Electrical contact materials obtained by spark plasma sintering technology for vacuum contactors

Abstract

Contact materials from W-Cu, W-Ag and WC-Ag systems obtained by spark plasma sintering technology to be used as electrical contacts for vacuum contactors were developed. The electrical contact materials have been obtained from homogenized powder composite mixtures of W-Cu (70-30, 60-40), W-Ag (70-30, 60-40), and WC-Ag (70-30, 60-40), by spark plasma sintering technology, in vacuum, under pressure of 50 MPa in the 900–1050 °C sintering temperature range, at a constant dwelling time of 5 minutes and a heating/cooling rate of 100°C/min. The physical, microstructural, electrical, mechanical and functional properties of the obtained electrical contact parts of 20 mm in diameter and 4÷5 mm in height were investigated in respect to chemical composition and sintering temperature. All the analyzed electrical contact materials have shown near fully dense and homogeneous microstructures with enhanced physical, mechanical, electrical and functional properties. Best performances have been obtained on the electrical contacts from WC-Ag with 40 wt. % Ag which had the lowest degree of porosity (4.77 %), the highest value of Vickers hardness (220±3 HV), the highest value of Young's modulus (180±5 GPa), the lowest value of electrical resistivity (4.65 μΩ·cm) and the lowest value of the medium chopping current (0.59 A).