JPH0375281A - Porous electroconductive ceramics sliding material - Google Patents

Abstract

PURPOSE:To obtain the title sliding part having high wear resistance and electri cal conductivity, comprising electroconductive reaction sintered ceramics having porosity in a specific range, wherein specific electroconductive metal nitrides are mutually bonded chemically. CONSTITUTION:A porous electroconductive ceramics sliding part comprising electroconductive metal nitrides containing metal elements belonging to the group III to group VIII, such as Ti, Zr, V, Ta, Ce, Co, Mn, Fe, Al, Si, Eu, Gd, Dy and Ni, mutually bonded chemically and having 5-30% porosity. The sliding part is used to constitute bearings, vanes, cylinders, crank shafts, guide rails, etc., and provides various kinds of devices especially compressors, refrigerators, railway vehicle-related materials, rotary actuators and linear actuators having excellent wear resistance, high-speed operation properties, high qualities, corrosion resistance and electrical conductivity which have never existed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a sliding member, particularly one having high wear resistance.

The present invention relates to porous electrically conductive reactive sintered ceramics suitable for members requiring electrical conductivity.

[Conventional technology]

Most machinery has a friction mechanism, and the most important factor that determines its lifespan is how to optimally combine wear-resistant materials. And the conditions of use of each device are diverse, for example.

Operating conditions without lubrication and even with lubrication at high speeds and high loads are harsh operating conditions. It would be ideal if there was a wear-resistant material that could be applied to all of these conditions, but it has both advantages and disadvantages, and at present no such material has been made. As described in Japanese Patent Publication No. 50-28365, wear-resistant sintered materials for refrigerator compressors include Mo, Ta, W,
A composite sintered material containing Nb metal sulfide and metal carbide is used, and although this material is a wear-resistant member with characteristics, it has the drawback of wearing out the mating material and is not suitable as a bearing material. Appropriate.

To solve this problem, the use of ceramics is being considered.

In general, SiC, 5iaN4, etc., which have excellent wear resistance, are known. Sintering techniques include normal pressure sintering, pressure sintering, and 9-reaction sintering. Among these, the pressureless sintering method and the pressure sintering method have a dimensional change rate of 15 to 20% during sintering, have poor deformation and dimensional accuracy, and require advanced technology. This large rate of dimensional change during sintering requires time and cost for processing after sintering, which is one of the reasons why engineering ceramics are difficult to become popular. On the other hand, it is known that the one-reaction sintering method has a smaller dimensional change rate during sintering than other materials, but as shown in JP-A-58-140375, nitride of metal Si powder However, the conductivity is not disclosed.

In addition, 5iaN+ binder, which has been conventionally used for refractories, is a material that is predicted to have a small dimensional change during sintering, but as disclosed in JP-A-58-88169, the conductivity is Not disclosed, mechanical strength 5
It has only about 0 MPa and is unsuitable for use as a structural material.

On the other hand, there is a strong demand for the development of conductive ceramics that are useful as heat-resistant heater materials and conductive materials.

If we can obtain ceramics with low electrical resistivity.

It is expected to improve the performance of current products and develop new uses for ceramics. Conventional conductive ceramics include, for example, Si
The above problem is solved by mixing C or 5iaN+ with a conductive compound and hot press sintering.

However, the hot press method requires a huge amount of energy for sintering, so there is a problem in that the manufacturing cost is high.

Furthermore, as disclosed in JP-A No. 60-60983, conductive ceramics are obtained by mixing 5isNa with a conductive compound and performing pressureless sintering, which is more energetically effective than the hot pressing method. Due to the use of a sintering aid, the dimensional change rate during sintering is 15 to 18%, resulting in problems such as deformation.

However, so far no study has been conducted on a latent member using low-resistance ceramics.

[Problem to be solved by the invention]

As mentioned above, conventional materials include seal materials, bearing materials,
When applied as a base material, cylinder material, crankshaft material, or actuator material, there is a problem that the material inevitably wears out the other material.

An object of the present invention is to provide a porous ceramic material that has excellent electrical conductivity as a seal material, bearing material, vane material, cylinder material, crankshaft material, and actuator material in the absence of lubrication and in lubrication.

The object of the present invention is to provide a sealing member and a bearing using porous conductive ceramics having a porosity of 5 to 30%.

The purpose of the present invention is to provide vane materials, cylinder materials, crankshaft materials, actuator materials, and various devices with excellent wear resistance, corrosion resistance, electrical conductivity, and high-speed operability for guide rails.

[Means to solve the problem]

For the above purpose, the metal powder belongs to groups III to VIII of the periodic table, in particular Ti, Zr, V, Nb and Ta.

Cr, Ce, Co, Mn, Hf, W, Mo, Fe.

Pr, Nd, Sm, Eu, Gd, Tb, Dy.

It is composed of at least one of Ho, Yb, Lu, Th, Co, and Ni, and for example, Ti nitride has a small electrical resistivity of about 10-5Ω order, and a porous sintered body with low resistance can be obtained. , oil in this qi/hole.

A sliding member with excellent wear resistance can be achieved by impregnating it with at least one of solid lubricant, grease, and resin.

In the present invention, the reason why the metal nitride produced from the metal Si powder is set to 50 vOQ% or less is that if the amount exceeds 50 voQ%, the resistivity becomes greater than 10 -3 Ω.

In addition, in the present invention, it is preferable that the content of the inorganic compound bonded with metal nitride is 70voQ% or less, 70voQ% or less.
This is because when it exceeds f1%, the amount of metal nitride as a binder decreases, resulting in a decrease in mechanical strength.

In the present invention, the inorganic compound is SiC with high hardness,
It is preferable to use at least one of TiN, TiC, ZrN, and ZrC. In addition, the average particle size of the inorganic compound is 0.5
It is preferable to set it to 100 micrometers. Because 0
．． This is because if it is smaller than 5 μm, the inorganic compound will easily fall off. Moreover, if the diameter is larger than 100 μm, particles tend to fall off, which may cause contamination. Especially 2 to 2
When it is 0 μm, it is effective in supporting the mating material and is optimal for preventing particles from falling off. Further, whiskers or long fibers may be used as the inorganic compound. The whiskers preferably have an average aspect ratio of 200 or less and an average length of 200 μm or less. Furthermore, by orienting the long fibers, it is possible to impart directionality to the electrical properties.

In the present invention, the porosity is preferably 30% or less. This is because when the porosity exceeds 30%, the strength decreases. The pores mainly consist of open pores. because,
In order to sinter a molded body made of metal powder in a nitriding gas atmosphere and obtain a sintered body by reacting with the nitriding gas and converting it into nitride, the nitriding gas must pass through the molded body. This is because it requires a ventilation hole to pass through. By sintering in this case.

Depending on the type of metal powder, metal powders may react with each other, but there is no problem in terms of characteristics. for example.

TiA(1, TiAfla, TiSi, ZrAQ, etc.) may be partially generated.

The compact is preferably heated for a long time at a temperature below the melting point of the metal powder in a nitriding gas atmosphere containing nitrogen and/or ammonia and optionally hydrogen, argon, helium, etc., and then heated at a high temperature.

In the present invention, the molding binder contains an appropriate amount of an organic polymer compound such as polyvinyl butyral or polyethylene, or an organic Si polymer compound such as a silicon imide compound or a polysilane compound, preferably 8 to 15 parts by weight. It is preferable that the particle volume filling rate is 65% or more.

The molding method is selected depending on the shape and required characteristics, such as injection molding, press molding, rubber press molding, extrusion molding, doctor blade method, mold powder molding, etc.

As the metal powder, commercially available products can be used as they are, or rounded particles or granulated powder pulverized by a mill or the like may be used.

The porous conductive ceramic in the present invention can also be subjected to electrical discharge machining.

In the present invention, it is preferable that the compound formed from the metal powder has a nitrided homogeneous phase center, because when sintered in an oxidizing gas, an oxide phase grows and the electrical resistivity increases.

In the present invention, by setting the electrical resistivity to 10 -8 Ω0 or less, particularly 10''4a11 or less, it is possible to provide antistatic, heater, and electric circuit functions.

Here, the oil with a viscosity of 400 centipoise or more contains graphite, molybdenum disulfide, tungsten disulfide, titanium disulfide, BN, fluorine resin, tetra disulfide, lulu, selenium disulfide, barium hydroxide, and iron chloride.

Silver iodide, talc, borax, kaolin, lead oxide.

Vermulite, paraffin wax, stearic acid,
It is also possible to use a lubricant mixed with at least one solid lubricant such as Fe-Mn lead phosphate.

This is because when using an oil unit, there is a possibility of running out of oil during long-term use under high temperature conditions, but a mixture of oil and solid lubricant eliminates this concern and is superior in reliability and durability. be.

In the present invention, when a porous conductive ceramic having a porosity of 5 to 30% is impregnated with a lubricant, an extremely excellent wear-resistant member can be obtained. However, it has been confirmed that when the porosity exceeds 30%, the amount of wear increases rapidly. Moreover, it has been confirmed that, conversely, when the porosity is less than 5%, the amount of wear increases. The reason for this is that by having an appropriate amount of pores, the pores provide an oil retaining effect.

Since an oil film is formed, galling does not occur due to the lubrication effect,
This is because it has excellent wear resistance. When the porosity exceeds 30%, the amount of wear increases because the mechanical strength between particles decreases. Therefore, in the present invention, the porosity is 5 to 30.
% of pores, a sliding member with excellent wear resistance and conductivity can be obtained.

[Effect]

In the present invention, by using porous reactive sintered conductive ceramics for the sliding member, wear resistance can be significantly improved and conductivity can be imparted. For this reason, various mechanical parts such as seals, bearings, and vanes.

cylinder, crankshaft, actuator.

It can be used for guide rails and gears, allowing for improved equipment quality and faster operation.

〔Example〕

Example 1 Polyethylene wax and synthetic wax were used as a molding binder on Ti metal powder with an average particle size of 4 μm.

4 parts by weight of an organic binder such as stearic acid was added and kneaded in a pressure kneader at 160° C. for 5 hours.6 Then, the kneaded product was crushed and used as a test material. These raw materials were heated to 150°C using a mechanical press.

It was molded in a cylinder-shaped mold under conditions of 1000 kg/aJ. This molding was performed at 3'C/h in an argon atmosphere.
After heating to 500°C at a temperature increase rate of
'Obtained a cylinder of Bei. Dimensional change rate during sintering is 1.5
%Met. A bearing was manufactured in the same manner. The pores of each of the above members were impregnated with fluorine oil.

Then, it is installed in the actual 1) P rotary compressor, with a rotation speed of 12,000 rpm *discharge pressure of 30 kgf/d,
An actual machine test was conducted for 1000 hours of continuous operation at a suction pressure of 5 kgf/aJ. After the test was completed, the compressor was disassembled and the amount of wear on each member was measured. Bearing steel was similarly tested for comparison.

The results are shown in Table 1, which confirms that the product of the present invention has superior wear resistance compared to conventional materials.

It has been confirmed that similar effects can be obtained by impregnating solid lubricants, fluororesin, grease, etc. in place of the above parts.

Example 2 80 parts by weight of metal Cr powder with an average particle size of 7 μm and an average particle size of 1
After mixing 20 parts by weight of 6 μm SiC powder with methanol in a bot mill and drying it, 9 parts by weight of polyethylene wax was added, and the mixture was mixed at 150°C using a pressure kneader.
Kneaded for hours. Then, the mixture was ground, heated at 150°C for 10
It was molded into a guide rail shape under conditions of 0100O/aJ (7). - After removing the wax content of the molded product, it is heat-treated stepwise to 1340'C in nitrogen gas over a long period of time.
An iaNa bonded SiC ceramic was obtained. At this time, the dimensional change rate from the molded body to the sintered body was as small as 0.12%, and a product with excellent dimensional accuracy was obtained. The porosity of the sintered body is 18%
, the pore diameter was 20 μm or less, and the electrical resistivity was 3×10 1 Ω0.

The sliding surface of the first surface was ground with a grindstone, and the surface roughness of the sliding surface was set to 0.1 μm as a ten-point average roughness. In order to evaluate the impregnation of fluorine oil with a viscosity of 400 centipoise in an autoclave, a test was conducted by incorporating it into a magnetic disk device. 5US440C was used for the bearing. The test conditions are
The magnetic head was reciprocated 10% of the time at a maximum speed of 1.4 m/s and a frequency of 60 Hz. The surface roughness of the sliding surface after the test was 0.1 μm in ten-point average roughness, and it was confirmed that it did not change from before sliding. Also, the difference in level between the sliding part and the non-sliding part is 0.0.
It was confirmed that the diameter was as small as 1 μm or less.

From this, it was found that the product of the present invention has excellent lubricant retention and therefore has excellent wear resistance and is suitable for actuators.

Examples 3 to 10 In the same manner as in Example 2, molded bodies with an outer diameter of 30 m, an inner diameter of 20 rm, and a thickness of 10 mm were molded and sintered by changing Ilj and the amount of shape binder. Table 2 shows the results of a test using a Matsubara abrasion tester using A Q zos as a mating material.

The sliding conditions were a surface pressure of 10 kgf/ad and a sliding speed of 1 m/m.
sec. The pores are impregnated with fluororesin.

From this, it can be seen that when the porosity exceeds 30%, the amount of wear increases rapidly, and the product of the present invention has excellent sliding properties.

Example 11 TiN bonded TiN ceramics manufactured from 50 wt% Ti powder and 50 wt% TiN powder (thermal expansion coefficient 7.2
2 x 10-'℃''''l, porosity 25%.

Density 4.1 g/al, electrical resistivity 4 x 10-'Ω
A print head bearing was manufactured using 0). The wear resistance (printing number: 109 times) was compared with a conventional tool steel bearing and a case using dense 5iaN4 with a porosity of 1%.

Tungsten was used for the wire.

As a result of a wear resistance test, it was found that the tungsten wire and bearing had extremely excellent wear resistance, with the amount of wear after recovery of 10" printing being less than 1 μm.

In contrast, tool steel bearings and dense 5is bearings with a porosity of 1%
It was found that Na had a large wear amount of 10 μm or more.The product of the present invention was good because no wear occurred because the oil impregnated in the pores provided a lubricating effect.

This greatly improved reliability. A similar effect can be obtained by impregnating with solid lubricant, fluororesin, or grease instead of oil.

(Effect of the invention) A bearing made of the porous conductive ceramic of the present invention.

By configuring the vane, cylinder, crankshaft, and guide rail, it has unprecedented wear resistance.

Claims (1)

[Claims] 1. Consisting of conductive reactive sintered ceramics with a porosity of 5 to 30%, in which conductive metal nitrides containing metal elements belonging to groups III to VIII of the periodic table are chemically bonded to each other. A porous conductive ceramic sliding part characterized by: 2, Ti, Zr, V, Nb, Ta, Cr, Ce, Co,
Mn, Hf, W, Mo, Fe, Al, Si, Pr, Nd
, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Lu,
At least one metal nitride of Th, Co, and Ni is chemically bonded to each other, and the content of Si nitride is 50 vol.
A porous conductive ceramic sliding component, characterized in that it is made of a conductive reactive sintered ceramic having a porosity of 1% or less and a porosity of 5 to 30%. 3. Conductive metal nitrides belonging to groups III to VIII of the periodic table, especially Ti, Zr, V, Nb, Ta, Cr, Ce, C
o, Mn, Hf, W, Mo, Fe, Al, Si, Pr,
Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, L
A molded body made of metal powder of at least one of u, Th, Co, and Ni is heated in a nitriding gas atmosphere to create a porosity of 5 to 30%, which is chemically bonded to each other by nitrides mainly generated from the metal powder. A porous sintered body comprising a conductive reactive sintered ceramic in which the content of Si in the molded body is 50 vol% or less in terms of nitride in the sintered body. Conductive ceramic sliding parts. 4, Ti, Zr, V, Nb, Ta, Cr, Ce, Co,
Mn, Hf, W, Mo, Fe, Pr, Nd, Sm, Eu
, Gd, Tb, Dy, Ho, Yb, Lu, Th, Co,
A conductive material made of a reaction sintered body in which at least one metal nitride of Ni and an inorganic compound consisting of at least one of carbides, nitrides, oxynitrides, oxides, silicides, and borides are chemically bonded to each other. A porous conductive ceramic sliding part characterized by being made of conductive ceramic. 5. The porous conductive ceramic sliding component according to any one of claims 1 to 4, wherein the sintered body has an electrical resistivity of 10^-^3 Ωcm or less. 6. The sintered body according to any one of claims 1 to 4 is a porous conductive body characterized in that the porous ceramic is impregnated with at least one of a solid lubricant, oil, grease, and resin. Ceramic sliding parts. 7. A seal, a bearing, a vane, a cylinder, a crankshaft, an actuator, a guide rail, and a gear, each comprising a porous conductive ceramic sliding component according to any one of claims 1 to 6.