This paper has developed a new compound curing agent powder for a modified phosphate binder (3 wt% of raw sand). This combination can be self-cured and achieve relatively high bonding strength. The optimal composition ratio of curing agent powder is fused magnesia powder:silica fume:sodium polyacrylate at a ratio of 6:6:5, respectively. In this case, the tensile strength of phosphate binder sand sample at 4 h and 24 h is 0.65 MPa and 1.27 MPa, respectively. Infrared spectroscopy and scanning electron microscopy were utilized to analyze the variation of functional groups and the morphology of bonding bridge fracture of phosphate bonded sand samples after the addition of curing agent (fused magnesia powder, silica fume and sodium polyacrylate). The result shows that fused magnesia powder, silica fume and sodium polyacrylate all participate in the polymerization and curing reaction of phosphate binder; furthermore, sodium polyacrylate can effectively mitigate the propagation of cracks on bonding film.

本文开发了一种新的用于改性磷酸盐粘合剂（生砂的3 wt％）的复合固化剂粉末。该组合可以自固化并获得相对较高的粘合强度。固化剂粉末的最佳组成比是分别为6：6：5的熔融氧化镁粉：硅粉：聚丙烯酸钠。在这种情况下，磷酸盐粘合剂砂样品在4 h和24 h的抗拉强度分别为0.65 MPa和1.27 MPa。利用红外光谱和扫描电子显微镜分析了添加硫化剂（熔融氧化镁粉，硅粉和聚丙烯酸钠）后磷酸盐粘结砂样品的官能团变化和粘结桥断裂的形态。结果表明，熔融的镁粉，硅粉和聚丙烯酸钠均参与磷酸盐粘合剂的聚合和固化反应。此外，聚丙烯酸钠可以有效地减轻裂纹在粘合膜上的扩展。