JPS5891059A - Composite ceramic sintered body and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a composite ceramic sintered body and a method for manufacturing the same, and more particularly, to a composite ceramic sintered body that is dense, has good heat dissipation, has high thermal conductivity, and high electrical insulation. The present invention relates to a ceramic sintered body and a method for manufacturing the same.

Technical background of the invention and its problems Conventionally, silicon carbide has been known to have excellent properties such as heat resistance, corrosion resistance, and wear resistance, as well as good electrical conductivity, semiconductivity, and high thermal conductivity. is widely known. Utilizing these properties, silicon carbide is used in various materials, and new applications are expected.

On the other hand, with the rapid development of the electronics industry, the integration and miniaturization of electronic circuits, etc. have progressed, and there is a need for materials with good heat dissipation and high thermal conductivity, especially for insulating circuit boards, etc. is increasing, and its development is strongly desired. Furthermore, materials having such good heat dissipation properties are expected to appear not only in the electronics industry but also in fields that require cooling of heat engines, industrial machines, and the like.

Currently, alumina (HLT Os) is widely used as a material for circuit boards, but this alumina has low thermal conductivity and has problems in terms of heat dissipation. Therefore, in order to improve the heat dissipation of the circuit board, it is necessary to mix other materials with alumina or use other materials. Such materials with better heat dissipation properties are limited to some extent by chemical bonding patterns and the like, and are therefore limited to, for example, diamond, cubic boron nitride, silicon carbide, beryllium, aluminum nitride, and the like. Among these, silicon carbide can be used as a material with a fairly high electrical resistance value in a high-purity single crystal state, or as a commonly used material, it has a low electrical resistance value and is not suitable for use in circuit boards etc. is problematic.

Therefore, such silicon carbide is currently positioned as a conductive material or a semiconductor material, as seen in applications such as heating elements.

SUMMARY OF THE INVENTION The present invention was made in such a situation, and its purpose is to provide a composite ceramic sintered body that is dense, has good heat dissipation properties, has high thermal conductivity, and has high electrical insulation properties. The object of the present invention is to provide a manufacturing method thereof.

Summary of the Invention The present inventors have completed the present invention by using silicon carbide as the main component of a ceramic sintered body.

That is, the composite ceramic sintered body of the present invention contains one or more metal oxides selected from the group consisting of calcium oxide, strontium oxide, and barium oxide.
It is characterized in that 1 to 3% of the plate is made of aluminum nitride, and the remainder is made of a composite material in which the surface of silicon carbide is coated with aluminum nitride.

In the following, the invention will be explained in more detail.

The composite ceramic sintered body of the present invention has a silicon carbide (1) surface covered with aluminum nitride (2) as shown in the drawing.
A composite coated with oxide is bonded with calcium oxide, strontium oxide, barium oxide, the metal oxide precursor, etc. as a sintering aid.

In such a sintered body, if the amount of metal oxide is less than 0.01% by weight, the effect as a sintering aid is insufficient, so densification is a must. As a sintering agent, its amount is excessive, and the amount of liquid phase generated during sintering increases, so the larger the amount, the more disadvantageous it is in terms of oversintering and heat conduction.

The composite ceramic sintered body of the present invention may further contain carbon in an amount of 10% by weight or less based on the amount of aluminum nitride. Such carbon is added for the purpose of removing oxygen present in the sintered body since aluminum nitride is easily oxidized.

Further, the composite ceramic sintered body of the present invention may further contain aluminum nitride in an amount of 100% by weight or less based on the amount of metal oxide.

Aluminum nitride has the effect of making the sintered body more dense, so by adding aluminum nitride, a sintered body with a higher sintered density can be obtained.

Next, a method for manufacturing a composite ceramic sintered body of the present invention will be explained. In this production method, one or more powders selected from the group consisting of calcium oxide powder, strontium oxide powder, barium oxide powder, and the metal oxide precursor powder are used as residual oxides of 0.01 to 3
% by weight, and the balance consists of a composite powder in which the surface of buoylene carbide is coated with aluminum nitride, and the mixed powder is molded,
It is characterized by being sintered in a non-oxidizing atmosphere.

The composite powder in which the surface of silicon carbide is coated with aluminum nitride used in the production method of the present invention is preferably one in which aluminum nitride is used in an amount of 3 to 120% by weight based on silicon carbide. The thickness of the aluminum nitride layer formed on the silicon carbide surface depends on the desired pressure resistance of the sintered body to be manufactured, and is preferably selected as appropriate. The particle size of such a composite is preferably 5μ or less, more preferably 2μ or less in order to obtain a denser sintered body.
μ or less. Further, the crystal type of silicon carbide used may be either an α-phase type or a β-phase type. Such a composite powder can be produced, for example, by a gas phase reaction method.

Further, the metal oxide powder used in the manufacturing method of the present invention has a function as a sintering aid. Among these, metal oxide precursor substances refer to substances that are converted into calcium oxide, strontium oxide, or barium oxide by calcination, such as carbonates, nitrates, acetates, etc. of calcium, strontium, or barium. can be mentioned. The finer the particle size of such a substance, the more preferable it is, for example, 1 μm or less, more preferably 0.5 μm or less.

The manufacturing method of the present invention includes a mixed powder consisting of the above-mentioned materials,
Furthermore, carbon powder or carbon precursor powder may be added in an amount of 10% by weight or less based on the amount of aluminum nitride as carbon. The carbon precursor powder refers to a substance that is converted into carbon by sintering, and examples of these include various resin-based substances. Further, aluminum nitride powder may be added in an amount of 100% by weight or less based on the amount of metal oxide.

The powder having the above composition is mixed by conventional processing methods and then subjected to a molding process. At the time of molding, for example, a binder such as paraffin may be added to improve workability, and then the molding treatment may be performed. In addition, when a binder is used, sintering is performed after degreasing. As such a molding method, for example, a tape molding method, an injection molding method, a mold molding method, etc. can be used, and by these molding methods,
The mixed powder is formed into a molded body having a predetermined shape.

This molded body is sintered in a non-oxidizing atmosphere. Examples of the non-oxidizing atmosphere include nitrogen gas, argon gas, and forming gas.

The sintering temperature is preferably 1700 to 1900°C. During sintering, aluminum nitride and a low melting point compound are generated by reciprocal reaction within the metal oxide amount temperature range, and as a result, the viscosity of the compact is reduced, and liquid phase sintering creates a dense, highly insulating, and highly thermally conductive compound. A sintered body having properties is obtained.

Other sintering methods that can be used include the H,IP (high temperature isostatic pressing) method and the hot press method, but it is preferable to use them as appropriate in consideration of economical efficiency and the like.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Aluminum nitride coated silicon carbide powder with a particle size of 1.2μ (
Silicon carbide aluminum dinitride - 1: (1,4 (weight ratio)) 10II powder consisting of 98 heavy phase parts and 2 parts by weight of calcium carbonate powder was prepared, and this was milled in a ball mill to 2 parts by weight.
Mixed for 4 hours. Next, 8g of paraffin was added as a binder to this mixture, and 500kg was molded using a molding method.
A pressure of /7 was applied to create a molded body measuring 37 x 37 x 10 m+5. After degreasing this molded body by heating it to 700°C in a nitrogen stream, it was heated to 180°C in a nitrogen atmosphere.
Sintering treatment was performed at 0°C for 2 hours.

When the electrical resistance value of the sintered body was measured at t7, it was found to be 1011Ωα, and
When we measured the thermal conductivity, which is a measure of heat dissipation, it was 0.3.
2 kr, m/Cm・℃・sec? c Tokai il? l satt'fc.

Examples 2 to 5 The same operations as those shown in the table were carried out in Example 1, except that the metal oxide or its precursor was replaced with another material, or aluminum nitride was added. Composite ceramic sintered bodies having the compositions of four yuzu types were each subjected to sintering treatment according to the regulations shown in the table.

The sintered density, thermal conductivity, and electrical resistance values of the obtained sintered bodies were measured. The results are also shown in the table.

Among the above examples, regarding the sintered body of Example 2, further:
When subjected to HIP treatment at 1750°C and 2000 atm for 2 hours, the sintered density was 3.26 g / cc.
It was confirmed that it rose to

Effects of the Invention As is clear from the above examples, the composite ceramic sintered body obtained by the manufacturing method of the present invention is dense with a high sintered density, and has excellent thermal conductivity and electrical insulation. It was ruled out that it was a thing.

[Brief explanation of the drawing]

The drawings show silicon carbide (SiC) and aluminum nitride (AA) used in the production of the composite ceramic sintered body of the present invention.
This is a conceptual diagram of a complex consisting of N. (1) -S iC1(2'l -AIN.

Claims (1)

[Claims] 1. 0.01 to 3% by weight of one or more metal oxides selected from the group consisting of calcium oxide, strontium oxide, and barium oxide, and the remainder nitriding the surface of silicon carbide. A composite ceramic sintered body characterized by being made of a composite coated with aluminum. 2. The composite ceramic sintered body according to claim 1, wherein the composite body contains 3 to 120% by weight of aluminum nitride based on silicon carbide. 3. The composite ceramic sintered body according to claim 1 or 2, further containing carbon in an amount of 10% by weight or less based on the amount of aluminum nitride. 4. Furthermore, add aluminum nitride to 1% of the amount of metal oxide.
The composite ceramic sintered body according to any one of claims 1 to 3, containing the composite ceramic sintered body in an amount of 00% by weight or less. 5. Calcium oxide powder, strontium oxide powder,
One or more powders selected from the group consisting of barium oxide powder and the metal oxide precursor powder are used as a metal oxide (1,01 to 3%, and the remainder is on the surface of silicon carbide. A method for producing a composite ceramic sintered body, characterized in that a mixed powder consisting of a composite powder coated with aluminum nitride is molded and sintered in a non-oxidizing π atmosphere.6 As the composite powder, silicon carbide is used. 7. The method for producing a composite ceramic sintered body according to claim 5, which uses aluminum nitride coated in an amount of 3 to 120% by weight. 7. The mixed powder is further coated with carbon powder or carbon n11. The precursor powder is 10% carbon based on the amount of aluminum nitride.
A method for producing a composite ceramic sintered body according to claim 5 or 6, wherein the following are added. 8. Composite ceramic sintering according to any one of claims 5 to 7, wherein aluminum nitride powder is further added to the mixed powder in an amount of 100% or less based on the metal oxide k. How the body is manufactured. 9. The method for producing a composite ceramic sintered body according to any one of claims 5 to 8, wherein the sintering is performed at a temperature of 1700 to 1900°C.