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硅溶胶是熔模铸造中常用的型壳粘结剂之一,但硅溶胶型壳制备过程中存在的突出问题是干燥慢,制壳周期长。本文采用真空干燥工艺对硅溶胶型壳进行干燥,探索了不同真空度及保压时间下型壳强度的变化规律。研究发现:与自然干燥相比,采用真空干燥工艺下的型壳能在较短时间内达到较高的强度。真空度为-0.07 MPa,保压20 min时型壳抗拉强度可达0.85 MPa。而自然干燥相同时间,型壳抗拉强度仅为0.38 MPa。若只考虑湿强度,真空干燥工艺可用于硅溶胶型壳的硬化,且选用真空度-0.07 MPa,保压30 min左右较为适宜。
Silica sol is one of the commonly used shell binder in investment casting. However, the outstanding problems in the preparation of silica sol shell are slow drying and long shell making cycle. In this paper, the silica sol shell was dried by vacuum drying process, and the variation of the shell strength under different vacuum degree and dwell time was explored. The study found that: Compared with the natural drying, the vacuum drying process under the shell in a relatively short period of time to achieve higher strength. The degree of vacuum is -0.07 MPa, the tensile strength of the shell can reach 0.85 MPa when the pressure is maintained for 20 min. The natural drying at the same time, the tensile strength of the shell is only 0.38 MPa. If only consider the wet strength, vacuum drying process can be used for the hardening of the silica sol shell, and the selection of vacuum -0.07 MPa, packing 30 min is more appropriate.