热挤压工艺对反应合成AgSnO_2材料显微组织的影响

Effect of Hot Extrusion on Microstructure of AgSnO_2 Prepared by Reaction Synthesis Processing

采用反应合成和热挤压方法制备新型AgSnO2电接触材料。利用金相显微镜和扫描电镜研究了反 应合成法制备的AgSnO2材料热挤压前后的显微组织,分析了挤压速度、挤压模具等工艺条件对 AgSnO2挤压线坯显微组织的影响,计算了采用平模挤压和45°锥模挤压的等效应力分布值,探讨了锥模 挤压改善AgSnO2加工性能的机理。发现快速挤压使AgSnO2锭坯产生严重的径向不均匀变形,导致 AgSnO2沿径向不均匀分布;而慢速挤压得到较均匀分布的SnO2,有利于AgSnO2力学性能的提高。研 究还发现,采用45°锥模挤压,出模口应力梯度较小,有利于改善AgSnO2丝材的后续加工性能。在本研 究的基础上,得出了比较合理的AgSnO2挤压工艺。

A new type of AgSnO2 contact material fabricated by Reaction synthesis processing and hot extrusion processing. Microstructure of AgSnO2 materials before and after hot extrusion were study by metallurgical microscope and scanning-electron microscope （SEM）,The effects of extrusion speed and extrusion die on microstructure of AgSnO2 wires were analyzed, the equivalent stress distribution with level extrusion die and 45° taper die were calculated, respectively, the mechanism of workability improvement of AgSnO2 was discussed. It was found that the fast extrusion made uneven distributed of SnO2 in AgSnO2 along the radial direction, however, the slow extrusion got evenly distributed SnO2 in AgSnO2 , helping raise the mechanical properties of AgSnO2. It was also found that using the 45° taper die, the stress gradient at the die outlet was small, bengfiting improvement of workability of AgSnO2 wire. Based on the above investigation, a reasonable extrusion process was established.