JPH0953422A - Copper infiltrative fe radical sintered alloy valve guide member with excellent wear resistance and low counter-attackability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a copper infiltrative Fe sintered alloy valve guide member of an internal combustion engine, having excellent wear resistance and low counter-attackability. SOLUTION: A valve guide member comprises C: 1 to 4%, Cu 1.5 to 6%, P: 0.1 to 0.8% in wt.%, and the rest is composed of a composition consisting of iron and inevitable impuroties, and a main basic material is made up of perlite phase. In addition, cementite phase, ferrite phase, and free graphite are all distributed in the basic material, and in this constitutetion, this valve guide member is composed of a copper infiltrative Fe radical sintered alloy made up of infiltrating copper or copper alloy to structure, where the ferrite phase existed in and around the cementite phase and to this Fe radical sintered alloy with a porosity of 6 to 20%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve guide member made of a copper-infiltrated Fe-based sintered alloy, which has excellent wear resistance, low opponent attack, and good thermal conductivity. Is.

[0002]

2. Description of the Related Art Generally, a valve guide member, which is a structural member of an internal combustion engine, has a function of supporting a reciprocating valve. Therefore, an inner surface of a through hole formed in a central portion in a longitudinal direction of the valve guide member. It is subject to sliding wear by the stem (shaft). Therefore, as described in, for example, JP-A-50-57010, JP-A-51-96714, and JP-A-50-75510, a Fe group having excellent wear resistance is used for the production thereof. Sintered alloy is used.

[0003]

On the other hand, in recent years, high output and high speed of internal combustion engines have been remarkable, and accordingly,
The operating conditions of these structural members become even more severe, and the valve guide members are subject to severe sliding wear with the valve (mating member) that reciprocates by being inserted into the central through hole. Among the above-mentioned conventional valve guide members and many other Fe-based sintered alloy valve guide members, those exhibiting excellent wear resistance under the above-mentioned severe conditions have a strong opponent attacking property, while low At present, those that show only aggression to the other party are inferior in wear resistance.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoints, as a result of research to develop a valve guide member made of an Fe-based sintered alloy having excellent wear resistance and low opponent attack, Fe powder, carbon powder, Cu -P alloy powder and Fe-P alloy powder are used, and these raw material powders are represented by weight% (hereinafter,% relating to composition indicates weight%) C: 1 to 4%, Cu: 1.5 to 6%, P:
0.1 to 0.8%, Fe: compounded to a compounding composition consisting of the rest, mixed under normal conditions in each case, and then press-molded into a green compact, and the green compact is liquified in a reducing atmosphere. Produced by phase sintering, having substantially the same composition as the above-mentioned composition, and the main body of the base material is a pearlite phase, and in the base material, a cementite phase, a ferrite phase, and free graphite are distributed. And a structure in which the ferrite phase is present around the cementite phase, and 6 to 20
When a valve guide member is made of a copper-infiltrated Fe-based sintered alloy obtained by infiltrating copper or a copper alloy into an Fe-based sintered alloy having a porosity of%, the resulting valve guide member is The pearlite phase of the base material and the cementite phase distributed in it show excellent wear resistance, and the ferrite phase is particularly in the peripheral part of the cementite phase, thereby significantly mitigating the opponent attacking property and lubricating property. According to the research results, it is possible to further improve the wear resistance by the free graphite having the above-mentioned properties and the local overheating prevention effect by the copper infiltration that contributes to the improvement of the thermal conductivity.

The present invention has been made based on the above-mentioned research results. C: 1 to 4%, C
u; 1.5 to 6%, P: 0.1 to 0.8%,
The remainder is a composition consisting of Fe and unavoidable impurities, the main body of the base material is a pearlite phase, a cementite phase, a ferrite phase, and free graphite are distributed in the base material, and the ferrite phase exists in the peripheral portion of the cementite phase. And an excellent wear resistance, which is constituted by a copper-infiltrated Fe-based sintered alloy obtained by infiltrating copper or a copper alloy into an Fe-based sintered alloy having a microstructure and a porosity of 6 to 20%. This is characterized by a valve guide member made of a copper-infiltrated Fe-based sintered alloy, which has a low opponent attacking property and an excellent thermal conductivity.

Next, the reason why the component composition and porosity of the Fe-based sintered alloy constituting the valve guide member of the present invention are limited as described above will be explained. (A) Component composition (a) CC The C component forms a pearlite phase of the base material and a cementite phase distributed in the base material to improve wear resistance, and forms free graphite to improve self-lubricating property. Therefore, it has the effect of further improving the wear resistance, but if the content thereof is less than 1%, the formation of the cementite phase and the free graphite is insufficient, and the desired wear resistance can be secured. On the other hand, if the content exceeds 4%, the cementite phase is particularly formed in a large amount to increase the aggressiveness against the other party, so the content is 1 to 4%, preferably 1.5%. It was set at ~ 3%.

(B) Cu In the Cu component, besides solid solution in the base material to strengthen it,
Although it has an action of promoting the formation of a ferrite phase, if its content is less than 1.5%, the desired effect cannot be obtained, while if it exceeds 6%, the formation of a cementite phase is suppressed. Therefore, the content is defined as 1.5 to 6%, preferably 2 to 4%.

(C) The P P component has the functions of not only improving the sinterability and improving the strength, but also promoting the formation of a cementite phase, but if the content is less than 0.1%, The desired effect is not obtained on the other hand, and if the content exceeds 0.8%, the formation of the ferrite phase will be suppressed,
Its content is 0.1-0.8%, preferably 0.2-
It was set to 0.5%.

(B) Porosity When the porosity is less than 6%, the uniformity of copper infiltration is impaired, and the proportion thereof is insufficient, so that the desired effect of improving the thermal conductivity cannot be secured. On the other hand, if the porosity exceeds 20%, the rate of copper infiltration becomes too large, and the wear resistance will decrease. Therefore, the porosity is 6 to 20%, preferably 10%.
It was set at ~ 15%.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the valve guide member of the present invention will be specifically described with reference to Examples. As the raw material powder, an Fe powder having a particle size of −80 mesh, a carbon powder of the same −200 mesh, a Fe—27% P alloy powder of the same −150 mesh, and a Cu-8% P alloy powder of the same −200 mesh were used. Each is blended to the blending composition shown in Table 1 and added with 1% zinc stearate and mixed in a V-type mixer for 30 minutes, and then formed into a green compact at a predetermined pressure within the range of 5 to 7 ton / cm ^2. Press molding, then this green compact,
In a decomposed gas atmosphere of natural gas, the temperature is kept at 650 ° C. for 30 minutes to degrease, subsequently the temperature is raised to a predetermined sintering temperature within a range of 1050 to 1150 ° C., and this temperature is kept for 60 minutes, Sintering was performed under slow cooling conditions to form Fe-based sintered alloy bodies A to Q having substantially the same composition as the above-described composition and the porosity shown in Table 1. In the combinations shown in Table 2, pure copper, Cu-3% Co alloy (hereinafter referred to as alloy 1), and Cu-3% Fe-1.5%
A wire having a diameter of 3.2 mm made of any one of Mn-1.5% Zn alloy (hereinafter referred to as alloy 2) was inserted over the entire length, and in this state, in an atmosphere of ammonia decomposition gas, temperature:
Copper infiltration treatment is performed under the condition of holding at 1100 ° C for 20 minutes,
By finally finishing, both length: 5
Valve guide member made of copper-infiltrated Fe-based sintered alloy of the present invention having dimensions of 0 mm x outer diameter: 12 mm x inner diameter: 6.6 mm (hereinafter,
Inventive valve guides) 1 to 11 and comparative copper infiltrated Fe-based sintered alloy valve guide members (hereinafter referred to as comparative valve guides) 1 to 6 were manufactured. The comparative valve guides 1 to 6 are made of a Fe-based sintered alloy having a composition in which any one of alloy components (marked with * in the table) is out of the range of the present invention. It is a thing.

Further, FIGS. 1 and 2 show a copy of a structure photograph (400 times) by a metallurgical microscope of the copper infiltrated Fe-based sintered alloy constituting the valve guides 2 and 4 of the present invention, respectively.
As shown in the drawings, in each of the valve guides 1 to 11 of the present invention, the matrix is mainly composed of a pearlite phase, and the cementite phase, the ferrite phase, and the free graphite (see FIG. 2) are contained in the matrix.
There may be coarse free graphite, as shown in.)
Was distributed, and the ferrite phase was present in the peripheral portion of the cementite phase, and the pores were infiltrated with copper.

Next, the various valve guides obtained as a result of the above were used for the displacement of a 2000 cc DOHC engine.
l With a press-fitted installation on the exhaust side of a cylinder head made of alloy casting, and finishing of the inner diameter, unleaded gasoline was used as the fuel, and an actual machine test of 300 hours operation at a rotation speed of 6500 rpm was performed. The inner diameter at the inner surface position of 5 mm in the length direction from the end edge on the side, and the minimum outer diameter of the valve stem (counterpart material) made of tuftride treated SUH-11 were measured, and the inner diameter before the test and the inner diameter after the test were compared. The amount of change and the amount of change in outer diameter were measured as the amount of wear to evaluate the wear resistance and the opponent attacking property. The results of these measurements are shown in Table 2.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

From the results shown in Table 2, all of the valve guides 1 to 11 of the present invention have extremely low opponent attack and excellent wear resistance, whereas the comparative valve guides 1 to 6 show As can be seen, when the content of any one of the alloy components of the Fe-based sintered alloy constituting this is out of the range of the present invention, free graphite, cementite phase,
It is clear that the mutual balance between the ferrite phase and the ferrite phase is lost, resulting in a decrease in wear resistance and an increase in opponent attack. As described above, the copper infiltration valve guide member of the present invention has excellent thermal conductivity without increasing opponent attack even if the operating conditions become severe due to higher output and higher speed of the internal combustion engine. In addition to providing the above, it exhibits excellent wear resistance.

[Brief description of drawings]

FIG. 1 is a copy of a micrograph (400 ×) of a structure of a copper infiltrated Fe-based sintered alloy that constitutes the valve guide 2 of the present invention, taken with a metallurgical microscope.

FIG. 2 is a copy of a micrograph (400 times) of a structure of a copper infiltrated Fe-based sintered alloy that constitutes the valve guide 4 of the present invention, taken with a metallurgical microscope.

Claims (1)

[Claims] 1. A composition containing, by weight, C: 1 to 4%, Cu; 1.5 to 6%, P: 0.1 to 0.8%, and the balance being Fe and inevitable impurities. The matrix is mainly composed of a pearlite phase, a cementite phase, a ferrite phase, and free graphite are distributed in the matrix, and the ferrite phase is present in the peripheral portion of the cementite phase, and 6 to 20% Copper having excellent wear resistance and low opponent attack, characterized by being composed of copper-infiltrated Fe-based sintered alloy obtained by infiltrating copper or copper alloy into Fe-based sintered alloy having porosity Valve guide member made of infiltrated Fe-based sintered alloy.