Size Determination of the Grains in a Plasma-Sprayed Cast Iron Splat Based on the Heat Transfer Between the Splat and the Substrate

Abstract

The size of the grains formed in individual splats has a significant effect on the properties of a thermally sprayed coating. In this work, the grain size in a plasma-sprayed cast iron splat was predicted based on a known relationship between the grain size and the thermal contact resistance at the splat–substrate interface. A numerical calculation method, based on a 2D heat transfer model, was used to study the relationship between the thermal contact resistance and the melting depth on the substrate surface. The thermal contact resistance was evaluated according to the observed maximum melting depth from the field emission scanning electron microscope micrographs of the individual splats. The estimated grain size with a range 51.3-73.6 nm was in close agreement with the experimental observations.