Interactions between TiAl and ZrO₂ Face Coat during Centrifugal Investment Casting

Abstract

γ-TiAl alloys are emerging as potential light-weight, high-temperature structural materials and possess wide capacities of engineering applications in aeronautics, space and automobile industries because of their low density, high specific strength and specific modulus, good oxidation-resistance and creep-resistance. Investment casting is introduced to complex TiAl net-shape or near net-shape components. In this research, ZrO2 (CaO stabilized) was chosen as the face coat materials for the investment casting of TiAl alloys. The present study mainly focuses on the fabrication of ceramic shell mould for TiAl investment casting. Optimisation of reducing the stress in cast-mould system was carried out. The processing technology of the invented ceramic shell moulds was successfully verified in the investment casting of prototype TiAl parts. The interfacial reaction between TiAl alloys and ZrO2 ceramic mould was analyzed using OM, SEM, EDS and XRD. The experimental results showed that, when the rotation speed is 200 rpm and 400 rpm, the thickness of reaction layer is about 5μm and 20μm, respectively.