SOLIDIFICATION OF CRYSTALLINE SILICON FROM REUSABLE CRUCIBLE MOLDS
A process for making silicon ingots using a multi-part, reusable, graphite crucible of at least two mold pieces configured for assembly into an open top mold having an interior surface functional as a mold cavity for receiving molten silicon; removing or reducing a prior applied release coating from the interior surface until a uniformly smooth finish is achieved; coating the interior surface with a first layer of release coating comprising silicon nitride; coating the interior surface with a second layer of release coat comprising silica suspended in water; coating the interior surface with a third layer of release coat comprising silicon nitride; curing the release coat on said crucible; casting a silicon ingot in the crucible; and then repeating the prior steps multiple times.