Process Analysis of Plasma Spraying of Recycled PET Based on a Heat Balance Model

In the present study, waste PET bottle was used as a recycled PET plate substrate for plasma spraying. The plasma spraying process to PET was analyzed by a heat balance model during the plasma spraying for the purpose of determining the optimal spraying condition. It was found that Cu and TiO₂ powders could be coated on the surface of recycled PET plate. The implantation of Cu and TiO₂ particles into the PET substrate was sometimes observed under a certain spray conditions. Both kinds of Cu and TiO₂ particles retained their original spherical shape. Cu coatings were formed when almost copper particles were melted to 1780 K greater than the melting point of Cu. In anatase TiO2 spraying process, heat input to anatase particles adhered to PET was much less than that to adhered rutile particles so that anatase TiO₂ could be coated on PET plates. Heat input during plasma spraying is, therefore, very important for endowing wasted PET materials with a new function by plasma spraying of metal and ceramics such as Cu and TiO₂. Although the idea about the heat balance is very simple, the analysis is useful for optimizing the spraying process of PET.