Micro-wear properties of carbon nitride coatings

Micro-wear tests of amorphous carbon nitride (CNx) coating against a diamond pin were carried out by using a atomic force microscopy. Micro-wear properties of CNx were shown as functions of coating condition, contact load, pin radius and contact pressure. The coating condition provides about 10 times difference of specific wear amount of CNx coating. The depth of wear of CNx coating increased drastically by increasing the contact load to above a critical value. CNx was influenced pin radius. The depth of wear scar of CNx coating changed depending on the pin radius under the same contact load. Combined with the effects of contact load and pin radius, the effect of contact pressure on specific wear amount was made clear. The specific wear amount of CNx coating increased with maximum contact pressure. On the other hand, specific wear amount of DLC was shown to be independent of maximum contact pressure. At the maximum contact pressure lower than about 10 GPa, the specific wear amount of CNx coating was smaller than that of DLC. Contact pressure dependence of wear of CNx coating was introduced by nano-scale delamination of the coating.