Nitrogen diffusion mechanism, microstructure and mechanical properties of thick Cr/CrN multilayer prepared by arc deposition system

A dense and uniform Cr/CrN multilayer with large thickness (≥42 μm) was synthesized on the stainless steel surface by arc ion plating system. The influence of different Cr modulation periods (5, 3, 2 min) on the microstructure, mechanical and oxidation properties was characterized and analyzed. The chemical composition, morphology and structure were analyzed by means of EPMA, SEM, XRD and TEM, The coating adhesion and wear performance were studied using scratch test and reciprocating wear tester, respectively. The multilayer was oxidized in a high temperature of 1000 °C for 5/10 h in atmosphere, and weight loss was measured by TGA. The results revealed that a high adhesion, high hardness and high wear resistance of the Cr/CrN multilayer to the steel substrate was achieved. Furthermore, N diffusion phenomenon was discovered and generate strong organic bonding inside the thick Cr/CrN multilayer, by forming gradients of elements and microstructure. The N diffusion resulted in a gradient distribution of the hardness inside the thick coating. Based on these results the Cr/CrN multilayer with large thickness is a promising candidate to be applied on many scenarios. In this work, including highlights as following:•Large thickness Cr/CrN multilayers with a good comprehensive performance.•Discover N element diffusion phenomenon and mechanism.•Excellent oxidation resistance at high temperature.