METHOD OF MAKING LARGE CROSS-SECTION INJECTION MOLDED OR SLIP CAST CERAMIC SHAPES

摘要

2074516 9111407 PCTABS00006 A method of producing crack free ceramic parts having large cross-sections is disclosed. An initial mixture of ceramic powder containing a binder and from 0.1 v/o to 10 v/o of whiskers or fibers which are made of carbon, graphite or high temperature melting or decomposition point organic polymers. The mixture is either injection molded or slip cast to form a shaped article. The shaped article is heated in a nitrogen atmosphere to a temperature of 450 ·C and then in an atmosphere of air at a temperature of 450 ·C to 600 ·C to completely remove the binder. The resulting binderless shaped article is then heated at 800 ·C for a period of time sufficient to completely remove the whiskers or fibers from the shaped articles. The article is then encapsulated in glass and hot isostatically pressed at a pressure of 30,000 psi to densify the article to approximately 99 % of theoritical. The resulting article has a complex geometry and a large cross-section but without detrimental cracks.