Investigation on Nano-Fused Silica in Silica-Based Ceramic Cores for Investment Casting

Abstract

In this work, nanofused silica and its effect on mechanical and chemical behavior of injection moulded silica-based ceramic cores were investigated. In order to simulate casting process condition, the sintered samples at 1180 °C were also heated up to 1500 °C. Flexural strength test was carried out on both sintered and heat treated samples. Phase evolution and microstructure were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the samples with 0.5 wt.% nanofused silica content had an optimal comprehensive properties for investment casting. The flexural strength of sintered samples with 0.5 wt.% nanofused silica at room temperature and at 1500 °C for 30 min were 30.3 MPa and 24.4 MPa, respectively, and the creep deformation at 1500 °C was 0.8 mm. The addition of nanofused silica was favorable for cristobalite transformation and the samples had a good leachability for the micro-cracks introduced by crystallization.