Abstract:
This study aims at improving mechanical properties of electrical contacts through copper and copper-matrix silicon-carbide reinforced composites produced with powder metallurgy. Copper powder was produced with the cementation method. Pure copper and mixtures of copper with 3 % of mass fraction of SiC powder were pressed with a uniaxial pressure of 280 MPa and sintered at 700 degrees C for 2 h in an atmospheric environment. After the sintering, these compacts were immediately pressed at a load of 850 MPa while the samples were hot. The characterization of the samples was made with microstructural investigations, relative-density experiments, electrical-conductivity and hardness measurements. XRD analyses revealed that there are no other phases besides Cu and SiC in the sintered samples. Electrical conductivity of pure copper was reduced from 91.7 1.8 % IACS to 66.4 +/- 0.9 % IACS but the hardness of pure copper was increased from 127 +/- 1.2 HVN to 142 +/- 6.0 HVN with the addition of 3 % of mass fraction of SiC. Contact-count experiments were made with these samples to determine the contact performance for (3000, 6000, 9000, 12.000 and 21.000) turns-on/off. The loss of the contact material increased with the increasing number of turn-ons, related with the increased copper oxide amount formed on the contact surfaces.
