JPH0860206A - Production of valve seat made of fe base sintered alloy having excellent wear resistance - Google Patents

Abstract

PURPOSE: To produce a valve seat made of an Fe-base sintered alloy having excellent wear resistance by interposing an alloy layer consisting essentially of Ni into the boundary part between the base of an Fe-C based alloy and hard particles of a Cr-Fe alloy to improve the adhesion property. CONSTITUTION: The structure of the Fe-base sintered alloy constituting the valve seat is formed by dispersing the hard particles of the Cr-Fe based alloy into the base of the Fe-C based alloy. The alloy layer consisting essentially of the Ni is made to exist continuously and/or intermittently at the boundary of the hard particles and the base, by which the adhesion property of the hard particles to the base is improved in this process for producing the valve seat. The valve seat is obtd. by mixing the hard particles coated with the Ni based alloy and the raw material powder for forming the base at a prescribed ratio and press molding the mixture, than subjecting the molding to degreasing and sintering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an Fe-based sintered alloy valve seat having excellent wear resistance.

[0002]

2. Description of the Related Art Conventionally, generally, for example, JP-A-51-14.
631, JP-A-61-117254, JP-A-62-96659, and the like.
Many valve seats made of e-based sintered alloys are known, and the Fe-based sintered alloys forming these valve seats are
It is also known that the base material of the e-C alloy has a structure in which hard particles of the Cr-Fe alloy are dispersed and distributed.

[0003]

On the other hand, in recent years, the performance and output of various internal combustion engines have been remarkably high and the operation speed has been remarkably high. Although the situation is becoming more severe, in the case of the above-mentioned conventional Fe-based sintered alloy valve seat,
Under the more severe conditions, the hard particles are liable to be peeled from the substrate, and the service life is reached in a relatively short time.

[0004]

Therefore, the present inventors have
From the above viewpoints, focusing on the above-mentioned conventional Fe-based sintered alloy valve seats, particularly as a result of research to improve the adhesion of the hard particles to the base material, the Fe-based sintered alloys forming the valve seats have been found. In, when an alloy layer containing Ni as a main component is interposed at the interface between the hard particles made of a Cr-Fe alloy and the base made of an Fe-C alloy, both the hard particles and the base of the alloy layer are formed. Since the binding force to the base material is extremely high, the adhesion of the hard particles to the base material is significantly improved.
The valve seat made of e-based sintered alloy exhibits excellent wear resistance for a long period of time because peeling of the hard particles from the base material is significantly suppressed even in practical use under severe conditions. I got the research result of doing.

The present invention has been made based on the above-mentioned research results, and is based on a Fe--C alloy base and Cr.
-F having a structure in which hard particles of a Fe-based alloy are dispersed and distributed
In a method of manufacturing a valve seat made of an e-based sintered alloy, an alloy layer containing Ni as a main component is continuously and / or intermittently present at an interface between the hard particles and a base material to form the hard particles. It is characterized by a method for improving the wear resistance of the Fe-based sintered alloy valve seat by improving the adhesion to the base material.

Further, in the method of the present invention, the hard particles are in weight% (hereinafter,% means weight%), and Cr: 40.
~ 65%, Co: 5-20%, Mo: 5-15
%, Ni: 5 to 30%, C: 0.5 to 3%,
Si: 0.5 to 2%, with the balance Fe
It is desirable to be composed of a Cr-Fe alloy having a composition of unavoidable impurities and the base material is C: 0.5 to 2
%, Ni: 3 to 10%, Co: 0.5 to 8
%, Mo: 0.5 to 2%, with the balance being F
It is desirable to use a Fe-C alloy having a composition of e and inevitable impurities. Further, in the method of the present invention, the proportion of hard particles dispersed in the matrix is preferably 5 to 25%.

[0007]

Next, the method of the present invention will be specifically described with reference to examples. As a raw material powder for forming hard particles, each has a predetermined average particle size within the range of 47 to 69 μm and Table 1
Cr-Fe alloy powders A to M having the composition shown in 1 are prepared, and 1 is used as the raw material powder for forming the base.
Ni powder, Co powder, Mo having a particle size of 00 μm or less
Powder, Fe powder, and graphite powder are prepared, and each of the above Cr-Fe alloy powders A to M is 5 μm.
Ni-containing Cr-Fe alloy powder after being mixed with a predetermined amount of carbonyl Ni having an average particle diameter of 1, then heated in a hydrogen atmosphere at 900 ° C. for 1 hour and cooled and then crushed. Then, these raw material powders were blended to the blending composition shown in Tables 2 and 3, and 1% zinc stearate as a lubricant was added thereto and mixed in a mixer for 30 minutes.
Press-molded into a green compact with a pressure of ton / cm ² , hold this green compact at 500 ° C. for 30 minutes to degrease, and then in a vacuum,
The present methods 1 to 13 and the conventional methods 1 to 13 were carried out by sintering at a predetermined temperature in the range of 1100 to 1200 ° C. for 1 hour, and the outer diameter was 34 mm.
× Thickness: A valve sheet made of an Fe-based sintered alloy having a dimension of 7 mm and having a composition substantially the same as the above-described composition was manufactured.

The various valve seats obtained as a result were subjected to a wear test for the purpose of evaluating wear resistance.
For the wear test, the valve seat was installed in a gasoline engine with a displacement of 2000cc, unleaded gasoline was used, valve material: JIS / SUS36, engine speed: 600
The maximum wear depth of the valve seat and the maximum wear depth of the valve, which is a mating member, were measured under the conditions of 0 rpm and test time: 100 hours. The results of these measurements are shown in Table 4.

[0009]

[Table 1]

[0010]

[Table 2]

[0011]

[Table 3]

[0012]

[Table 4]

[0013]

From the results shown in Table 4, the method of the present invention 1 to
The valve seat made of the Fe-based sintered alloy manufactured by No. 13 is an alloy layer containing Ni as a main component existing at the interface between the hard particles of the Fe-based sintered alloy and the base material that compose the valve seat (the raw material powder during sintering. In the coating Ni of the Ni-coated Cr-Fe-based alloy powder, which is the above, the Cr-Fe-based alloy constituting the hard particles and the constituent components of the base are solid-dissolved to form an alloy layer containing Ni as a main component) Since the adhesion of the hard particles to the base material is significantly improved by the action of, the excellent abrasion resistance is exhibited in the state of low opponent attack even under the above high-speed operating conditions, whereas the conventional methods 1 to 13 In the Fe-based sintered alloy valve seat manufactured in step 1, because the adhesion of the hard particles to the substrate is not sufficient, the hard particles are likely to be peeled off, and both the wear resistance and the opponent attack property are inferior. To become It is clear. As described above, according to the method of the present invention, it is possible to manufacture a valve seat composed of a Fe-based sintered alloy having excellent adhesion of hard particles to the base material, and thus the resulting Fe
The valve sheet made of base sintered alloy has a low opponent attack property even under severe conditions and exhibits excellent wear resistance.

[Procedure amendment]

[Submission date] October 6, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

The various valve seats obtained as a result were subjected to a wear test for the purpose of evaluating wear resistance.
In the wear test, the valve seat was installed in a gasoline engine with a displacement of 2000cc, unleaded gasoline was used, valve material: JIS / SUH 36, engine speed: 600
The maximum wear depth of the valve seat and the maximum wear depth of the valve, which is a mating member, were measured under the conditions of 0 rpm and test time: 100 hours. The results of these measurements are shown in Table 4.

Claims (1)

[Claims] 1. A method for manufacturing a valve seat comprising a Fe-based sintered alloy having a structure in which hard particles of a Cr—Fe alloy are dispersed and distributed in a base of an Fe—C alloy, the hard particles and the matrix. Fe group having excellent wear resistance, characterized in that an alloy layer containing Ni as a main component is continuously and / or intermittently present at an interface portion with and to improve adhesion of the hard particles to the substrate. Manufacturing method of sintered alloy valve seat.