JPH0131473B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a thin plate-shaped ceramic sintered body, and more particularly to a method for manufacturing a high-density thin plate-shaped ceramic sintered body having a predetermined precise shape. Conventionally, it has been difficult to finish a ceramic sintered body into a predetermined precise shape, and in particular, it has been extremely difficult to manufacture a thin plate-shaped ceramic sintered body having a precise shape. In other words, as a method for forming a green body for producing a thin plate-shaped ceramic sintered body as described above, a dry pressure forming method in which raw material powder is filled into a mold and pressure formed, or a slurry casting method is applied. Tape casting methods and the like are known. However, the formed body molded by the former dry pressure molding method is likely to have defects due to non-uniform mold filling or non-uniform distribution of molding pressure.
On the other hand, formed bodies formed by the tape casting method tend to have defects due to non-uniformity of the slurry during casting or migration during drying.
Both methods have the disadvantage that the sintered body tends to warp in shape after sintering. Therefore, when manufacturing a thin plate-shaped ceramic sintered body by sintering a green body, a manufacturing method is proposed in which the green body is held between a jig and sintered, for example, in the patent application filed in 1983.
Publication No. 69276 states, ``Multiple raw ceramic sheets are piled up and heated while applying a load using a plurality of porcelain plates for loading, and the porcelain plates for loading are heated according to the degree of sintering shrinkage of the raw ceramic sheets. A method for manufacturing a ceramic sheet sintered body characterized by sequentially separating the raw sheets and firing a plurality of green sheets while reducing the load.'' is also disclosed in Japanese Patent Application No. 56-69277. A plurality of green sheets are stacked in a firing porcelain container whose inner wall surface is structured in a step-like manner, and on top of this, a plurality of load-bearing porcelain plates of different dimensions are stacked in a reverse step-like manner. Then, the raw sheet is fired, and the loading porcelain plates are sequentially separated at the steps of the inner wall surface of the porcelain container for firing according to the degree of sintering shrinkage of the raw sheet during firing, and the load applied to the sheet is reduced. A method for manufacturing a ceramic sheet sintered body characterized by reducing the amount of sintered ceramic sheet. However, according to the above-mentioned method, depending on the material of the formed body, the jig used for holding the formed body may seize during sintering, resulting in the production of a thin plate-like sintered body having the desired precise shape. I couldn't do it. An object of the present invention is to provide a method that eliminates and improves the above-mentioned drawbacks of the conventional method of manufacturing a sintered body having a predetermined shape by holding a formed body between jigs and sintering it. According to Si, B, Al, W,
By holding a thin plate-shaped ceramic formed body containing as a main component ceramic fine powder made of at least one type of carbide selected from Ti, Ta, and Zn with a jig, and performing pressureless sintering. In a method for producing a thin plate-shaped ceramic sintered body, the formed body is constantly held between a jig and a buffer layer made of at least one of carbonaceous powder or carbonaceous fiber as a main component. The above object can be achieved by a method for manufacturing a thin plate-shaped ceramic sintered body, which is characterized by obtaining a thin plate-shaped ceramic sintered body which is uniformly shrunk by firing by pressure sintering. Next, the present invention will be explained in detail. According to the present invention, the thin plate-like formed body is held between the jigs via the buffer layer. The reason why the thin plate-like formed body is held between the jig and the buffer layer is that the formed body can be held uniformly to the extent that no deformation occurs during sintering, and the jig and the sintered body are This is because it is possible to prevent sticking and inhibition of shrinkage due to sintering, and to produce a thin plate-shaped ceramic sintered body having a predetermined shape and uniformly shrinking during firing. The thin plate ceramic production form of the present invention is:
The main component is ceramic fine powder made of at least one carbide selected from Si, B, Al, W, Ti, Ta, and Zr. The layer is composed mainly of at least one of carbonaceous powder and carbonaceous fiber. As the carbonaceous powder, for example, finely pulverized various types of coke, natural graphite, artificial graphite, calcined anthracite, etc., or carbon black such as contact black, furnace black, thermal black, lamp black, acetylene black, etc. can be used. Further, as the carbon fiber, for example, carbon fiber cut into short fibers, or paper, cloth, etc. made of carbon fiber can be used. In addition, when using the carbonaceous powder or carbon fiber cut into short fibers, the carbonaceous powder or carbon fiber cut into short fibers is added to the dispersion medium, and if necessary, It is advantageous to apply a uniformly dispersed suspension containing a binder and a dispersant to a jig. Moreover, paper, cloth, etc. with as little ash content as possible can also be used as the buffer layer. Furthermore, even better results can be obtained by applying the suspension to the paper or cloth to form a buffer layer. According to the present invention, the thickness of the buffer layer is 1 to
It is preferably within the range of 500 μm. The reason for this is that if the thickness is thinner than 1 μm, the buffering effect cannot be sufficiently exerted;
This is because if it is thicker than 500 μm, the volume occupied by the buffer layer will be large and productivity will not only deteriorate, but also the clamping effect of the buffer layer will tend to be uneven and small warps will easily occur. According to the present invention, the thickness of the thin plate-shaped ceramic sintered body is preferably 2 mm or less. The reason for this is that when the thickness is greater than 2 mm, defects such as warpage will hardly occur in the sintered body, and a sintered body with a predetermined shape can be easily obtained using a normal sintering method. It is. According to the present invention, when sintering the thin plate-like formed body mainly composed of fine ceramic powder made of carbonaceous material, it is preferable that the jig is a carbonaceous rigid body having a predetermined shape. According to the present invention, a thin plate-shaped ceramic sintered body having a predetermined shape can be suitably produced by sintering a thin plate-shaped green body mainly composed of fine ceramic powder made of carbonaceous material as described above. However, it can be advantageously applied when producing a thin plate-shaped silicon carbide sintered body mainly composed of silicon carbide fine powder. Next, the present invention will be explained with reference to examples. Example 1 97.3% by weight consists of β type crystals, contains 0.32% by weight free carbon, 0.21% by weight oxygen, 17.3m ² /
Benzene was added to a mixture of ⁵⁰⁰ g of silicon carbide fine powder having a specific surface area ^of 750ml,
3.5 g of polyethylene glycol was added and the slurry was spray dried after mixing for 10 hours using a ball mill. An appropriate amount of this dry powder was collected, and a molded product with a thickness of 60 μm was obtained using a metal press at a pressure of 1.8 t/cm ² . Next, the formed body was held and sintered in the form shown in FIG. 1 using a jig coated with a buffer layer of carbon black having a thickness of approximately 50 μm. Among the jigs, a thin graphite plate with a thickness of 2 mm is used as the jig inserted between the formed bodies,
The carbon black has an average particle size of 210 Å,
A thermal black with a specific surface area of 123 m ² /g was used. A Tammann type kiln was used as the kiln, and sintering was carried out at a maximum temperature of 2100°C for 30 minutes in an argon gas stream. All of the obtained sintered bodies had extremely excellent flatness, and almost no sintering occurred between the sintered bodies and the jig. Comparative Example 1 Sintering was performed using the same jig as in Example 1, but with no buffer layer formed. Most of the sintered body was attached to the jig, and it was extremely difficult to separate it. Example 2, Comparative Example 2 Sintered bodies were obtained in the same manner as in Example 1, except that the thickness of the carbon black layer serving as the buffer layer was varied as shown in Table 1. The results are shown in Table 1. The degree of warpage was determined by visual inspection. In all Examples, sintered bodies with excellent flatness could be stably obtained. When the buffer layer of Comparative Example 2 was thick, warpage that could be visually discerned was observed.

[Table] Example 3 Same as Example 1, but a material as shown in Table 2 was inserted as a buffer layer between the green body and the jig, and the green body was held between them to obtain a sintered body. . The results are shown in Table 2 by visual judgment of the warping condition in the same manner as in Example 2. Also, almost no burning occurred between the sintered body and the jig.

[Table] Example 4 A slip prepared by mixing appropriate amounts of polyvinyl butyral, polyethylene glycol, and ethyl alcohol with the same mixture as in Example 1 was molded using the doctor blade method to obtain a formed product with a thickness of 150 μm. Ta. The green body was placed in a degreasing furnace, and the temperature was raised from room temperature to 400°C at a rate of 15°C/hr in an argon gas stream to perform a degreasing treatment to obtain a defatted body. Next, a jig having a carbon black layer similar to that used in Example 1 and Example 3 were prepared.
A sintered body was obtained by using the material for the buffer layer used in Example 1 and holding the formed body in the form shown in FIG. All of the obtained sintered bodies had extremely excellent flatness, and there was almost no sintering between the sintered bodies or between the sintered bodies and the jig. Note that a thin graphite plate with a thickness of 1 mm was used as the jig inserted between the formed bodies. As described above, according to the method of the present invention, it is possible to stably and easily produce a high-density thin plate-shaped ceramic sintered body having a predetermined shape, which has been difficult to obtain using conventional sintering methods. In particular, the thin plate-shaped silicon carbide sintered body manufactured by the method of the present invention has high thermal conductivity and excellent heat dissipation properties, so it can be used for high heat dissipation that has been made smaller or more highly integrated with the development of electronic technology. It is possible to provide a material that is extremely suitable for applications such as substrates for integrated circuits where characteristics are required, and the effect of contributing to industry is extremely large.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing the clamping form of the produced body implemented in Example 1 of the present invention, and FIG. 2 is a longitudinal cross-sectional view showing the clamping style of the produced body implemented in Example 4 of the present invention. 1...graphite jig, 2...buffer layer, 3...generated form.

Claims (1)

[Scope of Claims] 1. A thin plate-shaped ceramic formed body containing as a main component ceramic fine powder made of at least one carbide selected from Si, B, Al, W, Ti, Ta, and Zn. , a method for producing a thin plate-shaped ceramic sintered body by holding it in a jig and subjecting it to pressureless sintering, wherein the formed body contains at least one of carbonaceous powder or carbonaceous fiber as a main component. 1. A method for producing a thin plate-shaped ceramic sintered body, which comprises obtaining a thin plate-shaped ceramic sintered body uniformly shrunk by firing by sintering the thin plate-shaped ceramic sintered body between jigs with a buffer layer made of aluminum interposed therebetween and sintering under pressure. 2. The method according to claim 1, wherein the jig is a carbonaceous rigid body having a predetermined shape when sintering the thin plate-like formed body whose main component is ceramic fine powder made of carbide. 3. The method according to any one of claims 1 to 2, wherein the thickness of the buffer layer is within the range of 1 to 500 μm. 4 The thickness of the thin plate ceramic sintered body is 2 mm.
A method as claimed in any one of claims 1 to 3 below.