Abstract: Effects of different facing oxides, including including yttria colloidal and powders (Y/Y), yttria stabilized zirconia colloidal and powders (ZY/ZY), zirconia colloidal and powders (Z/Z) and zirconia colloidal and zireonite powders (Z/ZS) on the qualities of investment castings are studied. The outward appearance, microstructures, and microhardness profiles of castings made of commercial pure titanium, Ti--Al--V and Ti--Al--Zr are investigated. Castings made by shells with yttria as face materials have the least contamination and by zirconite shells have the most contamination. Thermodynamic of metal-mold reactions is also taken into consideration.

Key words: titanium alloy, investment casting, oxide in investment mold