Improvement On Properties Of Arc Resistance Of CuW Alloy

Due to excellent properties in arc erosion resistance, fusion resistance and breakdown strength CuW alloys are widely used as contact materials in various high voltage breakers. With increasing development of the power system, they can not meet the requirements of increasingly stringent combination of higher voltage, larger capacity, lower over-voltage and intellience. The Cu-W alloy with CeO₂ addition and nano-CuW alloy were prepared by milling along with infiltration technique, the effect of different powder preparation techniques on the final microstructure, static properties and vacuum breakdown performance was studied. The following conclusions can be drawn from this investigation:1. Nano-scale CuO particles can be obtained by milling. However, the powders aggregate seriously with increasing milling time. CuO particles can be uniformly dispersed into W matrix after mixing for 4h. The optimum reduction mode for CuO is to reduce the mixture of W and CuO powders and the optimum temperature is 800℃. The W skleton almost forms when sintered at 900℃. It can obtain the best infiltration effect when the content of CuO powders is 7-11wt%. For the nano-CuW alloy, the electrical breakdown usually happen on the grain boundary and the breakdown strength increases slightly due to the finer grains and large numbers of grain boundary.2. The 0. 2¹wt% CeO₂ additive can be distributed uniformly in the tungston skelton by liquid- solid doping method. With increasing CeO₂, the hardness of the CuW alloy prepared by powder metallurgy increases, but the electrical conductivity does not change almostly. For the CuW alloy with CeO₂ addition , the electric breakdown appear on the CeO₂ particles and their surrounding ares. The molten copper has less splash and the breakdown pits are more shallow.3. During the breakdown process, the electric breakdown districts of CuW alloy usually appear on the Cu-rich region, and have serious splash, and the formation of lager breakdown pits.4. The CuW alloy with CeO₂ addition and nano- CuW alloy have small chopping current and long arc life.