Novel morphologies and growth mechanism of Cr2O3 oxide formed on stainless steel surface via Nd: YAG pulsed laser oxidation

Novel morphologies of chromium sesquioxide (Cr2O3) were successfully formed on AISI 304 stainless steel surface by Nd: YAG pulsed laser oxidation in air. The obtained Cr2O3 presented mainly dendritic, gear-like, flower-like and regular hexagonal morphologies with sizes from hundred nanometers to several micrometers. These various morphologies chiefly originated from two groups of diverse growth directions within (0 0 0 1) basal plane, i.e., 〈21¯1¯0〉 and 〈011¯0〉 directions. The preferential growth along different directions determined the final Cr2O3 morphologies. And the crystallographic analyses basically accorded with the experimental results. Moreover, the growth mechanism of the hexagonal Cr2O3 was analyzed in detail from its morphology evolution, and a corresponding growth model was reasonably proposed.