High-Velocity Air Plasma Spraying of (Ti, Cr)C-32 wt.% Ni Clad Powder

The influence of air plasma spraying (parameters such as plasma gun power, spraying distance, plasma gas flow, anode diameter) of (Ti, Cr)C-32 wt.% Ni clad powder on the characteristics of resultant coatings (structure, microhardness, porosity, phase composition) is studied. The experimental procedure is designed using the mathematical planning method. The experimental data are processed to derive regression equations, determining the quantitative dependence of average microhardness and stability of microhardness characteristics on spraying process parameters. It is found that plasma gun power and plasma gas flow have the greatest impact on microhardness of the coatings and Delta X/HVav parameter, which characterizes the reproducibility of coating properties. The spraying distance has hardly any influence on the properties studied within the test range (160-220 mm). The hardness of coatings produced from the (Ti, Cr)C-32 wt.% Ni clad powder (12.15-14.58 GPa) is higher than that of the coatings obtained by air plasma spraying of a mechanical mixture of 75 wt.% (Ti, Cr)C + 25 wt.% NiCr (5.3-12.6 GPa).