Corrosion Resistance and Durability of Superhydrophobic Coating on AZ31 Mg Alloy via One-Step Electrodeposition
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Corrosion Resistance and Durability of Superhydrophobic Coating on AZ31 Mg Alloy via One‑Step Electrodeposition Zheng‑Zheng Yin1 · Zhao‑Qi Zhang1 · Xiu‑Juan Tian1 · Zhen‑Lin Wang2 · Rong‑Chang Zeng1,3 Received: 1 August 2020 / Revised: 20 October 2020 / Accepted: 27 October 2020 © The Chinese Society for Metals (CSM) and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract To enhance durability and adhesion of superhydrophobic surface, an integrated superhydrophobic calcium myristate (Ca[CH3(CH2)12COO]2) coating with excellent corrosion resistance was fabricated on AZ31 magnesium (Mg) alloy via one-step electrodeposition process. Field-emission scanning electron microscopy, Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy as well as X-ray diffraction were employed to investigate the surface characteristics (morphology, composition and structure) of the coatings. Hydrophobicity of the coating was evaluated by means of contact and sliding angles. Additionally, potentiodynamic polarization, electrochemical impedance spectroscopy and hydrogen evolution tests were conducted to characterize the corrosion resistance. Results indicated that the coating exhibited super-hydrophobicity with large static water contact angle (CA) and small sliding angle of 155.2° ± 1.5° and 6.0° ± 0.5°, respectively, owing to spherical rough structure and low surface energy (7.01 mJ m−2). The average hydrogen evolution rate (HERa) and corrosion current density (icorr) of the coated sample were 5.3 μL cm−2 h−1 and 5.60 × 10−9 A cm−2, about one and four orders of magnitude lower than that of AZ31 substrate, respectively, implying the excellent corrosion resistance. The CA of the coating remained 155.6° ± 0.9° after soaking for 13 days, showing the super-hydrophobicity and stability of the coating. Simultaneously, the large critical load (5004 mN) for the coating designated the outstanding adhesion to the substrate by nano-scratch test. Keywords Magnesium alloy · Electrodeposition · Durability · Super-hydrophobicity · Adhesion · Corrosion resistance
1 Introduction Mg and its alloys have been attractive candidates for automotive, aerospace industry and 3C products owing to their excellent properties [1–3], such as lightweight, high specific strength and specific stiffness, electromagnetic shielding and recycling use [4–6]. However, applications for Mg alloys have been restricted seriously due to their lower potentials, Available online at http://link.springer.com/journal/40195 * Rong‑Chang Zeng [email protected] 1
Corrosion Laboratory for Light Metals, College of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China
2
College of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400065, China
3
School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China
being easily subjected to corrosion under acidic and neutral conditions [7–9]. And the oxide generated on the Mg surface i
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