Preparation of Nickel-Cobalt/Carborundum Carbide Composite Coatings by Supergravity Field-Enhanced Electrodeposition
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RIGINAL ARTICLE
Chinese Journal of Mechanical Engineering Open Access
Preparation of Nickel‑Cobalt/Carborundum Carbide Composite Coatings by Supergravity Field‑Enhanced Electrodeposition Xiaoyun Hu1* and Ningsong Qu1,2
Abstract Nickel-cobalt/silicon carbide (Ni-Co/SiC) composite coatings were fabricated by supergravity field-enhanced electrodeposition. The surface morphology and the distribution of the SiC particles in the coatings were examined by scanning electron microscope and energy dispersive X-ray spectrometry. The preferred orientations of the coatings were measured by X-ray diffractometry. The wear resistance and microhardness were measured by a reciprocating tribometer and a microhardness instrument, respectively. The results revealed that the use of the supergravity field enhanced the smoothness of the as-deposited Ni-Co/SiC coatings, and the SiC nanoparticles were uniformly distributed in comparison with that for conventional electrodeposition. When the rotation speed of the cathode, which provided the supergravity field, was 800 r/min, the SiC content in the coating reached a maximum of 8.1 wt%, which was a much higher content than the 2.2 wt% value obtained under conventional electrodeposition. The highest coating microhardness of 680 HV was also observed at this rotation speed. In addition, the wear resistance of the as-prepared Ni-Co/SiC coatings exhibited improved performance relative to that prepared under normal gravity. A minimum wear weight loss of 1.4 mg together with an average friction coefficient of 0.13 were also realized at a rotation speed of 800 r/min, values which were much lower than those for normal gravity. Keywords: Supergravity field, Electrodeposition, Microhardness, Wear resistance 1 Introduction Nickel-cobalt (Ni-Co) alloy coatings as an important engineering material exhibit many attractive features, such as high hardness, good wear and corrosion resistance, and good magnetoconductivity, thermal conductivity and electrocatalysis activity [1–4]. The coatings have been used extensively in diverse fields including magnetic sensor technology [5], aerospace, micro-electromechanical systems and nano-electromechanical systems [6]. Nowadays, the consensus is that particle-reinforced composite coatings exhibit better performance than alloy coatings [7–9]. Thus, to further improve certain properties of the target components, insoluble particles *Correspondence: [email protected] 1 Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China Full list of author information is available at the end of the article
are usually incorporated into the alloy coatings. Given the attractive features of Ni-Co alloys, much work has been done concerning the Ni-Co matrix. For instance, Cr2O3 [10], Al2O3 [11, 12] and diamond [13] have been successfully embedded into the Ni-Co matrix such that enhanced properties for these composite coatings have been obtained. Among the particulates used for strengthening purposes, SiC possesses excellent chemical stability and mechanical characteris
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