复合纤维配比对精铸硅溶胶型壳性能的影响
Effects of composite fiber ratio on the properties of silica sol shell for investment casting

为了分析复合纤维配比对熔模精铸中硅溶胶型壳的强度和透气性的影响，采用尼龙和陶瓷复合纤维制备硅溶胶型壳试样，在其中加入的尼龙纤维和陶瓷纤维的体积配比为100∶0、82.7∶17.3、61.5∶38.5、34.7∶65.3和0∶100，对获得的复合纤维增强型壳试样的生胚抗弯强度、焙烧后抗弯强度和透气性的变化规律进行研究。结果表明，当尼龙纤维在复合纤维中体积分数从0%~100%变化时，型壳生胚抗弯强度逐渐增大，焙烧后抗弯强度总体变化不明显，透气率先增大后减小。当尼龙纤维的体积分数为82.7%时，透气率达到最大值5.21。根据试样断口形貌及纤维增强行为分析，型壳生胚抗弯强度主要受纤维体积含量的影响；型壳焙烧后抗弯强度和透气性受陶瓷纤维体积含量、涂挂厚度和尼龙纤维烧失后留下孔洞数量的综合影响。 In order to analyse the influence of composite fiber ratio on the strength and breathability of reinforced silica sol shell for investment casting, the bending strength of the embryo and after baking and breathability of composite fiber reinforced shell samples were studied. Ceramic and nylon composite fibers were used to enhance silica sol shell samples. In the slurry, the volume ratio of the nylon fiber and ceramic fiber respectively were 100:0, 82.7:17.3, 61.5:38.5, 34.7:65.3 and 0:100. The results indicate that when the proportion of nylon fibers changes from 0% to 100% in the complex fibers, the bending strength of the embryo of the shell increases gradually, the overall change of the fired bending strength is not obvious, and the breathability rate has the trend of increasing first and then decreasing. When the volume content of nylon fibers is 82.7%, the breathability rate reachs maximum, which is 5.21. According to the analysis of the fracture morphology and fiber reinforced behavior, the bending strength of the embryo of mold shell is mainly affected by the volume content of fiber and the flexural strength and permeability of the shell after baking are influenced by the volume content of ceramic fiber, the thickness of coating and the number of holes that the nylon fiber left after being burning. 航空科学基金（2015ZE56015）；省教育厅项目（GJJ160687）