In-Situ Processing of Functional Graded Coatings by Means of Atmospheric Plasma Spraying

Functionally graded coatings exhibit outstanding thermomechanical performances that meet economic demands. By influencing the microstructural formation of the layers of the coated tool, the distribution and transfer of heat from the impact zone into the forming process is determined. Thus, largely affects the tool’s life cycle and microstructure in the surface area of the parts to be formed. With respect to graded coatings, examinations on simple substrates have already shown the applicability of different microstructure formations of coatings. In these approaches, varied parameter settings were investigated to identify the most significant factors and their effects on the formation of the microstructure. Furthermore, using different grain-sized powder materials and utilizing other thermal spraying methods, it is possible to generate either porous or dense coatings according to their requirement profile. The utilization of different thermal spray methods particularly leads to high costs caused by increased setup times. As opposed to traditional thermal spray deposition process parameters for graded coatings, generated by an in-situ process, need to become coordinated with the movements of the robot. In this study, we investigated the dependencies between the spray parameters of Atmospheric Plasma Spraying, such as spray distance and spray angle, and the formation of microstructures. The investigation focusses on the utilization of Alumina (Al₂O₃) which is widely used as a wear and corrosion resistant coating.