Synthesis of Ti(C, N, O) coatings by unbalanced magnetron sputtering

Several TiCNO coatings were deposited using an unbalanced magnetron sputtering system. The composition of C, N, O was first studied using GDOS (glow discharge optical spectrometer). The coating properties as a function of oxygen/nitrogen flow ratio were then studied by using SEM, scratch testing and nano-indentation measurement. The tribological properties of the coatings were then investigated using a ball-on-disk setup with alumina balls. The sliding speeds were set at 10, 20, and 30 cm/min. The results show that coating properties and performance are greatly affected by the flow rate of oxygen. With oxygen flow rate set at 4 sccm during deposition, the TiCNO coating shows the lowest wear rate and friction coefficient among all. Further increase in oxygen flow rate caused a decrease of wear resistance with the increase of friction coefficient. The wear debris were analyzed using Raman spectroscopy. The tribological behavior of the selected TiCNO coating was also compared with other Ti-based hard coatings.