AZ31镁合金表面葡萄糖和L-半胱氨酸仿生席夫碱阳极钙磷涂层的耐腐蚀性能

In vitro degradation resistance of glucose and L-cysteine-bioinspired Schiff-base anodic Ca−P coating on AZ31 magnesium alloy

通过往60℃传统钙磷处理液中添加适量的氨基酸型席夫碱,在镁合金表面于CaCl_(2)和KH_(2)PO_(4)混合溶液中制备席夫碱(含C=N的化合物)诱导的阳极Ca-P涂层。采用FE-SEM、FT-IR、XRD和XPS技术研究涂层的显微组织和化学成分,涂层试样的耐腐蚀性能则通过动电位极化(PDP)、电化学阻抗光谱(EIS)和析氢试验表征。结果表明,Ca-PSchiff base涂层中存在CaHPO_(4)(DCPA)和羟基磷灰石(HA),而Ca-P涂层中没有HA。此外,Ca-PSchiff base涂层厚度(18.13±5.78)μm大约为Ca-P涂层厚度(9.13±4.20)μm的2倍。电化学结果表明,Ca-PSchiff base涂层的腐蚀电流密度比Ca-P涂层降低两个数量级。最后,提出席夫碱作用下Ca-P涂层的形成机理。

A Schiff base(a compound containing a C=N bond)induced anodic Ca−P coating was prepared on AZ31 Mg alloy in a mixed solution of CaCl_(2) and KH_(2)PO_(4) at 60℃ in the presence of glucose and L-cysteine.The microstructure and chemical composition of the coatings were characterized using FE-SEM,FT-IR,XRD,and XPS.The in vitro degradation resistance of the coated samples was evaluated via potentiodynamic polarization(PDP),electrochemical impedance spectroscopy(EIS),and hydrogen evolution test.The experimental results show that the Ca−PSchiff base coating is composed of CaHPO_(4)(DCPA)and hydroxyapatite(HA),whereas HA is not present in the Ca−P coating.The Ca−P_(Schiff base) coating thickness is about 2 times that of Ca−P coating(Ca−P coating:(9.13±4.20)μm and Ca−P_(Schiff base):(18.13±5.78)μm).The corrosion current density of the Ca−P_(Schiff base) coating is two orders of magnitude lower than that of the Ca−P coating.The formation mechanism of the Ca−P_(Schiff base) is proposed.