Salt spray corrosion behavior and electrochemical performance of laser cladded Ni60–Ti3AlC2 composite coatings in 3.5% NaCl solution

Abstract

Ni60–4%Ti3AlC2, –8%Ti3AlC2 and –12%Ti3AlC2 composite coatings were prepared on S355 steel by laser cladding, and the effects of Ti3AlC2 mass fraction on the corrosion behavior electrochemical performance of obtained coatings were analyzed using a salt spray corrosion test chamber and electrochemical workstation. The results show that the Ni60–Ti3AlC2 composite coatings are composed of Ti3AlC2, TixAly, Al4C3, Al3Ti and TiC phases, and their grains are refined with the increase of Ti3AlC2 mass fraction. The Ni60–12%Ti3AlC2 composite coating has the best salt spray corrosion resistance among the three kinds of coatings, which is attributed to the formations of α–Al2O3 and TiO2 oxide films The differences of diffusion rates between the Al and the Ti change the pH value near the anode and cathode of Ni60–Ti3AlC2 composite coatings, which is conducive to the formation of double–layer dense passive films to protect the composite coatings from further corrosion.