JPH06199571A - Wear resistant ceramic material and its production - Google Patents

Abstract

PURPOSE:To obtain a ceramic material very excellent in wear resistance without using a high temp. and high pressure device by adding diamond powder or granules to part or all of a carbon source blended with reaction-sinterable silicon carbide. CONSTITUTION:A carbon source such as graphite, carbon black or a carbonizable org. compd. is blended with silicon carbide powder or granules to prepare starting material. Diamond powder or granules are then added to part or all of the carbon source and the starting material is heated in vacuum or in a nonoxidizing atmosphere without using a high temp. and high pressure device. Molten silicon is allowed to penetrate into the starting material and brought into a reaction with the carbon source in the starting material and bonding is carried out with newly formed silicon carbide to obtain the objective wear resistant ceramic material having <=1x10<-8>mm<2>/kg specific wear loss measured by a pin-on-disk method using a resin bonded diamond disk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a block gauge, a measuring portion of various measuring instruments, a magnetic disk reading portion, a dry sliding member such as a printer driving portion, a bearing to which a relatively high load is applied such as a bearing and a mechanical seal. The present invention relates to a wear-resistant ceramic material used for a member such as a dynamic member that requires dimensional stability and wear resistance, and a manufacturing method thereof.

[0002]

2. Description of the Related Art So-called engineering ceramic materials such as alumina, silicon carbide, silicon nitride and zirconia are used for structural members which are required to have wear resistance and dimensional stability.

As a typical example of an ultra-hard wear-resistant material, an iron-group metal such as cobalt is mixed with diamond powder, and silicon is used when heat resistance is required. Usually 5-6 GPa, 1400-1550
(° C.) In the stable region of diamonds, there is a cutting edge for cutting a diamond tool manufactured as a diamond sintered body by forming bonds between diamonds, and diamond compax used for diamond bits.

[0004]

Among these wear resistant members, the material having the best wear resistance can be a member containing diamond such as a diamond sintered body. However, these diamond sintered bodies are
It is necessary to use a high temperature and high pressure device in order to maintain the stable condition of diamond (usually 5 to 6 GPa, 1400 to 1550 ° C.) so that the diamond does not become graphitized. When manufacturing such a product, it is necessary to further increase the manufacturing equipment, and there is a technical and cost problem.

Further, conventional ceramic materials such as alumina, silicon carbide, silicon nitride and zirconia have excellent wear resistance as compared with metal materials, but generally have poor wear resistance as compared with diamond sintered bodies. There is.

The present invention requires a high temperature and high pressure device such as a diamond sintered body in its manufacturing process while having a wear resistance close to that of a diamond sintered body, which is extremely superior to conventional engineering ceramic materials. Without
Further, the present invention provides a wear-resistant ceramic material capable of manufacturing a relatively large member, and a method for manufacturing the same.

[0007]

In order to solve the above-mentioned problems, the present inventor has made a diamond powder granule extremely partly or wholly added to a part or all of a carbon source containing a reaction-sintered silicon carbide material. The present invention has been completed by succeeding in producing a ceramic material having excellent wear resistance without requiring high pressure conditions.

The present invention will be described in detail below.

The reaction-bonded silicon carbide material means graphite, carbon black, carbonaceous organic compounds such as phenol resin, melamine resin, urea resin, etc., which serve as a carbon source when heated, and silicon carbide powder particles (others). 20 micron or less is desirable for uniform mixing with the raw material of 1.), and the mixture is heated in a vacuum or in a non-oxidizing atmosphere to infiltrate the molten silicon and react with the carbon source to newly generate silicon carbide. It is a material that is bound by being generated.

By making a part or all of the carbon source of the raw material layer capable of producing this reaction-sintered silicon carbide material into a diamond powder, in a dry sliding test after the reaction sintering as described later. It is possible to reduce the specific wear amount by an order of magnitude as compared with conventional ceramic materials.

If the diamond particles blended in the raw material layer have reacted to the center of the particles and turned into silicon carbide, there is no point in blending the diamond particles. Therefore, the conditions for remaining as diamond after the reaction sintering are selected. There is a need.

Generally, when carbon source particles such as graphite and carbon black come into contact with molten silicon to form silicon carbide on the surface, about 5 to 10 microns react from the surface. Therefore, it is necessary to mix diamond particles having a particle size of several tens of microns or more in order to prevent silicon carbide from reaching the central portion. Desirably, in order to increase the packing density of diamond particles as much as possible, the particle size should be blended so that two peaks appear in the particle size distribution at a particle size of 20 microns or more, and if it becomes 300 microns or more, it is difficult to form and the surface is rough. Therefore, 300 μm or less is preferable.

The raw material layer may be a powder layer or a molded body. In the case of a molded product, a near net shape product can be manufactured by processing it into a product shape in advance. In any case, it is preferable to use a mold whose surface material is boron nitride and which allows the product to be fitted tightly inside, because the step of removing excess silicon after reaction sintering becomes simple.

Metallic silicon powder is placed in contact with this raw material layer. It is desirable that the metallic silicon powder be surrounded by a mold whose surface material is boron nitride so as not to flow out when it is melted by heating in the next step.

It is heated as it is in a vacuum or in a non-oxidizing atmosphere (preferably 1450 to 1500 ° C.) to melt the metallic silicon powder and directly react with carbon, that is, C + Si.
→ Silicon carbide is generated by the reaction of SiC.

After cooling and removing from the furnace, the metal silicon remaining on the surface is removed, and the surface is ground as required to prepare the product into a predetermined size.

The specific wear amount by the pin-on-disc method in the dry sliding wear test is used as the evaluation standard for the wear resistance of the reaction-sintered silicon carbide material containing diamond particles according to the present invention. The specific wear amount means the volume of the worn part per unit load during sliding and per unit sliding distance. For dry type sliding wear, the sliding material is independent of the sliding speed (peripheral speed) and test load. It is of a nature determined by the combination of.

The specific wear amount was measured by the device shown in FIG. 1 at a constant time, and the weight of the pin was measured to show the stable wear except the unstable part of the initial wear. It is calculated from the slope of the amount of wear. By using resin-bonded # 600 diamond used as a grindstone material for the disk side material, it is possible to clearly evaluate the difference in wear resistance from the conventional engineering ceramics.

As a result of the measurement of the specific wear amount by the pin-on-disk method, even the pressureless sintered silicon carbide material, which is said to have good wear resistance among conventional engineering ceramics, is 10 ^-6 to 10 ^-5 mm ² / kg. In contrast to the table, the silicon carbide material containing diamond particles according to the present invention is 1
It was confirmed that the specific wear amount was 0 ^-9 mm ² / kg and the wear resistance was excellent in terms of order.

Examples of the present invention will be shown below, but the present invention is not limited to the following examples, and various modifications and changes can be made based on the technical idea of the present invention. Of course.

[0021]

EXAMPLE Two kinds of commercially available artificial diamond powders having a particle size of 88 to 105 microns and a particle size of 12 to 15 microns were blended in a particle size of 75 parts by weight and 25 parts by weight, respectively, and further used as a carbon source and a forming binder. 25 parts by weight of a novolac type phenol resin having a carbonization rate of 40% was blended. After mixing in a mortar, 1000 kg / cm ²
Molding was carried out at a molding pressure of 12 × 5 × 60 mm. 75
Vacuum degreasing and carbonization at 0 ° C for 60 minutes, 3 × 4 ×
The substrate was opened at 20 mm. Inner dimension 3 × 4 × 20m
Fit the base material exactly into the m boron nitride formwork,
In contact with the base material, 1.5 g of metal silicon powder was filled by the above method. As it was, it was heated in a vacuum furnace at 1500 ° C. for 30 minutes to melt the metallic silicon powder and cause a permeation reaction into the base material to produce a reaction sintered silicon carbide material containing diamond powder particles. cooling·
After demolding, remove excess adhered metallic silicon by grinding and remove 3 × 4
A × 20 mm theft piece was manufactured. This test piece was set in the test device of the pin-on-disk method shown in FIG. 1, and a wear test was conducted while the test load was 1.3 kg and was dry at 60 rpm, but water was flowed around to allow sliding heat to escape. The results shown in Table 1 were obtained. The average value of the three test pieces was a specific wear amount of 1.5 × 10 ⁻⁹ mm ² / kg.

[Comparative Example] On the other hand, a test piece having the same size was made of pressure-bonded sintered silicon carbide and subjected to a wear test by the pin-on-disk method under the same conditions. As shown in Table 1, three test pieces were obtained. Has an average value of 7.2 × 10 ⁻⁶ mm ² / kg,
The specific wear amount was very large as compared with the reaction sintered silicon carbide material containing the diamond powder of the present invention.

[0023]

[Table 1]

[0024]

EFFECT OF THE INVENTION According to the wear-resistant ceramic material containing diamond powder and the method for producing the same of the present invention,
Wear-resistant ceramic materials that can withstand use under high load conditions that conventional engineering ceramics cannot withstand, or wear-resistant ceramics against sliding under solid contact under the condition that no lubricant is used. The material can be manufactured and provided in a normal vacuum furnace or a non-oxidizing atmosphere furnace without requiring a high temperature and high pressure apparatus as in the case of manufacturing a conventional diamond sintered body.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an apparatus for performing a pin-on-disk method for performing a dry sliding wear test of wear resistant ceramics of the present invention.

[Explanation of symbols]

1 pin (3 x 4 x 20 mm) 2 disc (φ60 mm resin bond # 600 diamond disc) 3 pin holder 4 test load 5 rotary table

Claims (2)

[Claims] 1. In a raw material layer in which a carbon source such as graphite, carbon black, or a carbonizing organic compound that becomes a carbon source by heating is optionally mixed with silicon carbide powder, a part or all of the carbon source is diamond. Diamond that is made into powder and granules, heated in vacuum or in a non-oxidizing atmosphere, melted silicon is infiltrated into the raw material layer, and is reacted with the carbon source in the raw material layer to be bonded by newly generated silicon carbide. Pin-on-disk method (load 1 kg, dry sliding condition) using a resin-bonded diamond disk (# 600, concentration 100), which is a reaction-bonded silicon carbide material containing powder particles.
A wear-resistant ceramic material having a specific wear amount of less than 1 × 10 ⁻⁸ mm ² / kg. 2. In a raw material layer in which a carbon source such as graphite, carbon black, or a carbonizing organic compound which becomes a carbon source by heating is optionally mixed with silicon carbide powder particles, part or all of the carbon source is diamond. As powder and granules, without using high temperature and high pressure equipment (5-6 GPa, 1400-155
It was heated in a vacuum or in a non-oxidizing atmosphere (not under the stable condition of diamond of 0 ° C.) to infiltrate the melted silicon into the raw material layer and react with the carbon source in the raw material layer to newly generate. A method for producing a wear-resistant ceramic material, which comprises bonding with silicon carbide.