Carbon based coatings for high temperature cutting tool applications

A new generation of carbon based composite coatings, with Cr and Ti as alloying elements and additions of B and/or N, was deposited by the unbalanced magnetron sputtering technique. The coatings were designed to produce a duplex layer with a hard coating of CrTiBCN as the intermediate layer and a carbon based tribological (solid lubricant) hard coating of C/CrTiB as the top layer in one deposition process. Chemical composition. physical properties and tribological behaviour of both the intermediate and the combined duplex layers were investigated for a wide range of temperatures (up to 600 degreesC). Hobs coated with these films were tested for cutting gears, using dry machining conditions. The Lest results under real conditions in production showed that this type of coating on hobs outperformed commercial TiN coatings. (C) 2002 Elsevier Science B.V. All rights reserved.