Coated piston ring for an internal combustion engine

A piston assembly, comprising:

• a piston including a ring groove;
• a piston ring disposed in said ring groove of said piston;
• said piston ring including a body portion surrounding a center axis, said body portion including a running surface facing away from said ring groove of said piston, a flank surface, and a transition surface between said running surface and said flank surface, said transition surface extending inwardly toward said center axis and at an angle between said running surface and said flank surface, wherein said transition surface includes a convex portion proximate said running surface;
• said piston ring including a running layer disposed over said running surface and over at least a portion of said transition surface, said running layer being formed of chromium nitride;
• said piston ring including a flank layer disposed over said flank surface and over at least a portion of said transition surface, said flank layer being formed of chromium;
• a portion of said flank layer which is disposed over said transition surface being disposed on a portion of said running layer;
• and
• said portion of said flank layer which is disposed on said running layer being spaced from said ring groove of said piston.