A novel spatial-distribution-function of electron beam-induced vapor plume for analyzing EBPVD thickness

This paper investigates the thickness distribution of substrate coating of electron-beam physical vapor deposition (EBPVD) using a novel spatial-distribution-function, which is different from the empirical modified law. The Knudsen cosine law and empirical modified law were usually used for predicting coating thickness in EBPVD. However, these two laws obtained from experiments and geometric concepts cannot provide the elucidation for physical point of view and all-inclusive spatial-distribution-functions. Therefore, instead of the spatial-distribution-functions based on the Knudsen cosine law for low evaporation rates and empirical modified law for the higher evaporation rates, the spatial distribution function based on the mass diffusion theory is proposed to analyze the coating thickness of EB-induced physical vapor deposition. The coating thicknesses predicted by these spatial-distribution-functions are compared with the data measured by the published papers. The results reveal that the coating thicknesses predicted by the spatial distribution function of the diffusion theory are more consistent with the measured data than these obtained from the spatial distribution function of the empirical modified law. The spatial distribution function proposed by this study is validated by correctly predicting the measured coating thickness for EBPVD of titanium and aluminum.