Fabrication and Characterization of High-strength Water-soluble Composite Salt Cores via Layered Extrusion Forming

This paper presents a novel process for preparing high-strength water-soluble salt cores with complex structure via layered extrusion forming using K2SO4 and KCl as the base salt materials, which is suitable for manufacturing hollow complex-shaped castings. The effects of fortifiers including alumina powder, sericite powder and silica powder on properties and microstructures of K2SO4-KCl composite salt cores were systematically investigated, and the strengthening mechanisms of the composite salt cores are discussed. The results indicate that the effect of alumina powder on the bending strength of K2SO4-KCl composite salt cores is significantly better than that of sericite powder and silica powder. When the content of alumina powder is 20 wt.%, the composite salt cores possess excellent comprehensive properties, and their bending strength, linear shrinkage, water-solubility rate, and moisture rate are 23.34 MPa, 13.86%, 76.73 g/(min center dot m(2)), and 0.11%, respectively. The proper content of alumina powder can refine the size of KCl grain and obtain a denser microstructure. Finally, the composite salt core components with high strength and complex structure were fabricated by using the optimized process parameters.