Abstract

Aerosol deposition is an emerging coating process for solid state deposition of ceramic particles at room temperature. The industrial applications for aerosol deposition method are MEMS, fuel cells, optical devices and RF components. During deposition, various parameters play influential roles such as nozzle geometry, powder size and material, pressure inside the deposition chamber and carrier gas pressure. Two different drag expressions for the particle phase modeling are proposed and compared in order to capture the physics governing the fluid-particle flow in partial vacuum conditions. Then, the main focus is dedicated to the effect of three-dimensional analysis, gas flow rate and substrate location on the gas flow and particle condition upon impact on the substrate. Numerical study is performed using a two-way coupled Eulerian-Lagrangian model for a slit sonic nozzle with various gas flow rates and standoff distances. Locations of the predicted shocks for the free jet case are validated against the theoretical and experimental studies in the literature. By placing a substrate in the computational domain at various standoff distances, the characteristics of gas flow, bow shock and importantly particle trajectories and conditions upon impact have been examined rigorously. Accordingly, the optimized model to predict particles velocity are proposed and the effect of different parameters on particles velocity during the spray and upon impact are discussed.