Optimization of atmospheric low-power plasma spraying process parameters of Al2O3-50wt%Cr2O3 coatings

The work is focused on the effect of the processing parameters of Al2O3-50wt%Cr2O3 coatings manufactured by low-power plasma spraying systems on the microstructure, mechanical properties, and tribological behaviour. Design of experiments followed by an optimization process using desirability functions has been applied for the selection of the processing parameters. The results indicate that power is the crucial parameter that controls the microstructure and consequently, the mechanical response of the coatings. At high powers, the highest volume of hard phases is attained, which leads to the highest hardness values and the best wear resistance at high applied loads. On the contrary, at low powers, the highest volume of spinels (tough phases) is observed, resulting in the highest indentation fracture toughness values and the best wear response at low applied loads. Therefore, the mechanical properties are directly related to the contents of the tough and hard phases.