JPH01320255A - Production of ceramic-bn based composite material - Google Patents

Abstract

PURPOSE:To obtain the title composite material having excellent sliding characteristic and worked surface precision by preforming a mixture of a BN precursor, wherein the interfacial spacing by X-ray diffraction and size of the crystallite are specified, and ceramic grains in a specified ratio, and then calcining the preform under pressure. CONSTITUTION:A mixture of 50-50wt.% BN precursor, wherein the BN (002) interfacial spacing by X-ray diffraction is controlled to 2.15-2.40Angstrom and the size of the crystallite to 50-2,000Angstrom , and 95-50wt.% ceramic grains is prepared. The mixture is preformed, and the preform is then calcined at 10-120MPa pressure to obtain the composite material. When <50wt.% ceramic is used in the material, the heat resistance, high strength, and high-hardness characteristic inherent in the ceramic can be hardly developed, and the effect of the mixed BN is not fully exhibited at >96% ceramic. When the interfacial spacing and size of the BN precursor are respectively higher than the upper limit and lower than the lower limit, crystallization by calcination is not sufficient, and the sliding property, workability, etc., due to mixing is not improved. When the interfacial spacing and size of the crystallite are respectively lower than the lower limit and higher than the upper limit, the grains of both components are not uniformly mixed, the kind of the composite ceramic is restricted, and the strength of the calcined body and the worked surface precision are deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a ceramic-IIN composite material that has excellent sliding properties, wear resistance, and processability.

[Conventional technology and issues to be solved] Ceramics have excellent heat resistance and corrosion resistance, high hardness,
Due to its high strength, it is widely used as a corrosion-resistant and wear-resistant +4 material for slurry transport pipe linings, mechanical seals, etc. However, the ball of the bearing, retainer-1
When used as a magnetic head base material, a precision sliding material such as a slider, or an engine component, it has not been widely put into practical use because of its large friction coefficient and low machined surface accuracy.

As a means to solve this problem, Japanese Patent Application Laid-Open No. 61-281086
``Method of impregnating a porous ceramic body with fluorine oil'' is disclosed in Japanese Patent Publication No. 1986-251586, and ``Method of impregnating a porous ceramic body with resin'', but both of them disclose ceramics-a mobile composite. system, cannot exhibit the excellent heat resistance of ceramics. In addition, since the porous ceramic body is simply impregnated with some material, the strength, hardness,
Machining surface accuracy is insufficient.

Further, JP-A-61-51614 discloses a method for sintering a mixture of rZrO3 and carbon, but since the composite component is carbon, the heat resistance is insufficient.

Also, JP-A-62-56376 and JP-A No. 62-563
Publication No. 77 discloses a "method for manufacturing a composite sintered body," but it involves molding and firing a mixture of aluminum nitride powder and BN powder, and since crystallized BN powder is used, the types of ceramics are limited. Moreover, the degree of dispersion is poor, and the machined surface accuracy of the fired body is low.

On the other hand, various magnetic media devices are currently on the market for recording and reproducing using flexible disks, hard disks, or magnetic tapes that have a magnetic layer coated on the surface or a thin magnetic layer formed on the surface. Development is currently underway. These recording and reproducing devices use many parts that are in sliding contact with the magnetic medium either permanently or temporarily. These parts must have excellent durability and must not damage the recording medium with which they come into relative sliding contact.

In particular, there is a strong trend toward higher speeds and higher densities, and stricter restrictions are being imposed on parts that come into sliding contact with the media, creating a need for materials that can replace conventional ceramics.

[Means for Solving the Problems] As a result of intensive research to solve the above-mentioned problems, the inventors of the present invention have found that they have excellent sliding properties and workability, and have the strength and hardness inherent to the iron material. We have completed a method for manufacturing a ceramic-BN composite material that can sufficiently bring out the following.

That is, the present invention is characterized in that a specific BN precursor is used as a BN source in the method for producing a ceramic-BN composite material. The BN precursor used here has a BN (002) plane spacing of 2.15 to 2.15 by X-ray diffraction.
In the present invention, after preforming a ceramic-BN precursor composition containing 5 to 50 wt% of this in the ceramic composition before firing, The present invention relates to a method for producing a ceramic-BN composite material, which is characterized by firing under a pressure of 10 to 120 MPa, preferably 20 to 100 MPa. The (OO2) interplanar spacing and crystallite size referred to in the present invention are determined from the 2θ value and half-width determined by the half-width midpoint method of the CuKα diffraction peak by X-ray diffraction, and are calculated using Bragg's equation and Scherrer equation, respectively. It is calculated from the formula.

The ceramic particles used in the present invention are preferably A(ho3, ZrCL, 'ri(L, MgO).

Oxides such as SrO, NiONlol; 5iC1Ti
C.

Carbide such as W C1B 4 Cs Z r C; 5i
aN*, A12N.

Nitride such as 'riN, ZrN; ZrBt, CrB, Ti
Examples include one or more borides selected from borides such as B2. Also, solid solutions of these compounds may be used. The purity of these powders is preferably 90 wt % or more as a ceramic component, and the particle size is preferably 0.05 to 5.00 μm. If the purity is less than 90 wt%, the characteristics of ceramics such as heat resistance and high hardness will not be exhibited. If the particle size is below the above range, the powder will form aggregates and will not form a uniform composite structure, and if it is above the above range, the sinterability will be poor, the strength will be low, and the density will not be high. The amount of ceramic particles used is preferably 50 to 95 wt%. If it is less than 50%, it is difficult to exhibit the heat resistance, high strength, and high hardness properties of ceramics, and if it is more than 96wt%, the composite effect of the BN composite is not sufficient.

The BN precursor used in the present invention has an X-ray diffraction ratio of 7>l3
Since the N(7)(002) plane spacing is in the range of 2.15 to 2.40 crystallites, it is necessary that the crystallite size is 50 to 2000 crystallites. Preferably, the BN precursor contains B, 0. The content is 5wL% or less. When the (002) plane spacing by X-ray diffraction of B N plane carrier exceeds 2.40 or the crystallite size is 5
If the number is insufficient, it becomes difficult to crystallize by firing, and properties such as sliding properties and workability cannot be improved by compounding.

(OO2) When the interplanar spacing is less than 2.15 particles or the crystallite size exceeds 2000 particles, it becomes difficult to mix BN particles and ceramic particles uniformly, and the types of ceramics to be composited are limited. , the strength and machined surface accuracy of the fired body will be inferior. The B,03 component in the BN precursor is 5
If it is more than wt%, the B, 03 component remains in the fired body,
Strength, workability, and sliding properties may be inferior.

Although the BN metahedron according to the present invention has insufficiently developed BN crystals and small crystallites, it has excellent activity and
- It has good compatibility and dispersibility with ceramics for boat fishing, and easily crystallizes into BN at the firing temperature of the ceramics used.

Specifically, the synthesis method of such a 13N precursor is a conventionally known synthesis method, for example, using boric acid, boron oxide, ammonium borate, etc. as a boric acid source, and using urea, melamine, non-andiamide, etc. It can be obtained by a nitridation reduction method using a nitrogen-containing organic substance, a method of decomposing diborane, a CVD method, etc., but the reduction nitridation method is industrially preferred. In these methods, it is necessary to select specific conditions in order to satisfy the above-mentioned [3N surface precursor condition.

The amount of the BN precursor used in the present invention is preferably 5 to 50 vt%. If it is less than 5wt%, the composite effect of the BN composite may be insufficient as described above, and if it is more than 50w (5wt%), the high strength and high hardness characteristics inherent to ceramics will not be expressed.

The method for manufacturing the ceramic-BN composite material of the present invention includes:
After mixing the above-described limited ceramic particles and the BN precursor, preliminary molding is performed by die pressing, cast molding, injection molding, or the like. If necessary, after degreasing, the preform is inserted into a hot die, a glass capsule, a metal capsule, etc., and heated to 10 to 120 MPa, preferably 20 to 1000
At a pressure of MPa and at a firing temperature of the ceramic,
Obtained by firing in a non-oxidizing atmosphere.

Generally, a pot press is used for hot dies, and an ITP (hot isostatic press) is used for capsules. The atmospheric gas may be Ar,
I-[c, N2, Co, etc. may be used alone or in combination of two or more.

[Example] Next, the characteristics of the ceramic-BN composite material obtained by the present invention will be described in detail in Examples.

Examples 1-10 and Comparative Examples 1-6 Examples 1-10 were prepared using ceramic particles shown in Table 1 and B
The N1iii precursor was wet mixed in ethanol, dried, preformed in a full-size press, and then hot pressed at a pressure of 10 to 60 MPa in a predetermined atmosphere and temperature.

Comparative Example 1 was baked at a predetermined temperature in a vacuum without pressure. Comparative Examples 2 to 6 were fired under the same conditions as the Examples.

The strength etc. of the above composite material were measured and are shown in Table 1. Bending strength is based on J[5I604R, hardness is measured using a Vickers hardness tester at a load of IOKgf, friction coefficient,
The amount of wear was determined by the pin-on-disk method, using a load of 9 f on 3, selecting the ceramic single sintered body as the mating material, and measuring 300.
The rotation speed was measured in rpm. The machined surface accuracy is determined by grinding with a surface grinder to Rmax = 120s, then using a polishing machine.
After lapping with 3 μm diamond paste and polishing with 1 μm diamond paste, the surface roughness was measured using a radar type non-contact surface roughness meter.

When the composite material of Example 1 was applied to a mechanical seal, it showed better sealing performance and long-term durability compared to conventional materials.

When the composite material of Example 4 was precisely machined into a rolling bearing retainer and used, it showed long-term durability without lubrication.

When the composite material of Example 5 was used as a twisted ring, it exhibited a lower coefficient of friction and higher durability than conventional materials.

When the composite material of Example 7 was used as a magnetic helad stabilizer, it showed long-term durability without lubrication.

When the composite material of Example IO was applied to a wire drawing die for steel wire, the steel wire did not seize and exhibited long-term durability.

Furthermore, by using parts using the present invention in various contact parts that come into sliding contact with the above-mentioned magnetic medium, the sliding characteristics with the medium can be improved, and the friction coefficient is small and the medium will not be damaged.
It was possible to provide stable recording and reproducing characteristics over a long period of time.

[Effects of the Invention] As described above, the ceramic-BN composite material prepared according to the present invention does not have the inherent strength and hardness of ceramics because the species, composite ratio, and firing conditions of the ceramic and BN precursor are limited. It is a material with excellent sliding properties and machined surface accuracy while maintaining the same properties. Therefore, it is an extremely suitable material for non-lubricated sliding members such as rolling bearings, mechanical seals, and magnetic head sliders. Use of the composite material of the present invention significantly improves the durability and reliability of the device, making it industrially useful.

Claims (5)

[Claims] 1. BN (002) plane spacing by X-ray diffraction is 2.15~
B with a crystallite size of 2.40 Å and 50 to 2000 Å
N precursor 5-50wt% and ceramic particles 95-5%
After preforming a mixture consisting of 0 wt%, 10 to 1
A method for producing a ceramic-BN composite material, which comprises firing under a pressure of 20 MPa. 2. Claim 1, wherein the ceramic particles are composed of particles of one or more of oxides, carbides, nitrides, and borides, and have a content of 50 to 95 wt%. A method for producing a ceramic-BN composite material. 3. In sliding parts in which the mechanical element has a movable part, contacts temporarily or permanently, and slides relative to each other, at least the sliding surface thereof is made of ceramic manufactured by the method according to claim 1. A sliding part characterized by being made of a BN-based composite material. 4. A precision machine using the sliding part according to claim 3. 5. In a magnetic media device comprising parts that are in temporary or permanent contact with a recording medium and slide relative to each other, at least the sliding surface thereof is a ceramic-BN composite material manufactured by the method according to claim 1. A sliding portion 6. A magnetic media device using the sliding component according to claim 5.