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通过试验找出了水玻璃砂VRH-CO_2硬化法的真空度与型砂强度及脱水率的关系,发现在真空脱水时,真空室内有一个降温过程,在本试验条件下的最大降温达11℃.用扫描电镜观察到VRH-CO_2硬化法的水玻璃粘结膜是由细小而均匀的硅酸胶粒所组成,面普通CO_2硬化法的水玻璃粘结膜是连片的硅酸凝胶结构.提出水玻璃砂VRH—CO_2硬化法的真空度以1.33~2kPa为宜,并指出了CO_2吹气量及保持时间,原砂质量及残留水分和环境湿度对型砂强度都有很大的影响.
The relationship between the degree of vacuum of VRH-CO 2 hardening method and the strength and dehydration rate of sand was found out through the test. It was found that in the vacuum dehydration, there was a cooling process in the vacuum chamber, and the maximum temperature drop reached 11 ℃ under the experimental conditions. Scanning electron microscopy showed that the water-glass adhesive film of VRH-CO 2 hardening method is composed of fine and uniform silicic acid gel particles. The common water-glass adhesive film of CO 2 hardening method is contiguous silicic acid gel structure. It is suggested that the vacuum degree of VRH-CO_2 hardening method should be 1.33 ~ 2kPa, and the inflow and holding time of CO_2, the quality of raw sand, the residual moisture and the humidity of environment have a great influence on the strength of sand.