Development of Plasma Spray Gun for Inner Diameter Suspension and Fabrication of Thermal Spray Coating

This study compares the performance of an ordinary plasma spray gun with that of recently developed gun designed for spraying feedstock suspensions on inner diameter surfaces. To evaluate the guns, yttrium oxide was deposited on 304 stainless steel while varying supply pressure, spraying distance, and gun traverse speed. Different methods of delivering suspension spray material to the gun were also investigated. Although Y₂O₃ inner-diameter coatings were successfully formed, hardness and cross-sectional porosity need improvement. Based on the findings, it may be necessary to increase substrate temperature, readjust spraying parameters, and optimize feedstock materials.