纳米复合银氧化锡触头材料的制备及电弧侵蚀特性/Preparation and arc erosion characteristics of nanocompo
关键词：电接触材料 AgSnO2 纳米复合 电弧侵蚀 型式试验
As the best replacement of silver cadmium oxide, silver tin oxide contact materials has been greatly developed nowadays in west countries. However the defect microstructure with coarse grains and oxide clusters, degraded the deformation abilities and electrical properties, so the application of silver tin oxide were limited. In this paper, a novel type of silver tin oxide alloy with nano-scale oxide has been fabricated by high- energy ball milling, hot pressing and sintering. The microstructure and properties of the nanocomposite alloy were investigated and the main conclusions can be obtained as follows:
1. The nanocomposite silver tin oxide powders can be prepared by high-energy ball milling. Its microstructure was characterized with the nano-scale tin oxide particles dispersed evenly inside the silver grains. A pure silver film appeared along the grain boundaries on annealing powders due to creep diffusion of silver atoms.2. Through hot pressing and sintering, the nanocomposite silver tin oxide contacts were obtained. The relative density was 99%, while the hardness and conductivity approached the national standards of contact materials. The microstructure of the alloys was similar as that of the precursor powders.
3. Compared with the commercial silver tin oxide indium oxide contacts, the nanocomposite silver tin oxide contacts showed lighter arc erosion. Molten droplets decreased obviously and thermal cracks were inhabited on the surface.
4. In the mode tests for CJX4-63 a.c. contactors, the nanocomposite silver tin oxide contacts exhibited very low over- temperature and contact resistance, excellent make-and-break abilities and electrical wear. Therefore, it was inferred that the nanocomposite silver tin oxide contacts could be used in practical low-voltage apparatuses.
5. The main reason of the good arc erosion characteristics above is that the melt viscosity was enhanced, and the grain boundaries were improved by the special microstructure of the alloys. It is also due to this reason that the contact resistance and over-temperature were greatly diseased.
Key words: contact materials, silver tin oxide, nanocomposite, arc erosion, mode test