A calcia mold facecoat is applied to a mold for casting parts composed of reactive metals such as titanium and titanium aluminide. The facecoat is composed of a calcium carbonate based slurry comprising a dense grain calcium carbonate powder and an aqueous based binder. It is applied to a wax...http://www.google.com/patents/US5766329?utm_source=gb-gplus-sharePatent US5766329 - Inert calcia facecoats for investment casting of titanium and titanium-aluminide alloys 
