Numerical simulation of coating growth and pore formation in rapid plasma spray tooling

Rapid plasma spray tooling (RPST) is a process that can quickly make molds from rapid prototyping or nature patterns without limitation of pattern's s ize or material. In this paper, the process of coating growth and pore form ation in RPST has been analyzed by numerical simulation. The objective of t his work was to determine the porosity in plasma sprayed coatings and verif y the developed computer model, which might serve for future thermal residu al stress studies of plasma sprayed coatings. The analysis was divided into two steps: particle flattening and coating growth. In the analysis, a ball istic model was used for modeling the in-flight powder particles. The metho d allows for the calculation of off-normal spray angle, which is common in plasma spraying of engineering components. Also, a set of rules for coating growth as well as pore formation in the coating has been proposed. Based o n these works, a computer program was developed to calculate the effects of process parameters, such as gun scanning velocity, spray angle, etc., on t he porosity of the coating. Finally, an experiment was carried out to verif y the effects of spray parameters on the porosity. The results agree with t he prediction of the model. (C) 2001 Elsevier Science B.V. All rights reser ved.