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采用反应合成和热挤压方法制备出新型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SnO2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°锥形模挤压,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,得到比较合理的AgSnO2挤压工艺。
A novel AgSnO2 electrical contact material was prepared by reaction synthesis and hot extrusion. The microstructures of AgSnO2 prepared by reactive synthesis before and after hot extrusion were studied by means of metallographic microscope and scanning electron microscope. The effects of extrusion speed, extrusion die and other process conditions on the microstructure of AgSnO2 extruded wire bar were analyzed. The equivalent stress distribution of flat die extrusion and 45 ° cone die extrusion was used to discuss the mechanism of cone die extrusion to improve the machinability of AgSnO2. It was found that the rapid extrusion resulted in serious radial inhomogeneous deformation of AgSnO2 billet, resulting in the uneven distribution of SnO2 in the radial direction. However, the slow extrusion resulted in a more uniform distribution of SnO2, which was beneficial to the improvement of the mechanical properties of AgSnO2. The study also found that 45 ° tapered die extrusion, die exit stress gradient is small, is conducive to improving the subsequent processing of AgSnO2 wire properties. On the basis of this study, a more reasonable AgSnO2 extrusion process was obtained.