Manufacturing of HVOF sprayed, finest structured cermet coatings using fine WC-12Co powders

The continuous increase in productivity and performance of modern sheet metal forming processes combined with the employment of novel, high strength materials cause high wear on tool systems. Coating technologies like thermal spraying provide a high potential to functionalize and to protect the surface of forming tools. However, it has to be ensured that the high shape and dimensional accuracy of the tool contour is preserved after the application of a wear protective coating. This aim cannot be achieved using currently applied, thermally sprayed coating systems with conventional, coarse grained microstructure. To solve this problem, novel finest structured coatings have been developed in this study by thermal spraying of fine WC-12Co powders using the HVOF technique. For this purpose the influence of varying HVOF combustion gas compositions on the spray process as well as on the corresponding coating properties has been investigated. Next to a high surface quality the focus was placed on achieving coatings with high hardness and corresponding high wear resistance, low porosity as well as a good adhesive strength on the substrate material.