Effects of Types of Copper Powder on the Properties of Cu-Ni-Si Powder Metal

Copper Nickel Silicon (CuNiSi) is an ideal material for replacing the more toxic copper beryllium alloys. Having good electrical conductivity, high strength and heat conduction, this alloy can be used in a multitude of applications that include valve stems, connectors, fuse clips, and contact springs. Depending on the size and shape of the particles, different types of copper can influence the properties of Cu-Ni-Si powdered metallurgy (PM) components. In this study, experimentation was conducted with three types of copper, oxide reduced, water atomized, and fine particle copper blended with Ni, Si, and lubricant. The three powders were compacted to three pressures of 30, 40, and 50 tsi and sintered at the same conditions. Tests such as transverse rupture strength, apparent hardness, tensile strength of the parts were performed. All Cu-Ni-Si powder decreased in density from green to sintered due to expansion of copper. It was found that the water atomized copper powder showed the highest transverse rupture strength (TRS) and tensile values when compared to the oxide reduced and fine copper powder at sinter. It was also noted that sizing, heat treating, and age hardening further increased the tensile strength of the parts. From the results, it was concluded that water atomized copper would be the best copper powder to use in Cu-Ni-Si powder metal due to its high TRS and tensile results.