DLC-Coated Tools for Micro-forming

For environmental protection, and for the exploration of size effects of friction in micro-forming, diamond-like carbon (DLC) has been gaining increasingly more attention as a candidate for substituting for conventional lubricants on account of its excellent tribological properties. Silicon-doped DLC, nano-laminated DLC, DLC with gradient properties, etc. have been developed to change and enhance its properties. The small dimensions of the micro-die cavities used in micro-forming have obvious effects on the surface topography and mechanical properties of DLC. Micro-sheet-forming experiments, such as strip drawing, bending, and deep drawing, have show that DLC can bear high contact stress and strain, improve the micro-forming properties, e.g., the limiting drawing ratio, and extend the working life of coated tools under dry condition. In micro-bulk forming, DLC can be used to reduce the forming load in micro-extrusion, and protect the template in respect of antiadhesion properties in nano-printing. In this paper, a model is introduced for analyzing the wear mechanism of DLC from the viewport of graphitization, by considering frictional work.