The effect of nano-sized Cr2O3 addition on the characteristics of NiCr-Cr2O3-Ag-BaF2/CaF2 coating

A conventional micro-sized NiCr-Cr2O3-Ag-BaF2/CaF2 blending feedstock (PS304; developed by NASA) leads to a non-uniform layered coating microstructure due to the difference in the physical and thermophysical properties of components. Therefore, in this research, we made a new feedstock of one system including a nano-component (under 100 nm Cr2O3) through the spray drying method. Microstructure and mechanical properties of the nano-Cr2O3 containing spray-dried coatings were evaluated and compared with the blended feedstock (PS304). The coating microstructure had more uniform, finer microstructure and the mechanical properties (Vickers microhardness and bonding strength) of spray-dried coatings were improved.