Tsakos Energy Navigation Limited
Piston ring with wear resistant coating

Abstract:

A wear resistant coated piston ring for an engine is provided. The piston ring includes a coating disposed on a ring body. The coating includes initially includes alternating first and second layers, wherein the first layers include trivalent chromium, and the second layers include nickel and phosphorous. The first layers are applied by depositing a trivalent chromium electrolyte, specifically Cr3+ electrolyte. The second layers are applied by electroless deposition. The coating is left in the as-is condition and is not heat treated before being disposed on a piston and then in an engine. The coating is naturally exposed to heat while the engine is running, and this heat causes the chromium, nickel, and phosphorous of the layers to diffuse and form a surface layer on a compound layer. The surface layer includes trivalent chromium, and the compound layer includes a ternary compound of chromium, nickel, and phosphorous.