Tribology of Sputtered Hard Coatings

High-rate-reactively-sputtered (HRRS) hard coatings have been deposited on steel rollers. The effects of substrate hardness and coating hardness on the tribological behavior of titanium nitride (TiN) coated steel rollers have been investigated with a roller-on-roller tribo-tester. The properties of both the substrate and the coating were found to be very important in determining the wear performance of the rollers. From experimental results it was noted that the relatively hard TiN coatings enhanced the scuffing-failure-load by ten times when deposited onto relatively hard substrates (Rc 62), but did not improve the performance of soft substrates (Rc 45). For a relatively soft substrate (Rc 45), the benefit of using the relatively soft TiN coating rather than the hard TiN coating has been demonstrated.