Modeling a MOCVD process to apply alumina films on the inner surface of bottles

摘要

Deposition inside a cavity with a narrow neck, i.e. a hollow body, is a challenge, in particular for the supply and the evacuation of the reactive phase and of the effluents through the same entrance. High gradients (pressure, velocity, species concentrations) and important convective mechanisms related to the impacting jet of the gaseous phase on the bottom inner wall of the cavity are created in that region. Given the increasing number of experimental parameters,modeling helps efficient process optimization with better understanding of physical and chemical phenomena occurring inside the hollow body. This study presents a numerical modeling using the CFD code Fluent to simulate a direct liquid injection metal organic chemical vapor deposition of amorphous alumina coatings from aluminum tri-isopropoxide (ATI) on the inner walls of a glass bottle. The model is used to predict local profiles of gas velocity, temperature and species concentrations into the reactor as well as local growth rate based on an apparent heterogeneous kinetic law of ATI decomposition. Comparison with experimental thickness profiles allows validating the model and leads to a better insight in the phenomena which impact film thickness inhomogeneity along the inner surface. The model contributes to the improvement of the reactor configuration by increasing the distance between nozzle and bottle and the outlet section of the nozzle.