Study On Breakdown Characteristics Of CuWCr Composites

CrW/Cu and CuW(Cr) composites were prepared by infiltration method. The microstructure and vacuum properties such as breakdown high-voltage and chopping current have been investigated in details according to the preparation procedure of CuWCr composites. The results show:1. The first-breakdown phase is related to the content of Cr substituted by Cu and of Cr reinforced. Chromium phase is the first-breakdown phase when Cr is partly replaced by Cu and the first-breakdown takes place on the boundary of Cr and Cu when Cr is completely substituted by Cu. In CuWCrFe composites , Cu phase is broken down first because Cr is reinforced by Fe. In CuW(Cr) composite, CuCr solute is the first breakdown phase, but when the Cr particles exist in a form of second-phase, the first breakdown takes place on both Cr particle and CuCr solute.2. With increase of infiltration temperature, the amount of CrW solute increases, which leads to the increase in hardness and breakdown voltage, but the decrease of electrical conductivity and chopping current on the condition of the same Cr content in the CrW/Cu composites. With the decrease of the Cr content in the CrW/Cu composites, the initial breakdown voltage increaseswhile the mean breakdown voltage slightly drops and the chopping current decreases. Because of the addition of Fe, the hardness and breakdown voltage increase obviously and the chopping current decreases accompanying with the loss of electrical conductivity.3. Both CrW/Cu and CuWCrFe composites possess higher breakdown voltage and lower chopping current value comparing with CuCr alloy and their vacuum electrical arc is more stable and durable. CuW(Cr) composite possesses lower chopping current and stable electrical arc, however its breakdown voltage is lower than CuW alloy.