低压触头用AgSn合金粉末氧化机理研究

Oxidation Mechanism of Ag-Sn Alloy Powders Used for Low Voltage Contactor

采用雾化法制备Ag(90.5%)/Sn(9.5%,质量分数)合金粉末,使用热重分析仪得出600,700,800℃内氧化动力学曲线,分析Ag-Sn合金粉末氧化前后的粒度、表面形貌、物相组成及表面成分。结果表明:氧化前后合金粉粒度变化极小,氧化后表面粗糙,在"鳞片"交界处出现细小空洞与缝隙,有体积膨胀迹象。根据控制扩散反应的因素不同,分为快速增重、混合增重和抛物线增重3个不同阶段。

Ag（90.5%）/Sn（9.5%） alloy powders （mass fraction） were prepared by atomization. The oxidation kinetics curves at 600, 700 and 800 °C were obtained using a thermogravimetric analyzer （TGA）. The particle size, surface morphology, phase structure and surface composition of AgSn alloy powders were investigated before and after oxidation. Results show that there is negligible difference in particle size before and after oxidation. After oxidation, a rougher surface and slight volume expansion are observed. Moreover, some small holes and cracks appear at the junction of ＂scales-like section＂. Based on the controlling diffusion factors, the oxidation phase can be divided into 3 typical stages： exponentially rapid mass gain stage, crossing transition stage and parabolic slow mass gain stage.