EFFECT OF MICROSTRUCTURE ON SLIDING CONTACT DAMAGE AND WEAR OF CERAMIC COATINGS

Hard and wear resistant ceramics coatings are often applied to metallic surfaces to enhance their tribological performance. Using the scratch and twin roller tests, we evaluated the surface contact damage and the mechanism of wear in different ceramic coating. In amorphous diamond-like carbon coating, the damage and eventual material removal occurred by straight cracking that follows the trajectory of the tensile stresses. Damage in a crystalline titanium nitride (TiN) coating with a columnar grain structure occurred primarily by inter-columnar cracking perpendicular to the surface. For crystalline chromium nitride (CrN) coating with equiaxed grains, contact damage consisted primarily of grain boundary cracking and wear is due to surface-layer grain pullout. Results of the present study showed the dominant effect of ceramic coating microstructure on the contact damage and wear mechanism.