摘要
Ag–CdO composites are still one of the most commonly used electrical contact materials in low-voltage applications owing to their excellent electrical and mechanical properties.Nevertheless,considering the restriction on using Cd due to its toxicity,it is necessary to find alternative materials that can replace these composites.In this study,the synthesis of Ag-ZnO alloys from Ag-Zn solid solutions was investigated by hot mechanochemical processing.The hot mechanochemical processing was conducted in a modified attritor mill at 138℃under flowing O2 at 1200 cm3/min for 3.0 h.The microstructure and phase evolution were investigated using X-ray diffractometry,field emission gun scanning electron microscopy and transmission electron microscopy.The results suggest that it is possible to complete the oxidation of Ag-Zn solid solution by hot mechanochemical processing at a low temperature and short time.This novel synthesis route can produce Ag-ZnO composites with a homogeneous distribution of nanoscale ZnO precipitates,which is impossible to achieve using the conventional material processing methods.Considering the fact that the fundamental approach to improving electric contact material performance resides in obtaining uniform dispersion of the second-phase in the Ag matrix,this new processing route could open the possibility for Ag-ZnO composites to replace non-environmentally friendly Ag-CdO.
Ag-CdO复合材料由于其优异的电气和力学性能,仍然是低压应用中最常用的电触头材料之一。然而,考虑到由于镉的毒性而对其应用的限制,有必要寻找可取代这种复合材料的替代材料。本研究以Ag-Zn固溶体为原料,采用热机械化学工艺制备Ag-ZnO合金。在138°C、1200 cm^3/min的氧气流下,在改进的球磨机中对合金样品进行热机械化学处理3 h,利用X射线衍射技术、场发射扫描电镜和透射电镜对合成材料的显微组织和相演变进行研究。结果表明,低温下的热机械化学处理可使Ag-Zn固溶体在短时间内完全氧化。这种新的合成方法可以制备出纳米ZnO相均匀分布的Ag-ZnO复合材料,而这是用传统的材料加工方法无法实现的。考虑到改善电触头材料性能的根本途径在于实现Ag基体中第二相的均匀分散,这一新工艺为Ag-ZnO复合材料取代非环境友好的Ag-CdO提供了可能。
基金
financially supported by the FONDECYT(Project No.11100284)
the Metallurgy Department of University of Atacama for the XRD and SEM analysis(Projects EQM130125 and EQUV 003)
