Hardness, Adhesion, and Tribological Properties of Tisin and Alticrn Coatings Under Dry and Lubricated Sliding Conditions

Most of the friction losses and wear in internal combustion engines occur between the cylinder liners and piston rings. Hard coatings applied to cylinder liners can increase the efficiency of internal combustion engines by improving tribological properties. The cathodic arc physical vapor deposition method was used to deposit TiSiN and AlTiCrN coatings on gray cast iron cylinder liner. The hardness, adhesion, and structural properties of the coatings were characterized by using nanoindentation tests, scratch tests, scanning electron microscopy, optical profilometer, X-ray diffraction, and energy dispersive spectroscopy. The tribological properties of the coatings were evaluated by reciprocating test under dry and lubricated sliding conditions at varying normal loads. The hardness of TiSiN and AlTiCrN coatings was 45GPa and 18GPa, respectively. The cohesion strength, adhesion strength, and crack propagation resistance of AlTiCrN coating were approximately 2, 1.3 and 2.5 times higher than TiSiN coating, respectively. Both coatings exhibited remarkable wear performance at high normal loads. Under dry sliding conditions at 25N normal load, the wear volume of AlTiCrN and TiSiN coatings were nearly 15 and 34 times, respectively, lower than the uncoated substrate. TiSiN coating for dry sliding conditions and AlTiCrN coating for lubricated sliding conditions showed the best tribological performance with the lowest wear rate.