Structure and Strength Effects in CVD Titanium Carbide and Titanium Nitride Coatings

Abstract

The first part of the study deals with the influence of CVD titanium carbide and titanium nitride coatings on the transverse rupture strength of M10 and P40 cemented carbide. The rupture strength is noticeably reduced by the coating, the extent of this decrease depending on coating thickness, coating structure, and the presence of a decarburization or brittle phase in the surface zone of the substrate material. Furthermore, it was found that a thin intermediate nickel layer does not have any positive effect on the rupture strength. The second part deals with investigations on the effect of substrate composition on the structure of the and coatings. In presence of nickel‐containing substrates, the forms dendritic structures, the coarse‐grained structures. Nickel is also incorporated into the coating. Increasing the reactant concentration in the gas phase intensifies these effects. Finally, the mechanisms underlying these effects are briefly discussed.