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

2018-09-08 13:31:11

触头 AgSnO2 silver TiN oxide



AgSnO2合金是一种新型无毒AgMeO触头材料,目前在西方发达国家已获得较为广泛的应用。但是,传统内氧化法制备的AgSnO2触头由于晶粒粗大,第二相分散性差,导致电气性能与加工性能不佳,严重阻碍了其发展。为此,本文采用高能球磨及热压烧结工艺制备纳米复合AgSnO2触头材料,并分析研究了该合金的显微结构和电弧侵蚀特性。结论如下:
1.高能球磨能够制备纳米氧化物粒子在银基体内弥散分布的Ag-SnO2复合粉末,退火处理后晶界处析出纯银层,这是银蠕变扩散的结果。
2.采用一定的热压烧结工艺可获得纳米复合AgSnO2触头,显微结构为纳米SnO2粒子弥散分布在Ag晶粒内,晶界处保持单质银层的存在。该合金的密度达到理论密度的99%,硬度和电导率等性能达到了国家标准水平;
3.与传统内氧化AgSnO2In2O3触头相比,电弧作用后纳米复合AgSnO2触头表现出良好的侵蚀形貌,没有出现明显的液体飞溅和裂纹现象;
4. 纳米复合AgSnO2触头通过了国家电力型式试验考核。结果表明,该合金具有显著降低的温升和接触电阻,良好的通断能力和电气耐磨性,能够在实际电器中应用;
5.组织和性能对照分析表明,纳米复合AgSnO2触头的温升和接触电阻显著降低并表现出较优异的电弧侵蚀特性的原因在于纳米SnO2粒子在Ag晶粒内弥散分布的新型组织结构提高了体系粘度、改善了晶界状态。

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