Research On Preparation Technology And Performance Of Doped Lower Silver Contact Materials

Ag-Sn O2 is one of the best development prospects in electrical contact materials.It possesses good fusion welding resistance, Arc erosion resistance and thermal stability. But there are also some shortcomings: big Contact resistance and high temperature rise have significant effects on electrical performance; its forming is difficult and the silver content of it is high. This article mainly uses high-energy ball milling method to produce low silver contact materials. Firstly, preparation technology of the silver content of 82% Ag-Sn O2 contact material is researched. In order to reduce silver content to 70% and ensure performance of contact materials,Cu is used to replace a part of Ag and some additives are added. The preparation technology and properties of doping Ag-Cu alloy contact material were also studied. Through a lot of experiments, results show that:1. For doping Ag(82) Sn O2 contact material, high-energy ball milling can make the samples of mechanical alloying, the oxide particles is set in silver evenly. It has good physical properties and formability. But for the physical blending, oxide powder and silver powder are mixed unevenly in the sample,reunion of nanometer oxide is serious and it has poor formability. Granulation process can enhance the mechanical properties and processability of samples made by high-energy ball milling.2. For doping Ag-Cu alloy contact material, through the following process the contact materials can get excellent performance: silver powder and nano oxide composite powder are mixing by High-energy ball mill for 2h, then annealing at 350℃, sintering at 750℃for 4h under N2 atmosphere, finally through after pressure and after burn, the silver content of 70% doping Ag-Cu alloy contact material is manufactured successfully.Add Sn O2 as strengthening phase in Ag-Cu alloy contact material, when content of Sn O2 is 10%, its conductivity is 51.9% IACS, hardness is 115.3 HV and relative density is 93.27%, the material conforms to the requirements of the standard and has good comprehensive performance.The microstructure of Ag-Cu-Sn O2 contact material prepared with the optimum technological process is observed. The results show that the organizational structure of Ag-Cu-Sn O2 contact material is small and all kinds of elements are distributed evenly, reunion phenomenon of Sn O2 is not obvious.3. The sample is discharged under the dc voltage of 6 kv for 50 times. Under the action of the high temperature of electric arc,the doping Ag(82) Sn O2 contact materials made by high-energy ball milling has slight erosion, its degree of ups and downs of the corrosion pit is small and the distribution of voltage resistance strength is concentrated. The surface erosion distribution of doping Ag-Cu-Sn O2 contact materials with oxide content of 10% is uniform and surface is flat after ablation.There is little of silver droplets and cracks appeared. Under the high temperature of electric arc,there is no oxide reunion and fusion welding resistance is fine. There are 44 figures, 18 tables and 109 references in this academic dissertstion.