The Development of a New Compound Curing Agent for a Modified Self-Cured Phosphate Foundry Binder

Abstract

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.