Solid Shroud for Energy Efficiency and Oxidation Control in Plasma Spraying

Modified plasma spraying processes using a solid shroud have been developed to address the challenges with the high energy consumption and oxidation of spray particles. Solid shroud reduces the mixing of the plasma jet with the ambient air and improves process efficiency. Previous studies indicate that utilizing a solid shroud increases plasma temperature, thereby enhancing the in-flight particle temperature. This allows for the spraying of ceramic materials like Al₂O₃ with lower power input while maintaining comparable deposition rates. Reduced air mixing provides the ability to deposit coatings of oxidation susceptible materials such as CoNiCrAlY. An optimization method, specifically particle swarm optimization (PSO), is coupled with an established CFD model of the plasma free-jet to iteratively determine optimal solid shroud geometries. Experimental validation involves measuring deposition efficiency and in-flight particle properties using DPV-2000 and Accuraspray 4.0. To assess oxidation reduction in CoNiCrAlY coatings, carrier hot gas extraction quantitatively measures oxide content. The optimized shroud geometry enhances plasma temperature due to reduced air mixing, potentially allowing for Al₂O₃ coating with lower energy input. The developed system implementing PSO enables the optimization of specific shroud geometries, enhancing energy efficiency and aligning with global goals to reduce energy consumption.