Properties of TiAlCN/VCN Nanoscale Multilayer Coatings Deposited by Mixed High-Power Impulse Magnetron Sputtering (HiPIMS) and Unbalanced Magnetron Sputtering Processes-Impact of HiPIMS During Coating

Nanoscale multilayer TiAlCN/VCN coating has been deposited by pure unbalanced magnetron sputtering (UBM) and high-power impulse magnetron sputtering (HiPIMS)-UBM techniques. The V+ HiPIMS etching used in both processes has shown excellent adhesion (Lc > 50) of the coating to the substrate. The plasma compositional analysis of V+ HiPIMS etching has shown high metal-to-gas ion ratio with ionization states of V up to 5+. Moreover, during the coating of TiAlCN/VCN, the plasma analysis has confirmed the higher production rate of metal ions in the case of HiPIMS-UBM in contrast to pure UBM. This has resulted to a denser closed columnar microstructure of the coating during the HiPIMS-UBM technique than UBM. A thermogravimetric analysis has shown increased oxidation-resistance temperature for coatings deposited by HiPIMS-UBM (approximate to 780 degrees C) with significantly lower mass gain. The scanning electron microscope and X-ray diffraction studies of the oxidized surface of the coating have revealed the formation of lubricant Magneli phase oxides of V2O5 and TiO2 at elevated temperature. The wear coefficient of the coating deposited by HiPIMS-UBM has shown two orders of magnitude lower value than that for the UBM-deposited coatings, which represents significant advantage for coatings deposited by UBM. This enhanced performance in oxidation-resistance dry sliding wear conditions can be attributed to the extremely dense structure of the HiPIMS coatings, which could be promising in elevated temperature applications.