FORFARANDE FOR FRAMSTELLNING AV VARMPRESSADE PRODUKTER AV ETT KERAMISKT MATERIAL BASERAT PA KISELNITRID

摘要

In manufacturing a hot pressed ceramic material based on silicon nitride, the ceramic material is introduced into a die cavity defined within a graphite die. There is provided between the ceramic material and the walls of the die cavity a further material which, at the elevated temperature of the hot pressing process, forms a substantially non-porous continuous barrier layer at or near the surface of the ceramic material so that reaction between the ceramic material and the graphite die is substantially prevented.