CR-C-N COATINGS DEPOSITED WITH DIFFERENT REACTIVE CARBON CARRIER GASES IN THE ARC PVD PROCESS

In recent years, significant improvements in the performance and quali ty or many machining processes have been achieved through the depositi on of PVD hard coatings on the applied tools. Depending on the machine d material process, e.g. turning, milling or drilling, not only differ ent machining parameters but also different coating materials are nece ssary. In interrupted cut machining of tempered steel, for example, th e lifetime of Ti-C-N-coated inserts is several limes greater than that of TiN-coated ones. This is a result of the favourable thermophysical and tribological properties of Ti-C-N. The potential for tool protect ion by CrN coatings is a result of the high ductility and low internal stresses of this coating material. CrN films can be deposited with gr eater film thicknesses, still maintaining very good adhesion. This pap er presents the development of new arc PVD coatings in the system Cr-C -N. Owing to the carbon content in the coating, an increased hardness and a better wear behaviour in comparison to CrN was expected. The eff ects of various carbon carrier gases on the coating properties were ex amined. The coating properties were investigated by mechanical tests, X-ray diffraction and SEM analysis. Some of the coatings were tested i n machining tests. The results of these tests are presented. (C) 1997 Elsevier Science S.A.