Modeling the Coverage of Splat Areas Arising from Thermal Spray Processes

Abstract

The coverage of a deposited material that arises from the integration of discrete splat areas is an essential parameter that needs to be understood during thermal spray processes. However, there is absence of a theoretical method to predict and estimate the area coverage per pass by a thermal spray torch; for example by the plasma spray process. In this study, a model is presented that calculates the splat area coverage for a thermal spray process of ceramic materials. A focused survey of the published literature takes into consideration experimental observations that are related to this work. The model accounts for physical events in thermal spray processes, such as the use of a mono‐modal feedstock and size of spray stream. The model predictions for the area coverage of plasma sprayed yttria‐stabilized zirconia (YSZ) ranged between 12% and 18% depending on the value assumed for the maximum flattening ratio. The results for the model were demonstrated via wipe studies where microscope glass slides were spray coated with YSZ and image analysis conducted. The average coverage calculated was approximately 13% for the sprayed images. The experiment verifies that the simulation results from the model predict adequately the splat area coverage of a thermal spray process.