Processing and characterization of AISI 316L coatings modified with Cu and CuO nanoparticles

Abstract

Nanoparticles (NPs) have been used to benefit from Cu properties, due to their unique physicochemical characteristics caused by a high surface-to-volume ratio. However, to enable the deposition of hardfacing coatings with NPs, it is of interest to evaluate the processability of nanocomposite materials. The processability of hardfacing coatings, measured by their soundness, porosity, hardness, and solidification structure, is particularly relevant to assess the effects of adding Cu NPs and CuO NPs to AISI 316L. This study prepared and deposited powder mixtures of AISI 316L atomized steel with 5 wt% Cu microparticles (MPs), Cu NPs, and CuO NPs, individually, to process coatings by plasma transferred arc. Results showed that Cu additions alter the processability of AISI 316L and that both NPs influenced dilution and wettability of layers, requiring higher deposition energy to avoid lack of fusion. The interaction between the powder and the plasma arc depends on the features of the powder mixtures and a hypothesis for the behavior of the powder mixtures used across the plasma arc is put forward. The more significant evaporation during hardfacing with powder mixtures with NP particles induced a more significant loss in Cu and an increase in porosity in the austenitic coatings. Further impacts of the Cu-based nanoparticles in the deposited powders mixtures are revealed by the finer solidification structure. Regardless of the features of the powder mixtures, Cu-containing coatings showed a lower hardness associated with Cu being in solid solution on the as-deposited condition.