Patent ID: 8641046

Claim:
A piston ring having a DLC coating, wherein the piston ring comprises on a base material, of the piston ring from inside to outside, an adhesive layer, a metal-containing amorphous carbon layer and a metal-free amorphous carbon layer, sp 2 bonds predominating in the metal-containing carbon layer, and the metal-free carbon layer comprising sp 2 and sp 3 bonds, and the sp 3 bond fraction being higher than in the metal-containing carbon layer such that an electrical resistance of the DLC coating develops, which is greater than 5000 k Ohm; wherein the base material is steel or cast iron; wherein the adhesive layer contains chromium; wherein the adhesive layer has a maximum thickness of approximately 2μm; wherein the metal-containing carbon layer has a metal content that decreases towards the outside; wherein the metal-containing carbon layer has a thickness of from about 1.5 to about 17 μm; wherein the metal-containing carbon layer comprises nanocrystalline carbide phases; wherein the metal-containing and/or the metal-free carbon layer contains hydrogen; wherein the piston ring has a surface hardness of from 1800 to 2800 HV 0.002; and wherein the piston ring lacks a run-in layer.