Comparison of in-situ oxidation behavior of Zr by micro-arc oxidation and selective laser melting

Al2O3-ZrO2 ceramic coatings were prepared on 6061 Al alloy by Micro Arc Oxidation (MAO) and Selective Laser Melting (SLM). Coatings prepared by MAO exhibit a porous structure and a progressive oxidation of the substrate as a function of processing time. Those made by SLM are denser, although the presence of cracks is observed throughout their surface. XRD results suggest that the ceramic coating consists of m-ZrO2, t-ZrO2 and gamma-Al2O3 phases for the MAO process, while a Zr3O phase is also present in SLM. The hardness of the MAO Al2O3-ZrO2 coating is higher than that obtained by SLM. Young's modulus of the MAO coating is lower, due to higher level of porosity observed in the coating prepared by MAO. Moreover, in-situ oxidation, heating and solidification processes are all discussed and compared within the context of MAO and SLM peculiarities. The processes and transformation mechanisms involved in the processing methods produce diverse microstructures.

Automated summary

In this study, Al2O3-ZrO2 ceramic coatings were prepared on 6061 Al alloy using MAO and SLM methods. The MAO coatings exhibited a porous structure and progressive oxidation of the substrate, while the SLM coatings were denser with cracks observed on the surface. XRD analysis revealed that the ceramic coating in the MAO process consisted of m-ZrO2, t-ZrO2, and gamma-Al2O3 phases, while a Zr3O phase was also present in SLM. The MAO Al2O3-ZrO2 coating exhibited higher hardness compared to the SLM coating, and the Young's modulus of the MAO coating was lower due to higher porosity. The in-situ oxidation, heating, and solidification processes and transformation mechanisms were discussed and compared for MAO and SLM.