Abstract In this study, hydroxyapatite (HA) coatings containing carboxymethyl cellulose (CMC) and graphene (Gr) were developed on AZ31 magnesium alloy through two-step electrophoretic deposition method. The morphology and chemical bonding of coatings were characterized and also the phase identification was done using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction, respectively. Moreover, the corrosion behavior of the applied coatings was compared with the bare AZ31 Mg alloy substrate in the simulated body fluid by the means of potentiodynamic polarization test and electrochemical impedance spectroscopy. Obtained results revealed that the novel HA-CMC-Gr coating possesses the highest corrosion resistance compared to the HA, HA-CMC, and HA-Gr coatings due to its uniform and compact structure. To investigate the mechanical properties and to elucidate the effect of CMC on the adhesion of coating-alloy interface, pull-off test was employed, where results demonstrated that the addition of CMC increases the adhesion force from 1.06 MPa to 1.62 MPa. Besides, the modulus of elasticity and the hardness of HA and HA-Gr composite coatings were compared by applying nanoindentation test. Interestingly, it is detected that the presence of Gr has considerably increased the elastic modulus of the coating by approximately 30% in comparison to the pure HA coating.

中文翻译：

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AZ31镁合金羟基磷灰石-羧甲基纤维素-石墨烯复合涂层的开发：腐蚀行为和力学性能

摘要 本研究通过两步电泳沉积法在 AZ31 镁合金上开发了含有羧甲基纤维素 (CMC) 和石墨烯 (Gr) 的羟基磷灰石 (HA) 涂层。对涂层的形貌和化学键合进行了表征，并分别使用扫描电子显微镜、傅里叶变换红外光谱和 X 射线衍射进行了相识别。此外，通过动电位极化测试和电化学阻抗谱，将所涂覆涂层的腐蚀行为与模拟体液中裸露的 AZ31 镁合金基体进行了比较。获得的结果表明，与 HA、HA-CMC 和 HA-Gr 涂层相比，新型 HA-CMC-Gr 涂层由于其均匀和致密的结构而具有最高的耐腐蚀性。为了研究力学性能并阐明 CMC 对涂层-合金界面附着力的影响，采用了拉拔试验，结果表明添加 CMC 使附着力从 1.06 MPa 增加到 1.62 MPa。此外，通过应用纳米压痕测试比较了HA和HA-Gr复合涂层的弹性模量和硬度。有趣的是，检测到与纯 HA 涂层相比，Gr 的存在使涂层的弹性模量显着增加了约 30%。通过纳米压痕试验比较了HA和HA-Gr复合涂层的弹性模量和硬度。有趣的是，检测到与纯 HA 涂层相比，Gr 的存在使涂层的弹性模量显着增加了约 30%。通过纳米压痕试验比较了HA和HA-Gr复合涂层的弹性模量和硬度。有趣的是，检测到与纯 HA 涂层相比，Gr 的存在使涂层的弹性模量显着增加了约 30%。