DLC-Coated Tools for Microforming

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