Contact Resistance and Arc Erosion of Tungsten-copper Contacts in Direct Currents

• Published in: Journal of Wuhan University of Technology. Materials science edition 2017-08, Vol.32 (4), p.816-822
• Main Authors: Ma, Douqin, Xie, Jingpei, Li, Jiwen, Wang, Aiqin, Wang, Wenyan
• Format: Article
• Language: English
• Subjects: Advanced Materials; Argon; Chemistry and Materials Science; Compacts; Contact; Contact resistance; Copper; Copper compounds; Energy measurement; Erosion mechanisms; Erosion resistance; Evaporation; Exposure; Heat treatment; Hot extrusion; Materials Science; Scanning electron microscopy; Time measurement; Transmission electron microscopy; Tungsten compounds; Ultrasonic testing; Vaporization; 扫描电子显微镜; 接触电阻; 燃弧时间; 电弧侵蚀; 直流电流; 触点; 透射电子显微镜; 钨铜
• ISSN: 1000-2413; 1993-0437
• DOI: 10.1007/s11595-017-1674-y

The arc erosion under medium direct currents in the argon flow was tested on tungsten-copper（W-Cu） contacts which were processed by hot extrusion and heat treatment. The scanning electron microscopy（SEM） and transmission electron microscopy（TEM） were used to study the microstructure of the W-Cu powders and compacts. The contact resistance, arcing energy, and arcing time were continuously measured by JF04C contact materials test system. Changes in tungsten-copper contact surface were observed by SEM. The test results showed that the arcing time and arcing energy all increase with current and voltage, but the changes of average contact resistance are more complicated. For a short arcing time, the average contact resistance decreases with increasing current due to the vaporization of Cu. However, for a longer arcing time, it slightly increases due to the formation of high resistant films, compound copper tungsten. The formation of compound copper tungsten was confirmed by the increased Rc kept in the range from 1.1 to 1.6 mΩ. The compound copper tungsten is first exposed with a tungsten and copper-rich surface, and then totally exposed due to evaporation of copper from the surface. At last a stabilized surface is created and the crystals decrease from 8 μm to 2 μm caused by the arc erosion.