Improved collapse properties of silica-based ceramic cores via flexibly regulating cristobalite content

Although silica-based ceramic cores have important applications in the precision casting of metallic devices, their high-temperature stability and removal performances are seriously affected by the liquid phase sintered fused silica. Herein, we develop a manufacturing strategy of high-collapse silica-based ceramic core via using cristobalite crystals as the sintering inhibitor, waterglass as the binder, and injection moulding at 100 & DEG;C and 80 MPa, followed by heat treatment simulating the casting process for sintering at 1200 & DEG;C and 1500 & DEG;C. The results demonstrated that the addition of cristobalite crystals could effectively form the core skeleton to ensure high-temperature performance. Meanwhile, it inhibited the liquid flow during sintering and induced the crytsallization from fused SiO2 glass into cristobalite crystals, and the resulting plenty of micropores and microcracks within the microstructure effectively improve the removal performance. Especially, the porosity was highest up to 35.36% and the flexural strength was only 6.74 MPa when the addition of cristobalite reached 45%, realizing a 100% removing by high-frequency and fast-speed specific mechanical vibration. And, the casting is guaranteed to be flat and free of defects. This work provides a simple and flexible strategy to manufacture high-collapse silica-based ceramic cores, which can be removed by specific mechanical vibration without immersion in acid or alkali solutions after casting.