Influence of Core/Shell Nanoparticles on the Fretting Behavior of Electrical Contacts

In order to guarantee long lifetime and high performance of electrical contacts, a plating is usually applied on the base material. Silver is a promising plating material because of a good balance between performance and costs. The conventional silver plating is soft; therefore, a thick silver plating should be used to prevent the wear through during the operation. In order to enhance the wear resistance and prolong the lifetime of the silver plating, silver platings are modified by co-depositing nanoparticles with a core/shell structure into the silver matrix. A novel method to prepare the Ag (shell)@Al
2
O
3
(core) nanoparticles by galvanic process is introduced in this paper. The influence of fabrication parameters in the galvanic process such as the concentration of silver nitrate solution and the plating voltage on the silver content in the Ag@Al
2
O
3
nanoparticles is investigated. Afterwards, different concentrations of core/shell nanoparticles are co-deposited into the silver plating to study the effect of nanoparticles on the microhardness, microstructure and the lifetime of the silver plating. As a result, the microhardness and the lifetime of the silver plating are significantly improved and a favorable nanoparticle concentration exists for the longest lifetime. Moreover, the mechanism of the lifetime improvement is determined.