A composite inorganic salt core with good water solubility and formability was proposed using potassium nitrate (KNO3) and potassium chloride (KCl) as base materials. The KNO3–KCl molar ratio has been optimized for the KNO3–KCl composite salt core, and then a low-cost bauxite powder acting as a reinforcing material was added to strengthen the optimized KNO3-KCl composite salt core for the application of hollow zinc alloy die castings. The results show that 70 mol% KNO3-30 mol%KCl composite salt core (CSC) possesses a good comprehensive performance, which has the maximum bending strength of 26.5 MPa and the excellent water solubility rate of 998 g/(min·m2). With increasing the bauxite powder content, the bending strength and vickers hardness of the CSC increase, but the water solubility rate of the CSC decreases gradually. When the bauxite powder content is 30 wt.%, the CSC has a bending strength of 42.99 MPa and vickers hardness of 39.2 HV, which respectively increased by 62.2% and 39.5%, and the water solubility rate is still higher than 692.9 g/(min·m2). The microanalysis reveals that the bauxite powder is stable and evenly distributed among the CSC matrix, which significantly refines the KCl primary phase, resulting in improving the properties of the CSC. Additionally, the crack deflection and branching caused by bauxite powder also enhance the properties of the CSC.
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The authors would like to thank the support of the National Nature Science Foundation of China (Grant No. 51775204) and the Research Project of State Key Laboratory of Materials Processing and Die & Mould Technology (Grant No. P2021-020), and the Analytical and Testing Center, HUST.
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Gong, X., Liu, F., Liu, X. et al. Properties Optimization and Strengthening Mechanism of KNO3–KCl Water-Soluble Composite Salt Core for Hollow Zinc Alloy Die Castings. Inter Metalcast 17, 563–572 (2023). https://doi.org/10.1007/s40962-022-00784-y