Piston ring with hard plating, and preparation method therefor

A piston ring with a hard plating, wherein an outer diameter (OD) surface and a side face of the piston ring respectively have the hard plating;

• the hard plating of the OD surface of the piston ring consists of an interlayer, a gradient metal nitride layer, and a diamond-like carbon (DLC) repetitive unit layer sequentially from bottom to top on an OD surface of a piston ring matrix;
• one DLC unit layer in the DLC repetitive unit layer consists of a DLC layer and a metal-doped DLC layer sequentially from bottom to top;
• a number of repetitions of the DLC unit layer is 4 to 6;
• the interlayer is a chrome layer;
• the gradient metal nitride layer is a gradient titanium nitride layer;
• the metal-doped DLC layer is a titanium-doped DLC layer;
• a thickness of the interlayer is 1 μm to 4 μm;
• a thickness of the gradient metal nitride layer is 0.1 μm to 2 μm;
• a thickness of the DLC layer in the one DLC unit layer is 4 μm to 8 μm;
• a thickness of the metal-doped DLC layer in the one DLC unit layer is 100 nm to 500 nm;
• a total thickness of the DLC repetitive unit layer is 25.5 μm to 37 μm;
• the hard plating of the side face of the piston ring is a chrome plating on a side face of the piston ring matrix;
• and a thickness of the chrome plating is 1 μm to 20 μm.