Nano-lamination in amorphous carbon for tailored coating in micro-dry stamping of AISI-304 stainless steel sheets

摘要

Nano-lamination is a new way to make full use of multi-layered structure for coating instead of the mono-layered coating system. Different from the conventional nano-lamination approach, where two different kinds of material system are deposited in layers, the amorphous carbon layer, a-C:H, is alternatively deposited with graphite-like cluster layer, resulting in an amorphous carbon base nano-laminated coating. In this nano-lamination. the pulse bias voltage and the pulse duration time are programmed to control the bilayer thickness and number of laminates. Furthermore. the mechanical properties are also controllable by varying the bi-layer thickness and sub-layer ratio. In this paper, the effect of number of layers and bi-layer thickness on the mechanical properties is investigated by the nano-indentation technique. Higher hardness and Young's modulus is attained with reduction of bi-layer thickness. The scratching test of this nano-laminated coating is made to demonstrate that it has sufficient scratch load above 100 N. Furthermore, a dry micro stamping test is performed to prove that this nano-laminated coating has sufficient wear-toughness enough to make dry stamping in 10,000 times in practice even if it has nearly the same Young's modulus and hardness as the mono-layered coating. No delamination or break-away occurs on the ironed surface of coated tools while severe delamination is observed in the conventional mono-layered coating.