CN108690931A

CN108690931A - The method for manufacturing wearability iron-base sintered alloy

Info

Publication number: CN108690931A
Application number: CN201810290965.7A
Authority: CN
Inventors: 筱原伸幸; 鸭雄贵; 植田义久; 米田贵则; 中村竹志
Original assignee: Fine Sinter Co Ltd; Toyota Motor Corp
Current assignee: Fine Sinter Co Ltd; Toyota Motor Corp
Priority date: 2017-04-04
Filing date: 2018-04-03
Publication date: 2018-10-23
Anticipated expiration: 2038-04-03
Also published as: JP2018178143A; CN108690931B; BR102018006453A2; US20180282844A1; JP6842345B2

Abstract

The wearability iron-base sintered alloy made of mixed-powder is manufactured, the mixed-powder includes the first hard particles, the second hard particles, graphite particle and iron particle.First hard particles are Fe-Mo-Ni-Co-Mn-Si-C alloying pellets.Second hard particles are Fe-Mo-Si alloying pellets.When the total amount of the above particle is set as 100 mass %, the mixed-powder includes the graphite particle of the first hard particles of 5 mass % to 50 mass %, the second hard particles of 1 mass % to 8 mass % and 0.5 mass % to 1.5 mass %.In sintering circuit, be sintered so that the hardness of first hard particles become 400 to 600Hv and the hardness of second hard particles be more than 600Hv.Then, carrying out oxidation processes makes the density contrast of the sintered body before and after the oxidation processes become 0.05g/cm³Or bigger.

Description

The method for manufacturing wearability iron-base sintered alloy

Background of invention

1. technical field

The present invention relates to the method for manufacture wearability iron-base sintered alloy, the wearability iron-base sintered alloy includes being suitble to In the hard particles for improving sintered alloy wearability.

2. description of the prior art

Sintered alloy based on iron can be applied to valve seat etc..Can further it change sintered alloy includes hard particles Into wearability.When including hard particles, graphite particle and iron particle are mixed into hard particles to form powder, and will Mixed-powder compression forming is at sintered alloy formed body.Then the sintered alloy formed body and therefore its quilt are usually heated It is sintered and becomes sintered alloy.

Method as sintered alloy as manufacture, it has been proposed that the method for manufacture wearability iron-base sintered alloy, The mixed-powder compression forming of hard particles, graphite particle and iron particle will be wherein mixed with into sintered alloy formed body, and And it is sintered sintered alloy formed body and the sintered alloy is made to diffuse to hard particles and iron with the C of graphite particle in formed body (referring for example to Japanese Unexamined Patent Application Publication 2004-156101 (JP 2004-156101 A) in particle.

Herein, hard particles include Mo:20 mass % to 70 mass %, C:0.2 mass % to 3 mass % and Mn:1 matter % is measured to 15 mass %, surplus includes inevitable impurity and Co.When by the total amount of hard particles, graphite particle and iron particle When being set as 100 mass %, mixed-powder includes the hard particles and 0.2 mass % to 2 mass % of 10 mass % to 60 mass % Graphite particle.Because hard particles are dispersed in such sintered alloy, it is possible to prevent from wearing.

Invention content

However, in the wearability iron-base sintered alloy manufactured in manufacturing method described in JP 2004-156101 A The basis material for connecting hard particles is soft, because the basis material is Fe-C materials, the C of wherein graphite particle has diffused to iron In particle.Therefore, when the metallic alloy of wearability iron-base sintered alloy and the sliding corresponding component being in contact with it is mutually golden each other When belonging to contact, the contact surface of wearability iron-base sintered alloy may be plastically deformed, and easily be sticked together on the contact surface Abrasion.This problem in order to prevent needs the hardness for improving wearability iron-base sintered alloy.However, there are wearability iron-baseds Therefore risk that the machinability of sintered alloy deteriorates, and be difficult to realize resistance to adhesive wear and machinability simultaneously.

The method that the present invention provides manufacture wearability iron-base sintered alloy, can ensure that machinability by this method while preventing Adhesive wear.

The inventors expect that the contact surface when the iron-based body of wearability iron-base sintered alloy is plastically deformed as described above Adhesive wear will accelerate.In this respect, inventor has studied except the hard for up to the present preventing fretting wear by it Addition passes through other hard particles for the plastic deformation that it can prevent iron-based body except particle.Therefore, inventor focuses on molybdenum Key component as hard particles, and it was found that when compound dissipates between the molybdenum carbide and iron-molybdenum being precipitated in sintering process When cloth is in iron-based body, the plastic deformation of iron-based body can be controlled.In addition to this, inventor obtains new discovery:When in the future When a part of iron is oxidized to ferroso-ferric oxide in the iron-based body of iron particle, its wearability can be improved and be sintered without deteriorating The machinability of alloy.

One aspect of the present invention is related to the method for manufacturing wearability iron-base sintered alloy, including:Molding procedure, this at By the mixed-powder compression forming including hard particles, graphite particle and iron particle at sintered alloy formed body in type process; And sintering circuit, it is sintered the sintered alloy formed body in the sintering circuit and makes in the sintered alloy formed body The C of graphite particle is diffused in the hard particles and the iron particle, wherein the hard particles include the first hard particles With the second hard particles, wherein when the amount of first hard particles is set as 100 mass %, the first hard particles packet Include Mo:20 mass % to 70 mass %, Ni:5 mass % to 40 mass %, Co:5 mass % to 40 mass %, Mn:1 mass % To 20 mass %, Si:0.5 mass % to 4.0 mass % and C:To 3.0 mass %, surplus includes Fe and can not keep away 0.5 mass % The impurity exempted from, wherein when the amount of second hard particles is set as 100 mass %, second hard particles include Mo: 60 mass % to 70 mass % and Si:2.0 mass % or less, surplus include Fe and inevitable impurity, wherein when by institute The total amount for stating the first hard particles, second hard particles, the graphite particle and the iron particle is set as 100 mass % When, the mixed-powder includes first hard particles of 5 mass % to 50 mass %, described in 1 mass % to 5 mass % The graphite particle of second hard particles and 0.5 mass % to 1.5 mass %, and wherein in the sintering circuit, carry out Sintering is so that the hardness of first hard particles becomes 400 to 600Hv, and the hardness of second hard particles is more than 600Hv, after the sintering circuit, to carrying out oxidation processes with the sintered body that formed body is sintered by the sintered alloy, So that contained a part of iron becomes ferroso-ferric oxide in the iron-based body of the iron particle, and the progress oxidation processes make Oxidation processes foregoing description sintered body density and oxidation processes after the sintered body density between difference become 0.05g/cm³Or more.

According to the present invention it is possible to ensure machinability while preventing adhesive wear.

Attached drawing briefly describes

The feature, advantage and technology and industrial significance for description illustrative embodiments of the invention that hereinafter reference will be made to the drawings, Wherein similar reference numeral represents similar element, and wherein:

Fig. 1 is the schematic conceptual views useful of the wear test used in embodiment and comparative example;

Fig. 2 is the schematic conceptual views useful of the machinability test used in embodiment and comparative example;

Fig. 3 A are to show embodiment 1-3 and the abrasion in comparative example 1 and 9 for the additive amount of the first hard particles Test the figure of the result of wear extent ratio;

Fig. 3 B are to show embodiment 1-3 and the tool in comparative example 1 and 9 for the additive amount of the first hard particles The figure of the result of wear extent ratio;

Fig. 4 A are shown in embodiment 1,4 and 5 and comparative example 3,4 and 9 for the additive amount of the second hard particles Wear test wear extent ratio result figure;

Fig. 4 B are shown in embodiment 1,4 and 5 and comparative example 3,4 and 9 for the additive amount of the second hard particles Tool wear amount ratio result figure;

Fig. 5 A are to show embodiment 1,6 and 7 and the mill in comparative example 5,6 and 9 for the additive amount of graphite particle The figure of the result of damage experiment wear extent ratio;

Fig. 5 B are to show embodiment 1,6 and 7 and the work in comparative example 5,6 and 9 for the additive amount of graphite particle Has the figure of the result of wear extent ratio;

Fig. 6 A are shown in embodiment 1,3,5 and 8 and comparative example 8 and 9 for the hardness of the first hard particles The figure of the result of wear test wear extent ratio;

Fig. 6 B are shown in embodiment 1,3,5 and 8 and comparative example 8 and 9 for the hardness of the first hard particles The figure of the result of tool wear amount ratio;

Fig. 7 A are to show that embodiment 1-8 is ground with the wear test in comparative example 7 and 9 for the density contrast of sintered body The figure of the result of damage amount ratio;

Fig. 7 B are to show embodiment 1-8 and the tool wear amount in comparative example 7 and 9 for the density contrast of sintered body The figure of the result of ratio;

Fig. 8 A are wear tests later according to the surface picture of the testpieces of embodiment 1;

Fig. 8 B are wear tests later according to the surface picture of the testpieces of comparative example 7;

Fig. 9 A are the macrographs according to the testpieces of embodiment 1;

Fig. 9 B are the macrographs according to the testpieces of comparative example 5;

Fig. 9 C are the macrographs according to the testpieces of comparative example 6;

Figure 10 A are the figures for showing the result of wear test wear extent ratio in embodiment 1 and 9 and comparative example 10;With

Figure 10 B are the figures for showing the result of tool wear amount ratio in embodiment 1 and 9 and comparative example 10.

The detailed description of embodiment

Embodiment of the present invention described in detail below.Which will be described by compression forming includes first and The mixed-powder of two hard particles, graphite particle and iron particle obtains the sintered alloy formed body according to the present embodiment (hereinafter referred to as formed body).By sintered moulded body and make the C of graphite particle diffuse in hard particles and iron particle to obtain Wearability iron-base sintered alloy (hereinafter referred to as sintered alloy).It is hard particles explained below, wherein mixed by compression forming The mixed-powder of hard particles is closed and the formed body obtained and the sintered alloy obtained by sintered moulded body.

1. the first hard particles

First hard particles are mixed into sintered alloy and relative to iron particle and sintered alloy as raw material Particle with high rigidity for iron-based body, and therefore prevent the fretting wear of sintered alloy.

First hard particles are the particles made of Co-Mo-Ni-Fe-Mn-Si-C alloys.Specifically, when by the first hard When the amount of particle is set as 100 mass %, the first hard particles include Mo:20 mass % to 70 mass %, Ni:5 mass % to 40 Quality %, Co:5 mass % to 40 mass %, Mn:1 mass % to 20 mass %, Si:0.5 mass % to 4.0 mass % and C: For 0.5 mass % to 3.0 mass %, surplus includes Fe and inevitable impurity.In addition, when necessary can by Cr with 10 mass % or Less range is added to the first hard particles.The hardness of the first hard particles is preferably 400 to 600Hv ranges before sintering It is interior.

Molten metal mist can be exercised by preparing that the molten metal that composition described above mixes is gone forward side by side in the above ratio The atomization process of change manufactures the first hard particles.In addition, alternatively, can by mechanical lapping by molten metal The solidifying body of solidification forms powder.As atomization process, gas atomization processing or water atomization processing can be carried out.However for sintering The considerations such as performance, more preferable gas atomization processing, because obtaining rounded grain.

Herein, according to the significance level of the characteristic of application component, consider limitation reason which will be described and in this way Hardness, solid lubricity, adhesiveness in range and cost, can suitably change above hard particles composition lower limiting value and Upper limit value.

1-1.Mo:20 mass % to 70 mass %

In the composition of the first hard particles, Mo can generate Mo carbide in sintering process together with the C of carbon dust, and Improve the hardness and wearability of the first hard particles.In addition, about Mo, because under applied at elevated temperature environment, it is in solid solution condition Mo and Mo carbide be oxidized to form Mo oxidation films, so can get for the advantageous solid lubricity of sintered alloy.

Herein, when Mo contents are less than 20 mass %, the amount of the Mo carbide not only generated is reduced, but also the first hard The oxidation onset temperature of grain improves, and prevents the generation of the Mo oxides under applied at elevated temperature environment.Therefore, the sintering of acquisition is closed The solid lubricity of gold is insufficient, and its rub resistance abrasiveness reduces.On the other hand, when Mo contents are more than 70 mass % When, it is not only difficult with atomization method and prepares the first hard particles, but also the tackness between hard particles and iron-based body reduces. It is highly preferred that Mo contents are 30 mass % to 50 mass %.

1-2.Ni:5 mass % to 40 mass %

In the composition of the first hard particles, Ni can expand the austenite structure of the matrix of the first hard particles and improve it Toughness.In addition, the solid solution capacity of the Mo of the first hard particles can be improved in Ni, and improve the wearability of the first hard particles.

In addition, Ni is diffused in the iron-based body of sintered alloy in sintering process, the austenite structure of iron-based body can be expanded, carried The toughness of high sintered alloy, improves the solid solution capacity of the Mo in iron-based body, and improves wearability.

Herein, when Ni contents are less than 5 mass %, it is difficult to expect the above effect of Ni.On the other hand, when Ni contents are super When crossing 40 mass %, although the above effect of Ni is maximized, the cost of the first hard particles improves.It is highly preferred that Ni contents are 20 mass % to 40 mass %.

1-3.Co:5 mass % to 40 mass %

Similar to Ni in the composition of the first hard particles, Co can expand the iron-based body and the first hard of sintered alloy Austenite structure in the matrix of grain, and improve the hardness of the first hard particles.

Herein, when Co contents are less than 5 mass %, it is difficult to expect the above effect of Ni.On the other hand, when Co contents are super When crossing 40 mass %, although the above effect of Co is maximized, the cost of the first hard particles improves.It is highly preferred that Co contents are 10 mass % to 30 mass %.

1-4.Mn:1 mass % to 20 mass %

In the composition of the first hard particles, because Mn effectively diffuses to sintering from the first hard particles in sintering process In the iron-based body of alloy, so the tackness between the first hard particles and iron-based body can be improved.It is closed in addition, Mn can expand sintering Austenite structure in the iron-based body of gold and the matrix of the first hard particles.

Herein, when Mn contents are less than 1 mass %, because the amount for diffusing to the Mn in iron-based body is small, hard particles Tackness between iron-based body reduces.Therefore the mechanical strength of the sintered alloy obtained reduces.On the other hand, when Mn contents When more than 20 mass %, the above effect of Mn is maximized.It is highly preferred that Mn contents are 2 mass % to 8 mass %.

1-5.Si:0.5 mass % to 4.0 mass %

In the composition of the first hard particles, Si can improve the tackness between the first hard particles and Mo oxidation films. Herein, when Si contents are less than 0.5 mass %, it is difficult to expect the above effect of Si.On the other hand, when Si contents are more than 4.0 When quality %, the mouldability deterioration of formed body and the density reduction of sintered alloy.It is highly preferred that Si contents are 0.5 mass % To 2 mass %.

1-6.C:0.5 mass % to 3.0 mass %

In the composition of the first hard particles, C is combined to form Mo carbide with Mo, and can improve the first hard particles Hardness and wearability.Herein, when C content is less than 0.5 mass %, abrasion resistant effect is insufficient.On the other hand, when C content is more than When 3.0 mass %, the mouldability deterioration of formed body and the density reduction of sintered alloy.It is highly preferred that C content is 0.5 matter Measure % to 2 mass %.

1-7.Cr:10 mass %

Hereinafter, in the composition of the first hard particles, Cr can prevent the excessive oxidation of Mo during use.For example, when burning Use environment temperature in conjunction with gold is high, and the amount of the Mo oxidation films generated in the first hard particles improves, and Mo oxides When film is removed from the first hard particles, addition Cr is effective.

Herein, when Cr contents are more than 10 mass %, the formation of the Mo oxidation films in the first hard particles is excessively prevented. Herein, it under corrosive environment such as alcohol ate environment, in order to improve corrosion resistance, needs to add Cr.On the other hand, possible In the environment of adhesive wear occurs, for accelerated oxidation, it is desirable to reduce Cr contents.

The grain size of the first hard particles of 1-8.

It can be according to the grain size of suitably first hard particles of selection such as application, type of sintered alloy.However, the first hard The grain size of grain is preferably in the range of 44 μm to 250 μm, and more preferably in the range of 44 μm to 105 μm.

Herein, when including with the hard particles of 44 μm of grain sizes are less than as the first hard particles, because grain size is too small, So the wearability of wearability iron-base sintered alloy can reduce.On the other hand, when include with more than 250 μm of grain sizes hard When particle is as the first hard particles, because grain size is too big, the machinability of wearability iron-base sintered alloy can deteriorate.

2. the second hard particles

It is similar to the first hard particles, the second hard particles be mixed into sintered alloy as raw material and relative to Particle with high rigidity for the iron-based body of iron particle and sintered alloy.Second hard particles are notable when to add on a small quantity Improve of sintered alloy hardness, the adhesive wear for preventing the iron-based body of sintered alloy to be plastically deformed and therefore reduce sintered alloy Grain.

Second hard particles are the particles made of Fe-Mo alloys, and work as the amount of the second hard particles being set as 100 matter Include Mo when measuring %:60 mass % to 70 mass % and Si:2.0 mass % or less, surplus include Fe and inevitably miscellaneous Matter.The hardness of the second hard particles is preferably within the scope of 600 to 1600Hv before sintering.

The solidifying body that molten metal has solidified is formed into powder to manufacture the second hard particles by mechanical lapping.In addition, It is identical as the first hard particles, the second hard particles can be manufactured by gas atomization processing, water atomization processing etc..

2-1.Mo:60 mass % to 70 mass %

In the composition of the second hard particles, Mo can generate Mo carbide in sintering process together with the C of carbon dust, and Improve the hardness and wearability of the second hard particles.In addition, about Mo, because under applied at elevated temperature environment, it is in solid solution condition Mo and Mo carbide be oxidized to form Mo oxidation films, can get for the advantageous solid lubricity of sintered alloy.In addition, When molybdenum carbide can prevent adhesive wear during use and iron-based body when the grain boundaries of iron-based body are precipitated in sintering process Plastic deformation.

Herein, it when Mo contents are less than 60 mass %, is difficult to that iron-based body is prevented to be plastically deformed according to above-mentioned molybdenum carbide, and Resistance to adhesive wear reduces.On the other hand, when Mo contents are more than 70 mass %, it is difficult to it is hard to prepare second using grinding method Matter particle, and its yield reduces.

2-2.Si:2.0 mass % or less

When in the composition that Si is included in the second hard particles, it is easy to manufacture the second hard particles using grinding method.This Place, when Si contents are more than 2.0 mass %, the hardness of the second hard particles improves, the mouldability deterioration of formed body, sintered alloy Density reduce, and the machinability of sintered alloy also deteriorates.

The grain size of the second hard particles of 2-3.

It can be according to the grain size of suitably second hard particles of selection such as application, type of sintered alloy.However, the second hard The grain size (maximum particle diameter) of grain is preferably in 100 μm or smaller and more preferable 75 μm or smaller range.Therefore, the second hard Grain can be evenly dispersed in matrix, and the hardness of sintered alloy can be improved.Herein, when including with being more than the hard of 100 μm of grain sizes When matter particle is as the second hard particles, because grain size is too big, the machinability of sintered alloy can deteriorate.Herein, consider system The grain size of second hard particles is preferably 1 μm or bigger in the case of standby.

3. graphite particle

It is diffused in iron-based body and hard particles as long as the C of graphite particle can be dissolved in sintering process, then graphite particle can To be natural graphite particles or synthetic graphite particles or their mixture.The grain size of graphite particle is preferably in 1 μm to 45 μm model In enclosing.As the powder for including preferred graphite particle, it is (commercially available from Nippon Kokuen Group to may be exemplified powdered graphite CPB-S).

4. iron particle

The iron particle for serving as sintered alloy matrix is the iron particle for containing Fe as key component.As including iron particle Powder, straight iron powder are preferred.However, as long as mouldability does not deteriorate and element (such as above the during compression forming The Mn of one hard particles) diffusion do not reduce, low-alloy steel powder can be used.It can be used Fe-C powder as low alloyed steel powder End.For example, the powder with consisting of can be used, when the amount of low-alloy steel powder is set as 100 mass %, it includes C: For 0.2 mass % to 5 mass %, surplus includes inevitable impurity and Fe.In addition, such powder can be gaseous state atomized powder End, water atomized powder or reduction powder.The grain size of iron particle is preferably in the range of 150 μm or smaller.

5. the mixing ratio of mixed-powder

Be prepared for include the first hard particles, the second hard particles, graphite particle and iron particle mixed-powder.When by Total amount when being set as 100 mass % of one hard particles, the second hard particles, graphite particle and iron particle, mixed-powder includes 5 matter Measure the first hard particles of % to 50 mass %, the second hard particles and 0.5 mass % to 1.5 matter of 1 mass % to 5 mass % Measure the graphite particle of %.

Mixed-powder can only include the first hard particles, the second hard particles, graphite particle and iron particle, as long as but institute The mechanical strength and wearability of the sintered alloy of acquisition do not reduce, so that it may if including other particles of about dry mass %.At this In the case of kind, it is for the total amount of the first and second hard particles, graphite particle and iron particle for mixed-powder When 95 mass % or more, it is contemplated that sufficient effect.For example, may include at least one for improving machinability in mixed-powder The particle of type, selected from by the following group constituted:Sulfide (such as MnS), oxide (such as CaCO₃), fluoride (such as CaF), nitride (such as BN) and oxysulfide.

Because including 5 matter for the total amount of the first hard particles, the second hard particles, graphite particle and iron particle The first hard particles for measuring % to 50 mass %, so the mechanical strength and rub resistance abrasiveness of sintered alloy can be improved simultaneously.

Herein, when for total amount including the first hard particles less than 5 mass %, by which will be described Inventor's experiment should be clearly understood that, cannot show according to the first hard particles substantially resistant to friction and wear effects.

On the other hand, when the amount of the first hard particles for total amount is more than 50 mass %, because first is hard The amount of matter particle is too big, when formed body is molded by mixed-powder, it is difficult to be molded the formed body.In addition, because the first hard There are more contacts between grain, and the part of iron particle sintering becomes smaller, so the rub resistance abrasiveness drop of sintered alloy It is low.

As mentioned above, relative to the first hard particles, the second hard particles, graphite particle and iron particle total amount and Speech includes second hard particles of the 1 mass % to 5 mass %, so can prevent the plastic deformation of iron-based body during use and subtract The adhesive wear of small sintered alloy.

Herein, when the content of the second hard particles for total amount is less than 1 mass %, by which will be described Inventor's experiment should be clearly understood that the resistance to adhesive wear of sintered alloy reduces.On the other hand, when relative to total amount For the content of the second hard particles when being more than 5 mass %, the machinability deterioration of sintered alloy.

Because including 0.5 for the total amount of the first hard particles, the second hard particles, graphite particle and iron particle The graphite particle of quality % to 1.5 mass %, so after sintering in the case of the first and second hard particles of no fusing, The C of graphite particle can be diffused in the first and second hard particles with solid solution condition, and can ensure that in iron-based body in addition Pearlitic structrure.Therefore, the mechanical strength and wearability of sintered alloy can be improved simultaneously.

Herein, when the content of the graphite particle for total amount is less than 0.5 mass %, because of the ferrite of iron-based body Tissue tends to increase, so the iron-based body of the sintered alloy strength reduction of itself.On the other hand, when relative to total amount graphite When the content of particle is more than 1.5 mass %, carburizing body tissue is precipitated and the deterioration of the machinability of sintered alloy.

6. the method for manufacturing wearability iron-base sintered alloy

By this method, by the mixed-powder compression forming obtained at sintered alloy formed body (molding procedure).It is burning In conjunction in gold formed body, including and the first hard particles, the second hard particles of same ratio, graphite particle in mixed-powder And iron particle.

Sintering is compressed into the sintered alloy formed body of type to manufacture sintered body, and makes in sintered alloy formed body The C of graphite particle is diffused in the first and second hard particles and iron particle (sintering circuit).In this case, not there is only Iron is more diffused to from iron-based body (iron particle) in the first and second hard particles, and the second hard particles do not contain carbon. Therefore, the carbon of graphite particle easily diffuses in the second hard particles, and the grain boundaries between the second hard particles generate Mo Carbide, and the hardness of sintered alloy can be improved.

In the present embodiment, by adjusting sintering temperature and sintering time the hardness of the first hard particles is become 400 to 600Hv and second the hardness of hard particles be more than 600Hv to be sintered.About in the sintered alloy obtained The first and second hard particles hardness, these hardness be using micro-vickers hardness tester 0.1kgf measurement load The value of lower measurement.When the hardness of the first hard particles is set in such range, it can be ensured that the wearability of sintered alloy And machinability.Herein, when the hardness of the first hard particles is less than 400Hv, the iron-based body of solid solution condition is in wherein carbon Difference of hardness is small, and the wearability of sintered alloy reduces.On the other hand, when the hardness of sintered alloy is more than 600Hv, sintering The machinability of alloy can deteriorate.

In addition, when the hardness of the second hard alloy to be set in such range, the wear-resisting of soft iron matrix can be improved Property.Herein, when the hardness of the second hard particles is less than 600Hv, the wearability of sintered alloy can reduce.

It can be by suitably setting content, sintering temperature and the sintering of the component ratio in the above content range, graphite particle Time adjusts the hardness of the first and second hard particles.Sintering temperature can be about 1050 DEG C to 1250 DEG C, and particularly about 1100 DEG C to 1150 DEG C.Sintering time under the above sintering temperature can be 30 minutes to 120 minutes, and more preferable 45 minutes extremely 90 minutes.Sintering atmosphere can be inert atmosphere such as inert gas atmosphere.As non-oxidizing atmosphere, nitrogen gas can be used Atmosphere, argon gas atmosphere, vacuum atmosphere etc..

Matrix by being sintered the iron-base sintered alloy obtained preferably includes the tissue containing pearlite to ensure that it is hard Degree.Tissue containing pearlite can be pearlitic structrure, the Ferritic Austenitic tissue of mixing or mixed pearlite-iron element Body tissue.In order to ensure wearability, preferably contain the ferrite with soft in a small amount.

After being prepared for sintered body, oxidation processes are carried out to sintered body and to contain in the iron-based body of iron particle A part of iron become ferroso-ferric oxide (Fe₃O₄).Carrying out oxidation processes makes the density contrast in sintered body before and after oxidation processes become For 0.05g/cm³Or more.In oxidation processes, the oxide for mainly including ferroso-ferric oxide is generated.Therefore, oxidation processes it The Quality advance of sintered body afterwards.Therefore, higher density contrast shows the larger amount of ferroso-ferric oxide generated.

When the density contrast before and after oxidation processes in sintered body is set as 0.05g/cm³Or more when, sintered alloy can be improved Wearability.Herein, the density contrast before and after oxidation processes in sintered body is less than 0.05g/cm³When, because four in sintered alloy The ratio of Fe 3 O is small, accelerates so while contacting thus adhesive wear with the metal of corresponding component.The result is that sintered alloy Wearability reduce.

In such oxidation processes, such as under steam atmosphere, heated under 500 DEG C to 600 DEG C of temperature condition Sintered body continues 30 minutes to 90 minutes.Therefore, in the density contrast of range above, the iron (Fe) as sintered body matrix can quilt It is oxidized to ferroso-ferric oxide (Fe₃O₄)。

7. the application of wearability iron-base sintered alloy

The sintered alloy obtained in the above manufacturing method is under applied at elevated temperature environment with those sintering than in the prior art The higher mechanical strength of alloy and wearability.For example, it is applicable to use compressed natural gas or liquid under applied at elevated temperature environment Exhaust gas by-pass valve and valve system (such as valve seat and valve guide) of the liquefied oil gas as the internal combustion engine turbocharger of fuel.

For example, when the valve seat of the air bleeding valve of internal combustion engine is made of sintered alloy, even with when valve seat with valve each other Adhesive wear and the wear pattern of the fretting wear when the two when sliding over one another when contact develop, with prior art phase Wearability than such valve seat is still improved.Particularly, use compressed natural gas or liquefied petroleum gas as fuel Use environment under, although being difficult to form Mo oxidation films under such circumstances, adhesive wear can be reduced.

It will describe to realize the embodiment of the present invention in practice together with comparative example below.

[Embodiment 1:The optimal Tian Jialiang &#93 of first hard particles;

It is prepared for the sintered alloy according to embodiment 1 according to following preparation method.As the first hard particles, gas is used Atomization method prepares the hard particles (commercially available from Daido Steel Co., Ltd) manufactured by alloy, and the alloy includes Mo: 40 mass %, Ni:30 mass %, Co:20 mass %, Mn:5 mass %;Si:0.8 mass % and C:1.2 mass %, surplus packet Include Fe and inevitable impurity (i.e. Fe-40Mo-30Ni-20Co-5Mn-0.8Si-1.2C).It is used according to JIS standards Z8801 First hard particles are classified as 44 μm to 250 μm of range by sieve.Herein, in this specification " granularity of particle " be by according to The method is classified obtained value.

As the second hard particles, the second hard particles manufactured by Fe-65 alloys using grinding method preparation (from Kinsay Matec Co., Ltd is commercially available), the Fe-65 alloys include Mo:65 mass %, surplus include Fe and inevitable Impurity.Second hard particles are classified as 75 μm or smaller range.

Next, preparation includes the powdered graphite (CPB-S, commercially available from Nippon Kokuen Group) of graphite particle With the reduced iron powder (JIP255M-90, commercially available from JFE Steel Corporation) including pure iron particle.It is mixed using V-type Clutch is by above first hard particles, the second hard particles of the respectively ratio of 40 mass %, 3 mass % and 1.1 mass % With graphite particle and remaining iron particle (specifically 55.9 mass %) together with mix 30 minutes.Thus to obtain mixed-powder.

Next, the mixed-powder compression forming obtained is circularized under the plus-pressure of 588MPa using molding die Testpieces is to form sintered alloy formed body (compression forming body).It is sintered at 1120 DEG C in inert atmosphere (nitrogen atmosphere) The compression forming body 60 minutes is to obtain sintered body.By under 550 DEG C of heating conditions for continuing 50 minutes under steam atmosphere Heating carrys out oxidation and sinter body.Sintered alloy (valve seat) testpieces according to embodiment 1 is formd as a result,.

[Embodiment 2 and 3:The optimal Tian Jialiang &#93 of first hard particles;

Sintered alloy testpieces is prepared in the same manner as in example 1.Embodiment 2 and 3 is hard for evaluating first The embodiment of the optimal additive amount of matter particle.Embodiment 2 and 3 difference from example 1 is that:As shown in table 1, relative to The first hard particles are added with the ratio of 5 mass % and 50 mass % respectively for entire mixed-powder.

[Embodiment 4 and 5:The optimal Tian Jialiang &#93 of second hard particles;

Sintered alloy testpieces is prepared in the same manner as in example 1.Embodiment 4 and 5 is hard for evaluating second The embodiment of the optimal additive amount of matter particle.Embodiment 4 and 5 difference from example 1 is that:As shown in table 1, relative to The second hard particles are added with the ratio of 1 mass % and 5 mass % respectively for entire mixed-powder.

[Embodiment 6 and 7:The optimal Tian Jialiang &#93 of graphite particle;

Sintered alloy testpieces is prepared in the same manner as in example 1.Embodiment 6 and 7 is to be used for evaluating graphite The embodiment of the optimal additive amount of grain.Embodiment 6 and 7 with embodiment 2 the difference is that:As shown in table 1, relative to entire Graphite particle is added with the ratio of 0.5 mass % and 1.5 mass % respectively for mixed-powder.

[Embodiment 8:The Ying Du &#93 of first hard particles;

Sintered alloy testpieces is prepared in the same manner as in example 1.The difference of embodiment 8 and embodiment 1 It is:Sintering temperature is lower than embodiment 1, and after being sintered the hardness of the first hard particles of sintered body decline (with reference to table 1, 545Hv)。

[Comparative example 1 and 2:The Bi compare Li &#93 of the optimal additive amount of first hard particles;

Sintered alloy testpieces is prepared in the same manner as in example 1.Comparative example 1 and 2 is hard for evaluating first The comparative example of the optimal additive amount of matter particle.Comparative example 1 and 2 difference from example 1 is that:As shown in table 1, relative to The first hard particles are added with the ratio of 0 mass % (not adding) and 60 mass % respectively for entire mixed-powder.This Place, can not possibly be by the moulding moulded body of mixed-powder in comparative example 2.

[Comparative example 3 and 4:The Bi compare Li &#93 of the optimal additive amount of second hard particles;

Sintered alloy testpieces is prepared in the same manner as in example 1.Comparative example 3 and 4 is hard for evaluating second The comparative example of the optimal additive amount of matter particle.Comparative example 3 and 4 difference from example 1 is that:As shown in table 1, relative to The second hard particles are added with the ratio of 0 mass % and 10 mass % respectively for entire mixed-powder.In addition, in comparative example 3 The graphite particle of 0.8 mass % ratios of middle addition.

[Comparative example 5 and 6:The Bi compare Li &#93 of the optimal additive amount of graphite particle;

Sintered alloy testpieces is prepared in the same manner as in example 1.Comparative example 5 and 6 is to be used for evaluating graphite The comparative example of the optimal additive amount of grain.Comparative example 5 and 6 difference from example 1 is that:As shown in table 1, relative to entire Graphite particle is added with the ratio of 0.4 mass % and 1.6 mass % respectively for mixed-powder.

[Comparative example 7:The Bi compare Li &#93 of the density contrast of sintered body;

Sintered alloy testpieces is prepared in the same manner as in example 1.In comparative example 7 during compression forming at Type pressure is higher than embodiment 1, and the density before oxidation processes is higher.Therefore, there are less holes inside sintered body, and And therefore prevent the raising reduction of sintered density after oxide generation and oxidation processes (i.e. density contrast reduces).

[Comparative example 8:The Bi compare Li &#93 of first hard particles hardness;

Sintered alloy testpieces is prepared in the same manner as in example 1.The difference of comparative example 8 and embodiment 1 It is:The hardness of sintering temperature first hard particles of sintered body higher than embodiment 1 and after being sintered it is higher (with reference to table 1, 650Hv)。

[Comparative example 9]

Sintered alloy testpieces is prepared in the same manner as in example 1.The difference of comparative example 9 and embodiment 1 It is:Use for including Co-40Mo-5Cr-0.9C alloys corresponding to the hard particles described in JP 2004-156101A Grain is used as the first hard particles, does not add the second hard particles, and do not carried out at oxidation to sintered body after the sintering Reason.

[Ying Dushiyan ]

For the sintered alloy testpieces according to embodiment 1 to 8 and comparative example 1 to 9, micro-vickers hardness tester is used The hardness of the first hard particles and the second hard particles is measured under the measurement load of 0.1kgf.As a result it is displayed in Table 1.

[Density measure tests ]

Measure the front and back quality according to embodiment 1 to 8 and the sintered alloy testpieces of comparative example 1 and 3 to 8 of oxidation processes. By the quality of measurement divided by the volume calculated by testpieces size, and calculate the close of testpieces (sintered body) before and after oxidation processes Degree.In addition, calculating the density contrast of the testpieces (sintered body) before and after oxidation processes.As a result it is displayed in Table 1.

[Mo Sunshiyan ]

Using the tester in Fig. 1 to being carried out according to the sintered alloy testpieces of embodiment 1 to 8 and comparative example 1 and 3 to 9 Wear test, and evaluate their wearability.In this test, as shown in Fig. 1, using propane gas burner 10 as adding Heat source, the slipper between the ring-shaped valve seats 12 being made of the sintered alloy of aforementioned preparation and the valve face 14 of valve 13 are placed In propane gas combustion atmosphere.Valve face 14 according to EV12 (SEA standards) by carrying out carbo-nitriding acquisition.The temperature of control valve seat 12 Degree so that its be 250 DEG C, when make valve seat 12 contact valve face 14 when pass through spring 16 apply 25kgf load, make valve seat 12 with 3250 beats/min of contact valve faces 14, and wear test carries out 8 hours.

Wear test is measured to try as abrasion in the total amount of the wearing depth of valve face 14 and the axial direction of valve seat 12 later Wear extent is tested, and calculates and wear test is used as by the value for being obtained the value in wear test wear extent divided by comparative example 9 Wear extent ratio.As a result it is displayed in Table 1.

Fig. 3 A, 4A, 5A, 6A and 7A show that embodiment 1 to 8 corresponds to wear test wear extent ratio with comparative example 1 and 3 to 9 Example mapping result, wherein by the sequence horizontal axis of figure represent the additive amount of the first hard particles, the second hard particles additive amount, The density contrast of the additive amount of graphite particle, the hardness of the first hard particles and sintered body.

In addition, under the microscope according to the experiment after embodiment 1 and 7 wear test of comparative example after observation abrasion test The surface of part.As a result it is shown in Fig. 8 A and Fig. 8 B.Fig. 8 A are wear tests later according to the surface of the testpieces of embodiment 1 Picture, and Fig. 8 B are the pictures on the surface of the testpieces after wear test according to comparative example 7.

Using how tal fibre corrosive liquid (nital) etching wear test before embodiment 1, comparative example 5 and comparative example 6 experiment Part, and the tissue of sintered alloy is observed under the microscope.As a result it is shown in Fig. 9 A to Fig. 9 C.Fig. 9 A are according to embodiment 1 The picture of the tissue of testpieces, Fig. 9 B are according to the picture of the tissue of the testpieces of comparative example 5, and Fig. 9 C are according to comparative example 6 Testpieces tissue picture.

[Qie Xiaoxingshiyan ]

Using tester shown in Fig. 2 to according to the sintered alloy testpieces of embodiment 1 to 8 and comparative example 1 and 3 to 9 into Row machinability test, and evaluate their machinability.In this test, each for embodiment 1 to 8 and comparative example 1 and 3 to 9 Prepare six testpieces 20 with 30mm outer diameters, 22mm internal diameters and 9mm total lengths.Using NC lathes, titanium aln precipitation is used The sintered-carbide tool (cutting element) 30 of coating with the cutting depth of 0.3mm, 0.08mm/rev feed, and is cut in 320m The testpieces 20 rotated with 970rpm rotary speeies apart from upper wet type cross cutting.Then, using light microscope survey tool The greatest wear depth of 30 flanks is calculated by will be in tool wear amount divided by comparative example 9 as tool wear amount It is worth the value obtained as tool wear amount ratio.As a result it is displayed in Table 1.

Fig. 3 B, 4B, 5B, 6B and 7B show that embodiment 1 and 3 to 8 corresponds to tool wear amount ratio with comparative example 1 to 9 Mapping result, wherein representing the additive amount of the first hard particles, the additive amount of the second hard particles, graphite by the sequence horizontal axis of figure The density contrast of the additive amount of particle, the hardness of the first hard particles and sintered body.

[Table 1]

(result 1:The optimal additive amount of first hard particles)

As shown in fig. 3, the wear test wear extent ratio of embodiment 1 to 3 is less than comparative example 1 to 9.Wear test is ground Damage amount ratio is reduced by the sequence of embodiment 2, embodiment 1 and embodiment 3.Therefore, when adding the first hard particles, it is believed that change Into the rub resistance abrasiveness of sintered alloy.However, in comparative example 2, it may be said that because being added to the first excessive hard particles, So the mouldability deterioration of formed body.Based on the above, the optimal additive amount of the first hard particles is relative to entire mixed-powder For 5 mass % to 50 mass %.

Herein, as shown in Figure 3B, the tool wear amount ratio of embodiment 1 to 3 is less than comparative example 9.Tool wear amount ratio Example is improved by the sequence of embodiment 2, embodiment 1 and embodiment 3.However, it is believed that when addition is than 3 more first hard of embodiment When particle, the machinability deterioration and the raising of tool wear amount ratio of sintered alloy.

(result 2:The optimal additive amount of second hard particles)

As shown in Figure 4 A, embodiment 1,4 and 5 and the wear test wear extent ratio of comparative example 4 are less than comparative example 3 and 9. However, as shown in Figure 4 B, the tool wear amount ratio of comparative example 4 is higher than embodiment 1,4 and 5.Herein, when observation wear test Later when the surface of testpieces, 3 scratch caused by adhesive wear of comparative example is more than other embodiments.

It is therefore contemplated that the second hard particles improve the hardness of sintered alloy after sintering, prevent from being sintered conjunction during use The plastic deformation of the iron-based body of gold, and reduce the adhesive wear of sintered alloy.Specifically, it is believed that because not with the first hard particles With the second hard particles without containing Ni, Co etc., so compared in the first hard particles, the iron-based around the second hard particles Body can harden, in sintering process molybdenum carbide iron-based body grain boundaries be precipitated, and therefore be sintered after iron-based body hardness It is improved.

Based on the above, when the additive amount of the second hard particles is too small, the surface of sintered alloy is easy to after wear test It is scraped off.On the other hand, it is believed that as in comparative example 4, when the additive amount of the second hard particles is too big, be sintered it Sintered alloy is too hard afterwards and machinability deteriorates.Based on result above, the optimal additive amount of the second hard particles is relative to whole 1 mass % to 5 mass % for a mixed-powder.

(result 3:The optimal additive amount of graphite particle)

As shown in Figure 5 A, embodiment 1,6 and 7 and the wear test wear extent ratio of comparative example 6 are less than comparative example 5 and 9. However, as shown in Figure 5 B, the tool wear amount ratio of comparative example 6 is higher than embodiment 1,6 and 7.

As illustrated in figure 9 a, pearlitic structrure is formed in the tissue of sintered alloy shown in embodiment 1.However, such as Fig. 9 C Shown in, in the tissue of sintered alloy shown in comparative example 6 carburizing body tissue is formed since the amount of graphite particle improves.Therefore Think that the tool wear amount ratio of comparative example 6 is higher than embodiment 1,6 and 7.

On the other hand, as shown in fig. 9b, it is believed that in the tissue of sintered alloy shown in comparative example 5, because of the tissue With ferrite as its major part, thus the wear test wear extent ratio of comparative example 5 higher than embodiment 1,6 and 7 with than Compared with example 6.Therefore, it can be ensured that the optimal additive amount of the graphite particle of the pearlitic structrure after sintering in iron-based body is relative to whole 0.5 mass % to 1.5 mass % for a mixed-powder.

(result 4:The optimal hardness of first hard particles)

As shown in FIG, embodiment 1,3,5 and 8 and the wear test wear extent ratio of comparative example 8 are less than comparative example 9. However, as depicted in figure 6b, the tool wear amount ratio of comparative example 8 is higher than embodiment 1,3,5 and 8.

Think because the hardness of first hard particles is right higher than embodiment 1,3,5 and 8 and comparative example 8 in comparative example 9 Answer component wear more, and the wear test wear extent ratio of embodiment 9 is higher than other embodiments.On the other hand, it is believed that Because the hardness (Hv) of the first hard particles is less than comparative example 8 and is 600 or smaller, reality in embodiment 1,3,5 and 8 The tool wear amount ratio for applying example 1,3,5 and 8 is less than comparative example 8.Herein, it may be said that because ensuring in embodiment 1,3,5 and 8 First hard particles with 400Hv or bigger hardness, it is ensured that wearability.

Therefore, after sintering the hardness of the first hard particles preferably within the scope of 400 to 600Hv.Herein, consider to improve iron Second hard particles of matrix wearability, under conditions of the additive amount of range above, the hardness of the second hard particles it is necessary to Higher than the hardness of the first hard particles, and it is more than at least 600Hv.

(result 5:The optimum density of sintered body is poor)

As shown in fig. 7, the wear test wear extent ratio of embodiment 1 to 8 is less than comparative example 7 and 9.Such as in Fig. 7 B Shown in, the tool wear amount ratio of comparative example 9 is higher than embodiment 1 to 8 and comparative example 7.

In comparative example 7, because the density contrast in sintered body before and after oxidation processes is less than 0.05g/cm³, so in sintered body The amount of the main oxide including ferroso-ferric oxide is less than the sintered body of embodiment 1 to 8.Therefore, it promotes and corresponding component Metal contacts, and as shown in figure 8B, in the testpieces (sintered body) of comparative example 7, it is believed that accelerate and corresponding component Adhesive wear.On the other hand, it is believed that the wearability of sintered alloy is already higher than comparative example 7 in embodiment 1 to 8, because of base Such adhesive wear is not present in this (referring for example to embodiment 1, Fig. 8 A).To be sintered therefore, it is necessary to carry out oxidation processes Density contrast in body before and after oxidation processes becomes 0.05g/cm³Or more.

[Embodiment 9:The You Lijing &#93 of second hard particles;

Sintered alloy testpieces is prepared in the same manner as in example 1.Embodiment 9 is for evaluating the second hard The embodiment of the optimized particle size of grain.Embodiment 9 difference from example 1 is that:As the second hard particles, using through dividing Grade is with the second hard particles with the grain size (granularity) in the range of more than 75 μm and less than or equal to 100 μm.

[Comparative example 10:The Bi compare Li &#93 of the optimized particle size of second hard particles;

Sintered alloy testpieces is prepared in the same manner as in example 1.Comparative example 10 is for evaluating the second hard The comparative example of the optimized particle size of particle.Comparative example 10 difference from example 1 is that:As the second hard particles, use Through being classified with the second hard particles with grain size in the range of more than 100 μm and less than or equal to 150 μm.Herein, according to The testpieces of comparative example 10 is included in the sintered alloy in the scope of the invention, and be set as comparative example 10 in order to reality Apply the comparison of example 1 and 9.

In the same manner as in example 1, wear test and cutting are carried out to the testpieces of embodiment 9 and comparative example 10 Property experiment, and measure wear test wear extent and tool wear amount.As a result in Figure 10 A and Figure 10 B with 1 or more embodiment As a result it shows together.

Figure 10 A be show embodiment 1 and 9 with the figure of the result of wear test wear extent ratio in comparative example 10, and Figure 10 B It is the figure for showing the result of tool wear amount ratio in embodiment 1 and 9 and comparative example 10.

(result 6:The optimized particle size of second hard particles)

As shown in FIG. 10A, embodiment 1 and 9 and the wear test wear extent of comparative example 10 are in similar proportion.However, as schemed Shown in 10B, the tool wear amount ratio of embodiment 1 and 9 is less than comparative example 10, and the tool wear amount ratio of embodiment 1 It is minimum in these embodiments.This is because since the grain size of the second hard particles is too big in comparative example 10, in some cases The machinability of lower testpieces (sintered body) deteriorates.Based on this as a result, the grain size (maximum particle diameter) of the second hard particles is preferably 100 μm or smaller range, and the grain size (maximum particle diameter) of more preferably the second hard particles is in 75 μm or smaller range.

Although embodiment of the present invention described in detail above, embodiment that the present invention is not restricted to these, and And various design variations can be carried out.

Claims

1. the method for manufacturing wearability iron-base sintered alloy, including:

Molding procedure, by the mixed-powder compression forming including hard particles, graphite particle and iron particle in the molding procedure At sintered alloy formed body;With

Sintering circuit is sintered the sintered alloy formed body in the sintering circuit, and the sintered alloy is made to be molded The C of graphite particle is diffused in the hard particles and the iron particle in body,

The method of the manufacture wearability iron-base sintered alloy, it is characterised in that

The hard particles include the first hard particles and the second hard particles,

Wherein when the amount of first hard particles is set as 100 mass %, first hard particles include Mo:20 matter % is measured to 70 mass %, Ni:5 mass % to 40 mass %, Co:5 mass % to 40 mass %, Mn:1 mass % to 20 matter Measure %, Si:0.5 mass % to 4.0 mass % and C:0.5 mass % to 3.0 mass %, surplus include Fe and inevitably it is miscellaneous Matter,

Wherein when the amount of second hard particles is set as 100 mass %, second hard particles include Mo:60 matter Measure % to 70 mass % and Si:2.0 mass % or less, surplus include Fe and inevitable impurity,

Wherein when by the total amount of first hard particles, second hard particles, the graphite particle and the iron particle When being set as 100 mass %, the mixed-powder include first hard particles of 5 mass % to 50 mass %, 1 mass % extremely Second hard particles and 0.5 mass % of 5 mass % to 1.5 mass % the graphite particle, and

Wherein in the sintering circuit, be sintered so that the hardness of first hard particles become 400 to 600Hv and The hardness of second hard particles is more than 600Hv, after the sintering circuit, to by sintered alloy formed body institute The sintered body of sintering carries out oxidation processes so that contained a part of iron becomes four oxidations in the iron-based body of the iron particle Three-iron, and carry out the oxidation processes make the density of the oxidation processes foregoing description sintered body and the oxidation processes it The difference between the density of the sintered body becomes 0.05g/cm afterwards³Or bigger.

2. according to the method described in claim 1, it is characterized in that when the amount of first hard particles is set as 100 mass % When, 10 mass % or less Cr are also added in first hard particles.

3. method according to claim 1 or 2, it is characterised in that the grain size of second hard particles is at 100 μm or more In few range.