JPS5939481B2 - Multi-layer sintered sliding member and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a sintered sliding member made of multiple layers, particularly a seamless sintered sliding member made of stainless steel or carbon steel, and a sintered sliding member made of multiple layers that is closely integrated with a sintered alloy layer on the inner surface of each seamless pipe made of stainless steel or carbon steel. The present invention relates to a sliding member and a method for manufacturing the same, and aims to obtain a sintered sliding member suitable for low-speed, high-load applications.

Conventionally, multi-layer sintered sliding members have been made by depositing a sintered metal layer on a thin steel plate and rolling the sintered metal layer inward to form a cylindrical shape, creating a so-called rolled bush. There are seamless pipes with a sintered metal layer tightly integrated on the inner surface.

However, the former has the disadvantage that large compressive stress is applied to the sintered alloy layer inside the cylinder when processing it into a cylindrical shape, resulting in a decrease in adhesion strength and non-uniformity between the thin steel plate and the sintered alloy layer. The drawback is that the thickness of the bonding gold layer cannot be made very large, which limits the range of use. Furthermore, the latter method has the disadvantage that it is difficult to obtain strong adhesion strength between the inner surface of the pipe and the sintered alloy layer. This species,
The performance of a multilayer sintered sliding member depends on the self-lubricity, wear resistance, strength, and adhesion strength of the sintered alloy layer. The present invention relates to a multilayer sintered sliding member belonging to the latter category, in which a sintered alloy layer with excellent self-lubricating properties and wear resistance is coated on the inner surface of a seamless pipe made of stainless steel or carbon steel. We have succeeded in obtaining a sintered sliding member consisting of multiple layers that are tightly integrated during sintering.

That is, the present invention provides a sintered alloy layer containing copper as the main component mixed with a certain amount of tin, nickel, phosphorus, and graphite on the inner surface of a seamless Nomaipe made of stainless steel or carbon steel, or A sintered sliding member consisting of a multi-layer closely integrated sintered alloy layer mixed with a certain amount of iron, more specifically, a weight ratio of 4 to 10% tin, 10 to 40% nickel,
A sintered alloy layer consisting of 0.5 to 4% phosphorus, 3 to 10% graphite, and the balance copper, or a sintered alloy layer containing 50% or less iron by weight of the above component composition, can be used as a stainless steel or carbon steel. The present invention provides a multi-layer sintered sliding member closely integrated with the inner surface of a seamless pipe, and a method for manufacturing the same. In the manufacturing method, a mixed powder having the above-mentioned component composition is pressure-molded to obtain a cylindrical green compact,
After inserting this green compact into the inner surface of a seamless pipe, it is sintered at a predetermined temperature for a predetermined time in a reducing atmosphere or vacuum, and a sintered alloy layer obtained by sintering this green compact is formed. The volumetric expansion of the compact during sintering causes the components of the compact to diffuse into the inner surface of the pipe, thereby making the sintered alloy layer tightly integrated with the inner surface of the pipe. The volumetric expansion during sintering of compacted powder is particularly affected by the graphite component, and has traditionally been considered a drawback in sintered sliding members from the viewpoint of dimensional stability and reduction in sintered compact density. There is.

One of the points of the present invention is that it actively utilizes the volumetric expansion during sintering of a green compact due to graphite mixture, which has been considered a drawback in the past. In the present invention, tin that constitutes the sintered alloy layer is alloyed with copper, which is the main component, to form bronze, which contributes to improving the strength, toughness, mechanical strength, and wear resistance of the sintered alloy layer. Together with nickel, which will be described later, it has the effect of increasing the porosity of the sintered alloy layer.

If the amount of the mixture is less than 4% by weight, the above-mentioned effectiveness will not be achieved, and if the amount of the mixture exceeds 10% by weight, the sinterability will be adversely affected. Therefore, the mixing amount of tin is 4~
10% by weight, especially 5 to 8% by weight, is suitable. Nickel diffuses into copper, which is the main component, and contributes to improving wear resistance and strength of the base.

During sintering, nickel diffuses into the inner surface of the pipe and alloys the interface, increasing the adhesion strength of the sintered alloy layer to the inner surface of the pipe and partially alloying with phosphorus, which will be described later, to form a nickel-phosphorus alloy. However, the nickel-phosphorus alloy, which has good affinity with copper, is present at the interface between the sintered alloy layer and the pipe, and together with the alloying by diffusion of the nickel at the interface, the sintered alloy layer is firmly attached to the inner surface of the pipe. It has the effect of closely integrating it. Furthermore, nickel has the effect of increasing porosity by forming voids in the sintered alloy layer as it diffuses into the copper during sintering. and,
If the mixed amount is 10% by weight or less, the above-mentioned effects cannot be obtained, and even if the mixed amount exceeds 40% by weight, there is no noticeable difference in the above-mentioned effects, so the upper limit was set at 40% by weight. Therefore, the amount of admixture of nickel is 10 to 40% by weight.
is appropriate. Phosphorus is partially alloyed with copper, which is the main component, and with nickel, which is an ingredient, increasing the strength of the base and contributing to improved wear resistance.

Since phosphorus has a strong reducing power, it has the effect of cleaning the inner surface of the pipe by its reducing action and promoting alloying by diffusion of nickel into the inner surface of the pipe as described above. In addition, Nickel
The effects of the phosphorus alloy are as described above. The appropriate mixing amount is 0.5 to 4% by weight. In order to give graphite self-lubricating properties, it is necessary to mix it in an amount of at least 3% by weight, but if the mixing amount is increased, for example to exceed 10% by weight, it may cause sintering of the green compact. This poses a problem in terms of stability and adhesion to the inner surface of Nomaip. As mentioned above, graphite has the effect of expanding the green compact during sintering, but in the present invention, in order to effectively utilize the volumetric expansion of the compact due to the graphite mixture, the above-mentioned points are taken into consideration. Therefore, the amount of contamination is particularly important. Table 1 shows the experimental results of measuring the expansion coefficient after sintering of green compacts mixed with graphite. Ingredient composition: 8% by weight of tin, 28% by weight of nickel, 1% by weight of phosphorus.
% by weight, graphite 5% by weight, and the balance copper.
This was loaded into a mold at a molding pressure of 3 tons/d and 5 tons/Cll to obtain a cylindrical green compact with an inner diameter of 8.1 mm, an outer diameter of 14.2 mm, and a length of 22.4 T nm, which was used as a sample. .

This sample (green compact) was then sintered in a reducing atmosphere at a temperature of 870°C for 20 minutes and at a temperature of 940°C for 40 minutes, and the dimensions of the sintered body after sintering were measured. It is. The numerical values in the table are the dimensions of the sintered body after sintering the green compact. From the results of this experiment, the dimensions of the green compact after sintering are 8.6 to 13% on the inner diameter side, 11 to 14% on the outer diameter side, and 11 to 14% on the length side of the dimensions before sintering. Swelling of 12-22% was observed. In the present invention, the expansion of the green compact due to the graphite content during sintering is effectively used, and the outer diameter side of the green compact is covered with a seamless pipe, and when the green compact is sintered, the outer diameter side of the green compact is covered with a seamless pipe. By restraining the expansion on the outer diameter side of the pipe, a high contact pressure is generated on the inner surface of the Nomaipe due to the expansion during sintering of the compact, and this contact pressure causes mutual diffusion of metal components at the interface, making the sintered compact a pipe. It is tightly integrated with the inner surface, and the adhesion strength between the inner surface of the seamless pipe and the sintered alloy layer has a high value of 1000 kg/d or more.

The expansion of a green compact due to graphite content depends on the amount of graphite mixed in, but from the viewpoints of sintering properties, self-lubricating properties, and adhesion to the inner surface of the pipe, etc., it is recommended to mix more than 10% by weight. I have confirmed that this is not a good thing. Furthermore, in the present invention, the composition of the components forming the sintered alloy layer described above, that is, 4% to 10% by weight of tin, 10% to 40% of nickel, and 0% of phosphorus.
．． 5 to 4% graphite, 3 to 10 (f) graphite, and the balance steel, iron can be mixed in an amount of 50% or less by weight. Iron does not form a solid solution with copper, which is the main component, but is dispersed in the alloy and is particularly effective in increasing the strength of the base.When copper diffuses into iron during sintering, it reduces the porosity of the sintered body. It has the effect of increasing This effect of increasing porosity becomes effective when used as an oil-impregnated sliding member. In addition, iron generally shows a tendency to alloy with phosphorus in the presence of phosphorus and precipitate a hard iron-phosphorus alloy, but in the present invention, nickel in the component has the effect of suppressing that alloying, so compared to This allows a large number of people to mix together.
The multilayer sintered sliding member of the present invention contains 3 to 10% by weight of graphite as a lubricating substance in its sintered alloy layer, so it can be used under dry friction conditions. Since the bond layer has increased porosity, it is preferable to impregnate it with lubricating oil and use it as an oil-impregnated sintered sliding member.

Next, embodiments of the present invention will be described in detail in the order of their manufacturing steps.

Example 1 [First step] A seamless pipe made of carbon steel and having dimensions of 24 mm in inner diameter, 34 mm in outer diameter, and 30 mm in length is prepared.

[Second step] 8% by weight of atomized tin powder passing through 250 meshes,
28% by weight of electrolytic nickel powder passing through 250 meshes
, 7% by weight of phosphorous copper (14.5% phosphorus) powder passing through 120 meshes, 5% by weight of graphite powder passing through 150 meshes
, the remainder of the electrolytic copper powder that has passed through 150 meshes is mixed in a mixer for 10 minutes to obtain a mixed powder.

[Copper: 58%, Tin: 8%, Nickel: 2801), Phosphorus:
1(f), graphite: 5%] [3rd step] The mixed powder obtained in the above 2nd step was loaded into a mold, and the molding pressure was 3 tons/T.
I has an inner diameter of 18 mm, an outer diameter of 23.95 mm, and a length of 30 mm.
A cylindrical green compact is manufactured.

[Fourth step] The cylindrical compacted powder obtained in the third step is inserted into the seamless nozzle made of carbon steel prepared in the first step, and heated at 870°C in a reducing atmosphere furnace. Sinter for 20 minutes at a temperature of .

[Fifth step] After the sintered alloy layer is closely integrated with the inner surface of the seamless pipe through the fourth step, it is machined to desired dimensions to obtain a multilayer sintered sliding member. .

In the multilayer sintered sliding member obtained in Example 1, the adhesion strength between the inner surface of the seamless pipe and the sintered alloy layer was 15.
001<9/(-1i.

Furthermore, the adhesion strength of the multi-layer sintered sliding member obtained by variously changing each component within the range of the above-mentioned composition showed a high value of 1400 kg/CfL or more. Example [First Step] A seamless Nomaipe made of stainless steel having dimensions of 24 mm in inner diameter, 34 m in outer diameter, 71 L, and 30 mm in length is prepared.

[Second step] 7% by weight of atomized tin powder passing through 250 meshes,
28% by weight of electrolytic nickel powder passing through 250 meshes
, Phosphorous copper (14.5% phosphorus) powder passing through 120 meshes 20.7% by weight, graphite powder passing through 150 meshes 8
The remainder of the electrolytic copper powder that passes through 150 meshes (weight%) is mixed in a mixer for 10 minutes to obtain a mixed powder.

[Copper: 54 (Ff), Tin: 7%, Nickel: 28%, Phosphorus: 3%, Graphite: 8%] And reduced iron that passes through 100 meshes for 60% by weight of the mixed powder consisting of the above component composition. 40% by weight of powder is mixed, and the overall composition is copper: 3
2.4% by weight, tin: 4.2% by weight, nickel: 16.8
Weight%, Phosphorus: 1.8% by weight, Graphite: 4.8% by weight, Iron:
A mixed powder consisting of 40% by weight is obtained. [Third step] The mixed powder obtained in the second step was loaded into a mold, and the molding pressure was 5 tons/CTil to form an inner diameter of 18 mm and an outer diameter of 23.9 mm.
A green compact with a length of 5m1L and 30mm is produced.

[Fourth step] The cylindrical compact obtained in the third step above was inserted into the seamless pipe made of stainless steel prepared in the first step, and this was heated at a temperature of 930°C in a reducing atmosphere furnace. Sinter for 30 minutes.

[Fifth step] After the sintered alloy layer is closely integrated with the inner surface of the seamless pipe through the fourth step, it is machined to desired dimensions to obtain a multilayer sintered sliding member. .

In the multilayer sintered sliding member obtained in the example,
The adhesion strength between the inner surface of the seamless pipe and the sintered alloy layer is 150
It was 0 kg/d.

In the multilayer sintered sliding members obtained in Example 1 and Examples, the adhesion strength between the inner surface of the seamless pipe and the sintered alloy layer is increased to 1400 kg/ml or more due to the inclusion of graphite. In addition to the high contact pressure on the inner surface of the pipe due to the expansion of the green compact during sintering, the interface is cleaned by the reducing action of the phosphorus component in the component composition, which promotes alloying by diffusion of the nickel component into the inner surface of the pipe. Furthermore, the presence of nickel and phosphorus alloys, which have good affinity with steel, at the interface allows the sintered alloy layer to be tightly integrated with the inner surface of the seamless pipe.

Next, the results of a friction and wear test performed on the multi-layered sintered sliding member obtained through the above manufacturing process using a journal tester under the following conditions will be described. Test conditions (1) Composition of test 1 test piece (weight ratio) Test piece 6: 58% copper, 8% tin, 28% nickel, 1% phosphorus, and 501 graphite on the inner surface of a seamless Nomaipe made of carbon steel.
) Bearing bushing test piece 8 with closely integrated sintered alloy layer: Copper 3 on the inner surface of a seamless pipe made of carbon steel
2.4 Hirotin 4.2%, Nickel 16.8%, Phosphorus 1.8%
, Bearing bushing with closely integrated sintered alloy layer consisting of 4.8% graphite and 40% iron (2) Test piece dimensions Both test piece 6 and test piece 8 have an inner diameter of 18 mm and an outer diameter of 3 mm.
4mm (wall thickness of sintered alloy layer 3mm), length 30mm (3mm)
) Compatible material: Carbon steel for mechanical structures (S45C) Burning abrasive hardness: Rockwell C5O~55, surface roughness: 1.5 g or less (4) Surface pressure and sliding speed Surface pressure: 150k9/(-1ii, 200k9/d) Sliding speed: 1.0 m/Mln (5) Sliding time 20 hours (6) Lubrication The sintered alloy layer is impregnated with gear oil as a lubricant.The results of the first friction and wear test conducted under the above test conditions are as follows. 2
As shown in the table.

The test results show that the multi-layered sintered sliding member of the present invention has extremely excellent friction and wear characteristics, and its performance has been demonstrated in low-speed, high-load applications that cannot be achieved with sliding members made of a single sintered body. Squid A7. It is something that can be demonstrated without any effort.

As detailed above, the multi-layer sintered stationary member of the present invention has greatly improved load characteristics because its sintered alloy layer is tightly integrated with the inner surface of the seamless nomaipu. Coupled with the friction and wear characteristics of the sintered alloy layer, the range of application of the sintered sliding member can be expanded.

In addition, since the sintered alloy layer contains graphite as a lubricating substance, it can not only be used under dry friction conditions, but also because the sintered alloy layer has increased porosity, it can be impregnated with lubricating oil. It can also be used as an oil-impregnated sintered sliding member.

Claims (1)

[Claims] 1. On the inner surface of a seamless pipe made of stainless steel or carbon steel, 3 to 10% tin, 10 to 40% nickel, 0.5 to 4% phosphorus, 3 to 10% graphite, and the balance by weight. A sintered sliding member consisting of multiple layers in which sintered alloy layers made of copper are tightly integrated. 2. On the inner surface of a seamless pipe made of stainless steel or carbon steel, a chemical composition consisting of 4 to 10% tin, 10 to 40% nickel, 0.5 to 4% phosphorus, 3 to 10% graphite, and the balance copper is applied to the inner surface of a seamless pipe made of stainless steel or carbon steel. On the other hand, a sintered sliding member is made up of a multilayer structure in which three sintered alloy layers containing 50% or less iron by weight are tightly integrated. 3 A mixed powder consisting of 4 to 10% tin, 10 to 40% nickel, 0.5 to 4% phosphorus, and 3 to 10% graphite, the balance being copper, is press-molded to produce a cylindrical green compact. After inserting the green compact into the inner surface of a seamless pipe made of stainless steel or carbon steel, it was heated to 800°C in a reducing atmosphere or vacuum.
It is sintered at a temperature of ~950°C for 20 to 60 minutes to form a sintered alloy layer, and the volume expansion during sintering of the green compact produces high contact pressure on the inner surface of the pipe, and this contact pressure causes the inner surface of the pipe to A method for manufacturing a sintered sliding member consisting of multiple layers, characterized by causing diffusion of compacted powder components into the pipe, thereby closely integrating the sintered alloy layer with the inner surface of the pipe. 4 Contains 50% or less iron by weight with respect to a component composition consisting of 4 to 10% tin, 10 to 40% nickel, 0.5 to 4% phosphorus, 3 to 10% graphite, and the balance copper. The mixed powder is pressure-molded to produce a cylindrical green compact, which is inserted into the inner surface of a seamless pipe made of stainless steel or carbon steel, and then heated for 800 min in a reducing atmosphere or vacuum.
It is sintered at a temperature of ~950°C for 20 to 60 minutes to form a sintered alloy layer, and the volume expansion during sintering of the green compact produces high contact pressure on the inner surface of the pipe, and this contact pressure causes the inner surface of the pipe to A method for manufacturing a sintered sliding member consisting of multiple layers, characterized by causing diffusion of compacted powder components into the pipe, thereby closely integrating the sintered alloy layer with the inner surface of the pipe.