STUDIES ON SYNTHESIS OF ALUMINUM-CONTAINING LAYER SYSTEMS ON STEEL AND CERMET SUBSTRATES BY PACVD

The deposition of aluminium containing, especially aluminium oxide coa tings on steel and cermets was performed by the plasma assisted chemic al vapour deposition (PACVD) process using a metallo-organic compound (AlH3.NEt3) as precursor. The usefulness of the precursor in the PACVD process was investigated. The deposition process of non-conducting al uminium oxide layers was developed by pulse d.c.-PACVD. Optical emissi on spectroscopy (OES) was used for in situ process control. The invest igation by OES enables the identification of the species in the discha rge (Al and other) and thus supports the successful process developmen t. The structure, chemical composition, bonding types in the layers, h ardness, adhesion, roughness, friction coefficient and friction behavi our by a pin on the disk test have been investigated. The layers consi st of Al, O and traces of carbon using the metallo-organic precursor. The friction coefficient is > 50% less compared to an uncoated steel s ubstrate up to the breaking through of the layer by a pin on the disk test. (C) 1998 Elsevier Science S.A.