JP2000144351A - Valve seat made of iron-base sintered alloy and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve seat made of iron-base sintered alloy, excellent in wear resistance and reduced in attacks on mating materials. SOLUTION: This valve seat has a composition consisting of, by weight, 15-40% Cu, 0.3-12% Ni, 0.8-3.0% C, and the balance Fe with inevitable impurities and containing, if necessary, 0.1-10% Co and 0.1-10% Cr and also has a structure where a hard particle phase 3 of 500-1700 MHV is dispersed in a matrix formed by binding an Fe-base alloy phase 1 composed essentially of Fe with a Cu-base alloy phase 2 composed essentially of Cu. The Fe-base alloy phase 1 is an Fe alloy phase containing Ni, Cu, and C and also containing >=50 wt.% Fe, and the Cu-base alloy phase 2 is a Cu alloy phase 4 containing Ni, Fe, and C and also containing >=50 wt.% Cu. Further, the concentrations of Ni and C, contained in the Fe-base alloy phase, are higher than the concentrations of Ni and C contained in the Cu-base alloy phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve seat made of an iron-based sintered alloy having excellent abrasion resistance and low aggressiveness to a partner.

[0002]

2. Description of the Related Art As sintering technology has advanced, various mechanical parts made of iron-based sintered alloy can be produced in large quantities with high precision, and valve seats have also been produced by sintering. As an example of a valve seat made of an iron-based sintered alloy,
Cr: 1 to 3% by weight, Mo: 0.5 to 3% by weight, Ni:
0.5 to 3% by weight, Co: 2 to 8% by weight, C: 0.6 to
In a substrate containing 1.5% by weight and Nb: 0.2 to 1% by weight, the balance being a composition comprising Fe and unavoidable impurities and an iron-based alloy structure mainly comprising a pearlite phase and a bainite phase. , Cr: 25 to 45% by weight, W: 20 to 30% by weight, Co: 20 to 30% by weight,
C: 1 to 3% by weight, Si: 0.2 to 2% by weight, Nb:
Hard particles containing 0.2 to 2% by weight, the balance being Fe and unavoidable impurities; Mo: 25 to 3
2% by weight, Cr: 7 to 10% by weight, Si: 1.5 to 3.
There is known a valve seat made of an iron-based sintered alloy having a structure in which 5% by weight of hard particles having a composition of Co and unavoidable impurities is uniformly dispersed in a total of 10 to 25% by volume. See JP-A-3-158445).

[0003]

However, in recent years, a direct injection engine for directly injecting fuel into a combustion chamber, which has been developed and put to practical use in pursuit of high performance, high fuel efficiency and light weight, and an increase in air-fuel ratio, have been proposed. In a lean burn engine or the like that performs lean combustion, the temperature in the combustion chamber becomes higher than that of a conventional engine. Under such a high temperature, the conventional valve seat does not provide sufficient wear resistance, and furthermore, the valve which is a mating material is severely worn. There was a disadvantage.

[0004]

Means for Solving the Problems Accordingly, the present inventors have:
From the above-mentioned viewpoints, a study was conducted to obtain a valve seat made of an iron-based sintered alloy having higher abrasion resistance and less aggressiveness to a valve as a mating material at a high temperature than in the past. ) Cu: 15-40% by weight, Ni:
0.3 to 12% by weight, C: 0.8 to 3.0% by weight, the balance being Fe and an unavoidable impurity, and containing Fe as a main component in a Fe-based alloy phase mainly containing Cu. A hard particle phase having a micro Vickers hardness (hereinafter referred to as MHV): 500 to 1700 is 5 to 30% by volume in a base having a structure formed by bonding with a Cu-based alloy phase as a component.
The iron-based sintered alloy valve seat composed of the iron-based sintered alloy dispersed in a state of being surrounded by the Fe-based alloy phase at a ratio of: is stronger than the conventional iron-based sintered alloy valve seat. Excellent abrasion resistance and low opponent aggression,
(B) Cu: 15 to 40% by weight, Ni: 0.3 to 12% by weight, C: 0.8 to 3.0% by weight, the balance being Fe
And MHV in a substrate having a composition composed of unavoidable impurities and having a structure in which an Fe-based alloy phase mainly composed of Fe is bonded by a Cu-based alloy phase mainly composed of Cu.
Made of an iron-based sintered alloy composed of an iron-based sintered alloy in which 500 to 1700 hard particle phases are dispersed at a rate of 5 to 30% by volume and surrounded by the Fe-based alloy phase having a petal cross section. The valve seat is composed of (c) hard particles containing Co or / and Cr, which are more excellent in strength and abrasion resistance and less aggressive than a conventional iron-based sintered alloy valve seat. , C powder and Ni-Cu alloy powder (or a mixed powder of Ni powder and Cu powder), and then molded and sintered, a part of the hard particle component Co or / and Cr diffuses into the matrix, Cu: 15
40% by weight, Ni: 0.3 to 12% by weight, C: 0.8 to
A base sheet containing 3.0% by weight, Co: 0.1 to 10% by weight or / and Cr: 0.1 to 10% by weight is formed, and a valve seat made of an iron-based sintered alloy having a base having such a component composition. Has obtained the finding that the strength and wear resistance are further improved and the opponent aggressiveness is further reduced as compared with the conventional iron-based sintered alloy valve seat.

The present invention has been made on the basis of the above findings. (1) Cu: 15 to 40% by weight, N
i: 0.3 to 12% by weight, C: 0.8 to 3.0% by weight, the balance being Fe and an Fe-based alloy phase containing Fe and inevitable impurities and containing Fe as a main component. MH is contained in a base material which is bonded by a Cu-based alloy phase containing
V: a valve seat made of an iron-based sintered alloy having a structure in which a hard particle phase of 500 to 1700 is dispersed in a state of being surrounded by the Fe-based alloy phase in a ratio of 5 to 30% by volume,
(2) Cu: 15 to 40% by weight, Ni: 0.3 to 12% by weight, C: 0.8 to 3.0% by weight, the balance being Fe
MHV: 500 to 17 in a base having a composition of unavoidable impurities and combining an Fe-based alloy phase mainly containing Fe with a Cu-based alloy phase mainly containing Cu.
(3) a valve seat made of an iron-based sintered alloy having a structure in which the hard particle phase of No. 00 is dispersed in a state of being surrounded by the Fe-based alloy phase having a petal cross section at a ratio of 5 to 30% by volume.
Cu: 15 to 40% by weight, Ni: 0.3 to 12% by weight,
C: 0.8 to 3.0% by weight, Co: 0.1 to 10% by weight
Containing, and the remainder has a composition consisting of Fe and unavoidable impurities, and in a body formed by combining an Fe-based alloy phase mainly composed of Fe with a Cu-based alloy phase mainly composed of Cu,
MHV: a valve seat made of an iron-based sintered alloy having a structure in which a hard particle phase of 500 to 1700 is dispersed in a state of being surrounded by the Fe-based alloy phase at a ratio of 5 to 30% by volume,
(4) Cu: 15 to 40% by weight, Ni: 0.3 to 12% by weight, C: 0.8 to 3.0% by weight, Co: 0.1 to 10%
% By weight, the balance being Fe and an unavoidable impurity.
A hard particle phase having an MHV of 500 to 1700 contains 5 to 3 hard particles in a matrix formed by a Cu-based alloy phase containing u as a main component.
A valve seat made of an iron-based sintered alloy having a structure in which the Fe-based alloy phase is dispersed in a petal-like cross section at a rate of 0% by volume, (5) Cu: 15 to 40% by weight,
Ni: 0.3 to 12% by weight, C: 0.8 to 3.0% by weight, Cr: 0.1 to 10% by weight, the balance being composed of Fe and unavoidable impurities. MHV: 500 to 170 in a substrate formed by combining an Fe-based alloy phase containing a main component with a Cu-based alloy phase containing Cu as a main component.
0: a valve seat made of an iron-based sintered alloy having a structure in which a hard particle phase of 0 is dispersed in a state of being surrounded by the Fe-based alloy phase at a ratio of 5 to 30% by volume, (6) Cu: 15 to 40
% By weight, Ni: 0.3 to 12% by weight, C: 0.8 to 3%.
Cu-based alloy containing 0% by weight and Cr: 0.1 to 10% by weight, the balance being a composition comprising Fe and inevitable impurities, and a Fe-based alloy phase containing Fe as a main component and Cu as a main component. MHV: 500-
The hard particle phase of 1700 contains 5 to 30% by volume of the F
A valve seat made of an iron-based sintered alloy having a structure dispersed in a state of being surrounded by a petal-like cross section by an e-based alloy phase, (7) Cu: 15 to 40% by weight, Ni:
0.3 to 12% by weight, C: 0.8 to 3.0% by weight, C
o: 0.1 to 10% by weight, Cr: 0.1 to 10% by weight, the balance being Fe and an unavoidable impurity and having a composition mainly composed of Fe In the base material bonded by the Cu-based alloy phase as a component, M
HV: 5 to 30% by volume of hard particle phase of 500 to 1700
A valve seat made of an iron-based sintered alloy having a structure dispersed in a state of being surrounded by the Fe-based alloy phase at a ratio of
(8) Cu: 15 to 40% by weight, Ni: 0.3 to 12% by weight, C: 0.8 to 3.0% by weight, Co: 0.1 to 10%
% By weight, Cr: 0.1 to 10% by weight, the balance being F
e and an unavoidable impurity, and an MHV: 500 to 1 in a body formed by combining an Fe-based alloy phase mainly composed of Fe with a Cu-based alloy phase mainly composed of Cu.
700 hard particle phase in the proportion of 5 to 30% by volume
A valve seat made of an iron-based sintered alloy having a structure dispersed in a state of being surrounded by a base alloy phase in a petal cross section is characterized.

For example, as the hard powder, Fe: 10
When a hard powder consisting of a Mo-based alloy containing 50% by weight and the balance of Mo is added and sintered, Mo contained in the hard powder hardly diffuses into the base material during sintering. 15 to 40% by weight, Ni: 0.3 to 12% by weight, C: 0.8 to 3.0% by weight, the balance being Fe
And a base formed by combining an Fe-based alloy phase having a composition of unavoidable impurities and containing Fe as a main component with a Cu-based alloy phase containing Cu as a main component.
0 wt% and further diffused from the substrate: Ni.
01-5%, Cu: 0.01-5% and C: 0.1-
MHV comprising Mo-based alloy containing 3%: 500-1
700 hard particle phases are formed in the substrate, and the valve seat made of the iron-based sintered alloy of the present invention described in the above (1) or (2) is produced.

Therefore, the present invention relates to (9) the MH
V: The hard particle phase of 500 to 1700 is composed of Mo and Fe
The valve seat made of an iron-based sintered alloy according to the above (1) or (2), comprising a Mo—Fe-based alloy mainly composed of:

Further, for example, Fe:
C having a composition containing 10 to 50% by weight and the balance being Co
When a hard powder composed of an o-based alloy is added and sintered, Co contained in the hard powder diffuses into the base material during sintering, so that Cu: 15 to 40% by weight, Ni: 0.3 to 12% by weight, C: 0.8 to 3.0% by weight, Co: 0.1 to 10% by weight, the balance being Fe and an Fe-based alloy phase having a composition of Fe and unavoidable impurities and containing Fe as a main component.
Is formed by bonding with a Cu-based alloy phase whose main component is Fe. On the other hand, Fe: 10 to 50% by weight, Ni: 0.01 to 5% diffused from the base, and Cu: 0. 01
A hard particle phase of MHV: 500 to 1700 comprising a Co-based alloy containing ５5% and C: 0.1-3% is formed in the matrix, and the hard particle phase of the invention according to the above (3) or (4) is formed. A valve seat made of an iron-based sintered alloy is made.

Therefore, the present invention relates to (10)
V: The hard particle phase of 500 to 1700 is composed of Co and Fe.
The valve seat made of an iron-based sintered alloy according to the above (3) or (4), which is made of a Co-Fe-based alloy containing (i) as a main component.

[0010] Further, for example, as the hard powder, Cr:
When a hard powder composed of a Ni-based alloy containing 10 to 40% by weight and Mo: 5 to 25% by weight and the balance being Ni is added and sintered, the Cr contained in the hard powder during the sintering is reduced to the substrate. But Mo does not diffuse into the substrate,
u: 15 to 40% by weight, Ni: 0.3 to 12% by weight,
C: 0.8 to 3.0% by weight, Cr: 0.1 to 10% by weight
Containing, and the remainder has a composition consisting of Fe and unavoidable impurities, and forms a matrix formed by combining an Fe-based alloy phase mainly containing Fe with a Cu-based alloy phase mainly containing Cu,
On the other hand, Cr: 10 to 40% by weight, Mo: 5 to 25% by weight
Fe further diffused from the substrate: 2 to 20%,
MHV composed of a Ni-based alloy containing Cu: 0.01 to 10% and C: 0.1 to 3%: 500 to 1700
The hard particle phase in the range of
Alternatively, the iron-based sintered alloy valve seat of the present invention described in (6) is produced.

Therefore, the present invention relates to (11) the MH
V: The hard particle phase of 500 to 1700 is characterized by the iron-based sintered alloy valve seat according to the above (5) or (6), comprising a Ni-based alloy containing Ni, Cr and Mo as main components. Things.

Further, for example, as the hard powder, Mo:
15 to 35%, Cr: 2 to 13%, Si: 0.5 to 5%
When the hard powder containing the Co-based alloy of Co is added and sintered, the Co and Cr contained in the hard powder diffuse into the base during sintering, and Mo hardly diffuses into the base. Cu: 15 to 40% by weight, Ni: 0.
3 to 12% by weight, C: 0.8 to 3.0% by weight, Co:
Fe-based alloy phase containing 0.1 to 10% by weight, Cr: 0.1 to 10% by weight, the balance being Fe and unavoidable impurities, and containing Fe as a main component. To form a matrix that combines with the Cu-based alloy phase
Mo: 15 to 35%, Cr: 2 to 13%, Si: 0.5
-5% and further diffused from the substrate: 0.0
Hard particles in the range of MHV: 500 to 1700 composed of a Co-based alloy containing 1 to 5%, Cu: 0.01 to 5%, Fe: 2 to 20% and C: 0.1 to 3%. The phase is formed in the base material, and the valve seat made of the iron-based sintered alloy of the present invention described in the above (7) or (8) can be produced.

Therefore, the present invention relates to (12) the MH
V: The hard particle phase of 500 to 1700 is composed of Co, Mo, C
The valve seat made of an iron-based sintered alloy according to the above (7) or (8), comprising a Co-Mo-Cr-Si-based alloy containing r and Si as main components, is characterized.

Further, for example, as the hard powder,
And Cr: 5 to 40%, W: 15 to 30%, Co: 5 to
30%, C: 0.1-3%, Si: 0.1-3%, N
b: A hard powder containing 0.1 to 3%, the balance being Fe-based alloy of Fe, is added and sintered. When sintering, Co and Cr contained in the hard powder diffuse into the base material. Cu: 15 to 40% by weight, Ni: 0.3 to 12% by weight, C: 0.8 to 3.0% by weight, Co: 0.1 to 10% by weight, Cr: 0.1 to 10% by weight Containing, the balance being Fe
And a base formed by combining an Fe-based alloy phase mainly composed of Fe and having a composition composed of unavoidable impurities with a Cu-based alloy phase mainly composed of Cu.
%, W: 15 to 30%, Co: 5 to 30%, C: 0.1
-3%, Si: 0.1-3%, Nb: 0.1-3%, and Ni diffused from the substrate: 0.01-8%,
MH composed of an alloy containing Cu: 0.01 to 8%
V: A hard particle phase in the range of 500 to 1700 is formed in the base material, and the valve seat made of the iron-based sintered alloy of the present invention described in the above (7) or (8) is produced.

Therefore, the present invention relates to (13) the MH
V: The hard particle phase of 500 to 1700 is Fe, Cr,
Fe-Cr- containing W, Co, C, Si and Nb as main components
A valve seat made of an iron-based sintered alloy according to the above (7) or (8), comprising a W-Co-C-Si-Nb-based alloy.

Further, for example, as the hard powder, by weight%, Cr: 5 to 40%, Mo: 15 to 30%, Co:
5 to 30%, C: 0.1 to 3%, Si: 0.1 to 3%,
When a hard powder containing 0.1 to 3% Nb and the balance being Fe is used, the Co and Cr contained in the hard powder diffuse into the base during sintering.
u: 15 to 40% by weight, Ni: 0.3 to 12% by weight,
C: 0.8 to 3.0% by weight, Co: 0.1 to 10% by weight, Cr: 0.1 to 10% by weight, the balance being Fe and unavoidable impurities, and Fe A base is formed by combining an Fe-based alloy phase containing a main component with a Cu-based alloy phase containing Cu as a main component.
-40%, Mo: 15-30%, Co: 5-30%,
C: 0.1-3%, Si: 0.1-3%, Nb: 0.1
~ 3% and further diffused from the substrate: 0.0
A hard particle phase in the range of MHV: 500 to 1700 composed of an alloy containing 1 to 8% and Cu: 0.01 to 8% is formed, and the present invention according to the above (7) or (8), A valve seat made of an iron-based sintered alloy is made.

Therefore, the present invention relates to (14) the MH
V: Hard particle phase of 500 to 1700 is Fe, Cr, M
o-Co-C-Si-Fe-Cr-
The above (7) comprising a Mo—Co—C—Si—Nb-based alloy
Or, the valve seat made of an iron-based sintered alloy according to (8) is characterized.

The hard particle phase having an MHV of 500 to 1700 may include a hard particle phase composed of the alloys described in 9, 10, 11, 12, 13 and 14. Therefore, the present invention relates to (15) MHV: 500 to 1700
The hard particle phase of (9), (10), (11),
(3), (4), (5), (6), (7) or (7) wherein all or a part of the hard particle phase composed of the alloy according to (12), (13) and (14) is mixed. (8)
The valve seat is made of an iron-based sintered alloy as described above.

The hard particle phase dispersed in the base material of the iron-based sintered alloy valve seat may be a hard particle phase having an MHV in the range of 500 to 1700. The hard particle phase dispersed in the base material of the base sintered alloy valve seat is a hard particle phase of MHV: 500 to 1000, a hard particle phase of MHV: 800 to 1700, and MHV: 500 to 1000 and MHV: 800 to 800.
It is more preferred to use 1700 hard particle mixed phases separately.

For example, if the material of the valve as the mating material is SU
In the case of an austenitic heat-resistant steel such as H35 or SUH36, the hard particle phase dispersed in the base material of the valve seat made of an iron-based sintered alloy is more preferably a hard particle phase in the range of MHV: 500 to 1,000. When the material of the valve as a mating material is a martensitic heat-resistant steel such as SUH3 or SUH11, the hard particle phase dispersed in the base material of the valve seat made of an iron-based sintered alloy has an MHV of 800 to 17
More preferably, the hard particle phase is 00.
When the face surface material of the valve which is the mating member is a ferrite of a Co-based heat-resistant alloy, the hard particle phase dispersed in the base material of the valve seat made of an iron-based sintered alloy is MHV: 500 to 1000.
And a hard particle mixed phase having an MHV of 800 to 1700 is preferable.

The Fe-based alloy phase mainly composed of Fe constituting the base material of the valve seat made of the iron-based sintered alloy is Ni, C
Fe, containing components diffused from u, C and hard particles,
An Fe alloy phase containing 0% by weight or more, and a Cu-based alloy phase containing Cu as a main component contains Ni, Fe and C, and contains 50% of Cu.
The concentration of Ni and C contained in the Fe-based alloy phase is higher than the concentration of Ni and C contained in the Cu-based alloy phase.

Therefore, F constituting the base material in the valve seat made of the iron-based sintered alloy according to the above (1) to (13).
The Fe-based alloy phase containing e as a main component is a Fe alloy phase containing Ni, Cu, C and components diffused from hard particles and containing 50% by weight or more of Fe.
The Cu-based alloy phase containing u as a main component is a Cu alloy phase containing Ni, Fe, C, and components diffused from hard particles, containing at least 50% by weight of Cu, and N contained in the Fe-based alloy phase.
a valve seat made of an iron-based sintered alloy in which the concentration of i and C is larger than the concentration of Ni and C contained in the Cu-based alloy phase;
It is characterized by the following.

The valve seat made of an iron-based sintered alloy according to the present invention is characterized in that Fe powder, graphite powder, Cu-Ni
Alloy powder, Cu powder, Ni powder, MHV: 500-17
A hard powder of No. 00 and a hard powder of MHV: 500-1700 are prepared, and these raw material powders are mixed and mixed in a predetermined ratio, and further mixed with a zinc stearate powder which is a lubricant at the time of mold molding by a double cone mixer. Then, press molding is performed to produce a green compact, and the green compact is manufactured by sintering in a nitrogen atmosphere containing hydrogen at a temperature of 1100 to 1300 ° C. The sintering temperature is more preferably from 1,900 to 1,200 ° C.

In the method of manufacturing a valve seat made of an iron-based sintered alloy according to the present invention, the element powders of the Cu powder and the Ni powder can be used as raw material powders.
It is more preferable to use a Cu—Ni alloy powder instead of the element powders of the u powder and the Ni powder, and the reason is considered to be due to the following sintering mechanism. That is, C
When the u-Ni alloy powder is blended, a large amount of Cu liquid phase is not generated at a stretch even if the temperature is raised to the solid-liquid coexistence region of the Cu-Ni alloy in the initial stage of sintering, and sintering proceeds gently, Deformation such as distortion and bending does not occur in the sintered body. In the middle stage of sintering, Ni of the Cu-Ni alloy powder is Fe
It has high affinity for and diffuses into Fe powder. When the Ni concentration in the Fe powder is increased, the solid solubility limit of Cu in Fe is increased, so that the diffusion of Cu into Fe is activated and the adhesion between Fe and Cu is improved. In the later stage of sintering, C
Since the Ni content in the u-Ni alloy phase is low, C
The melting point of the u-Ni alloy powder is lowered, a large amount of liquid phase is generated at a stretch, and dynamic liquid phase sintering proceeds. Note that even if a large amount of liquid phase is generated at a stretch in the latter stage of sintering, the sintered body is not distorted or bent since sufficient sintering has already progressed. Since the sintering of the iron-based sintered alloy valve seat of the present invention using the Cu-Ni alloy powder as the raw material powder is considered to be due to the mechanism described above, the iron-based sintered alloy valve seat of the present invention is used. As a raw material powder used in the production, particularly, a Cu—Ni alloy (N
i: a master alloy containing 1 to 25% by weight, with the balance being Cu and unavoidable impurities.

These mechanisms are the mechanisms for forming the base material of the iron-based sintered alloy valve seat of the present invention. The hard powder having an MHV of 500 to 1700 does not melt even after sintering. Maintaining substantially the same shape, the hard powder of MHV: 500 to 1700 adsorbs the Fe powder existing around the hard powder during sintering, and the Fe powder crosses the hard particle phase around the hard particle phase in a petal-like shape (as viewed three-dimensionally). And a semi-dense Fe-based alloy phase is formed in a dispersed state in a surrounding state. The Fe-based alloy phase having a petal cross-section (semi-dangling when viewed three-dimensionally) increases the contact area with the Cu-based alloy phase and further increases the bonding strength between the Fe-based alloy phase and the Cu-based alloy phase as compared with the related art. .

Next, the reason why the component composition of the iron-based sintered alloy constituting the iron-based sintered alloy valve seat of the present invention is limited as described above will be described. [I] Hard particle phase The reason for limiting the MHV of the hard particle phase dispersed in the iron-based sintered alloy valve seat base to 500 to 1700 is that the MHV
Is less than 500, it is not preferable because sufficient wear resistance cannot be obtained. On the other hand, if the MHV exceeds 1,700, the valve is excessively worn, which is not preferable. In addition, even if 5% by volume is dispersed in the base material made of an iron-based sintered alloy, it is not preferable because sufficient wear resistance cannot be obtained. It is not preferable because of insufficient toughness. Therefore, the dispersion amount of the hard particle phase is set to 5 to 30% by volume. A more preferable range of the dispersion amount of the hard particle phase is 8 to 25% by volume. During the sintering, the base components Fe, Cu, Ni and C diffuse and penetrate into the hard particle phase. Therefore, a small amount of Fe, Cu, N
i and C are included.

[II] Base Cu: 15 to 40% by weight, Ni: 0.3 to 12% by weight,
C: contains 0.8 to 3.0% by weight, and, if necessary, contains constituent elements of the hard powder in a diffused manner, and the remainder has a composition of Fe and unavoidable impurities, and contains Fe as a main component. The alloy has a structure in which the Fe-based alloy phase is bonded by a Cu-based alloy phase containing Cu as a main component. The reason why the composition is limited to the above-described composition is as follows.

(A) Cu Cu has the effect of improving the density, strength and abrasion resistance. However, if its content is less than 15% by weight, the amount of liquid phase generated is not sufficient, so that the density, strength and resistance to abrasion are insufficient. The effect of abrasion is not sufficient. On the other hand, if it exceeds 40% by weight, the liquid phase becomes excessively large, which is not preferable because deformation occurs during sintering and dimensional dispersion increases. Therefore, the content of Cu is set to 15 to 40% by weight. A more preferred range for the Cu content is 17-30% by weight, and an even more preferred range is 20-28% by weight.

(B) Ni Ni has the effect of increasing the melting point of the Cu alloy phase in the Cu alloy phase, controlling liquid phase sintering, and improving the strength and toughness of the Fe alloy phase. If the amount is less than 0.3% by weight, the effect is not sufficient.
Even if the content exceeds 2% by weight, no further effect is obtained.
Therefore, the content of Ni is set to 0.3 to 12% by weight. A more preferable range of the Ni content is 2 to 6% by weight.

(C) C C has the effect of improving the strength and hardness, but if its content is less than 0.8% by weight, the effect is not sufficient, while the content exceeds 3.0% by weight. This is not preferred because the resulting toughness is reduced. Therefore, the content of C is 0.8 to
It was determined to be 3.0% by weight. A more preferable range of the content of C is 0.9 to 1.6% by weight.

(D) Base Structure The base of the iron-based sintered alloy valve seat of the present invention is C
u: 15 to 40% by weight, Ni: 0.3 to 12% by weight,
C: a Cu-based alloy containing 0.8 to 3.0% by weight, the balance being composed of Fe and unavoidable impurities, and a Fe-based alloy phase mainly composed of Fe as a major component Although it has a structure bonded by an alloy phase, the components of the hard particles may diffuse and be contained in the Fe-based alloy phase and the Cu-based alloy phase. F surrounding the hard particle phase
e-base alloy phase is petal-shaped in cross section (semi-dangling when viewed three-dimensionally)
It is more preferable that the Fe-based alloy phase surrounding the hard particle phase becomes petal-shaped (semi-dangling when viewed three-dimensionally) so that the Fe-based alloy phase and the Cu-based alloy phase Is increased, and a greater bonding force is obtained.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION The raw material powder has an average particle size of 55.
μm Fe powder, Cu—Ni alloy powders ae having the component compositions and average particle diameters shown in Table 1 below, average particle diameter: 11 μm Cu powder, average particle diameter: 10 μm Ni powder, average particle diameter : 18 μm graphite powder was prepared, and hard powders A to F having the component compositions shown in Table 2 below were prepared.

[0033]

[Table 1]

[0034]

[Table 2]

Example 1 The Fe powder, the Cu-Ni alloy powders a to e in Table 1, the graphite powder, and the hard powders A to F in Table 2 were mixed and mixed in the ratios shown in Tables 3 and 4 to obtain raw materials. A mixed powder was prepared.

[0036]

[Table 3]

[0037]

[Table 4]

To this raw material mixed powder, zinc stearate powder, which is a lubricant at the time of molding, is added in an amount equivalent to 0.8% by weight on an outer surface, mixed, and press-molded to form an outer diameter of 34 mm, an inner diameter of 34 mm. : 27 mm, thickness: 7 mm, to produce a valve seat compact. This green compact was heated in a mixed atmosphere of N ₂ -5% H ₂ at a temperature of 1140 ° C.
Sintered under the condition of holding for 20 minutes, and the valve seat made of the iron-based sintered alloy of the present invention (hereinafter referred to as the valve seat of the present invention)
And comparative iron-based sintered alloy valve seats (hereinafter referred to as comparative valve seats) 1 to 6 were produced. The component compositions of the bases of the valve seats 1 to 16 of the present invention and the comparative valve seats 1 to 6, the dispersion amount (volume%) of the hard particle phase, and the MHV were measured, and the results are shown in Tables 5 to 7. In addition, the dispersion amount of the hard particle phase was measured by measuring the area ratio of the hard particles by image analysis, and then converting the area ratio into a volume ratio. Further, the MHV of the hard particle phase was measured by micro Vickers hardness measurement.

The valve seat 1 of the present invention thus produced was cut and polished, and the structure was observed with a metallographic microscope. FIG. 1 shows a structure photograph centered on the hard particle phase. In FIG. 1, reference numeral 1 denotes an Fe-based alloy phase, 2 denotes a Cu-based alloy phase, and 3 denotes a hard particle phase formed by the hard powder A. Further, the valve seat 3 of the present invention was cut and polished, and the structure was observed with a metallographic microscope. A structure photograph centered on the hard particle phase is shown in FIG. In FIG. 2, 1 is an Fe-based alloy phase, 2 is a Cu-based alloy phase, and 3 is a hard particle phase formed by hard powder C. As is clear from the sketches of the metal structures in FIGS. 1 and 2, the valve seats 1 and 3 of the present invention have a base obtained by bonding an Fe-based alloy phase 1 with a Cu-based alloy phase 2, and in particular, disperse in the base. MHV 500-1
It can be seen that the 700 hard particle phase 3 is dispersed in a state surrounded by the Fe-based alloy phase 1 ′ having a petal cross section (semi-dangling when viewed three-dimensionally). Further, with respect to the valve seats 2 and 4 to 14 of the present invention, it was observed whether or not an Fe-based alloy phase 1 ′ having a petal cross section (semi-dangling when viewed three-dimensionally) was present in the substrate. 7 are shown.

Further, as a result of measuring the component contents of the Fe-based alloy phase and the Cu-based alloy phase in the structures of the valve seats 1 and 3 of the present invention by EPMA, the Fe-based alloy phase contains Ni, Cu and C; Fe is contained in an amount of 50% by weight or more, the Cu-based alloy phase contains Ni, Fe and C, and contains Cu in an amount of 50% by weight or more. N included
It was confirmed that the concentration was higher than the concentrations of i and C. The Fe-based alloy phase and the Cu-based alloy phase partially contain the components of the hard particle phase by diffusion and infiltration, while the hard particle phase partially diffuses and infiltrates Fe, Cu, Ni and C. Turned out to be included.

Further, Cr: 2% by weight, Mo: 1.5% by weight, Ni: 1.5% by weight, Co: 5% by weight, C: 1.0%
% By weight, Nb: 0.6% by weight, the balance being Fe and an unavoidable impurity, and a base having an iron-based alloy structure mainly composed of a pearlite phase and a bainite phase. A valve seat made of a conventional iron-based sintered alloy (hereinafter, referred to as a conventional valve seat) made of an iron-based sintered alloy having a structure in which particles A and E had a structure in which a total of 17% by volume of particles were uniformly dispersed was prepared.

Abrasion test Valve seats 1 to 16 of the present invention, comparative valve seat 1
The following abrasion tests were carried out on No. 6 and the conventional valve seat. A valve having an umbrella portion made of SUH36 material and having an outer diameter of 30 mm is prepared. The umbrella portion of this valve is maintained at a temperature of 900 ° C.
16. Each of the comparative valve seats 1 to 6 and the conventional valve seat are pressed into a jig whose inside is water-cooled, and a seating load: 30 kg, a valve seating frequency: 3,000 times / min in a gasoline combustion atmosphere for 150 hours. The maximum wear of the valve seat and the valve was measured, and the results are shown in Tables 5 to 7.

[0043]

[Table 5]

[0044]

[Table 6]

[0045]

[Table 7]

From the results shown in Tables 3 to 7, the valve seats 1 to 16 of the present invention show that the maximum wear of the valve seat itself and the maximum wear of the valve which is the mating material are smaller than those of the conventional valve seat. I understand. However, the comparative valve seats 1 to 6 having a component composition out of the range of the present invention show an unfavorable value in at least one of the maximum wear amount of the valve seat and the maximum wear amount of the valve which is the mating member. You can see that.

Example 2 Fe powder, Cu powder, Ni powder, and graphite powder, all of which are elemental powders, were blended and mixed to produce a ground forming mixed powder having the blending composition shown in Table 8, and this ground forming mixed powder was prepared. Table 8 shows hard powders A to F for forming a hard particle phase with respect to the powders.
A raw material mixed powder is prepared by blending and mixing at the ratio shown in (1), and zinc stearate powder, which is a lubricant at the time of mold molding, is added to the raw material mixed powder in an amount equivalent to 0.8% by weight in an outer case. Then, the mixture was press-formed to prepare a valve-seat-shaped green compact having dimensions of outer diameter: 34 mm, inner diameter: 27 mm, and thickness: 7 mm. This green compact was heated in a mixed atmosphere of N ₂ -5% H ₂ at a temperature of 1140 ° C.
The valve seat 17 of the present invention which has been sintered under the conditions of holding for 20 minutes and has a base and a hard particle phase having the component compositions shown in Table 9
To 22 were prepared.

When the valve seats 17 to 22 of the present invention were cut and polished, and the structure was observed with a metallographic microscope, the structure was similar to the structure prepared using the Cu—Ni alloy powder of Example 1. Hard particle phase is Fe-shaped cross section
It was found that the Fe-based alloy phase was dispersed in a state of being surrounded by the base alloy phase, but the Fe-based alloy phase having a petal cross section was slightly less than the structure produced using the Cu—Ni alloy powder of Example 1. . Further, the valve seats 17 to 2 of the present invention are used.
As a result of measuring the component contents of the Fe-based alloy phase and the Cu-based alloy phase having the structure of No. 2 by EPMA, the Fe-based alloy phase contained Ni, Cu and C, and contained 50% by weight or more of Fe. The phase contains Ni, Fe and C and contains Cu in an amount of 50% by weight or more, and the concentration of Ni and C contained in the Fe-based alloy phase depends on the concentration of N contained in the Cu-based alloy phase.
It was confirmed that the concentration was higher than the concentrations of i and C. The Fe-based alloy phase and the Cu-based alloy phase partially contain the components of the hard particle phase by diffusion and infiltration, while the hard particle phase contains Fe, Cu, Ni and C by diffusion and infiltration. I knew it was.

The obtained valve seats 17 to 22 of the present invention were subjected to a wear test under the same conditions as in Example 1, and the maximum wear of the valve seats and valves was measured. The results are shown in Table 9.

[0050]

[Table 8]

[0051]

[Table 9]

From the results shown in Tables 8 and 9, when comparing the valve seats 17 to 22 of the present invention with the conventional valve seats prepared in Example 1, the valve seats of the present invention 17 to 22 are compared with the conventional valve seats. It can be seen that the maximum wear amount of the valve seat itself and the maximum wear amount of the valve as the mating material are small.

[0053]

As described above, the valve seat made of an iron-based sintered alloy according to the present invention has a small amount of wear and a small aggressiveness with respect to a valve as a mating material. Can greatly contribute to

[Brief description of the drawings]

FIG. 1 is a sketch drawing of the structure of a valve seat made of an iron-based sintered alloy of the present invention.

FIG. 2 is a sketch of a structure of a valve seat made of an iron-based sintered alloy of the present invention.

[Explanation of symbols]

 Reference Signs List 1 Fe-based alloy phase 1 'Fe-based alloy phase with petal cross section 2 Cu-based alloy phase 3 Hard particle phase

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F01L 3/02 F01L 3/02 H B22F 5/00 Z

Claims (17)

[Claims] 1. Cu: 15 to 40% by weight, Ni: 0.3
-12% by weight, C: 0.8-3.0% by weight, the balance being composed of Fe and unavoidable impurities, and
e-based Fe-based alloy phase to Cu-based
Micro Vickers hardness (hereinafter referred to as MHV): 50 in the base material bonded by the u-base alloy phase
A valve seat made of an iron-based sintered alloy, having a structure in which hard particle phases of 0 to 1700 are dispersed in a state of being surrounded by the Fe-based alloy phase at a ratio of 5 to 30% by volume. 2. Cu: 15 to 40% by weight, Ni: 0.3
-12% by weight, C: 0.8-3.0% by weight, the balance being composed of Fe and unavoidable impurities, and
e-based Fe-based alloy phase to Cu-based
A hard particle phase having an MHV of 500 to 1700 is dispersed in a matrix formed by the u-based alloy phase at a ratio of 5 to 30% by volume in a state of being surrounded by the Fe-based alloy phase in a petal cross section. An iron-based sintered alloy valve seat having a structure. 3. Cu: 15 to 40% by weight, Ni: 0.3
-12% by weight, C: 0.8-3.0% by weight, Co: 0.
A substrate containing 1 to 10% by weight, the balance being Fe and unavoidable impurities, and having an Fe-based alloy phase mainly composed of Fe combined with a Cu-based alloy phase mainly composed of Cu. A valve made of an iron-based sintered alloy having a structure in which a hard particle phase of MHV: 500 to 1700 is dispersed in a state of being surrounded by the Fe-based alloy phase at a ratio of 5 to 30% by volume. Sheet. 4. Cu: 15 to 40% by weight, Ni: 0.3
-12% by weight, C: 0.8-3.0% by weight, Co: 0.
A substrate containing 1 to 10% by weight, the balance being Fe and unavoidable impurities, and having an Fe-based alloy phase mainly composed of Fe combined with a Cu-based alloy phase mainly composed of Cu. An iron-based sintering method characterized by having a structure in which a hard particle phase of MHV: 500 to 1700 is dispersed in a petal-like cross section by the Fe-based alloy phase at a ratio of 5 to 30% by volume. Bonded gold valve seat. 5. Cu: 15 to 40% by weight, Ni: 0.3
-12% by weight, C: 0.8-3.0% by weight, Cr: 0.
A substrate containing 1 to 10% by weight, the balance being Fe and unavoidable impurities, and having an Fe-based alloy phase mainly composed of Fe combined with a Cu-based alloy phase mainly composed of Cu. A valve made of an iron-based sintered alloy having a structure in which a hard particle phase of MHV: 500 to 1700 is dispersed in a state of being surrounded by the Fe-based alloy phase at a ratio of 5 to 30% by volume. Sheet. 6. Cu: 15 to 40% by weight, Ni: 0.3
-12% by weight, C: 0.8-3.0% by weight, Cr: 0.
A substrate containing 1 to 10% by weight, the balance being Fe and unavoidable impurities, and having an Fe-based alloy phase mainly composed of Fe combined with a Cu-based alloy phase mainly composed of Cu. An iron-based sintering method characterized by having a structure in which a hard particle phase of MHV: 500 to 1700 is dispersed in a petal-like cross section by the Fe-based alloy phase at a ratio of 5 to 30% by volume. Bonded gold valve seat. 7. Cu: 15 to 40% by weight, Ni: 0.3
-12% by weight, C: 0.8-3.0% by weight, Co: 0.
1 to 10% by weight, Cr: 0.1 to 10% by weight,
The base having a composition of Fe and unavoidable impurities and having a Fe-based alloy phase containing Fe as a main component bonded by a Cu-base alloy phase containing Cu as a main component has a hardness of MHV: 500 to 1700. A valve seat made of an iron-based sintered alloy having a structure in which a particle phase is dispersed in a state of being surrounded by the Fe-based alloy phase at a ratio of 5 to 30% by volume. 8. Cu: 15 to 40% by weight, Ni: 0.3
-12% by weight, C: 0.8-3.0% by weight, Co: 0.
1 to 10% by weight, Cr: 0.1 to 10% by weight,
The base having a composition of Fe and unavoidable impurities and having a Fe-based alloy phase containing Fe as a main component bonded by a Cu-base alloy phase containing Cu as a main component has a hardness of MHV: 500 to 1700. A valve seat made of an iron-based sintered alloy having a structure in which a particle phase is dispersed at a ratio of 5 to 30% by volume in a state of being surrounded by the Fe-based alloy phase in a petal cross section. 9. The iron-based sintered alloy according to claim 1, wherein the hard particle phase having MHV: 500 to 1700 is made of a Mo—Fe alloy containing Mo and Fe as main components. Valve seat. 10. The iron-based sintered alloy according to claim 3, wherein the hard particle phase of MHV: 500 to 1700 is made of a Co—Fe alloy containing Co and Fe as main components. Valve seat. 11. The hard particle phase having an MHV of 500 to 1700 is a Ni-based alloy containing Ni, Cr and Mo as main components.
The valve seat made of an iron-based sintered alloy according to claim 5 or 6, wherein the valve seat is made of a Cr-Mo alloy. 12. The hard particle phase having an MHV of 500 to 1700 is made of a Co—Mo—Cr—Si alloy containing Co, Mo, Cr and Si as main components. A valve seat made of the iron-based sintered alloy described in the above. 13. The hard particle phase having an MHV of 500 to 1700 is a Fe—Cr—W—Co—C—Si—Nb alloy containing Fe, Cr, W, Co, C, Si, and Nb as main components. The valve seat made of an iron-based sintered alloy according to claim 7 or 8, wherein the valve seat is made of: 14. The hard particle phase of MHV: 500 to 1700 is Fe—Cr—Mo—Co—C—Si—Nb containing Fe, Cr, Mo, Co, C, Si and Nb as main components.
The valve seat made of an iron-based sintered alloy according to claim 7 or 8, wherein the valve seat is made of a base alloy. 15. The hard particle phase of MHV: 500 to 1700 is characterized in that all or a part of the hard particle phase composed of the alloy according to claim 9, 10, 11, 12, 13 or 14 is mixed. The valve seat made of an iron-based sintered alloy according to claim 3, 4, 5, 6, 7, or 8. 16. Raw material powders such as Fe powder, C powder,
A method for producing a valve seat made of an iron-based sintered alloy, comprising preparing a Ni-Cu alloy powder and a hard powder, mixing these raw material powders, molding and sintering. 17. Raw material powders such as Fe powder, C powder,
A method for producing a valve seat made of an iron-based sintered alloy, comprising preparing a Ni powder, a Cu powder and a hard powder, mixing these raw powders, molding and sintering.