Interrelation between microstructure and anti-corrosion property of cold splayed coatings

For corrosion protection, sacrificial coatings are one solution to limit degradation of metallic ma-terial in aggressive environment. Al and Zn are deposited by various techniques, cold spray method is suitable for creating thick layer and for local restoration of damaged surface. Unlike Thermal Spray dep-osition techniques, Cold Spray avoid particle melting and face transformation due to deposition under melting temperature of feedstock materials, cooling of nozzle also helps to control overheating. For anti-corrosion application, high density coating with a strong metal-coating adhesion are required. Since cold spray deposition is a semi-empirical method, deposition parameters have to be optimized experimentally regarding the porosity of the layer and the deposition efficiency. In this work, both porosity and deposition efficiency have been used for Al and Zn coating by LPCS spray and HPCS, respectively. If numerous works refer to Al coating, only few deals with Zn coating by cold spray. The aim of this talk is to propose a comparison based on electrochemical and microstructural characterizations of the performances of Al and Zn coating designed by cold spray. The densification is obtained either by mechanical pining effect by spraying of mixture of metal with hard particles of ox-ide/carbide (alumina), or laser surface melting.