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三维喷印(Three-dimensional Printing,3DP)具有成形材料类型广泛、系统成本低、成形效率高等特点,在砂型(芯)快速制造领域具有广阔的应用前景。针对3DP成形覆膜砂砂型(芯)初坯强度低的问题,通过添加α半水石膏方式改性原始宝珠覆膜砂,试验研究了α半水石膏添加量对抗拉强度、发气量、透气性的影响。结果表明,适量添加α半水石膏有利于初坯强度的提升,但α半水石膏的加入会增大砂型的发气量,并在一定程度上降低透气性。3%的α半水石膏含量混合粉末的初坯抗拉强度达0.931 MPa,是原始覆膜砂粉末的3倍,850℃的发气量为13.3mL/g,透气率为50.07。
Three-dimensional printing (3DP) has the characteristics of wide range of forming materials, low system cost and high forming efficiency. It has broad application prospects in the field of rapid manufacturing of sand (core). Aiming at the problem of low initial strength of 3DP formed sand sand mold (core), the effect of α-hemihydrate gypsum on tensile strength, gas evolution, air permeability Impact. The results showed that the addition of α hemihydrate gypsum is good for improving the strength of the green body. However, the addition of α hemihydrate gypsum increases the gas evolution of the sand and decreases the air permeability to a certain extent. The initial tensile strength of 3% α-hemihydrate gypsum mixed powder reached 0.931 MPa, which was 3 times that of the original coated sand powder. The gas evolution at 850 ℃ was 13.3 mL / g and the air permeability was 50.07.