Effect of annealing conditions on in situ formation of Cr2O3 diffusion barrier

The previous investigation suggested the approach for an in situ formation of Cr2O3 diffusion barrier by annealing the cold-sprayed Ni coatings on 310SS. In this paper, the influences of annealing conditions on the growth kinetics of Cr2O3 and substrate microstructure were investigated. Results show that Cr2O3 formed at the selected annealing temperatures of 850, 900 and 950 degrees C for different durations of 4, 8 and 20 h. Increasing temperature enhanced the growth kinetics of Cr2O3 and the Mn content in the oxide layer. The annealing process for the growth of Cr2O3 improves the coating adhesion compared to the as-deposited coating. However, annealing at 950 degrees C resulted in the precipitation of chromium carbides and enhanced the element inter-diffusion across the substrate/coating interface.