Patent ID: 9732852
Date: 2017-08-15
CPC Classifications: C23C,F16J

Claim:
1. A three-piece oil ring for an internal combustion engine, comprising: an expanding element defining at least a first side and a second side opposite the first side, a first upper annular segment associated with the first side of the expanding element and a second lower annular segment associated with the second side of the expanding element, wherein each of the first annular segment and the second annular segment include a first internal side surface and a second external side surface, and a chemical vapor deposition coating of a metallic tungsten matrix material homogeneously dispersed on at least one of the expanding element, the first annular segment and the second annular segment, the metallic tungsten matrix material containing a distribution of tungsten nanocarbides including at least one of WC, W2C, W3C and W12C, wherein the coating includes a thickness between 5 μm and 150 μm and a hardness between 1000 HV and 3500 HV; and wherein the coating defines an external surface facing away from the at least one of the expanding element, the first annular segment and the second annular segment, and wherein the distribution of tungsten nanocarbides provides a hardness variation in the coating such that the hardness at the external surface is reduced according to a depth of the coating away from the external surface.