JPH0469118B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sliding material with excellent sliding properties and wear resistance, which is obtained by impregnating fluorine-based oil into the open pores of a semalik porous body. .

[Conventional technology]

In general, ceramics often have excellent physical and chemical properties, and are excellent materials for wear-resistant materials such as mechanical seals and bearings, and pump parts for highly corrosive solutions such as acids and alkalis. Are known.

By the way, many ceramics which have high hardness and excellent wear resistance generally have poor self-lubricating properties. Therefore, as a material for solving the above-mentioned problems, an invention related to a "ceramic composite in which a fluorine-containing polymer is bonded to ceramics" is published in JP-A-58-161982, and also in JP-A-57-1989. 118080
The publication states, ``A porous ceramic bearing is impregnated with tetrafluoroethylene resin or trifluorochloride ethylene resin, or both of the above fluorides are combined with molybdenum disulfide, tungsten disulfide, molybdenum selenide, or selenium. An invention relating to a solid lubricated bearing characterized in that the bearing is impregnated with a mixture of tungsten oxide and tungsten oxide is disclosed.

[Problem that the invention seeks to solve]

However, all of the above-mentioned inventions impart lubricating properties by compounding with a solid lubricant, and nothing is said about ceramics suitable for use with liquid lubricants and lubricants suitable for said ceramics. There is no known ceramic sliding material that uses a liquid lubricant, which is not described, and is particularly suitable for applications such as mechanical seals, bearing parts, or sliding members under vacuum conditions.

[Means for solving problems]

As a result of various studies aimed at solving the above-mentioned problems, the present inventors have found that they can mold ceramic powder into a formed body of any shape, without making the pores existing in the formed body independent. By bonding ceramic powder, the ceramic porous body has open pores with a three-dimensional network structure. By impregnating the open pores of the ceramic porous body with fluorine-based oil, sliding properties and wear resistance can be improved. The present invention has been completed based on the new discovery that it is possible to produce extremely superior sliding materials.

The present invention will be explained in detail below.

The ceramic porous body of the present invention can be produced by forming a three-dimensional network structure by molding ceramic powder into a formed body having an arbitrary shape and bonding the ceramic powder without making the pores existing in the formed body independent. It is necessary that the material has open pores. The reason for this is that when the pores become independent when the ceramic powder is combined, the independent pores, that is, the independent pores, are not impregnated with fluorine oil, which improves the sliding properties and wear resistance that are the object of the present invention. Although it is difficult to produce sliding materials with excellent properties, porous bodies with open pores in a three-dimensional network structure are extremely suitable for impregnation with fluorine oil.

The ceramic porous body has an open porosity of 5 to 5.
Preferably, it is 55% by volume. The reason for this is that if the open porosity is lower than 5% by volume, the substantial amount of fluorine-based oil impregnated will be small, making it difficult to fully demonstrate the lubricating properties of the fluorine-based oil. On the other hand, if it is higher than 55% by volume, the strength of the porous body will be low and the particles will be easily detached.

The ceramic porous body has an average grain size of crystals.
Advantageously, it is less than 10 μm. The reason for this is that if the average grain size of the crystals is larger than 10 μm, the surface roughness of the surface of the porous body tends to increase, and the sliding properties deteriorate.

As the ceramic powder, it is advantageous to use one with as high hardness as possible from the viewpoint of wear resistance, and examples thereof include Al ₂ O ₃ , SiO ₂ , ZrO ₂ , SiC,
TiC, _B4C , _WC , _Cr3C2 , _{Si3N4 ,} BN, TiN,
It is preferable that the material mainly contains one or more selected from Tac, AlN, TiB ₂ , CrB ₂ or compounds thereof.

The sliding material of the present invention is required to be a porous ceramic body having open pores in a three-dimensional network structure, and the open pores of the material are impregnated with fluorine-based oil. The reason for this is that the sliding properties can be significantly improved by impregnating a ceramic base material with excellent wear resistance with a fluorine oil having excellent lubricating properties. In addition, fluorine-based oil not only has excellent solvent resistance, chemical stability, and heat resistance, but also is extremely difficult to evaporate.
Extremely good sliding properties can be imparted even under harsh conditions such as at high temperatures and in vacuum.

As the fluorine oil, one or a mixture of two or more selected from fluoroethylene, fluoroester, fluorotriazine, perfluoroalkyl polyether, fluorosilicone, derivatives thereof, or polymers thereof may be used. is advantageous and can be used in liquid, grease or wax form.

It is preferable that the sliding material of the present invention is impregnated with at least 10 parts by volume of fluorine-based oil per 100 parts by volume of the open pores of the ceramic porous body. The reason for this is that if the amount of fluorine-based oil impregnated is less than 10 parts by volume, it is difficult to improve the sliding properties and wear resistance.

Next, a method for manufacturing the sliding material of the present invention will be explained.

The sliding material of the present invention is produced by molding ceramic powder, which is a starting material, into a formed pair of arbitrary shapes, bonding the formed body without clogging the pores present in the formed body, and then forming a porous ceramic body. It can be manufactured by impregnating fluorine-based oil into the open pores of a porous ceramic body.

Advantageously, the starting ceramic powder has an average particle size of 10 μm or less. The reason for this is that when ceramic powder with an average particle size larger than 10 μm is used, there are fewer bonding points between particles, which not only makes it difficult to produce a high-strength porous body, but also makes it difficult to produce a high-strength porous body. This is because it deteriorates.

Various methods can be used to form the ceramic powder into a formed body of any shape and to bond without clogging the pores present in the formed body. For example, the ceramic powder itself may be sintered under pressure. There is a method of self-bonding by pressure sintering,
A method in which a substance that generates ceramic through a reaction is added to ceramic powder and bonded by reaction sintering, and a method in which a metal such as Co, Ni, Mo, or a binder such as glass cement is blended with ceramic powder. A method of bonding by pressure sintering or pressure sintering,
A method of bonding ceramic powder with a thermosetting resin or thermoplastic resin as a binder can be applied.

Examples of methods for impregnating the open pores of the porous ceramic body with fluorine-based oil include a method in which the porous ceramic body is immersed in fluorine-based oil whose viscosity has been lowered by heating, and the porous ceramic body is impregnated under vacuum or pressure. General impregnation methods can be applied.

Next, the present invention will be explained with reference to examples.

Example 1 2 parts of polyvinyl alcohol was added to 100 parts by weight of α-type alumina powder with an average grain size of 0.4 μm and a purity of 90%.
parts by weight, 1 part by weight of polyethylene glycol, 0.5 parts by weight of stearic acid and 100 parts by weight of water, and then spray-dried.

An appropriate amount of this dried material was collected and molded using a metal mold at a pressure of 1.5 t/cm ² to a diameter of 46 mm and a thickness of 15 mm.
mm, and a density of 2.3 g/cm ³ (59% by volume) was obtained.

The formed body was charged into an alumina crucible and sintered in air under atmospheric pressure at a temperature of 1300°C, which is a temperature range in which more than 5% by weight of the liquid phase is not produced.
Baked for an hour.

The obtained sintered body has crystals with an average grain size of approximately 2.7 μm and is bonded in a three-dimensional network structure, and has a density of 2.3 g/
cm ³ , and the average bending strength was 6.9 Kgf/mm ² .

This sintered body was processed into a bearing ring for a rolling bearing with the nominal number 6004, and then immersed in perfluoroalkyl polyether heated to 100°C to reduce the viscosity under reduced pressure.

The proportion of perfluoroalkyl polyether impregnated into this sintered body in the voids of the sintered body is approximately
It was 75% by volume.

When a rolling bearing was assembled using bearing balls made of dense silicon carbide sintered body for the raceway ring of this rolling bearing, it had extremely good sliding characteristics and extremely good durability. One thing was recognized.

Example 2 2 parts by weight of wax, 1 part by weight of polyethylene glycol, 0.5 parts by weight of stearic acid, and 100 parts by weight of benzene were blended with 100 parts by weight of silicon nitride powder with an average particle size of 0.4 μm, and mixed in a ball mill for 5 hours. After that, it was spray dried. The silicon nitride powder contained 21.5% by weight of free silicon, 1.7% by weight of oxygen, 1% by weight of carbon, 0.07% by weight of iron, 0.2% by weight of aluminum, and 0.03% by weight of magnesium.

An appropriate amount of this dried material was collected and molded using a metal mold at a pressure of 1.5 t/cm ² to a diameter of 46 mm and a thickness of 16 mm.
A product body with a density of 1.95 g/cm ³ was obtained.

The formed body was placed in a graphite crucible and fired at a temperature of 1600° C. for 1 hour in a nitrogen gas atmosphere at atmospheric pressure.

The obtained sintered body had crystals connected in a three-dimensional network structure, and had a density of 2.33 g/cm ³ and an average bending strength of 16.5 Kgf/mm ² .

This sintered body was prepared in the same manner as in Example 1, and the perfluoroalkyl polyether was added to the voids of the porous body.
The bearing ring of a rolling bearing was impregnated with 64% by volume, and the rolling bearing was assembled.

It was confirmed that this rolling bearing has extremely good sliding characteristics even under a vacuum of 10 ^-5 torr and has extremely good durability.

Example 3 Average particle size is 0.28 μm, β-type crystal content is 94.6
100 parts by weight of silicon carbide powder, 1 part by weight of boron carbide powder, 2 parts by weight of carbon black powder, 5 parts by weight of polyvinyl alcohol, and 300 parts by weight of water were mixed in a ball mill for 5 hours, and then spray-dried. did. The silicon carbide powder contained 0.29% by weight of free carbon, 0.17% by weight of oxygen, 0.03% by weight of iron, and 0.03% by weight of aluminum.

An appropriate amount of this dried product was collected, molded, and held in an argon gas atmosphere at 1900°C for 10 minutes to obtain a sintered body.

The obtained sintered body had a density of 2.59 g/cm ³ , an average bending strength of 51 Kgf/mm ² , and a three-dimensional network structure with open pores.

This sintered body was impregnated with perfluoroalkyl polyether under vacuum so that approximately 77% by volume of the voids were impregnated. Using a ring-on-ring sliding tester, the material was tested in an air atmosphere to form silicon carbide with a theoretical density of 98%. Using a sintered body as a mating material, a sliding test was carried out.
The results shown in FIG. 1 were obtained.

As can be seen from Figure 1, this material has a wide PV
It has extremely excellent sliding properties within a range of values, making it suitable as a wear-resistant sliding material for mechanical seals, sliding bearings, etc.

Example 4 A sintered body similar to Example 3 was processed into a bearing ring for a rolling bearing in the same manner as in Example 1, and then fluorotriazine was impregnated into the voids of the sintered body at a ratio of about 80% by volume. Assembled the rolling bearing.

This rolling bearing had extremely good sliding characteristics even in a high-temperature atmosphere of 250°C, and had extremely good durability.

〔Effect of the invention〕

As described above, the sliding material of the present invention has excellent wear resistance, and is used in mechanical components that are subject to a large load per unit area, such as rolling bearing balls, retainers, raceway rings, mechanical seals, and sliding bearing parts. It is an extremely suitable material for parts, and by selecting the fluorine-based oil used, it is a material that can obtain excellent sliding properties even in various atmospheres including high temperatures and vacuum. This is extremely useful industrially, as it can significantly improve the durability, reliability, and field of use of the device.

[Brief explanation of the drawing]

Figure 1 shows the friction coefficient of the sliding material of Example 3.
It is a graph showing the relationship with PV value.

Claims (1)

[Scope of Claims] 1. Open pores in a ceramic porous body in which ceramic powder is bonded without clogging the pores present in a formed body formed into an arbitrary shape, and has open pores in a three-dimensional network structure. A sliding material impregnated with fluorine-based oil. 2 The ceramic porous body has an open porosity of 5
55% by volume of the sliding material according to claim 1. 3 The ceramic porous body has an independent porosity of 10
Claim 1 or 2 which is less than % by volume
Sliding materials described in Section 1. 4. The sliding material according to any one of claims 1 to 3, wherein the fluorine oil is impregnated in an amount of at least 10 parts by volume per 100 parts by volume of open pores of the ceramic porous body. 5 The ceramic powder contains Al ₂ O ₃ , SiO ₂ ,
_ZrO2 , SiC, TiC, TaC, _B4C , WC, _{Cr3C2 ,}
Claims 1 to 4 which mainly contain one or more selected from Si ₃ N ₄ , BN, TiN, AlN, TiB ₂ , CrB ₂ or compounds thereof sliding material. 6. Claims 1 to 5, wherein the sliding material is a ball, retainer, and raceway of a rolling bearing, a mechanical seal, or a sliding bearing component.
The sliding material described in any of paragraphs.