Coefficients of friction of TiN coatings with preferred grain orientations under dry condition

In order to decrease the friction loss of mechanical parts, frictional properties of TiN coatings with preferred grain orientations deposited by arc ion plating (AIP) were investigated. The preferred grain orientation of TiN coatings is controlled by changing the substrate bias voltage. In a ball-on-disc tribometer, a TiN coating with a (1 1 1) preferred grain orientation deposited at a substrate bias voltage of -200 V revealed a lower coefficient of friction than one with a (2 0 0) preferred grain orientation. In order to understand the frictional properties of the TiN-deposited specimens, the microstructures and chemical compositions of TiN coatings were investigated. The good frictional properties of the TiN coating with a (1 1 1) preferred grain orientation deposited at -200 V is due to the creation of a thin Ti oxide layer on the surface of SUJ2 ball that has good lubricity and prevents adhesion of Fe from SUJ2 ball to TiN coatings.