Computational Model for Predicting Coating Thickness in Electron Beam Physical Vapor Deposition

Electron Beam Physical Vapor Deposition (EB-PVD) is an important process for material coatings such as thermal barrier coatings on turbine blades and titanium carbide coatings on cutting tools. A generic computational model is proposed in this paper for predicting coating thickness on complex workpieces using EB-PVD. The surface of the workpiece is represented as a mesh of finite elements, and the accumulated coating thickness on each element is computed based on its location in the vapor plume using a ray-casting algorithm. Analytical models are derived and experimentally tested for workpieces with simple geometry. Coating thicknesses predicted by the computational model agree well with those predicted by analytical models and experimental results. A method is also proposed to characterize and predict process efficiencies and the time required to achieve a minimum coating thickness. The computational model is suitable for workpieces with complex, three-dimensional geometry using any line-of-sight coating process. Applicability of the model is illustrated by simulating turbine blade coating using EB-PVD.