ABSTRACT

Electrical contact materials WC-based to be used as electrical contacts for vacuum contactors were developed by spark plasma sintering process. The electrical contact materials were developed from homogenized powder composite mixtures of WC-Cu (60-40) and WC-Co-Cu (59.5-0.5-40), which were spark plasma sintered in vacuum, in the interval of temperatures of 1015-1045 °C, under 50 MPa pressure and a dwell time of 300 s, at a heating rate and a cooling rate of 100°C/min. The obtained electrical contact pieces of 20.5 mm in diameter and 3 mm in height were investigated from the physical, microstructural, electrical, mechanical and functional properties point of view. At optimal sintering temperatures (1035°C-1045°C) and the same dwell time (300 s), we have obtained electrical contact pieces with homogeneous microstructures and excellent physical and mechanical properties for both studied systems. We have obtained best performances on the electrical contacts from WC-Cu with 40 wt.% Cu which had low degree of porosity (5.16 %), high value of Vickers hardness (226±5 HV), high value of Young’s modulus (160±2 GPa) and the lowest values for electrical resistivity (4.35 μΩ×cm), chopped current (1.76 A) and standard deviation (0.37%). A small amount of sintering additive (0.5 wt%Co) to the WC-40wt% is helping to increase the densification degree and mechanical properties but decreases electrical properties and also, increases the functional parameters. Thus, in compare with the WC-40wt.%Cu electrical contacts, the chopped current for the WC-0.5wt.%Co-40wt.%Cu is increasing with 16%.

WC-Cu Electrical Contacts Developed by Spark Plasma Sintering Process