Effect of heat treatment on properties of cold sprayed nanocrystalline copper alumina coatings

Cold gas dynamic spraying appears to be the most appropriate thermal spraying technique for depositing nanocrystalline powders given its low deposition temperature. Nanocrystalline copper alumina coatings were deposited on copper substrates and the effect of heat treatment temperature on porosity, grain size, microhardness and conductivity of the coatings was studied and compared with that of cold sprayed copper. The role of alumina in inhibiting grain growth and in strengthening the copper matrix was investigated. An attempt has been made to assess the contribution of various mechanisms to the conductivity of nanocrystalline copper alumina coatings.