JPH06101428A - Copper infiltration iron system sintered alloy made valve seat for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a valve seat which can exhibit its excellent abrasion resistance for a long time, and its low aggressive power against its counterpart. CONSTITUTION:A valve seat is made of copper infiltration iron system sintered alloy whose composition is formed by dispersing-including 3 to 15% of hard heat resistance phase of Fe-Cr-W-Co system alloy having 700 to 1800 of MH by the total occupying rate in the hard bases element of Fe-Cr-Mo-V-W system alloy having 400 to 800 by weight% of MHv and if necessary, dispersing- including 2 to 12% of the high temperature oxidation resistance phase of Co-Cr- Mo system alloy having 500 to 1000 of MHv therein, and which is formed in such a way that Cu or Cu alloy is infiltrated in an iron system sintered alloy having 10 to 30% of porosity.

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 a copper-infiltrated iron-based sintered alloy for an internal combustion engine, which exhibits excellent wear resistance even when used under severe conditions and has a significantly low opponent attack. It is a thing.

[0002]

2. Description of the Related Art Conventionally, a large number of valve seats have been proposed for various internal combustion engines such as automobiles.

[0003]

On the other hand, in recent years, various internal combustion engines have been remarkably improved in performance and speed, and along with this, the operating environment of the valve seat, which is a structural member thereof, has become more severe. In order to cope with this, there is a strong demand for the development of a valve seat having even more excellent wear resistance.

[0004]

Therefore, the present inventors have
From the above viewpoints, as a result of research to develop a valve seat with excellent wear resistance,
On a hard substrate of an Fe-Cr-Mo-VW-based alloy having a micro Vickers hardness (MHv) of 400 to 800,
Fe-Cr-WC having MHv: 700 to 1800 in proportion to the whole.
The hard heat-resistant phase of the o-based alloy: 3 to 15% is dispersedly contained, and if necessary, the high temperature oxidation-resistant phase of the Co-Cr-Mo based alloy having MHv: 500 to 1000 is 2 to 12%. When a copper-infiltrated iron-based sintered alloy obtained by infiltrating Cu or a Cu alloy into an iron-based sintered alloy substrate having a composition of dispersed inclusion and a porosity of 10 to 30% is used, the resulting copper dissolution is We obtained the research result that the valve seat made of the iron-impregnated sintered alloy exhibits excellent wear resistance in practical use under severe conditions and has extremely low opponent attack.

The present invention has been made based on the above-mentioned research results, and in a hard base material of an Fe-Cr-Mo-VW-based alloy having MHv: 400 to 800, in a proportion of the whole, Fe-Cr-WC with MHv: 700-1800
Hard heat-resistant phase of o-based alloy: 3 to 15%, and further, if necessary, high-temperature oxidation resistant phase of Co-Cr-Mo based alloy having MHv: 500 to 1000: 2 to 12%. And a copper-infiltrated iron-based sintered alloy in which Cu or a Cu alloy is infiltrated into an iron-based sintered alloy substrate having a porosity of 10 to 30%, and has excellent wear resistance and opponent attackability. Is characterized by a valve seat made of a copper-infiltrated iron-based sintered alloy for an internal combustion engine that is small.

In the valve seat of the present invention,
The hard base material of the iron-based sintered alloy substrate constituting this is C: 0.7 to 2%, Si: 0.1 to 0.5
%, Mn: 0.1 to 0.5%, Cr: 2 to 6%, M
o: 2 to 10%, V: 1 to 6%, W: 1 to 1
Fe-Cr-Mo-V-W having a composition of 0%, and optionally, Co: 0.2 to 10%, with the balance being Fe and inevitable impurities.
System alloys and hard heat-resistant phases that exist as dispersed phases are: Cr: 25-45%, W: 20-30%, C
o: 20 to 30%, Nb: 0.2 to 2%, C:
Fe-Cr-W-Co alloy having a composition of 1 to 3% and the balance of Fe and unavoidable impurities, and a high temperature oxidation resistant phase optionally contained as a dispersed phase is Cr: 25-32%, Mo: 7-10%, S
It is desirable to be composed of a Co-Cr-Mo based alloy containing i: 1.5 to 3.5% and the balance being Co and unavoidable impurities.

Therefore, the above-mentioned hard matrix, hard heat-resistant phase, and high-temperature oxidation-resistant phase in the iron-based sintered alloy substrate constituting the valve seat of the present invention are respectively made of the above-mentioned Fe-Cr-Mo-V-W system. Alloy, Fe-Cr-WC
By comprising an o-based alloy and a Co-Cr-Mo-based alloy, the above-mentioned hardness is obtained, and the content ratios of the hard heat-resistant phase and the high-temperature oxidation-resistant phase are 3 to 15 respectively.
% And 2 to 12%, an effective hardness balance can be formed between the above hardness and the hardness of the hard base material, and the valve seat has excellent wear resistance for a long time. It will be exerted throughout.

Further, the porosity of the iron-based sintered alloy substrate constituting the valve seat of the present invention is set to 10 to 30% because copper infiltration is not sufficiently performed when the porosity is less than 10%. The reason is that the aggressiveness against the opponent under harsh conditions becomes large, while when the porosity exceeds 30%, the wear resistance becomes sharply reduced.

[0009]

EXAMPLES Next, the valve seat of the present invention will be described in detail with reference to Examples. 10 as raw material powder
Atomized Fe-Cr-Mo-VW-based alloy powder for forming a hard matrix having a grain size of 0 mesh or less and having the hardness and composition shown in Tables 1 to 7, atomized Fe for forming a hard heat-resistant phase- A Cr-W-Co alloy powder and an atomized Co-Cr-Mo alloy powder for forming a high temperature oxidation resistant phase were prepared, and these raw material powders were compounded at the compounding ratios shown in Tables 1 to 4, and stearin was used as a lubricant. Zinc acidate: 1%
2 to 7 tons after mixing with a mixer for 30 minutes
Press-molded into a green compact at a predetermined pressure within the range of / cm ² ,
The green compact is held at 500 ° C. for 30 minutes for degreasing (removal of the zinc stearate), and then sintered for 1 hour at a predetermined temperature within a range of 1100 to 1200 ° C. in an ammonia decomposition gas atmosphere. Then, an iron-based sintered alloy having a composition substantially the same as the composition and the porosity shown in Tables 5 to 7 as well as dimensions of outer diameter: 34 mm x inner diameter: 27 mm x thickness: 7 mm. A base material is formed, and oxygen-free copper (referred to as pure copper) is added to each of the base materials.
1.5% Zn (referred to as Cu alloy 1), and Cu-3.
Cu alloys 1 and 2 each having a composition of 5% Fe-2.1% Zn (referred to as Cu alloy 2) were placed in the combinations shown in Tables 5 to 7, and in this state, in a methane shift gas atmosphere. , Temperature: 1100 ° C. for 15 minutes to infiltrate copper, and after copper infiltration, heat treatment is performed at a predetermined temperature within a range of 600 to 700 ° C. for 1.5 hours. Seats 1-18 and comparative valve seats 1-
10 were manufactured respectively.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

[Table 5]

[0015]

[Table 6]

[0016]

[Table 7]

The comparative valve seats 1 to 10 contain porosity of the iron-based sintered alloy base material, hard heat-resistant phase, high-temperature oxidation-resistant phase, hardness of hard matrix, and hard heat-resistant phase. Either of the proportions is outside the scope of this invention.

Next, regarding the various valve seats obtained as a result of this, valve material: SUH3 substrate, stellite plating, valve heating temperature: 850 ° C., valve seating frequency: 3000 rpm, atmosphere: 0.4 kg Propane gas at a pressure of / cm ² ;
A wear test was performed under the following conditions: combustion gas with oxygen at a flow rate of 6 l / min, surface heating temperature of valve seat (internal water cooling): 350 ° C, test time: 50 hours, maximum wear depth of valve seat and mating member The maximum wear depth of a valve was measured. The results of these measurements are shown in Tables 5-7.

[0019]

From the results shown in Tables 5 to 7, the valve seats 1 to 18 of the present invention all show excellent wear resistance and their opponent attacking property is small, while the comparative valve seats 1 to 1 As can be seen from No. 10, if any of the requirements constituting the valve seat deviates from the scope of the present invention, one of the wear resistance and the opponent attacking characteristic may be inferior. it is obvious. As described above, the valve seat made of the copper-infiltrated iron-based sintered alloy for an internal combustion engine of the present invention, even in practical use under severe conditions, in a state in which the wear of the mating member is significantly suppressed, for an extremely long period of time. It exhibits excellent wear resistance.

Claims (2)

[Claims] 1. Micro Vickers hardness (MHv): 4
Fe-Cr-Mo-V-W-based alloy having a Fe-Cr-Mo-V-W-based alloy containing 0.00-800 in a total weight ratio of MHv: 700-1800.
Hard heat-resistant phase of o-based alloy: 3 to 15% by dispersion, and copper infiltration obtained by infiltrating Cu or Cu alloy into an iron-based sintered substrate having a porosity of 10 to 30% A valve seat made of a copper-infiltrated iron-based sintered alloy for an internal combustion engine, which is excellent in wear resistance and is composed of an iron-based sintered alloy. 2. Micro Vickers hardness (MHv): 4
Fe-Cr-Mo-V-W-based alloy having a Fe-Cr-Mo-V-W-based alloy containing 0.00-800 in a total weight ratio of MHv: 700-1800.
Hard heat-resistant phase of o-based alloy: 3 to 15%, high-temperature oxidation resistant phase of Co-Cr-Mo-based alloy having MHv: 500 to 1000: 2 to 12%, and composition containing 10 to 30%. A copper melt for internal combustion engines, which is excellent in wear resistance, characterized by being composed of a copper-infiltrated iron-based sintered alloy obtained by infiltrating Cu or a Cu alloy into an iron-based sintered alloy substrate having a porosity of Valve seats made of sintered iron alloy.