Chemical analysis of boundary lubrication film formed on metal nitride coatings with ethanol by means of TOF-SIMS

Tribochemistry of metal nitride coatings in the presence of alcohol was investigated by using a stable isotopic tracer. The tribological properties were evaluated by a ball-on-disk type tribo-tester with steel ball and metal nitride coated disk under reciprocating motion. It was found that the friction coefficient of CrN was approximately 60% lower than that of TiN. On the other hand, TiN afforded lower wear than CrN. Considerable amount of deposit was observed on TiN. The rubbed surfaces were chemically analyzed by means of time-of-flight secondary ion mass spectroscopy (TOF-SIMS). In order to eliminate the undesirable fragment ions originated from organic contaminations in TOF-SIMS analysis, pentadeuterioethanol was used as an isotopic tracer. It was found that CrN reacted with alcohol to provide chromium ethoxide as boundary film. On the other hand, transferred Fe ion from the ball was the major contents on rubbed surfaces of TiN coatings.