| 摘要 |
PURPOSE:To avoid a generation of division, resonance and phase shift by providing an airtight and thin layer of the same seramic or glass material as a porous ceramic matter or glass ceramic matter on a single or both surfaces of said ceramic matters. CONSTITUTION:1,000g fine powdery mixture containing 94.0wt% alumina, 2.0wt% calcium carbonate, 1.0wt% magnesium hydroxide and about 3.0wt% clay is dispersed into the 350cc water. At the same time, some amount of adhesive and dispersant are added. Then foamed polyurethane sheet is dipped into such solution. This sheet is then compressed and dried to obtain a green porous material. Then, a similar sheet- like matter is formed. A flexible sheet matter is adhered onto the single surface of said porous matter by use of a vinyl acetate emulsion adhesive. Then it is sintered for about 5hr at 1,600 deg.C for instance. As a result, a porous matter having ceramic particles sintered at the center part and an airtight nonporous thin layer formed to one body on the single surface is obtained. |
