The thicknesses of HVOF-sprayed WC-12Co wear protective coatings usually range between 50 – 500 μm. These thicknesses ensure a homogeneous coating structure as well as sufficient material reserves for efficient wear protection. For applications which require high shape accuracies, a cost intensive finishing of the thick coatings, in terms of grinding and polishing, is necessary. Thus, smooth and thin coatings are favored. In this study, thin HVOF-sprayed carbide coatings are developed by means of fine sintered and agglomerated WC- 12Co powders (2 – 10 μm). The use of fine powders enables the reduction of the coating thickness down to values below 50 µm. To influence and adjust the thickness of the coatings the powder flow, the gun velocity and the track pitch were systematically varied. During these tests the hardness and the roughness of the coatings were scrutinized.

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 (Al 2 O 3 ) which is widely used as a wear and corrosion resistant coating.