Plasma Spraying of Metal Coatings using CO₂ Based Gas Mixtures

The use of gas mixtures containing hydrocarbons for plasma generation results in higher plasma enthalpy because, molecular gases must dissociate before ionization which requires larger energy input. The torch developed at CACT which operates with CO₂+CH₄ gas mixtures was used for coating deposition with input power in a range of 30 to 45 kW. This study was focused on the effect of CO₂+CH₄ mixtures on the particle parameters during spraying of Ni alloy powder. Results of gas composition analysis at various distances from the nozzle exit are presented. The particle in-flight conditions, coating microstructure, and deposition efficiency also were analyzed.