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Wear and Corrosion Properties of 316L-SiC Composite Coating Deposited by Cold Spray on Magnesium Alloy Jie Chen1,2 • Bing Ma1 • Guang Liu1 • Hui Song1 • Jinming Wu2 • Lang Cui1 Ziyun Zheng1

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Submitted: 21 March 2017 / in revised form: 31 May 2017 Ó ASM International 2017

Abstract In order to improve the wear and corrosion resistance of commonly used magnesium alloys, 316L stainless steel coating and 316L-SiC composite coating have been deposited directly on commercial AZ80 magnesium alloy using cold spraying technology (CS). The microstructure, hardness and bonding strength of assprayed coatings were studied. Their tribological properties sliding against Si3N4 and GCr15 steel under unlubricated conditions were evaluated by a ball-on-disk tribometer. Corrosion behaviors of coated samples were also evaluated and compared to that of uncoated magnesium alloy substrate in 3.5 wt.% NaCl solution by electrochemical measurements. Scanning electron microscopy was used to characterize the corresponding wear tracks and corroded surfaces to determine wear and corrosion mechanisms. The results showed that the as-sprayed coatings possessed higher microhardness and more excellent wear resistance than magnesium alloy substrate. Meanwhile, 316L and 316L-SiC coating also reduced the corrosion current density of magnesium alloy and the galvanic corrosion of the substrates was not observed after 200-h neutral salt spray exposure, which demonstrated that corrosion resistance of a magnesium alloy substrate could be greatly improved by cold-sprayed stainless steel-based coatings.

& Jie Chen [email protected] Hui Song [email protected] 1

Inner Mongolia Metallic Materials Research Institute, Ningbo 315103, China

2

School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China

Keywords cold spraying
corrosion
magnesium alloy
SiC
stainless steel
wear

Introduction Due to their low density and exceptional strength-to-weight ratio, magnesium alloys have become a commonly preferred choice for weight reduction in aerospace and automotive applications (Ref 1-3). However, the main problems of magnesium alloys are their high reactivity and low hardness; hence, the insufficient corrosion resistance and poor wear resistance limit their extensive implementation (Ref 4, 5). One of the most effective approaches to overcome these disadvantages is surface treatment, which can provide sufficient protection from both wear and corrosion without altering the microstructure and properties of the substrate. In comparison with the currently available surface treatment techniques for magnesium alloys, such as microarc oxidation (Ref 6), chemical conversion (Ref 7), laser cladding (Ref 8) and chemical vapor deposition (Ref 9), cold spraying technology is a relatively new and environmentally friendly technology. Unlike other thermal spraying techniques, the coating deposited in the cold spray process is formed in the solid state at a lower temperature without involving both feedstock and substrates i