Modification of surface hardness, wear resistance and corrosion resistance of cold spray Al coated AZ31B Mg alloy using cold spray double layered Ta/Ti coating in 3.5 wt % NaCl solution

Daroonparvar, M.; Khan, M.U. Farooq; Saadeh, Y.; Kay, C.M.; Kasar, A.K.; Kumar, P.; Esteves, L.; Misra, M.; Menezes, P.; Kalvala, P.R.; Bakhsheshi-Rad, H.R.; Gupta, R.K.

doi:10.1016/j.corsci.2020.109029

Cold spray additive manufacturing (CSAM) has gained significant attention for its rapid solid deposition capabilities. However, the presence of defects such as pores and voids limits its performance, particularly in electrochemical environments. In this study, a novel post-surface treatment, plasma electrolytic oxidation (PEO), was applied and investigated as a feasible solution to overcome these defects. Results demonstrated a successful PEO deposition on cold-sprayed 316L stainless steel (SS) due to the rapid formation and discharge of aluminate electrolytes along the surface. However, due to the severely strained and highly crystalline surface, the electric field that allows for the deposition of Al(OH)42 anions was reduced. As consequence, an uneven and rough deposition took place. Nonetheless, a successful Al2O3 film of 12.30 lm thickness was formed. Experimental tests were further conducted in simulated aqueous and biologicalbased solutions to test the electrochemical resistance of the deposit. Results reveal a noticeable enhancement in corrosion resistance for both solutions. This enhancement can be attributed to the ‘‘postponing’’ and ‘‘blocking’’ effect enabled by the Al2O3 film, which prevented the electrolyte solution from penetrating the CS surface. Collectively, these findings suggest that PEO is indeed a promising technique to mitigate the chemical degradation of CSAM’d 316L SS.

More Like this