Metal surface Cr/CrN/CrCN/Cr-DLC multilayer composite self-lubricating film and preparation method thereof

The invention belongs to the technical field of surface treatment, and discloses a Cr/CrN/CrCN/Cr-DLC multi-layer composite self-lubricating film and a preparation method thereof. The thin film material is composed of a Cr layer, a CrN layer, a CrCN layer and a DLC layer which are stacked in sequence, wherein the CrCN layer and the DLC layer are distributed in a gradient mode. The pretreated 304 stainless steel substrate is placed on a substrate mounting rack of coating equipment, a high-purity C target and a high-purity Cr target which are mounted on the inner wall of a furnace body serve as carbon sources and corresponding metal doping sources, high-purity argon and acetylene are introduced into a vacuum chamber, argon serves as main ionization gas, acetylene serves as a film, a hydrogen element is introduced, and the quality of the film is improved; and by adopting the design method of the gradient transition layer, not only is the binding force of the film improved, but also the wear resistance and the an