Molding medium method for making same and evaporative pattern casting process

Abstract From the Canadian patent

A molding medium and process for making it preferably for use in the evaporative pattern casting process is disclosed. The molding medium comprises in one, embodiment, a base granular molding material having spherically shaped grains wherein the individual grains of the material are coated with a refractory material. Preferably the grains are coated first with a binding agent and then mixed with a refractory material, which may be zirconium oxide. After coating, the material is fired at a high temperature, crushed and screened to size according to one, method. Alternatively the base molding material may itself, be a refractory material in which case the refractory, material is fixed with a …