JPH07138714A - Wear resistant iron-based sintered alloy and its production - Google Patents

Abstract

PURPOSE:To produce an iron-based sintered alloy excellent in wear resistance. CONSTITUTION:Ni-based alloy power having a compsn. contg., by weight, 2 to 15% Co and 2 to 10%, preferably >3 to 10% Mo, and the balance Fe with inevitable impurities is mixed with Ni-based alloy powder having a compsn. contg. 5 to 20% Mo, 20 to 40% Cr, 10 to 20% W and 10 to 30% Fe, furthermore contg., if necessary, 0.5 to 4% C and <=2% Si, and the balance Ni with inevitable impurities and a lubricant for compacting, which is compacted to form a green compact. This green compact is sintered to form an iron-based sintered alloy. Though the hard grains dispersed into the matrix of the iron-based sintered alloy are constituted of an Ni-based hard alloy and they are hard themselves, C is furthermore incorporated, thereby it combines with Mo, Cr, W, Si and Fe to form carbides to improve the wear resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron-based sintered alloy having excellent wear resistance and a method for producing the same. INDUSTRIAL APPLICABILITY The present invention is useful for sintered parts such as valve seats, piston rings, and collars of exhaust systems used in internal combustion engines of vehicles such as automobiles.

[0002]

2. Description of the Related Art The prior art of an iron-based sintered alloy having wear resistance will be described by taking a sintered alloy for a valve seat used in an internal combustion engine of an automobile as an example. Conventionally, as sintered alloys for valve seats, Fe-C-Co-Ni-based materials, Fe-C-based materials have been used to improve wear resistance, and ferromolybdenum (Fe-Mo) and ferrochrome (Fe-Cr) are used.
An intermetallic compound such as Fe-C-Cr-Mo-V alloy added is used (Japanese Patent Laid-Open No. 56-15).
4110).

Further, Fe-containing Cr and Mo
Sintered alloy in which iron-based hard particles composed of Cr, Mo, V, etc. are dispersed in the C matrix structure to improve wear resistance and opponent attacking property (JP-A-60-224762), and Fe-C-
Sintered alloys having improved wear resistance by dispersing hard particles of FeMo and FeW in a Co-Ni matrix structure and further impregnated with a Pb alloy or the like (JP-A-62-202058).
Japanese patent publication).

The properties required of the valve seat material include not only wear resistance but also corrosion resistance and heat resistance. Here, the wear resistance is mainly taken by the hard particles, and the corrosion resistance and heat resistance are mainly taken by the matrix structure, and the two are combined to secure the durability.

[0005]

By the way, in recent years, in the field of using wear-resistant iron-based sintered alloys, demands for improving the properties of the sintered alloys have been further increased. For example, in an internal combustion engine of an automobile, long life, high output, high rotation,
There is an ever-increasing demand for improvements in exhaust gas purification measures or fuel efficiency improvement measures. Therefore, for engine valves and valve seats in internal combustion engines of automobiles,
It has become unavoidable to withstand harsh operating environments more than ever, and it is necessary to further improve heat resistance and wear resistance, and also to improve corrosion resistance at high temperatures.

[0006] However, the base of the iron-based valve seat material that has been conventionally provided is formed by mixing element powders of respective elements such as Ni powder, Co powder, Mo powder, which are alloying elements, with iron powder. Using the mixed powder described above, a green compact is formed by using this mixed powder as a raw material, and the green compact is sintered to form a sintered body, whereby Ni, Co, Mo, etc. are diffused in iron. . Therefore, it is difficult to completely diffuse these alloying elements into iron, and it is difficult to improve the characteristics in proportion to the alloying amount.

Therefore, in order to efficiently bring out the effect of the addition of alloying elements, it is conceivable to adopt a powder in which the alloying elements are alloyed with iron in advance. Since the compressibility of the powder is lowered by the solution hardening, it is difficult to increase the density of the green compact, which is disadvantageous for improving the strength and durability. The present invention has been made to solve the above-mentioned problems in the conventional iron-based sintered alloy. Claims 1 to 8 disperse Ni-based hard particles having a carbide of Mo, Cr, W, Fe or Si in an iron-based matrix structure, so that a severe environment for use such as valve seat materials in recent years. It is an object of the present invention to provide a wear-resistant iron-based sintered alloy having improved wear resistance, particularly wear resistance at high temperature, and a method for producing the same.

Further, according to claims 4 to 8, by using a mixed powder obtained by mixing the Ni-based hard alloy powder and the graphite powder with the iron-based alloy powder, the compression-moldability of the iron-based alloy powder forming the matrix. Of the Ni-based hard alloy powder by sintering to diffuse Ni into the matrix, thereby ensuring the oxidation resistance of the matrix and further improving the wear resistance, especially at high temperatures. An object is to provide a method for producing a base sintered alloy.

Further, in addition to the above-mentioned problems, the third and the eighth aspects of the present invention provide a valve seat material or the like in recent years by infiltrating an infiltrant into pores of a sintered body forming the above-mentioned sintered alloy. Thus, it is an object of the present invention to provide a wear-resistant iron-based sintered alloy which can be used in a severe environment of use and has further improved wear resistance, particularly wear resistance at high temperatures, and a method for producing the same.

[0010]

The present inventors have found that the wear resistance,
In order to improve corrosion resistance and oxidation resistance, the chemical composition and alloying morphology of the matrix of the iron-based sintered alloy for valve seats, the type and addition amount of hard particles, the matrix structure and the sintering conditions, etc.
We have earnestly studied. As a result, by finding a specific composition range and alloying morphology of the base that exhibits excellent oxidation resistance and corrosion resistance at high temperatures, and by dispersing hard particles having carbides in the specific composition range in this base, The present invention has been completed by finding that good wear resistance, corrosion resistance, and oxidation resistance can be maintained, and finding that it is more economical than conventional materials.

That is, the inventor of the present invention forms a green compact with a mixed powder obtained by mixing an Ni-based hard alloy powder and a graphite powder with an iron-based alloy powder that does not positively contain Ni, and then presses the green compact. By sintering the body in a predetermined temperature range, the compressibility of the iron-based alloy powder forming the matrix is ensured, and the Ni of the Ni-based hard alloy powder is diffused into the matrix along with the sintering to prevent oxidation of the matrix. Property, especially oxidizability at high temperature, and further, C of graphite powder is diffused during sintering to form carbides in the matrix or inside the Ni-based hard alloy powder, which results in wear resistance of the iron-based sintered alloy. It is intended to further secure the heat resistance, oxidation resistance, and heat resistance. The iron-based sintered alloy having excellent wear resistance according to claim 1 has an overall composition of Co: 1.4 to 15%, Mo: 1.5 to
16%, Cr; 0.4-12%, W; 0.2-6.0
%, C; 0.4 to 3.2%, Ni; 0.2 to 9.0%, the balance consisting of inevitable impurities and Fe, Co; 2
~ 15%, Mo; 2-10%, C; 0.2-2%, N
i: a matrix structure containing 10% or less and the balance consisting of inevitable impurities and Fe, Mo: 5 to 20%, Cr: 20 to 40
%, W; 10 to 20%, C; 0.5 to 5.0%, Fe;
It is characterized in that it comprises a sintered body containing 5 to 30% and the rest containing 2 to 30% of hard particles consisting of unavoidable impurities and Ni. The iron-based sintered alloy having excellent wear resistance according to claim 2 has a total composition by weight of Co: 1.4 to 15%, Mo: 1.5 to
16%, Cr; 0.4-12%, W; 0.2-6.0
%, C; 0.01 to 4.0%, Ni; 0.2 to 9.0
%, Si: 0.6% or less, the balance consisting of inevitable impurities and Fe, Co: 2 to 15%, Mo: 2 to
10%, C; 0.2 to 2%, Ni; 10% or less, and the balance consists of inevitable impurities and Fe.
5 to 20%, Cr; 20 to 40%, W; 10 to 20%,
C: 0.5-4.0%, Fe: 5-30%, and further S
i: A sintered body containing 2% or less, and the balance being 2 to 30% of hard particles composed of unavoidable impurities and Ni dispersed therein. In the iron-based sintered alloy having excellent wear resistance according to claim 3, the sintered body according to claim 1 or 2 has pores, and at least Pb, Cu, or Pb-Cu based alloy is present in the pores. It is characterized in that 1% to 25% of the infiltrant containing one kind as a main component is infiltrated with respect to 100% when the weight of the sintered body is 100%. The method for manufacturing an iron-based sintered alloy having excellent wear resistance according to claim 4 contains Co: 2 to 15%, Mo: 2 to 10% by weight, and the balance is inevitable impurities and Fe. Mo: 5 to 20%, Cr: 20 to 40%, based on the iron-based alloy powder,
W: 10 to 20%, Fe: 10 to 30%, the balance being Ni-based hard alloy powder consisting of inevitable impurities and Ni, graphite powder 0.2 to 2% and a molding lubricant were mixed and molded, 132
The present invention is characterized in that an iron-based sintered alloy composed of a sintered body is manufactured by sintering at a temperature lower than the melting point of the Ni-based hard alloy powder from 3K. The method for producing an iron-based sintered alloy according to claim 5 is the method according to claim 4, wherein the Mo content of the iron-based powder alloy is more than 3% and 10% or less. The method for manufacturing an iron-based sintered alloy having excellent wear resistance according to claim 6 contains Co: 2 to 15%, Mo: 2 to 10% by weight, and the balance is inevitable impurities and Fe. Mo: 5 to 20%, Cr: 20 to 40%, based on the iron-based alloy powder,
W; 10 to 20%, Fe; 10 to 30%, and C; 0.5
.About.4%, Si; Ni: 2% or less, the balance being Ni-based hard alloy powder consisting of unavoidable impurities and Ni, and graphite powder 0.2 to
2% and a molding lubricant are mixed, molded, and sintered at a temperature lower than the melting point of Ni-based hard alloy powder from 1323K to produce an iron-based sintered alloy composed of a sintered body. To do. In the method for producing an iron-based alloy powder having excellent wear resistance according to claim 7, the iron-based alloy powder according to claim 6 has a Mo content of 3
% And 10% or less. The method for producing an iron-based sintered alloy having excellent wear resistance according to claim 8 is the same as in claim 4 to claim 7, wherein the sintered body has pores, and Pb, Cu, and Pb-Cu based alloys are contained in the pores. It is characterized in that an infiltrant containing at least one kind of alloy as a main component is infiltrated by 1 to 25% with respect to 100% when the sintered body is taken as 100% by weight.

[0012]

In the iron-based sintered alloy according to claims 1 to 3, the matrix structure is Co: 2 to 15%, Mo: 2 to 10%, Ni: 1
Since 0% or less is composed of solid-dissolved alloy elements, the degree of solid solution homogeneity of the alloy elements in the matrix is high, and therefore, compared with the conventional method in which various element powders are mixed, excellent corrosion resistance is achieved with a small amount of alloy. , Oxidation resistance and wear resistance can be obtained.

The base of the iron-based sintered alloy according to claims 1 to 3 is N
Since i is included, the oxidation resistance is improved, and Mo carbide is generated in this base. Iron-based alloy powder (Fe-2 to 15% Co-2 to
The alloy powder having a composition of 10% Mo) constitutes the matrix in the iron-based sintered alloy of claims 1 to 3. The Ni-based hard alloy powder in the manufacturing method of claims 4 to 8 constitutes the hard particles of claims 1 to 3. The hard particles are Ni-based hard alloys and are hard themselves. Further, the hard particles are C (if the Ni-based hard alloy powder contains C in the powder state as in claim 6, the C is contained therein, or the C of the graphite powder added in claims 4 to 8). ), Mo, Cr, W, Fe, S
By combining with i to form a carbide, the wear resistance of the hard particles themselves is further improved.

In the manufacturing method of claims 4 to 8, the iron-based alloy powder constitutes the matrix of the iron-based sintered alloy as described above, and since Ni is not positively contained in the powder state,
During molding of the green compact, the compressibility of the iron-based alloy powder itself forming the matrix is secured, which is advantageous for increasing the density of the green compact. Furthermore, Ni in the Ni-based alloy powder that constitutes the hard particles diffuses into the matrix during sintering, and improves the oxidation resistance of the matrix, particularly the oxidation resistance and heat resistance at high temperatures.

Further, in the manufacturing method of claims 4 to 8, at the time of sintering, C of the graphite powder is M in the Ni-based hard alloy powder.
By combining with O, Cr, W, Fe or the like, or with Mo or the like in the iron-based alloy powder to form a carbide, the wear resistance of the matrix and the Ni-based hard alloy powder is improved. (Structure) The base metal structure of the sintered alloy of the present invention is generally determined to be a structure in which pearlite, austenite, and bainite are mixed. The generated carbide is dispersed in the matrix structure. Further, hard particles composed of Ni-based hard alloy powder that has generated carbide are dispersed in the matrix structure. (Iron-based alloy powder) The iron-based alloy powder of claims 4 to 8 constitutes the matrix of the iron-based sintered alloy of the present invention as described above, and the weight ratio of Co: 2 to 15%, Mo; It contains 2 to 10%, and the balance consists of unavoidable impurities and Fe. Co; 2 to 15% Co has the effect of forming a solid solution in the matrix to strengthen it and improve heat resistance and corrosion resistance, but if the Co content in the iron-based alloy powder is less than 2%, that effect is obtained. On the other hand, if the content exceeds 15%, the effect is further improved, but the economy is lacking. Therefore, considering this point, the content is defined as 2 to 15%. Mo; 2-10% Mo is solid-dissolved in the matrix to strengthen it and shows an effect of improving the strength in a high temperature range. In a sintered body containing carbon, a part of carbide is generated to form wear resistance. Shows the effect of improving. These effects are insufficient if the content of the iron-based alloy powder is less than 2%, more preferably more than 3%, and even if the content exceeds 10%, the effect is recognized, but the iron-based alloy is Since it causes a decrease in the compressibility of the powder,
Its content was defined as 2-10%. For the above reasons, it is preferable that the iron-based alloy powder has a Mo content of more than 3% and 10% or less. (Ni-based hard alloy powder) The Ni-based hard alloy powder contributes to improvement of wear resistance of the iron-based sintered alloy. The Ni-based hard alloy powder is a hard particle powder developed by the present inventors and constitutes the hard particles in claims 1 to 3. Ni-based hard alloy powder is Mo; 5-20%, Cr; 20-40%, W; 1
0 to 20%, Fe; 10 to 30% are included. Mo, Cr,
W, Si and Fe combine with C to form a carbide, which contributes to the improvement of the wear resistance of the iron-based sintered alloy.

It is preferable that the Ni-based hard alloy powder further contains C: 0.5 to 4.0% and Si: 2% or less, if necessary. Ni-based hard alloy powder is Fe
10 to 30%, especially 12 to 22%, 15 to 2
Can be 0%. The Fe in the Ni-based hard alloy powder, that is, the hard particles, is mainly intended to control the opponent attack of the iron-based sintered alloy. The reason is that Fe carbide has a lower hardness than other carbides. In addition, when the Ni-based hard alloy powder is a spray powder formed by a spraying method, the sprayability is secured by including Si. A part of Ni and Fe of the Ni-based hard alloy powder diffuses into the matrix by sintering, and acts to improve the oxidation resistance of the matrix and the retention of the hard particles in the matrix.

The Ni-based hard alloy powder is preferably 2 to 30% of 100% when the mixed powder (excluding the lubricant) constituting the green compact, that is, the sintered body is 100% by weight. . Therefore, in claim 1, the hard particles are defined as 2 to 30% when the whole sintered body is taken as 100%.
Here, if the addition amount of the Ni-based hard alloy powder is less than 2%, the abrasion resistance is insufficiently improved, and even if it is added in excess of 30%, the improvement is small relative to the addition, and the moldability is deteriorated. Therefore, it is appropriate that the addition amount of the Ni-based hard alloy powder be 2 to 30%. Further, based on the above reason or the application and type of the iron-based sintered alloy, the amount of the Ni-based hard alloy powder can be, for example, the upper limit value of 27%, 23%, 15%, and the lower limit value of 3%, 5%.
%, 8%

Although the reasons for limiting the compositions of the iron-based alloy powder and the Ni-based hard alloy powder have been described above, the reasons for limiting the composition of the matrix structure and the hard particles in the iron-based sintered alloy basically correspond to this. Is. (C) C solid-dissolves in the matrix to strengthen the matrix, and partly diffuses into the Ni-based hard alloy powder (corresponding to the hard particles dispersed in the matrix) to form Mo, Cr, W in the Ni-based hard alloy powder.
And the like form carbides to increase the hardness of the Ni-based hard alloy powder, that is, hard particles, and are effective in improving wear resistance. C can be supplied from graphite powder. The graphite powder is preferably 0.2 to 2% of 100% when the entire mixed powder (excluding the lubricant) constituting the green compact, that is, the sintered body is 100% by weight. Further, as in claim 6, the Ni-based hard alloy powder may contain C in advance. In claim 4, if the amount of graphite powder added is less than 0.2%, the above effect cannot be expected, and if it exceeds 2.0%, the sintered alloy may be embrittled. 0.2-2.0% is preferable. For example, 0.6 to 1.3
%, 0.7 to 1.0%. (Sintering temperature) The sintering temperature of the sintered alloy of the present invention is 1323K.
To a temperature below the melting point of the Ni-based hard alloy powder.
This is because if the sintering temperature is less than 1323 K, the progress of sintering is insufficient and the wear resistance is insufficient, and if the sintering temperature exceeds the temperature lower than the melting point of the Ni-based hard alloy powder, the crystal grains become coarse. This is because it is not preferable. (Infiltrant) In claims 3 and 8, the sintered body forming the sintered alloy has a skeleton shape and has pores, and the pores are infiltrated with the infiltrant. Infiltration is suitable for wear resistant iron-based sintered alloys used under more severe conditions (eg valve seats of internal combustion engines). The infiltrated agent infiltrated intervenes in the contact portion between the mating material (for example, valve) and the iron-based sintered alloy of the present invention, and acts as a lubricant. As a result, mutual wear resistance and seizure resistance between the mating material (for example, valve) and the iron-based sintered alloy of the present invention (for example, valve seat) are improved. Further, the infiltrant improves the thermal conductivity of the iron-based sintered alloy of the present invention, thereby effectively lowering the temperature of the contact surface (for example, the valve seat contact surface) of the iron-based sintered alloy and improving the wear resistance. , Further improve the seizure resistance.

In the third and eighth aspects, the infiltration agent is 1 to 25% with respect to 100% when the weight ratio of the sintered body is 100%. Therefore, when the infiltration amount of the infiltration agent is 25%, infiltration agent / (sintered body + infiltration agent) = 25 / (100 + 2
It means 5). Here, if the infiltrant is less than 1%, the effect of infiltration cannot be exerted so much, and if it exceeds 25%, the skeleton constituting the sintered alloy may have an adverse effect such as embrittlement or weakening. There is 1% to 25 in this sense
% Is suitable, and 10 to 22% is particularly suitable among 3 to 23%.

As the infiltrant, lead, lead-copper alloy, copper or a metal system containing these as main components is suitable. As the lead-copper alloy, Cu-30 wt% Pb can be adopted.

[0021]

EXAMPLE A preferred example of the present invention will be described in comparison with a comparative material to clarify the features of the present invention. (Examples 1 to 7) In these examples, Mo: 4.
An iron-based spray alloy powder A having 9%, Co: 4.6%, and the balance being substantially Fe is used. Mo: 1.2% by weight, C
o: An iron-based spray alloy powder D having 4.7% and the balance being substantially Fe is used. Mo; 2.2% by weight, Co; 4.
An iron-based spray alloy powder E having 6% and the balance being substantially Fe is used. An iron-based spray alloy powder F having a weight ratio of Mo: 3.1%, Co: 4.5% and the balance substantially Fe is used.
The iron-based spray alloy powders A, D, E, and F described above all have a particle size of 177 μm or less.

Further, by weight ratio, Cr: 35.2%, W: 1
2.5%, Mo; 8.7%, Fe; 18.7%, C;
2.6%, Si; 0.6% N with the balance being essentially Ni
The i-based spray alloy powder B (particle size 149 μm or less) is used.
Further, by weight ratio, Cr: 26.7%, W: 16.2%, M
o; 13.3%, Fe; 17.0%, Si; 0.6%,
C: Ni spray alloy powder C (particle size 149 μm or less) with 2.7% and the balance being Ni is used. The composition of each alloy powder described above is 100% by weight of each alloy powder itself.
It means the ratio when it is set to%.

Then, the alloy powders A to F, the hard particles (Ni-based hard alloy powder), the graphite powder and the lubricating zinc stearate are appropriately weighed so as to have the composition shown in Table 1,
The powder was mixed with a V-type mixer to obtain a mixed powder. In addition, Table 1 shows the ratio when the weight ratio of the mixed powder (excluding the lubricant evaporated during sintering, that is, alloy powder + hard particles + graphite powder) is 100%.

Thereafter, the mixed powder is molded at a molding pressure of 7 ton / c.
It was compressed at m ² to form a green compact. The obtained green compact was heated at a temperature of 1393 K in a decomposed ammonia gas atmosphere for 3 hours.
Sintered for 0 minutes, whereby each of Examples 1 to 7 and Comparative Material 1,
2 was produced. In each of the test pieces of Examples 1 to 7, carbide was dispersed in the matrix structure, and further, Ni-based hard particles (Ni-based alloy powder) in which the carbide was generated were dispersed in the matrix structure.
Table 2 shows the alloy composition of the produced sintered alloy. The ratios in Table 2 are ratios when the weight ratio of the sintered alloy is 100%.

[0025]

[Table 1]

[0026]

[Table 2] For the test pieces of Examples 1 to 7 and Comparative Materials 1 and 2 described above, a valve-valve seat tester simulating an actual machine was used.
The wear resistance of each test piece at high temperature was evaluated. In this test, each test piece was formed into a ring-shaped valve seat shape. This test device reproduces the hitting wear condition of the valve and the valve seat by a mechanism that heats the valve and the valve seat by combustion of propane gas and opens and closes the valve by driving a cam.

In the above test, the material of the mating valve was JIS SUH35, and the valve temperature was 1120.
K, control to keep the temperature of the valve seat at 670K,
The cam rotation speed is set to 2200 rpm and the operation time is 72 Ks.
The wear of the valve seat as a test piece was measured as the amount of increase in the contact width of the valve seat. The test results obtained are shown in FIG.

As shown in FIG. 1, the contact width increase of the comparative material 1 containing no hard particles is 205 μm, while the contact width increase of Examples 1 to 7 of the present invention is 89 to 90 μm. 12
It was 3 μm, and it was confirmed that the sintered alloy according to the present invention had excellent wear resistance. Further, FIG. 2 is a diagram in which the horizontal axis represents the amount of Mo in the alloy powder (Table 2) constituting the matrix and the horizontal axis represents the width addition amount per valve seat. As is clear from the characteristic line of FIG. 2, when the Mo content exceeds 2%, the wear amount decreases, and when the Mo content exceeds 3%, the wear properties of the test piece become stable, and the contact width increase amount is slightly 100 μm. Be stable when it exceeds the limit. (Examples 8 to 11) This example is an example of infiltrating a sintered body with an infiltrant. In this example, Mo: 4.9% by weight, C
o: 4.6%, with the balance being iron-based spray alloy powder A having a Fe particle size of 177 μm or less. This iron-based spray alloy powder A is the same as the iron-based spray alloy powder A used in Examples 1 to 7. Further, Cr: 35.2% by weight,
W: 12.5%, Mo: 8.7%, Fe: 18.7%,
Ni-based spray alloy powder B having C: 2.6%, Si: 0.6%, and the balance being substantially Ni having a particle size of 149 μm or less is used.
This Ni-based spray alloy powder B was N used in Examples 1 to 7.
It is the same as the i-based spray alloy powder B.

Also in this example, the above powder was weighed together with the graphite powder and the lubricant zinc stearate powder so as to have the composition shown in Table 3, and then mixed with a V-type mixer to obtain a mixed powder. Next, this mixed powder is molded at a molding pressure of 7 ton / cm.
^{It was} compressed at ² to prepare a test piece. However, Example 10
For, a test piece was prepared by compressing at a molding pressure of 6.3 ton / cm ² . This is to increase the ratio of the infiltrant in the test piece of Example 10. Subsequently, sintering was carried out by holding at 1404K for 30 minutes in a nitrogen atmosphere in which nitrogen gas was blown. The test piece after sintering was subjected to the infiltration treatment under the same atmosphere and the same temperature condition as those at the time of sintering. The infiltration treatment was performed by placing an infiltration agent on the test piece. The infiltrant is
As shown in Table 3, Pb was used in Examples 8 to 10, and Cu-30 wt% Pb was used in Example 11. Comparative material 3 is not infiltrated.

An Ogoshi-type wear test was carried out on the obtained test pieces under the following conditions. The test result shows that Comparative Material 3 is 1
The relative display of 00 is shown in Table 4. The Ogoshi abrasion test conditions are as follows. That is, the material of the mating material (ring-shaped rotor) is JIS SUH35, the block material is the test piece (fixed type) of the example and the comparative material, the sliding speed is 0.51 m / s, and the friction distance is 100 m. The temperature before starting the test was 773K for the mating material and 6 for the block material.
It is 93 K, the final load is 31.5 N, and the measurement item is the wear scar width of the block material.

[0031]

[Table 3]

[0032]

[Table 4] Here, as is clear from the comparison between Examples 8 to 11 and Comparative Material 3, the infiltration width decreases due to infiltration, depending on the infiltration amount. Therefore, although there are some differences in the effect of the infiltration agent, it is clear that the infiltration effect is large.
However, comparing Examples 9 and 10, Example 10 with a larger infiltration amount has a larger wear scar width of the test piece. It is considered that this is because the infiltration amount has an appropriate range, and the skeleton is starting to weaken more than the effect of reducing the wear scar width by increasing the infiltration amount. Therefore, the infiltration amount of 1 to 25% is appropriate. (Others) Sintering is not limited to the above case, but may be performed in a vacuum, an inert gas atmosphere, or the like, that is, it can be performed in a non-oxidizing atmosphere. In the claim, Co of the iron-based alloy powder is 2 to
Although it is set to 15%, the upper limit value can be set to 13%, 10%, 8%, 6%, 5% and the lower limit value can be set to 3% depending on the use and type of the iron-based sintered alloy. Further, although Mo in the iron-based alloy powder is set to 2 to 10% in the claims, the upper limit can be set to 8%, 7% and 6%, and the lower limit can be set depending on the use and type of the iron-based sintered alloy. It can be 2.5% and 3%. Further, in the claims, the Ni-based hard alloy powder is Mo; 5 to 20%, Cr; 20 to 40%,
W; 10 to 20% is included, but Mo can be 6 to 18%, 7 to 13%, and Cr is 22 to 40%, 30 to 30%.
40%, W is 11-19%, 12-18%
You can

The Ni-based hard alloy powder according to claim 6 is C;
5-4.0%, Si; 2% or less is contained. Of these, C
Can have an upper limit of 3.5% and 3.2% and a lower limit of 0.8
%, 1.0%, and the upper limit of Si is 1.0%, 0.5
Can be%. The above definition of the composition is similarly applicable to the matrix structure of the iron-based sintered alloy and the composition of the hard particles.

[0034]

As described above, the invention of the wear-resistant iron-based sintered alloy of the present invention and the method for producing the same is, by weight ratio, C
O; 2 to 15%, Mo; 2 to 10%, and the balance is M based on the iron-based alloy powder consisting of unavoidable impurities and Fe.
o: 5-20%, Cr: 20-40%, W: 10-20
%, Fe; 10 to 30%, and optionally C; 0.5 to 4%, Si; 2% or less, and the balance being Ni-based hard alloy powder consisting of unavoidable impurities and Ni. Graphite powder 0.2 to 2% and molding lubricant are mixed and molded.
The hard particles that are sintered at a temperature lower than the melting point of the Ni-based hard alloy powder from 23K, and are dispersed in the matrix structure of the iron-based sintered alloy are Ni-based hard alloys and are themselves hard. However, by further containing C, Mo, C
By combining with r, W, Si and Fe to form a carbide, the wear resistance is further improved.

According to claims 4 to 8, N is added to the iron-based alloy powder.
Since the mixed powder in which the i-based hard alloy powder and the graphite powder are mixed is used, the iron-based alloy powder does not positively contain Ni,
Therefore, it is possible to avoid excessive hardening of the iron-based alloy powder forming the matrix and ensure the compression moldability of the iron-based alloy powder. Further, by diffusing Ni of the Ni-based hard alloy powder into the matrix by sintering, it is possible to secure the oxidation resistance of the matrix of the sintered alloy, particularly the oxidation resistance and heat resistance at high temperatures.

Further, in claims 3 and 8, Pb, Cu, Pb
-Since the infiltrant containing at least one of the Cu-based alloys as the main component is infiltrated, the effect that the infiltrant intervenes in the contact portion between the iron-based sintered alloy of the present invention and the mating material to function as a lubricant It can be expected that wear resistance and seizure resistance can be improved.
Further, the infiltrant can improve the thermal conductivity of the iron-based sintered alloy and can be expected to be advantageous in preventing the temperature rise at the contact portion with the mating material, and in this sense, further improve the wear resistance.

[Brief description of drawings]

FIG. 1 is a diagram showing the number of increase in the contact width of a valve seat of an example of the present invention and a comparative material in a wear test.

FIG. 2 is a diagram showing the relationship between the number of increase in the contact width of the valve seat and the amount of Mo in the matrix in the wear test.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiko Ito 1 Toyota-cho, Toyota-shi, Aichi Toyota Automobile Co., Ltd.

Claims (8)

[Claims] 1. The total composition by weight ratio is Co: 1.4 to 15
%, Mo; 1.5 to 16%, Cr; 0.4 to 12%,
W: 0.2-6.0%, C: 0.4-3.2%, Ni;
0.2 to 9.0%, the balance being inevitable impurities and Fe
Co; 2 to 15%, Mo; 2 to 10%, C; 0.2 to 2
%, Ni; 10% or less, with the balance being inevitable impurities and F
In a base structure composed of e, Mo: 5 to 20%, Cr: 20 to 40%, W: 10 to 2
2% of hard particles containing 0%, C; 0.5 to 5.0%, Fe; 5 to 30%, and the balance being inevitable impurities and Ni.
An iron-based sintered alloy having excellent wear resistance, which is composed of a sintered body in which 30% is dispersed. 2. The total composition by weight ratio is Co; 1.4 to 15
%, Mo; 1.5 to 16%, Cr; 0.4 to 12%,
W: 0.2-6.0%, C: 0.01-4.0%, N
i; 0.2 to 9.0%, Si: 0.6% or less, the balance consisting of inevitable impurities and Fe, Co: 2 to 15%, Mo: 2 to 10%, C: 0. 2 to 2
%, Ni; 10% or less, with the balance being inevitable impurities and F
In a base structure composed of e, Mo: 5 to 20%, Cr: 20 to 40%, W: 10 to 2
0%, C: 0.5 to 4.0%, Fe: 5 to 30%, Si: 2% or less, and the balance is inevitable impurities and Ni.
An iron-based sintered alloy having excellent wear resistance, which is composed of a sintered body in which 2 to 30% of hard particles made of is dispersed. 3. The sintered body according to claim 1 or 2, wherein the sintered body has pores, and an infiltrant containing at least one of Pb, Cu and a Pb-Cu alloy as a main component is contained in the pores. When the weight ratio of the sintered body is 100%, it is 1-2 with respect to 100%.
Iron-based sintered alloy with excellent wear resistance, characterized by being infiltrated by 5%. 4. A weight ratio of Co: 2 to 15%, Mo: 2-1
With respect to the iron-based alloy powder containing 0% and the balance being unavoidable impurities and Fe, Mo: 5 to 20%, Cr: 20 to 40%, W: 10 to 2
0%, Fe; 10 to 30% and the balance is unavoidable impurities and Ni
Ni-based hard alloy powder consisting of, graphite powder 0.2 to 2% and a molding lubricant are mixed and molded, and sintered by sintering from 1323K at a temperature lower than the melting point of the Ni-based hard alloy powder. A method for producing an iron-based sintered alloy having excellent wear resistance, which comprises producing an iron-based sintered alloy comprising a bound body. 5. The Mo content of the iron-based powder alloy exceeds 3% to 1
It is 0% or less, The manufacturing method of the iron-based sintered alloy excellent in wear resistance of Claim 4 characterized by the above-mentioned. 6. A weight ratio of Co: 2 to 15%, Mo: 2 to
With respect to the iron-based alloy powder containing 10% and the balance being inevitable impurities and Fe, Mo: 5 to 20%, Cr: 20 to 40%, W: 10 to 2
0%, Fe; 10 to 30%, C; 0.5 to 4%, S
i; Ni-based hard alloy powder containing 2% or less and the balance being unavoidable impurities and Ni, graphite powder 0.2 to 2% and a molding lubricant are mixed and molded, and 1323K to Ni-based hard alloy powder A method for producing an iron-based sintered alloy having excellent wear resistance, which comprises producing an iron-based sintered alloy composed of a sintered body by sintering at a temperature lower than the melting point of. 7. The Mo content of the iron-based alloy powder exceeds 3% and 1
It is 0% or less, The manufacturing method of the iron-based sintered alloy excellent in wear resistance of Claim 6 characterized by the above-mentioned. 8. The sintered body according to any one of claims 4 to 7 has pores, and an infiltrant containing at least one of Pb, Cu and a Pb-Cu alloy as a main component is contained in the pores. When the weight ratio of the sintered body is 100%, it is 1 to 25 with respect to 100%.
% Infiltrated iron-based sintered alloy having excellent wear resistance.