Fabrication and properties of sic reinforced copper-matrix-composite contact material

Abstract

This study aims at improving mechanical properties of electrical contacts through copper and copper-matrix silicon-carbidereinforced 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 °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.