A Study of the Influence and Mechanism of Alumina Ceramic Powder on the High-Temperature Strength of NaCl–Na2CO3 Cores in Die-Casting Production

Water-soluble salt core materials have high bending strength at room temperature. During high-pressure casting, water-soluble salt cores must withstand high temperatures and impact loads. To obtain a composite water-soluble salt core suitable for high-pressure casting components, sodium chloride and sodium carbonate are used as base salt materials. Ceramic particles of alumina are used as reinforcement materials in the preparation of a water-soluble composite salt core with excellent high-temperature strength via gravity casting. The microstructures of the salt core and fracture surface are observed and characterized. The use of alumina to enhance the sensitivity of the binary salt cores results in a low thermal crack sensitivity coefficient. The alumina particles dispersed in the matrix prevent crack propagation. Simulation results show that sodium aluminate has strong interfacial bonding abilities with other components in the salt core, affecting its high-temperature strength. Further results confirm that sodium aluminate formation enhances the high-temperature strength of salt cores.