Nickel matrix composite electrocoatings as stationary electrical contacts

Abstract

The electrical contact characteristics are dominated by the interfacial transport processes, thermal generation and dissipation rates, mechanical fatigue during the operations, material phase transitions and migration effects as a result of transient phenomena during arcing. The work presented in this paper explores the possibility of using as electrical contacts composite nickel matrix electrodeposits prepared under direct current (DC) and pulse current (PC) conditions. The codeposition of liquid-containing microcapsules (/spl mu/caps) along with the metal matrix from electrolytic baths leads to the development of a totally new type of material, the liquid-containing metal electrocoating with prespecified properties. The incorporation of oil-containing polymeric wall /spl mu/caps in the nickel matrix ensures a self-lubrication-cooling action during fretting or transient operation. The electrical properties of composite nickel electrodeposits have been investigated for possible utilization as electrical contacts. Different preparation conditions have been employed. Their contact resistance and interfacial temperature for a great number of operation cycles have been monitored under constant axial contact force using low current excitations. SEM and XRD analysis were applied for the inter-electrode surfaces for investigating their structural characteristics.