Thermodynamic assessment of chrome-spinel formation in laser-sintered coatings with Cr2O3 particles

Formation of a thin passive layer has been performed using short pulse laser dispersion of Cr2O3 particles in a C22 steel substrate. As a result, the coating’s corrosion resistance is substantially improved compared to unprocessed samples. Microstructure analysis by TEM, XPS, and XRD showed that laser processing leads to dissolution of Cr2O3 with formation of Cr and Fe oxides, chrome-spinel, and metallic Cr dispersed in alpha and gamma Fe. Thermodynamic assessment revealed that the formation of pure chromium is caused by reduction of Cr2O3 and oxidation of iron. This reaction is promoted by shifting of chemical equilibrium at elevated temperatures in the molten zone under short pulse laser processing.status: publishe