Simulation of Plasma Electrolytic Oxidation (PEO) of AM50 Mg Alloys and its Experimental Validation
The PEO process is a useful surface technology to improve wear performance and corrosion resistance on light metals such as Mg, Al and Ti and their alloys. It has been studied for several decades, but up to now, its mechanism is still not fully understood. In order to improve the understanding of PEO process and get better process design for industrial application, it is worth studying numerical approaches of the PEO process. This thesis provides a modeling and simulation approach to study the PEO process on Mg alloy AM50 under constant voltage mode. A numerical model has been built to describe the PEO process using Finite Element Method in COMSOL. Experiments are performed to provide data input for the modeling and simulation, and also to validate the correctness and usefulness of the modeling. From comparison, the simulation result of coating thickness is in good agreement with the experimental result. The application of the model was verified by studies investigating the influences of different voltage, a complex substrate geometry and the electrode distance on the formation of PEO coatings. The approach of the model can predict the coating thickness close to the experimental results and explain the effects of the main process parameters on the coating growth reasonably. Therefore, the methodology provided by the numerical model has been demonstrated to be a useful tool for predicting the coating thickness and explaining the effects of different parameters on Mg alloy under constant voltage mode.