铝磷酸盐热硬砂抗吸湿机理探讨  

Discuss on Humidity Resistance Mechanism of Aluminum-Phosphate Heat Cured Sand

作　　者：夏露[1] 黄晋[1] 张友寿[1] 董仕杰[1] 李四年[1] 

机构地区：[1]湖北工业大学机械工程学院,湖北武汉430068

出　　处：《铸造》2011年第2期188-191,共4页Foundry

基　　金：湖北省科技厅自然科学基金项目(2009CDB297)

摘　　要：结合铝磷酸盐热硬砂抗吸湿性能测试,借助于扫描电子显微镜和X射线衍射仪,分析了改性剂对热硬砂抗吸湿性能的影响,探讨了铝磷酸盐热硬砂的抗吸湿机理。结果表明:粘结膜断口形貌不同,性能差异很大,具有塑性的粘结膜具有较高的干强度和较好的抗吸湿性。32B0M0和32B0M10粘结剂在胶凝过程中均有晶体相析出,导致粘结膜产生相变应力,产生裂纹,使水分子易于侵入,导致强度下降。32B0M10胶凝产物中有非水溶性的MgHPO4.7H2O晶体,提高了铝磷酸盐热硬砂的抗吸湿性,32B8M15粘结剂的胶凝产物为非晶态,没有应力扩展倾向,粘结膜具有塑性,裂纹较少。因此32B8M15热硬砂具有较高的干强度和较好的抗吸湿性。The effect of modifier on humidity resistance of AI-phosphate heat cured sand was analyzed by using of SEM and XRD combined with humidity resistance test, and the humidity resistance mechanism was discussed. The results reveal that the properties of heat cured sand are different because of different fracture morphology of bond membrane, and the bond membrane with plastic has higher dry strength and better humidity resistance. The crystal phase is precipitated during jelling process of both binders 32BOMO and 32BOM10, which results in the occurrence of transformation stress and crack in the bond membrane, so water molecule is easy to infiltrate in, and lead to decrease of compressive strength. The MgHPO4.7H2O crystal in the gel products of binder 32BOM10 is water insoluble, so it can improve humidity resistance of AI-phosphate heat cured sand. Gel product of binder 32B8M15 is amorphous, there is no tendency of stress extension; and becasue the bond membrane is plastic, fewer cracks can be found. So 32B8M15 heat cured sand has higher dry strength and better humidity resistance.

关 键 词：铝磷酸盐热硬砂 抗吸湿机理 粘结膜 断口 胶凝产物 

分 类 号：TG221[金属学及工艺—铸造]