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

Development and Investigation of Tungsten Copper Sintered Parts for Using in Medium and High Voltage Switching Devices

“…As elemental powders we used W powder (purity of 99.95%, Fisher diameter of 4.37 µm, Scott density of 4.22 g/cm 3 , tap density of 7.57 g/cm 3 , Eurotungstene Metal Powder, France), electrolytic Cu powder (purity of 99.9%, particle size up to 63 µm, apparent density of 1.6 g/cm 3 , GGP Metalpowder AG, Germany) and Ni powder (purity of 99.9%, average particle size of 5 µm, Merck, Germany).…”

“…The density was determined at 16°C by Archimedes' principle, in ethyl alcohol with density of 0.7928 g/cm 3 , using an analytical balance (Kern AEJ, Switzerland) equipped with a set for density determination of liquids and solids. The measurements were carried out in triplicate, and their mean values are presented.…”

“…W-Cu materials are of a major interest for thermal-electrical applications like electrical contacts used in low voltage (LV), medium voltage (MV) and high voltage (HV) switching devices working in vacuum, sulfur hexafluoride (SF 6 ) gas or oil [1][2][3][4][5][6][7][8][9][10][11][12][13][14].…”

“…W-Cu composites are considered as pseudo-alloys and advanced engineering materials due to their specific physical, electrical, thermal and mechanical properties. W-Cu powder mixtures are produced by various methods, from which the common methods are mechanical mixing, mechanical alloying and high energy ball milling of elemental powders in dry or wet conditions [2][3][4][5][6][7][8][9][10][11][12][13][14].…”

“…High sintering temperatures or long holding times help to improve the densification but Cu may leach out from the skeleton which leads to Cu segregation and results in non-homogeneous microstructure and poor product performance [7,8]. Therefore it is necessary the achievement of new W-Cu composites by alternative techniques than conventional ones like spark plasma sintering (SPS) to minimize microstructure coarsening and to improve homogeneity of contact materials [2,3,[16][17][18][19]. By SPS process, consolidation of powders is performed rapidly with uniaxial force, high heating/cooling rates and a pulsed (on-off) direct electrical current [18,19].…”