Effect of zircon content on chemical and mechanical behavior of silica-based ceramic cores

In this work, the effect of zircon content on the mechanical and chemical behaviors of injection molded silica-based ceramic cores has been investigated. In order to simulate a casting process condition, the sintered samples at 1220 C were consequently heated up to 1430 C. Three point bending tests were carried out on all the prepared samples. The chemical resistance of the prepared cores was evaluated by leaching of samples in 43% KOH solution at its boiling point. Phase evolution and microstructure were investigated by XRD and SEM, respectively. Results showed that increasing zircon content led to an increase in MOR and decrease in leachability owing to the decrease in content of fused silica with lower strength and chemical stability. The leaching rate of sintered ceramic cores was decreased after the simulated casting heat treatment at all zircon contents due to crystallization of cristobalite, with a higher chemical stability, on the surface of fused silica particles.