运用扫描电镜对特种覆膜砂试样的破坏机理进行了分析 ,研究了酚醛树脂粘结剂用于特种砂时的粘结机理。研究结果表明 :采用偶联剂进行表面处理的特种覆膜砂具有较高的强度 ,其关键在于偶联剂使树脂与特种砂砂粒间断裂方式由附着断裂转变为内聚断裂 ,表明偶联剂能改善特种砂粒表面与树脂的粘附性 ,使树脂更为牢固地附着在砂粒表面 ,充分发挥树脂的粘结效率 The damage mechanism of special coated sand samples was analyzed by scanning electron microscopy. The bonding mechanism of phenolic resin binder for special sand was studied. The results show that the special coated sand with the coupling agent has higher strength. The key point is that the coupling agent can change the mode of the fracture between the resin and the special sand grains from the attachment fracture to the cohesive fracture, indicating that the coupling agent Can improve the adhesion of special sand and resin surface, the resin is more firmly attached to the surface of the sand, give full play to the resin bonding efficiency