铝合金用覆膜砂不同温度下发气特性研究

Gas Evolution Characteristics of Precoated Sand for Aluminum Alloy at Different Temperatures

用覆膜砂铸造铝合金铸件气孔缺陷很大,一部分源于覆膜砂自身的发气特性所致,因此针对覆膜砂工艺进行了大量试验研究。更加通用和量化的方法是使用数值模拟算法对砂芯中的气体进行模拟仿真,但准确的覆膜砂发气模型的构建尚缺乏数据支撑。通过试验修正发气性测量仪,测量了5种覆膜砂在不同温度下的发气曲线,分析了覆膜砂发气量和发气速率与温度的关系,得到了覆膜砂最大发气量和温度的公式。并结合热重分析技术,确定了覆膜砂的发气反应存在低温区和高温区两个阶段。

A large part porosity problems of aluminum alloy casting comes from the gas-evolution properties of precoated sand itself. In view of the specific casting process of precoated sand on a large amount of experimental study, a more general and quantitative method is to apply numerical simulation algorithm to the simulation of gas and core. However, accurate gas model of precoated sand is still lack of data support. Gas evolution curves of 5 kinds of precoated sand were measured at different temperatures by modifying the gas evolution instrument, and the relationship between volume of precoated sand and gas evolution rate or temperature was analyzed. The formula of the maximum gas volume and temperature of precoated sand were presented. It was confirmed that the gas reaction of precoated sand has two stages: low temperature zone and high temperature zone.