cr3C2 .
  9. 　前記硬質相構成粒子はさらにCrをCr3C2換算で５質量％以下含むことを特徴とする請求項６に記載の軽量硬質合金。 7. The lightweight, hard alloy according to claim 6, wherein the hard phase particles further contain 5 mass % or less of Cr in terms of Cr3C2 .
  10. 　請求項１～４のいずれかに記載の軽量硬質合金を用いる軽量硬質合金部材。
          A lightweight hard alloy member using the lightweight hard alloy according to any one of claims 1 to 4.
PCT/JP2023/039776 2022-11-03 2023-11-02 Lightweight hard alloy and lightweight hard alloy member WO2024096134A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015156005A1 (en) * 2014-04-10 2015-10-15 住友電気工業株式会社 Cermet and cutting tool
WO2022074904A1 (en) * 2020-10-09 2022-04-14 日本タングステン株式会社 Pulverizing, stirring, mixing, and kneading machine members
JP7157887B1 (en) * 2022-03-08 2022-10-20 日本タングステン株式会社 Grinding, stirring, mixing, kneading machine parts

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015156005A1 (en) * 2014-04-10 2015-10-15 住友電気工業株式会社 Cermet and cutting tool
WO2022074904A1 (en) * 2020-10-09 2022-04-14 日本タングステン株式会社 Pulverizing, stirring, mixing, and kneading machine members
JP7157887B1 (en) * 2022-03-08 2022-10-20 日本タングステン株式会社 Grinding, stirring, mixing, kneading machine parts

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