Author(s)

A. T. T. Tran, M. M. Hyland

Abstract

Thermal spray coatings have been widely applied to enhance the appearance, adhesion, wear, oxidation, and corrosion resistance of materials in various industrial applications. Coatings form by the impact and spreading of high velocity molten coating droplets (splats) on a substrate. Coating buildup occurs as subsequent droplets overlap. A fundamental understanding of the complex interaction between a droplet and solid substrate can help to predict and improve the splat spreading process and thus the quality of coatings at a larger scale. In this study, a three dimensional model has been developed to simulate the impact, spreading and solidifying process of a micrometre-sized molten nickel droplet on a smooth stainless steel surface. The model is based on computational fluid dynamics (CFD), and combines a multiphase Eulerian fixed-grid model with a volume of fluid method (VOF) to track the droplet free surface. The effects of thermal contact resistance and contact angle on droplet shape were investigated. We demonstrate that high values of thermal contact resistance or contact angles can induce droplet breakup. The numerical results will provide new insights into the interpretation of empirical results as well as enhance the physical understanding of the fluid mechanism that leads to splashing

Keywords

CFD, contact angle, droplet deformation, droplet modelling, metallic droplet, solidification, splashing, VOF