Production and characterization of novel electrical contact materials developed using layered metallic powders

In this study, in order to produce novel electrical contact materials using layered metallic powders; electroless silver, nickel and chrome coatings were applied on copper powders. Using the obtained layered powders, functional graded novel electrical contact materials were produced by powder metallurgy method. First of all, in order to determine the most suitable powder morphology for electroless coating quality; Electroless silver coating processes were applied to copper powders obtained by milling copper powders at different times. It was determined that the flake morphology was the most suitable for electroless coating processes. Two different functionally graded electrical contact materials (FGECM) produced by using layered powders by powder metallurgy method after electroless coating processes were designed as three layers. Although the lower and middle layers for both FGECMs contain the same materials; spherical copper powders were used in the bottom layer and silver-coated copper powders were used in the middle layer. For the first FGECM, in the upper layer; 3-layer powders containing nickel, silver and copper were used in the outer, middle and bottom layers, respectively, while 3-layer powders containing chromium, silver and copper were used for the second FGECM. The investigation of physical-mechanical properties, wear performance and arc-erosion resistance was carried out for the produced materials. While the electrical conductivity value obtained from FGECMs containing nickel was determined as approximately 85 IACS%, the hardness values increased up to approximately 125 HB. Although the electrical conductivity values decreased by approximately 15% compared to pure copper, the hardness values increased by approximately 50% compared to pure copper. Wear and arc-erosion resistances also increased approximately 3 and 10 times, respectively, compared to pure copper.