| 摘要 |
Ceramic moulded articles of Si3N4, SiC etc. are compressed until free of pores within an evacuated capsule of high temp. resistant glass. The glass starting materials are deposited on the ceramic in a non-vitrified state and they are heated to their reaction temp. until the glass layer has formed an adhesive capsule around the moulded article. - In one method Al is vaporised onto porous reaction-sintered silicon nitride which in a first heat treatment step is held at atmospheric pressure for a long time at a relatively low temp. to convert the metallic Al to Al2O3. The silicon nitride is then subjected to a second heat treatment for a short time in vacuo at a high temp. to convert Al2O3 and SiO2 to the glass. - Simultaneous encapsulation and evacuation of a porous compact is simply produced prior to hot isostatic pressing. |
