(V) Evaluation of cold sprayed CuCr coatings for vacuum switching applications

In the present study, cold sprayed copper-chromium (CuCr) coatings are investigated as an alternative to traditional CuCr composites which are used for vacuum switching applications. Test samples for this study are produced by depositing pre-mixed Cu and Cr powders using cold spray technique with N2 as carrier gas. Microstructures of these coatings are characterized by SEM and their compositional distribution is studied using EDX. Electrical and hardness properties of these coatings are measured, and compared with bulk CuCr composites (with similar Cr wt%) which are produced by press-sinter-infiltrate (PSI) method and vacuum induction melting (VIM) method. Furthermore, the coatings are subjected to electrical arcs in a vacuum chamber, and the arc propagation on surface of cold sprayed coatings vs bulk composites is analyzed by observing arc track morphology using SEM. Finally, the vacuum arc-erosion rate of the cold sprayed coatings is established.