Properties of TiN-TiG multilayer coatings using plasma-assisted chemical vapor deposition

A multilayer of TiN-TiC has been deposited on commonly used die steels (D2) by the pulsed DC plasma-assisted chemical vapor deposition process. The TI C layer was successfully deposited at 580 degrees C with a gas mixture of T iCl4, CH4, H-2 and Ar. A minimum flow of TiCl4 (3.5 g/h) and CH4 gas (18-20 sccm) were used to minimize the excess carbon phases and the chlorine cont ent in the TiC deposited layer. A gas volume ratio of TiCl4/CH4 in the rang e 0.34-0.38 is required to obtain dense TiC films with minimum excess carbo n phases and low chlorine content of less than 2.5 at.%. The Ti/C ratio of the most dense film was measured as about 1.11, which corresponds to the su b-stoichiometric carbon composition of 46 at.%, using Rutherford backscatte ring spectrometry (RBS) and Auger electron spectroscopy. This implies that a single phase of TiC can be formed near a sub-stoichiometric composition w ith no extra phases such as carbon and oxide phases in the TiC layer. In ad dition, the existence of the oxide phase in the TIC layer deposited with lo w methane gas flow was proved by the RES measurement. (C) 1999 Elsevier Sci ence S.A. All rights reserved.