JPH04337A - Copper-base sintered alloy excellent in wear resistance at high temperature - Google Patents

Abstract

PURPOSE:To obtain a Cu-base sintered alloy for a bearing excellent in wear resistance at a high temp. and seizing resistance by subjecting the powder of a Cu-Sn alloy in which the fine powder of specified W-Si series intermetallic compounds are uniformly dispersed to compacting and sintering. CONSTITUTION:By volume, 1 to 15% of at least one kind of the fine powder of W-Si series intermetallic compounds among W-Fe-Si, W-Ni-Si and W-Co-Si having 1 to 50mum average grain size is mixed into the molten metal of a Cu-Sn alloy contg. 1 to 15wt.% Sn, and this mixture is thereafter pulverized by a water atomizing method. This Cu-Sn alloy powder in which the fine powder of the W-Si series intermetallic compounds are uniformly dispersed is compacted and is thereafter sintered. The Cu-base sintered alloy in which fine pores performing the role of a lubricating oil sump are present in the ratio of 1 to 15vol.% and excellent in wear resistance at a high temp. and seizing resistance as a bearing material can be obtd.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention relates to a copper-based sintered alloy that has excellent wear resistance at room temperature and high temperature, especially at high temperature, and is used for valve guide members of internal combustion engines or turbochargers. This bearing relates to a copper-based sintered alloy used for sliding members such as members.

[Conventional technology]

Conventionally, iron-based materials such as chilled castings, Cu-28 (by weight), have been used as members for manufacturing various mechanical parts of internal combustion engines.
%Zn-6%Ai)
or Cu-1 shown in JP-A No. 1-42537
Copper-based sintered alloys are known in which a solid lubricant such as graphite is added to a typical composition of 0%5n-0, 3%P-3%N1.

[Problem to be solved by the invention]

However, as the output of modern internal combustion engines has increased, the temperature inside the combustion chamber has become higher than before. etc. are also exposed to higher temperatures than before.

The wear resistance and seizure resistance of such sliding members decrease as the temperature increases, and there is also a significant difference between the temperature inside the combustion chamber of the internal combustion engine and the temperature outside. Externally mounted sliding members such as valve guides or turbocharger bearings that are exposed near the combustion chamber are exposed to higher temperatures than before. expands further than before due to thermal expansion, which creates a gap between the valve guide and the valve, thereby causing (a)
(b) If there is a gap between the valve guide and the valve, the valve guide will not function properly and the valve will vibrate during operation. However, there were also problems such as a decline in valve function.

To solve these problems, iron-based materials such as the above-mentioned chill castings,
Because of their low thermal conductivity, low seizure resistance, and low conformability, when used as sliding members that are partially exposed near the combustion chamber of an internal combustion engine, such as valve guides or turbocharger bearings, Due to the low thermal conductivity, large thermal expansion occurs in the partially exposed portion near the combustion chamber of the internal combustion engine, which is undesirable because it creates a gap with the valve or bearing. Also, Cu-28%Zn-6%
A copper-based molten alloy having the typical composition of Due to the lack of this, seizure resistance and conformability are also lacking. Therefore, copper-based sintered alloys to which solid lubricants such as graphite are added have come to be used. Although these copper-based sintered alloys have few problems with thermal conductivity, seizure resistance, and conformability, , abrasion resistance and heat resistance were insufficient.

[Means to solve the problem]

Therefore, in order to solve the above-mentioned problems, the inventors of the present invention have developed materials for valve guides or turbos that have excellent wear resistance and seizure resistance, as well as excellent thermal conductivity, especially at room and high temperatures. As a result of conducting research to obtain a copper-based sintered alloy that can be used as a component for charger bearings, it was found that a Cu alloy base material containing Sn: 1 to 15% by weight, with the remainder consisting of Cu and unavoidable impurities. , having an average particle size of 1 to 50 m.
-Si-based gold intermetallic compound uniformly dispersed in an amount of 1 to 15% by volume,
Copper-based sintered alloys with a structure in which pores are distributed at 1 to 15% by volume have excellent thermal conductivity and excellent seizure resistance and wear resistance at high temperatures. When used as a component for a valve guide in an internal combustion engine or a bearing for a turbocharger, especially when this copper-based sintered alloy is used as a valve guide component in an internal combustion engine, the valve guide has excellent thermal conductivity. Even if the area near the combustion chamber of the engine is heated to a high temperature, the heat in the valve guide part exposed near the combustion chamber escapes to the outside and does not become high temperature.
Therefore, it has been found that the diameter of the valve guide does not expand due to thermal expansion, does not deteriorate its function as a valve guide as shown in (a) and (b) above, and exhibits excellent effects over a long period of time.

This invention was made based on this knowledge, and the average particle size: 1 to 50
The copper-based sintered alloy has a structure in which W-Si intermetallic compounds in the range of 1 to 15% by volume are uniformly dispersed and vacancies are distributed by 1 to 15% by volume. .

The W-3i intermetallic compound is WFeSi.

One or more of WNiSI and WCoSi.

Next, the reason why the W--Si based intermetallic compound and the pores of the copper-based sintered alloy of the present invention are limited as described above will be explained.

(a) 5n Sn forms a matrix together with Cu and has the effect of improving the strength and toughness of the alloy at high temperatures.It also improves adhesion resistance, seizure resistance at high temperatures, and resistance at room and high temperatures. It has the effect of improving wear resistance, but if it is less than 1% by weight, it has no effect. On the other hand, if it is contained in more than 15% by weight, the thermal conductivity decreases and the seizure resistance at high temperatures decreases. It becomes like this.

Therefore, the content of Sn was set at 1 to 15% by weight.

(b) Void Vacancies are distributed on the sliding surface and play the role of oil reservoirs, contributing to improvements in seizure resistance and conformability due to deformation of the pores especially at high temperatures, but 1% by volume If the amount is less than 15% by volume, the effect will not be obtained, while if the distribution is more than 15% by volume, not only will the strength decrease, but also the thermal conductivity will decrease, resulting in poor heat resistance and seizure resistance at high temperatures. This is not preferable because it also reduces wear resistance.

Therefore, the distribution amount of pores was determined to be 1 to 15% by volume.

(c) W-3j-based gold metal compound The w-si-based intermetallic compound is uniformly dispersed in the copper-based sintered alloy base of the present invention and suppresses the growth of adhesive parts at room temperature and high temperature. It has the effect of improving wear resistance, preventing thermal deformation, and improving wear resistance at high temperatures by improving heat resistance, but it has no effect when the average particle size is less than 1-1% by volume, and on the other hand, If the average grain size becomes coarser, exceeding 50%, or exceeding 15% by volume, the strength and toughness of the alloy will decrease, and the aggressiveness of the alloy will increase, which is undesirable. Therefore, the W--Si based intermetallic compound was determined to have an average particle size of 1 to 50-50 and a total amount of 1 to 15% by volume. The W-Si intermetallic compounds uniformly dispersed in the copper-based sintered alloy base of this invention include WFeSi, WNi
One or more of Si and WCoSI.

The copper-based sintered alloy of the present invention may contain P, Mg, Zn, and Pb as unavoidable impurities, but if the total content is 1.5% or less, the alloy properties will not be impaired in any way. Since it is not a substance that can be used as a substance, its content can be tolerated.

Contains Sn of this invention: 1 to 15% by weight, and the rest is Cu.
In the Cu alloy matrix with a composition consisting of and inevitable impurities,
Producing a copper-based sintered alloy having a structure in which a W-Si intermetallic compound having an average particle size of 1 to 5 o- is uniformly dispersed by 1 to 5% by volume and pores are distributed by 1 to 15% by volume. To do this, a Cu-Sn alloy obtained by water atomizing a Cu-Sn master alloy in which a W-Si based intermetallic compound having an average particle size of 1 to 50 was dispersed in a Cu-Sn composite in advance. The powder is used as a raw material powder. In this raw material powder, fine W--Si based intermetallic compounds are firmly bonded in the matrix.

In addition, the Cu-Sn alloy powder in which the fine W-Si intermetallic compound is firmly bonded to the above matrix is used as a regular Cu-3n alloy powder.
A mixed powder mixed with atomized powder may also be used.

Furthermore, W-5L intermetallic compounds with an average particle size of 5Qm or less are added to commonly used fixed lubricants such as zinc stearate.
The resulting mixed powder is mixed with ordinary Cu-5n atomized powder, and this is pressed to form a green compact, and even when this green compact is molded, the copper-based sintered alloy of the present invention can be obtained. be able to. Alternatively, wet mixing may be performed using an organic solvent such as acetone or alcohol.

〔Example〕

Next, the copper-based sintered alloy of the present invention will be specifically explained with reference to Examples.

First, average particle size: 1-50t! W=Sl within the range of r@
Intermetallic compound powder: WFeSi powder, WNiSi powder, and WCoSi powder are prepared, and these W-Si based intermetallic compound powders are mixed with Cu having a composition containing Sn: 1 to 15% by weight and the remainder consisting of Cu and inevitable impurities. Added to molten alloy, W-8i gold metal compounds: WFeSi, WN
i Sl.

A Cu-Sn master alloy in which one or two of WCoS+ are uniformly dispersed is produced, and this Cu-Sn master alloy is water atomized to produce a raw material powder having almost the same composition as the Cu-8rl master alloy described above. Then, these raw material powders were
Press-molded into a green compact at a predetermined pressure within the range of ~7 ton/c-, and heated at 850°C in hydrogen gas with a dew point of 20°C to -30°C.
Sintering is carried out at a predetermined temperature within the range of ~950"C for 1 hour, and then sintered at a predetermined temperature within the range of 300~600"C for 1 hour to control the amount of pores.
After holding for a minute, by repressurizing, the Cu-based sintered alloys 1 to 23 of the present invention and the comparative Cu-based sintered alloys having the pore volume and the W-8t gold metal compound average particle size shown in Table 1. Consisting of gold 1 to lO, length: 10 pieces, width: 10 weights 11
Length: Blocks with dimensions of 40+n were made.

Furthermore, a w-Si intermetallic compound with an average particle size of 25 m was added to the normal Cu-5n alloy atomized powder = WFeSi
, WNiSl, and WCoSi, the mixture is press-molded to form a green compact, and the green compact is sintered.
A block having dimensions of length: lo+n, width: 10 mm, and length: 40+n was produced.

Cu-based sintered alloys 1 to 2 of the present invention produced in this way
The thermal conductivity of blocks consisting of Comparative Cu-based Sintered Alloys 1 to 10 and Comparative Cu-based Sintered Alloys 1 to 10 were measured, and the results are shown in Table 1. The above comparative Cu-based sintered alloys 1 to 1O have the component content, W-Si
Intermetallic compounds: Those whose average particle size or pore content is out of the scope of the present invention (indicated by a square mark in Table 1).

On the other hand, 5U, which is commonly known as a valve material for internal combustion engines, was used as a partner material for the block-on-ring type wear test.
H3 steel material, outer diameter: 40mm, inner diameter: 30mm, thickness: 15mm
A ring having a dimension of mm was prepared, and using the above block and ring, as shown in FIG.
After applying engine oil as a lubricant around ring 2, a load of 2 kg is applied to block 1, and ring 2 is moved at a sliding speed at room temperature and in an atmosphere of 600°C. : Rotate at 1.2m/sec,
The ring 2 continues to rotate until the coefficient of friction increases rapidly and seizure is determined, and the time until seizure occurs and the amount of wear on the block 1 at the time of seizure are measured. An accelerated wear test was conducted using a block-on-ring type wear tester to observe the surface condition, and the measured values and observation results are shown in Table 1. Above ring 2
The observation results of the surface of the ring 2 after the test are shown in Table 1 as 0 when the surface is substantially smooth, Δ when it is a rough surface, and × when it is an adhesive surface.

〔Effect of the invention〕

From the results shown in Table 1, Cu-based sintered alloys 1 to 1 of the present invention
No. 27 has superior wear resistance and seizure resistance compared to conventional Cu-based sintered alloys, and
As seen in base sintered alloys 1 to 10, the constituent components, W-
If any of the Sj-based gold intermetallic compound average particle size and pore volume falls outside the scope or conditions of this invention, thermal conductivity,
Wear resistance, seizure resistance or attack resistance under high temperatures,
It is clear that at least one of these properties is inferior.

As mentioned above, the Cu-based sintered alloy of the present invention has thermal conductivity, wear resistance at high temperatures, seizure resistance, or attack resistance, so it can withstand exposure to high temperatures associated with high output. Even when used as a structural member of an internal combustion engine, especially a valve guide member, the temperature of the valve guide near the combustion chamber does not increase, the diameter of the valve guide does not increase, and there is no leakage of engine oil. It can be used satisfactorily as a structural member of a high-output internal combustion engine, especially as a valve guide, and in practical use, it exhibits excellent performance over a long period of time, resulting in excellent industrial effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a block-on-ring type wear test method. 1...Block, Death...Ring.

Claims (2)

[Claims] (1) Sn: 1 to 15% by weight, W-Si based intermetallic compound having an average particle size of 1 to 50 μm: 1 to 15% by volume is uniformly dispersed, and the number of pores is 1 to 1.
A copper-based sintered alloy with excellent wear resistance at high temperatures, characterized by having a structure with a distribution of 5% by volume. (2) The above W-Si based intermetallic compound is WFeSi,W
2. The copper-based sintered alloy having excellent wear resistance at high temperatures according to claim 1, wherein the total amount of at least one or two or more of NiSi and WCoSi is 1 to 15% by volume.