摘要
镁(Mg)及其合金,因具有良好的机械性能及体内可降解性,受到医疗器械科研人员和医务工作者的广泛关注。但是,镁在生理环境溶液中过快的降解速率限制了它的临床应用,且镁器械作为承载力植入物在生理载荷和腐蚀介质共同作用下,易发生应力腐蚀开裂(Stress corrosion cracking,SCC),造成材料提前断裂失效。本文采用不同特性的类陶瓷微弧氧化(Micro-arc oxidation,MAO)膜层、生物相容性好且可降解的聚乳酸-羟基乙酸共聚物(PLGA)高分子涂层及化学转化生成的氟化镁(MgF_(2))层,改善医用镁合金的耐蚀性和SCC行为;采用扫描电镜、光学显微镜、X射线衍射分析AZ31和ZK40镁合金2种基材的显微组织,以及表面改性膜层的微观结构、耐蚀性和物相成分组成;通过动电位极化技术,分析未改性和表面改性后基材的腐蚀行为;在汉克斯平衡盐溶液中采用慢应变速率拉伸测试获得应力-应变曲线,以分析不同试样的断口形貌特征。结果表明:尽管AZ31和ZK40镁合金2种基材表面的相同改性涂层具有相近的腐蚀速率,但抗SCC性能存在明显差异;PLGA涂层虽然耐蚀性最优,但其抗SCC最差,AZ31合金抑制SCC最好的为MAO膜层,而ZK40镁合金抑制SCC最好的是MgF_(2)转化层。
Magnesium(Mg)and its alloys,due to their excellent mechanical properties and in vivo degradability,have attracted widespread attention from biomedical device researchers.However,the rapid degradation rate of Mg alloys in physiological environment limits their application.As a load-bearing implant,Mg device is prone to stress corrosion cracking(SCC)under the combined effect of physiological load and corrosive media,leading to premature material fracture failure.Therefore,this paper intends to prepare various surface modification coatings,such as ceramic micro-arc oxidation(MAO)film,poly(lactic-co-glycolic acid)(PLGA)polymer coating with good biocompatibility and degradability,and MgF_(2) conversion layer,to improve the corrosion resistance and SCC behavior of biomedical Mg alloys.The microstructure,corrosion resistance,and phase composition of the AZ31 and ZK40 substrates,as well as the surface modified layers,were measured by scanning electron microscopy(SEM),optical microscopy(OM),and X-ray diffraction(XRD).The corrosion behavior of uncoated and surface modified Mg substrates were analyzed by potentiodynamic polarization(PDP).Slow strain rate tensile(SSRT)testing was performed in Hank’s solution to obtain the engineer stress-strain curves,and the fracture morphology characteristics of different samples were analyzed.The results indicate that although the same modified layers on the surface of AZ31 and ZK40 substrates exhibit similar corrosion rate,there are significant differences in the resistance to SCC.PLGA coating shows the best corrosion resistance,while lowest resistance to SCC in all surface coated samples.Compared the data of SCC susceptible indices,the MAO film is the best inhibitor of SCC for AZ31 alloy,while the MgF_(2) conversion layer is preferable for ZK40 alloy.
作者
陈连喜
胡晨晨
钱雯
赖俊楠
王小健
赵春旺
CHEN Lianxi;HU Chenchen;QIAN Wen;LAI Junnan;WANG Xiaojian;ZHAO Chunwang(School of Materials and Energy,Foshan University,Foshan 528000,Guangdong,China;Institute of Advanced Wear&Corrosion Resistant and Functional Materials,Jinan University,Guangzhou 510632,Guangdong,China)
出处
《实验力学》
北大核心
2025年第2期193-207,共15页
Journal of Experimental Mechanics
基金
广东省自然科学基金面上项目(2022A1515011752)
高性能金属耐磨材料技术国家地方联合工程研究中心开放基金项目(JNIWRM2022001)。
关键词
医用镁合金
表面改性涂层
耐蚀性
应力腐蚀开裂
显微结构
沿晶腐蚀
biomedical magnesium alloy
surface modification coating
corrosion resistance
stress corrosion cracking
microstructure
intergranular corrosion
