Tribological behavior of PACVD TiN coatings in the temperature range up to 500°C

Titanium nitride (TiN), is still the standard coating for cutting as well as forming applications. The aim of this study is to investigate the tribological behavior of low-friction plasma-assisted chemical vapor deposition (PACVD) TiN coatings with low chlorine content as well as the thermal stability of the low-friction effect. Dry sliding experiments at temperatures ranging from room temperature to 500 degreesC were conducted on PACVD TiN coatings, deposited onto high speed steel substrates. The coatings were worn against ball-bearing steel and Al2O3 balls using a ball-on-disc configuration. Characterization of the wear tracks was done by scanning electron microscopy, electron-probe microanalysis and an optical 3d profiling system. Extremely low-friction coefficients against ball-bearing steel and Al2O3 balls of 0.14-0.17 have been obtained at room temperature for coatings with chlorine contents between 3.2 and 3.7 at.%. The friction coefficient against Al2O3 increases to values of approximately 0.6-0.8 for temperatures above 70 degreesC. The lowest coating wear coefficient with 1.93 X 10(-16) m(2)/N was obtained for Al2O3 balls at room temperature, whereas for temperatures exceeding 200 degreesC increased abrasion of the coating takes place, resulting in higher wear rates. (C) 2002 Elsevier Science B.V. All rights reserved.