主权项 |
1. A piston ring for internal combustion engine comprising a base and at least an outer surface, the base being comprised of a given metallic alloy, the outer surface of the ring comprising a ceramic coating, the ceramic coating being comprised of a deposit of Chromium Nitride and Niobium Nitride, wherein the coating:
has a porosity rate lower than 10%, has a columnar crystalline structure; (ii) comprises a combination of phases of Chromium Nitride and Niobium Nitride, the Niobium Nitride phase being present in the range of 30 to 60% by weight of the coating; and (iii) the outer surface of the coating is composed of Niobium Nitride. |