锌合金压铸用二元复合水溶性盐芯的制备与性能

针对复杂内腔锌合金压铸件难清理及型芯强度要求高的问题,以高熔点盐氯化钾和低熔点盐硝酸钾组成混合盐为制芯材料,采用熔融重力浇注工艺制备了高强度二元复合水溶性盐芯.对比分析了氯化钾盐芯、硝酸钾盐芯和20% KCl--80% KNO3二元复合水溶性盐芯的性能特征.采用扫描电镜和X射线衍射等测试方法分析了水溶性盐芯的微观形貌与物相组成.研究结果表明:与单质盐芯相比,二元复合盐芯综合性能更佳,其表面基本无裂纹与褶皱,抗弯强度可达21.2 MPa,24 h吸湿率为0.568%,80℃的水溶速率可达208.63 kg·min-1·m-3.复合盐芯在裂纹扩展时走向发生了偏转,这是复合盐芯抗弯强度提高的主要原因.

Preparation and properties of a binary composite water-soluble salt core for zinc alloy by die casting

For realizing complicated shapes of the inner cavity of zinc alloy castings by pressure die casting,the problem of poor leachability has to be solved and the high-strength requirement of the water-soluble salt core should be met. High-melting potassium chloride salt and low-melting potassium nitrate salt were used as the core materials. High-strength binary composite water-soluble salt core (WSSC) was formed by the process of melting and gravity pouring. The performance characteristics of the potassium chloride core,potassium nitrate core,and binary composite WSSC (20% KCl--80% KNO3) were investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies were performed to examine the micro-morphology and phase composition of WSSC. The results indicate the following:the binary composite WSSC has excellent comprehensive performance, its bending strength can exceed 21.2 MPa,the 24 h hydroscopicity rate is 0.568%,the water-soluble rate can exceed 208.63 kg·min-1·m-3in water at 80℃ and its surface has no cracks and folds unlike the pure salt core. Crack growth in the binary composite salt core occurs by deflection,which is the main reason for the improvement in bending strength.