The microhardness, scratch, Rockwell-C indentation, cyclic impact and wear tests show that the SNC-DLC sample has higher surface hardness and load-bearing capacity than the CG-DLC sample. Elemental analysis by energy dispersive X-ray reveals the enhancement of Cr diffusion into the steel substrate for the SNC-DLC sample. X-ray diffraction confirms an amorphous nature of the carbon coating. Then the DLC coating with Cr adhesive interlayer was sputter deposited on the coarse-grained and the surface nanocrystallized steel substrates (noted as CG-DLC, SNC-DLC samples, respectively). Surface mechanical attrition treatment (SMAT) was used to generate a nanocrystalline surface layer on the steel substrate.
In this work SNC is used as a pretreatment method to improve mechanical properties of the DLC coating on the 304 stainless steel. Surface nanocrystallization (SNC) can markedly improve surface mechanical properties of metallic materials and accelerate thermal diffusion of elemental atoms.
