JPH0617549B2 - Wear resistant member with self-lubricating property - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a member made of a sintered alloy having excellent self-lubricating property and wear resistance.

[Technical background of the invention and its problems]

Conventionally, as an alloy material for forming a machine part having a sliding contact part, in order to suppress the wear of the sliding contact part of the mechanical part, the alloy surface is hardened by a treatment such as quenching or nitriding so as to have wear resistance. Is used. In addition, for example, cylinders and rotors of rotary compressors use meehanite cast iron whose surface is hardened by adding an element such as boron.

However, in order to suppress the wear of mechanical parts having a sliding contact portion, it is not enough to simply harden the alloy surface, and by providing the alloy with excellent self-lubricating property, its lubricating action is sufficient. Wear can be suppressed.

Therefore, a sintered alloy in which lubricating components such as molybdenum disulfide, sulfur and lead are dispersed is used. However, in this sintered alloy, the lubricating component decomposes during the sintering,
It is difficult to obtain the desired performance by disappearing or dropping. Moreover, the surface of this sintered alloy is not sufficiently hardened.

Therefore, it has been desired to develop an alloy material having excellent self-lubricating property in addition to wear resistance.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and provides a member made of a sintered alloy having excellent self-lubricating property and wear resistance.

[Outline of Invention]

The wear resistant member having self-lubricating property of the present invention has a matrix structure consisting of 3 to 10% by weight of chromium, 1 to 5% of carbon and the balance of inevitable impurities and iron in a matrix structure substantially consisting of tempered martensite. , A metal carbide, a metal oxide, and free graphite are dispersed in the sintered alloy.

In addition, chromium 3 to 10% by weight, graphite 1 to 5% and molybdenum 0.3 to 5%, vanadium 0.2 to 1.5.
%, Tungsten 0.3 to 3%, nickel 0.5 to 5
%, Copper 0.5 to 5% alone or in combination, the remainder being substantially iron, and the matrix structure consisting essentially of tempered martensite, in which metal carbide, metal oxide and free graphite are dispersed. It is made of a sintered alloy.

The wear resistant member having self-lubricating property of the present invention is formed of a sintered alloy having a matrix structure that is substantially tempered martensite (partly corresponding to ferrite) and has hardness and toughness. Metal carbide having high hardness is present in this matrix structure. Therefore, the self-lubricating wear-resistant member of the present invention has a very hard surface and excellent wear resistance. Further, in the wear resistant member having self-lubricating property of the present invention, for example, the metal oxide generated inside the pores in the matrix tissue by the steam treatment seals the pores.
Therefore, the lubricating oil can be stored in the holes, and the oil retaining property can be improved. The metal oxide also has anti-adhesion properties. Further, free graphite is generated by being dispersed in the matrix structure, and this free graphite enhances the lubricity as a solid lubricant. Therefore, the wear resistant member having self-lubricating property of the present invention has improved self-lubricating property by both the oil retaining property by the metal oxide and the free graphite of the solid lubricant. That is, the mechanical component formed of the wear resistant member having self-lubricating property of the present invention retains the lubricating oil when the lubricating oil is supplied and performs good lubrication, and even if the lubricating oil runs out, the free graphite As a result, the lubricating action can be maintained. In this way, the wear resistant member having self-lubricating property of the present invention can sufficiently suppress the wear on the sliding contact surface with which other parts are slidingly contacted by the combination of the wear resistance and the self-lubricating property. By sealing the holes with the metal oxide, airtightness can be imparted to the wear resistant member having self-lubricating property.

The wear resistant member having self-lubricating property of the present invention is chrome,
It is composed of carbon and iron at a predetermined ratio. Chrome is
In the sintering process, it combines with a part of graphite that is a carbon source to disperse and generate carbides, and the other forms a solid solution in the matrix to enhance hardenability and enables the formation of hard martensite by air cooling after sintering. In addition, it has the effect of delaying the temper softening of the martensite matrix during steam treatment. Chromium exhibits a sufficient effect at 3% or more, and this effect is maintained up to 10% without impairing the workability. It is preferably 3.5 to 8%.

Part of the carbon source, graphite, combines with chromium in the sintering process to disperse and generate carbides, and the other part forms a solid solution in the matrix to form martensite in the cooling process during sintering. Further, a part of the graphite acts as a solid lubricant by being dispersed and generated as free graphite in the matrix. Graphite produces the above effect at 1% or more, and this effect can be maintained up to 5% without causing embrittlement. It is preferably 1.5 to 4%.
The graphite has a powder particle size of about −325 mesh and a particle size of −100 mesh for free graphite.

Free graphite is preferably present in the range of 5 to 40% by volume in order to improve the self-lubricating property.

More preferably, molybdenum, vanadium, tungsten, nickel, and copper are added to the sintered alloy of the present invention alone or in combination.

Molybdenum partially enters the carbide, and the other part forms a solid solution in the matrix to enhance the hardenability, contributes to the formation of martensite, and delays the temper softening of martensite. If the content of molybdenum is less than 0.3%, the effect is not obtained, and if it exceeds 5%, the corresponding advantage cannot be obtained.

Vanadium has the same effect as molybdenum, and contributes to the improvement of wear resistance together with chromium and molybdenum.
If vanadium is less than 0.2%, it has no effect, and if it exceeds 1.5%, the hardenability is impaired.

Tungsten has the effect of partly forming carbides and delaying the temper softening of martensite. Tungsten has no effect below 0.3%, 3%
If it exceeds, the toughness is impaired.

Copper has the effect of increasing the strength of the base, and nickel has the effect of increasing the strength of the base as well as the toughness, but in both cases, there is no effect at the end of 0.5%, and if it exceeds 5%, the dimensional accuracy of the alloy is The hardness decreases in the case of nickel.

When producing a wear resistant member having self-lubricating property of the present invention, for example, chromium powder, graphite powder as a carbon source,
If necessary, other metal powders are added and mixed to press the raw material powder to form a compact, and the compact is sintered and cooled. Next, the obtained sintered body is steam-treated.

The wear resistant member having self-lubricating property of the present invention is chrome,
Molybdenum, tungsten, vanadium, and a part of graphite that is a carbon source generate and precipitate hard carbide having high wear resistance during sintering, and chromium that forms a solid solution in the matrix,
With molybdenum and vanadium, the matrix becomes sufficiently martensite even at a normal cooling rate, that is, an air cooling rate. Further, during sintering, graphite having a large powder particle size is dispersed in the matrix and free graphite is formed and deposited. Note that it is important not to raise the sintering temperature too much in order to generate free graphite. Therefore, the sintered body is composed of a martensite matrix and metal carbide and free graphite dispersed in this matrix. Then
When the sintered body is subjected to steam treatment, a new metal oxide is generated in the pores of the sintered body and dispersed in the matrix. During the steam treatment, softening due to tempering of the matrix is delayed by chromium, molybdenum, vanadium, and tungsten that are solid-dissolved in the matrix of the sintered body, and the tough characteristics of the matrix can be maintained.

INDUSTRIAL APPLICABILITY The wear resistant member having self-lubricating property of the present invention is applied to a machine part requiring wear resistance and lubricity, that is, a machine part having a sliding contact surface. For example, it is applied to the components of a rotary compressor used in a refrigerator or the like as shown in FIG. In the figure, 1 is a cylinder, 2 is a rotor, and 3 is a vane. The inner peripheral surface of the cylinder 1 and the hole 1a through which the pane 3 is inserted, the outer peripheral surface of the rotor 2, and the side surface of the pane 3 serve as a sliding contact surface, and wear resistance and lubricity are required respectively.
Note that lubricating oil is supplied between the sliding contact surfaces of the cylinder 1 and the vanes 3 and between the cylinder 1 and the rotor 2, but this tends to be insufficient. Therefore, it is effective to form the cylinder 1, the rotor 2 and the vanes 3 with the wear resistant member having self-lubricating property of the present invention.

Although the cylinder 1, the rotor 2 and the vanes 3 are required to have airtightness, the wear-resistant member having self-lubricating property of the present invention has a problem because the metal oxide seals the holes to have airtightness. There is no.

Example of Invention

 Examples of the present invention will be described.

Grain size in weight ratio-325 graphite powder with mesh of 0.5 to 3%
And 0.8 to 2% of graphite powder having a particle size of -100 mesh,
Granularity-100 mesh stainless steel 410 (L) powder 5
~ 50%, remaining grain-100 mesh low alloy steel powder (Fe
-Ni-Cu-Mo) was added with about 1% of zinc stearate and mixed in a V mixer for 10 to 40 minutes to obtain a mixed powder. In addition, stainless steel 410 (L) powder is chromium 1
1.0 to 13.5%, Mn 1% or less, Si 1% or less, and other substantially composed of iron. Next, this mixed powder is pressed with a molding pressure of about 3 to 7 ton / cm ² to obtain a pressure of 10 mm × 16 mm.
A 5 mm plate-shaped test piece was formed, and the obtained formed body was sintered at a sintering temperature of 1050 in a high-purity hydrogen atmosphere with a dew point of -20 ° C or lower.
Sintered at ~ 1150 ° C, 15-45 minutes. Then, the sintered body obtained has a vapor pressure of about 2 kg / c in supersaturated steam.
Steam treatment was performed under the conditions of m ² , temperature of about 600 ° C., and time of 3 hours. Then, the following abrasion resistance test was performed on this sintered body. When rotated, a ring piece (SCM-21 carburized and hardened material) was combined with a sintered body, and a test was carried out for 2 hours at a sliding speed of 3 m / min by applying a load of 25 kg (lubrication condition: thin the oil before the test. Boundary lubrication conditions after coating and then supplying no oil). SUJ-2 steel (sample A), Fe-1.7Ni-1.5Cu-0.5Mo- as comparative materials
The same test is performed using a sintered body (sample B) that has been steam-treated at 1.2 C and a Fe—Cr—C sintered body (sample C) that is tempered martensite containing a metal oxide and a metal carbide. It was As a result, the amount of wear was about half of that of the present invention based on sample B.

The amount of wear of sample A was slightly larger than that of sample B, and sample C was slightly smaller.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain a wear-resistant member having excellent wear resistance and self-lubricating property and having self-lubricating property with very little wear.

[Brief description of drawings]

The drawings are cross-sectional views showing a rotary compressor which is an example of an application of the wear resistant member having self-lubricating property of the present invention. 1 ... Cylinder, 2 ... Rotor, 3 ... Vane.

Claims (2)

[Claims] 1. Chromium 3 to 10% and carbon 1 to 5% by weight.
And self-lubricating property, which is composed of a sintered alloy in which a metal carbide, a metal oxide and free graphite are dispersed in a matrix structure which is composed of unavoidable impurities and iron and which is substantially composed of tempered martensite. Abrasion resistant member. 2. Chromium 3 to 10% and carbon 1 to 5% by weight.
And molybdenum 0.3-5%, vanadium 0.2-
1.5%, tungsten 0.3-3%, nickel 0.5
.About.5% and copper 0.5 to 5% alone or in combination, the rest consisting of unavoidable impurities and iron, and metal carbide, metal oxide and free graphite in the matrix structure which is substantially composed of tempered martensite. A wear-resistant member having self-lubricating properties, characterized in that the wear-resistant member is made of a sintered alloy in which are dispersed.