Process for applying a coating to a centrifugal casting mold

Claim 1

A process for applying a heat-conductive and gas-permeable coating to a centrifugal casting mold for casting copper or alloys thereof and then casting thereover a pin-hole free copper alloy casting, said mold having an internal surface, said process comprising the steps of introducing into the mold, prior to introducing the molten metal into the mold, a suspension of powdery material consisting essentially of zirconium oxide (ZrO 2 ) and an inorganic binder of aluminum oxide (Al 2 O 3 ) in fine particle form, applying said material to the interior surface of the mold in the form of a thin smooth layer having a thickness of 0.1-0.3 mm., so that a heat-conductive and gas-permeable layer which is non-gas producing is provided on the internal surface of the centrifugal casting mold and which thin, smooth, heat-conductive and gas-permeable layer is capable of rapidly cooling a molten copper or copper alloy melt cast thereagainst, and thereafter centrifugally casting the molten copper or alloy thereof into said mold to form a pin-hole free casting of good dimensional accuracy.