JPH0340106B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sliding member, particularly to a sliding member that can be applied to sliding surfaces of internal combustion engine piston rings, cylinder liners, air compressors, shift forks, and the like.

[Conventional technology]

In internal combustion engines, there is a need for higher rotation speeds and higher compression ratios to improve performance, use of light alloys and miniaturization of parts to reduce weight and improve fuel efficiency, etc. There is an increasing need to improve wear resistance, anti-seizure materials, and low-friction materials over conventional parts, and much research has been carried out in the past.

Conventionally, as one of such countermeasures, it has been known to form a wear-resistant coating layer on the sliding part by thermal spraying or plating with metal, oxide, or carbide.
There are many examples of its application.

[Problem to be solved by the invention]

A specific explanation will be given below using a piston ring as an example. For the wear-resistant coating layer of piston rings, surface treatments are applied to the outer peripheral surface of the iron-based piston ring base material to form a layer with excellent wear resistance, such as chrome plating, Mo spraying, and high carbon Fe-Cr alloy spraying. There is. Chrome plated piston rings do not have good seizure resistance with the mating cylinder liner cast iron material, so they are prone to seizure and scratch wear called scuffing.

As a countermeasure for this problem, Ni, P,
Low-alloy cast iron cylinder liners containing CrMo and/or B and Nb are used, but these have poor castability and workability compared to ordinary cast iron (e.g. JISFC23), and therefore cylinder liners are costly. There are problems such as high temperatures.

In addition, in the case of chrome-plated piston rings,
Although the wear of the cylinder bore, which is the mating member, is reduced, there is a drawback that the wear resistance of the chrome plating layer of the piston ring itself is poor.

Mo sprayed piston rings have good seizure resistance with the mating cylinder liner cast iron material, but
In engines that are subject to heat loads of ℃ or higher, the bonding strength between the piston ring base material and the sprayed layer and within the sprayed layer is poor due to Mo oxidation, and Mo itself is expensive, making piston ring products expensive. It has disadvantages such as:

The object of the present invention is to provide a sliding member that improves the wear resistance and seizure resistance of the sliding member itself and does not cause wear and seizure of mating members, particularly the sliding surfaces of piston rings, cylinder liners, pistons, etc. The purpose is to provide a sliding member that can be applied to.

[Means to solve the problem]

For this purpose, 55 to 70% by weight (the same shall apply hereinafter) Cr,
High carbon Fe-Cr alloy powder with a composition containing 3-9% C, balance Fe and unavoidable impurities Si, Mn, P, S; 30-85%; Mo powder; 10-85%.
50% and a soft alloy powder consisting of Al alloy powder, Cu alloy powder, and carbon steel powder alone or in combination of two or more; a mixed powder consisting of 2 to 35% is plasma sprayed onto the surface of the base material to form a thermal spray layer. This is achieved by a sliding member characterized in that it is provided.

[Effect]

In the present invention, high carbon Fe-Cr alloy powder,
The reason why a mixed powder of Mo powder and soft alloy powder is used is to take advantage of the advantages of each powder.

In other words, the hardness of the plasma sprayed layer of high carbon Fe-Cr alloy powder is 830 to 1000 on the Vickers hardness, which is about the same hardness as hard chrome plating, and it has excellent wear resistance. It has the disadvantage that there is a lot of wear on the mating member.

The hardness of the Mo gas sprayed layer is the Bitker's hardness.
60 to 800, and although the sliding member itself has a lot of wear, it has the advantage that the mating member has little wear and is excellent in seizure resistance.

On the other hand, the hardness of the soft alloy sprayed layer is 50 to 500 on the Bitkers hardness scale, and it has the advantage that it is not so hard and causes very little wear on the mating material.
At the same time, it has the disadvantage that the sliding member itself is subject to a lot of wear.

The Vickers hardness of the layer plasma-sprayed with a mixed powder of the three types of powders that individually exhibit the above characteristics is 400 to 900, and the wear resistance of the sliding member itself is that of a high carbon Fe-Cr alloy. It is equivalent to a sprayed layer,
Abrasion of the mating member is less than that of the Mo sprayed layer, and its seizure resistance is equivalent to that of the Mo sprayed layer, showing extremely excellent sliding properties.

Next, in the present invention, the reason for limiting the amount of each powder added will be explained.

The reason why the amount of high carbon Fe-Cr alloy powder added is 30 to 85% is that the amount of high carbon Fe-Cr alloy powder added is 30% to 85%.
This is because if it is less than 85%, the wear of the sliding member itself will increase, and if it exceeds 85%, the wear of the mating member will increase.

In addition, the amount of Mo added in the thermal spray powder was set at 10 to 50% because if the amount of Mo added is less than 10%, no improvement in seizure resistance will be obtained, and if it exceeds 50%, the wear resistance of the thermal sprayed layer itself will decrease. At the same time, oxidation resistance at high temperatures decreases.

Furthermore, the reason why the amount of soft alloy powder added is set at 2 to 35% is because if the soft alloy powder is less than 2%, the wear of the mating member will increase, and if it exceeds 35%, the wear of the thermal spraying etc. itself will increase. This is because there will be more.

As the soft alloy powder, Al-based alloy powder, Cu-based alloy powder, or carbon steel powder may be used alone or in a mixture of two or more, and this mixed powder and high carbon Fe-
By spraying a powder containing an appropriate blend of Cr alloy powder and Mo powder onto the surface of the base material, the soft alloy particles and Mo powder particles are retained between the particles of the high carbon Fe-Cr alloy powder. Furthermore, by forming the sprayed layer with a structure in which three types of powder are combined, it is possible to reduce the hardness of the sprayed layer without weakening the bonding strength between the particles of the sprayed layer and the bonding strength between the sprayed layer and the base material. can.

Among soft alloys, Al-based alloys include Al-Si alloy, Al-Cu alloy, Al-Mg alloy, Al-Mn alloy,
An Al-Zn-Mg alloy can be used, and a hypereutectic Al-Si alloy (Si content of 12% or more) is preferred in terms of wear resistance.

The wear resistance of this alloy improves as the Si content increases, but as the Si content increases, the adhesion decreases, so an Al-15-24% Si alloy is suitable.

If the Al-Si alloy powder with the above ratio is made by the atomization method, the hardness is high (about Hv1200), and the fine primary Si crystals are uniformly dispersed in the sprayed layer, resulting in better wear resistance and less wear on the mating material. Excellent in that respect.

Among soft alloys, Cu-based alloys include brass (55-72% Cu - 28-45% Zn), bronze (81-90%
Cu - 3% or less zn - 4 to 9% Sn - 6% or less Pb),
Phosphor bronze (87~91%Cu-9~12%Sn-0.05~0.2
%P), Al bronze (8~10.5%Al-1~6%Fe-6
% or less Ni - 1.5% or less Mn - balance Cu), etc. High strength brass is particularly excellent in terms of wear resistance, and phosphor bronze and Al bronze are also preferable.

Carbon steel with a wide range of carbon contents can be used, but cast iron with self-lubricating graphite distribution, or carbon steel with a low carbon content that is soft iron and has good adhesion, is preferable.

However, since the higher the carbon content, the higher the hardness and the better the abrasion resistance, the higher the carbon content is, the better, as long as the adhesion does not deteriorate.

In order to thermally spray the above-mentioned three types of mixed powders, plasma spraying is preferred from the viewpoint of adhesion to the substrate, and the powder particle size is preferably finer than 350 mesh (44μ). This is because if it is coarser than 44μ, the porosity will increase and the wear resistance and scuffing resistance will deteriorate.

The thickness of the sprayed layer is preferably 0.02 to 0.5 mm. 0.02mm
This is because if it is thinner, a sprayed layer with a uniform thickness cannot be obtained on the surface, and if it is thicker than 0.5 mm, the sprayed layer tends to peel off.

〔Example〕

Next, the sliding member according to the present invention will be specifically explained based on examples and compared with a conventional sliding member.

Example 1 A: Chrome plating, B: Mo gas spraying, C: High carbon Fe-
Cr alloy (composition: Fe-66%Cr-7%C-1.8%Si,
Powder particle size 44~10μ or less) plasma spraying of powder,
D: 40% high carbon Fe-Cr alloy powder and 40% Mo powder
Plasma spraying of mixed powder consisting of 20% soft alloy AL-24% Si alloy powder, E: 70% high carbon Fe-Cr composite powder, 20% Mo powder and 10% soft alloy Fe-08%C
Plasma spraying of mixed powder consisting of alloy powder, F:
Plasma spraying of mixed powder consisting of 50% high carbon Fe-Cr alloy powder and 50% Mo powder, G: 100% soft alloy
Plasma spraying of Al-24%Si alloy powder from 0.20~
0.30mm, and each plated surface and thermal sprayed surface were ground. This is the mating part with an outer diameter of 25.6 mm and an inner diameter of
It was installed so that it was in contact with the end surface of a 20.0 mm, 15.0 mm thick carbon steel (JISS45C) test piece, and cable motor oil SAE30 was supplied as a lubricant to the contact surface.
The load was increased stepwise from 25Kg to 500Kg and the seizure limit load was investigated.

As a result, A: The chrome-plated test piece was
C: Seizing occurred at 325-350 kg for those plasma-sprayed with high carbon Fe-Cr alloy powder, and at 450-475 kg for those plasma-sprayed with F and G powders. : Mo sprayed and plasma sprayed with the mixed powder of D and E, which is an example of the present invention, did not cause seizure even at 500 kg.

Example 2 As in Example 1, A, B, C,
Process D, E, F, G, each 0.20~0.30mm
A coating layer was formed, and each plated and thermally sprayed surface was ground.

These test pieces were set in a friction surface wear tester and brought into contact with one surface (16 x 16) of a mating member made of cast iron (equivalent to JISFC23) with a size of 16 x 16 x 10 mm. A wear test was conducted for 1 hour at a rotation speed of 160 rpm and a load of 60 kg while supplying SAE30 oil.

The test results are shown in the figure. In the figure, the upper part of the horizontal axis shows the wear amount (wear loss; unit: mg) of the chrome plated rotating test piece and various thermal sprayed products, and the lower part shows the wear amount (wear scar depth; The unit is μ), and the symbols A to E are as in Example 1.
The friction test results are shown for each of the friction test results.

Observation of the country and friction surface revealed the following. The outer circumferential surface of the cylindrical test piece A, which was subjected to the chrome plating treatment, had a slight degree of seizure, and although the amount of wear on itself was large, the wear on the mating member was small.

The Mo gas sprayed material B did not cause seizure and had little wear on the mating member, but had a large amount of wear on itself.

The product that was plasma sprayed with 100% high carbon Fe-Cr alloy powder showed a slight tendency to seize, and while the amount of wear on itself was very small, there was a lot of wear on the mating member.

Plasma spraying of mixed powder consisting of 50% high carbon Fe-Cr alloy powder and 50% Mo powder shows no seizure and the amount of wear of the spraying itself is very small.
There was a lot of wear on the mating parts.

Plasma spraying of a mixed powder consisting of G's 100% soft alloy Al-24% Si alloy powder showed no seizure and little wear on the mating material, but the amount of wear on the material itself was extremely large. .

On the other hand, no seizure was observed when the mixed powder of D and E according to the present invention was plasma sprayed.
Its own wear amount is 100% of G soft alloy Al-24%
It is much less than that of plasma sprayed Si alloy powder, 1/2 to 1/3 that of chrome plating of A and Mo gas sprayed of B, and 100% less than that of C's 100%
% high carbon Fe-Cr alloy powder by plasma spraying, Fe
It is comparable to plasma sprayed mixed powder consisting of 50% high carbon Fe-Cr alloy powder and 5% Mo powder, and the wear of mating parts is also comparable to that of 100% high carbon C.
Approximately 1/3 of plasma sprayed with Fe-Cr alloy powder, 1/3 of plasma sprayed with mixed powder consisting of 50% high carbon Fe-Cr alloy powder and 50% Mo powder.
2, which is equal to or lower than B, which was sprayed with Mo gas.

As described above, the sliding member according to the present invention is optimal as a sliding member under severe conditions where wear resistance and seizure resistance are required.

〔Effect of the invention〕

The effects of the present invention are listed below.

(1) The wear resistance of the sprayed material itself and its counterpart material is extremely small, which is superior to conventional Mo spraying or chrome plating treatments.

(2) Seizure resistance is superior to those treated with chrome plating, and equivalent to Mo gas sprayed products.

(3) It can be manufactured at a lower cost than conventional Mo spraying,
Furthermore, the powder used is widely available commercially and is therefore easy to obtain.

Therefore, due to the above-mentioned effects, the material of the present invention has the advantage that it can be optimally used as a sliding member such as a piston ring, cylinder liner, or piston that requires wear resistance and seizure resistance.

[Brief explanation of drawings]

The figure is a graph showing the results of the wear test of Example 2 of the present invention.

Claims (1)

[Claims] 1 55-70% by weight (same below) Cr, 3-9% C,
The balance is Fe and unavoidable impurities such as Si, Mn,
High carbon Fe-Cr alloy powder with a composition containing P and S; 30 to 85%; Mo powder; 10 to 50%;
Soft alloy powder consisting of Al-based alloy powder, Cu-based alloy powder, and carbon steel powder alone or in combination of two or more; 2~
A sliding member characterized by having a sprayed layer formed by plasma spraying a mixed powder consisting of 35% on the surface of a base material.