Structure and tribological properties of TiN coatings grown by hybrid HIPIMS and CFUBMS deposition

摘要

Over the past decade, high power impulse magnetron sputtering (HIPIMS) has attracted substantial attention because of its ultra-dense plasma deposition environment. However, early examples of the HIPIMS process showed significantly decreased deposition rates. In this paper, a hybrid process utilising one HIPIMS powered magnetron in a closed field unbalanced magnetron sputtering (CFUBMS) configuration with other three direct current (DC) powered magnetrons, was developed to grow a TiN hard coating reactively on high speed steel and stainless steel substrates, to compare with a similar TiN coating grown purely by reactive CFUBMS deposition. The deposited coatings were characterized by XRD, FEG-SEM and cross-sectional TEM, and evaluated by Knoop indentation and un-lubricated ball-on-disk tribo-tests. The results showed that the hybrid sputtering process achieved a deposition rate of 0.047 μm/min, only about 23% lower than the pure DC sputtering. The benefits of including HIPIMS in hybrid sputtering deposition have been found to be the increase in the hardness of the coating from 3.5 to 3.9 GPa and, perhaps more importantly, a significant reduction in the magnitude of the compressive residual stress in the coating, from -6.0 to -3.5 GPa. The dry sliding coefficient of friction and the specific wear coefficients were in the range of 0.8-0.9 and 1 to 2×0-15 m3N-1m-1 respectively.