Knowledge based coating design of CVD TiN-TiBN-TiB2 architecture

Chip removal operations for high tech materials like aerospace components or refractory metals need tool coatings with high wear resistivity. When widely used coatings like PVD TiAlN, CrAlN or CVD TiCN-Al2O3 cannot fulfil the demands properly, special solutions are needed. One possible solution is the use of CVD TiN-TiB2 coatings which covers high hardness as well as good coating adhesion. Unlikely for CVD processes, this coating shows residual compressive stress, which protect the cutting edges and increase the toughness of the tools comparable to PVD systems. The present work shows, how high-resolution characterization techniques were applied to design an improved coating architecture based on material properties and stress gradient design. A multilayered system was developed, to optimize the transition of material properties and microstructure from cemented carbide to the TiB2 layer. The increased process reliability of these tools is validated in milling of titanium alloys, as needed i.e. for the manufacturing of aerospace components.