Model-based expert system for design and simulation of APS coatings

This article aims at presenting an expert system to assist the design and the simulation of 2-D shapes of alumina-titania (i.e., Al2O3-13 wt.% TiO2) Atmospherically Plasma Sprayed (APS) coatings. Indeed, the expert system derives from a spray deposition mathematic model resulting from experiments. The varied processing parameters were the geometric and the kinematics parameters, mainly, such as: the relative speed gun-substrate, the spray distance, the spray angle, the relative positioning powder injector-spray gun trajectory, the number of passes and the powder feed rate. The variations of the geometry and some of the structural parameters were analyzed relatively to the aforementioned varied parameters. Thus, a large set of spray pattern parameters was designed. This set considers mostly the spray pattern geometry. All the relationships between the processing parameters and the spray pattern parameters were hence grouped in a spray deposition model. The second step of this work consisted in optimizing the robotic (i.e., spray gun) trajectory using a robotic code, which permits a realistic simulation of the spray gun speed and its inertia. Using this simulation software, a trajectory file was built. In the third step of the work, an expert system was developed by combining the spray deposition model with the trajectory. The tasks of the expert system are: (1) to assist the user in designing the coatings by selecting the processing parameters and (2) to simulate the coating shapes by integrating the gun trajectory.