镁合金腐蚀研究进展(26)—镁合金表面层层组装DNA涂层耐蚀性能 脱氧核糖核酸 （deoxyribonucleic acid, DNA） 是 一种由核苷酸重复排列组成的长链聚合物。所谓核苷酸，是指一个核苷加上一个或多个磷酸基团；核苷则是指一个碱基加上一个糖类分子。DNA骨架是由磷酸与糖类基团交互排列而成的一种长链聚合物 。 本文首次利用DNA和 聚乙烯吡咯烷酮（ polyvinylpyrrolidone, PVP ） 在镁合金表面通过层层组装技术(layer-by-layer (LbL) assembly)构建聚电解质多层膜(PVP/DNA) n 。该涂层表现出良好的耐蚀性能和生物相容性。特别地，该涂层在浸泡模拟体液中还表现出良好的类生物矿化效果。矿化产物有助于镁合金用于骨植入材料。 究其原因，主要可以归因于三点：（1）DNA分子中的磷酸基 团可以作为钙磷产物形核生长的诱导剂；（2）DNA与 PVP 的静电吸引作用可以有效地将钙离子吸附于分子层间；（3）PVP可以络合钙离子形成配合物。基于以上三点构建的层层组装多层膜在骨植入材料领域有一定的应用前景。 该项成果“ In vitro corrosion resistance of a layer-by-layer assembled DNA coating on magnesium alloy （Share link）” In vitro corrosion resistance of a layer-by-layer assembled DNA coating on.pdf 发表在国际期刊 Applied Surface Science ( IF4.439 ) ( 457, 2018: 49–58） 。第一作者 为博士生崔蓝月，通讯作者为曾荣昌教授和李硕琦博士。 Fig. 1 The schematic construction of the (PVP/DNA) n /Mg via LbL assembly. Fig. 2 (a–h) SEM images of the (PVP/DNA) 20 /Mg soaked in SBF for 6, 12, 24, 48, 72, 96, 120 and 432 h; (i) EDS spectra and (j) corresponding Ca/P molar ratio of the (PVP/DNA) 20 /Mg immersed in SBF for 0 ( Fig. 2 dI), 6, 12, 24, 48, 72, 96, 120 and 432 h. Fig. 3 a) XPS overview spectra and the evolution of (b) P 2p , (c) C 1s , (d) N 1s and (e) O 1s signals of (PVP/DNA) n /Mg surfaces. Fig. 4 EIS and the fitted results for the (I) AZ31 substrate, (PVP/DNA) n /Mg, n = (II) 5, (III) 10, (IV) 20 and (V) 40: (a) Nyquist plots, (b) Bode plots of |Z| vs. frequency, (c) Bode plots of phase angle vs. frequency in SBF and (d) equivalent circuits. Fig. 5 EIS curves and the fitted results for the (PVP/DNA) 20 /Mg: (a) Nyquist plots, (b) Bode plots of |Z| vs. frequency, (c) Bode plots of phase angle vs. frequency in SBF and (d) R ct values vs. immersion time and corresponding equivalent circuits. Fig. 6 Schematic representation of the degradation mechanism of the (PVP/DNA) 20 coating: (a and b) Ca-P nucleation and growth, (c) electrochemical corrosion of the substrate.
针对镁合金阳极氧化膜含有多孔和少量通孔结构，只能提供初期保护效果的问题 ，有必要解决阳极氧化膜涂层的封孔问题。封孔方法包括：自封孔、沸水封孔、硅酸盐、碱处理和有机高分子涂层 。碱处理的目的是把氧化镁变成氢氧化镁，体积增大，把孔堵塞；硅烷处理膜层很薄。这两种方法提高MAO膜的耐蚀性能都比较有限。我们这里提出MAO碱处理后，再进行硅烷处理，取得了较好的自愈合耐蚀功效。 论文“ Corrosion resistance of a self-healing microarc oxidation/polymethyltrimethoxysilane composite coating on magnesium alloy AZ31 ”（镁合金AZ31 表面自愈合阳极氧化膜/ 硅烷复合涂层的耐蚀性）在线发表在腐蚀领域权威期刊《 Corrosion Science 》( 2017, http://dx.doi.org/10.1016/j.corsci.2017.01.025 ) 。 Fig. 1 Schematic representation of the film formation mechanisms of the MAO/PMTMS coating. Fig. 2 Schematic representation of the corrosion mechanisms of the MAO/PMTMS coating Highlights The MAO/PMTMS coating has a compact morphology with some spherical particles. The MAO/PMTMS coating (thickness =13.65 μm) possesses a good corrosion resistance. The PMTMS film acts as a physical and blocking barrier. The self-healing of PMTMS film plays an important role in its long-term protection. The PMTMS film peels off due to its swelling and the stress of corrosion products. 亮点 阳极氧化膜 / 硅烷复合涂层带有球状颗粒，且致密； 阳极氧化膜 / 硅烷复合涂层（ 13.65 μm 厚）具有良好耐蚀性能 ； 硅烷膜起着物理隔离作用； 硅烷膜在长期保护过程中具有自愈合的重要作用； 硅烷膜由于膨胀和腐蚀产物应力而剥落（ 失效 ）。 Abstract A micro-arc oxidation (MAO)/polymethyltrimethoxysilane (PMTMS) hybrid coating was fabricated via MAO processing and subsequent sealing with alkaline treatment and PMTMS. The surface morphologies, chemical compositions and corrosion resistances of the coatings were investigated using FE-SEM, FTIR, XRD and electrochemical and hydrogen evolution measurements. The results indicated that the alkaline treatment was beneficial to the silane treatment and that the MAO coating was efficiently sealed by the PMTMS film. The MAO/PMTMS coating significantly enhanced the corrosion resistance of the AZ31 alloy due to its self-healing function. Additionally, we suggest and discuss a corrosion mechanism for the coating. 摘要 镁合金阳极氧化膜经过碱处理和硅烷处理获得阳极氧化膜 / 硅烷（ MAO/PMTMS ）复合涂层。通过 FE-SEM, FTIR, XRD 、电化学和析氢实验研究了该涂层的形貌、化学成份和耐蚀性能。研究结果显示，碱处理有利于硅烷处理和阳极氧化膜被硅烷封孔。 MAO/PMTMS 膜具有自愈合功能，提高了 AZ31 镁合金的耐蚀性能。另外，我们提出和讨论了涂层的腐蚀机理。 参考文献： Lan-Yue Cui, Rong-Chang Zeng * , et al, Degradation mechanism of micro-arc oxidation coatings on biodegradable Mg-Ca alloys- The influence of porosity, Journal of Alloys and Compounds , 695(2017) 2464-2476 . R. C.Zeng, et al, In vitro corrosion and cytocompatibility of a microarc oxidation coating and poly(L-lactic acid) composite coating on Mg-1Li-1Ca alloy for orthopaedic implants. ACS Applied Materials Interfaces , 2016, 8 (15): 10014–10028; R. C.Zeng, et al, In vitro degradation of MAO/PLA coating on Mg-1.21Li-1.12Ca-1.0Y alloy, Front. Mater. Sci. , 8 (2014) 343-353 .
Mg-Li-Ca合金腐蚀机理及动力学表征 曾荣昌 山东科技大学 金属及其合金表面氧化膜和腐蚀产物膜结构决定了其耐蚀性能。镁合金作为一种新型结构和功能材料，其腐蚀的科学本质问题如腐蚀产物膜、多相合金同时发生腐蚀的数理表达等一直未能被清楚地认识和给出，是目前腐蚀科学领域的研究前沿和热点之一。其中， Mg-Li 合金作为最轻的金属结构材料，在生物医用领域具有重要应用前景。 通过 EPMA 、 XPS 、 SEM 、 EDS 、 XRD 等现代表面分析技术，研究发现 双相 Mg-9.29Li-0.88Ca 合金微观组织结构特征，即：由 α-Mg，β-Li 和 Mg 2 Ca 组成，其中 Mg 2 Ca 相位居 α/β 相界面 α 相一侧。 双相 Mg-Li-Ca 合金表面自然氧化膜具有四层结构：最外层主要为富 Li 的化合物 (Li 2 O, LiOH和Li 2 CO 3 ) ，第二层主要为 Li 和 Mg 的氧化物、氢氧化物和碳酸盐 （ LiOH, Li 2 O 2 ,Li 2 CO 3 , MgCO 3 和 LiH ）组成，第三层为 Li 和 Mg 的氧化物 (Li 2 O 2 ,Li 2 O, MgO 和 CaO) ，最里层为在晶界上和 α-Mg ， β-Li 相中 的氧化物 。 Mg-9.29Li-0.88Ca 合金因为挤压变形，其机械性能，包括 UTS 、 YS 、 EL 和耐蚀性能都有所提高。腐蚀形态由铸态合金的点蚀变为挤压态合金的全面腐蚀。 在铸态合金表面发生点蚀需要一段很长的潜伏期，然而，对于挤压态合金，由于产生的腐蚀产物堵塞了自然氧化物的微裂纹，所以发生全面腐蚀。 双相 Mg-Li-Ca 合金腐蚀机制示意图 (a) 铸态合金表面腐蚀产物膜剥落是由于膜内有应力存在，内表面暴露于溶液中， (b)挤压 态合金表面膜的塞状通道被 LiOH, Mg(OH) 2 , CaCO 3 and MgCO 3 化合物封闭堵塞 该项研究明确了 Ca 、 Li 元素在 Mg-Li-Ca 合金中的作用，提出了 Mg 合金表面腐蚀产物膜 PB 比的新概念和物理模型，运用这一理论很好地解释了晶粒细化对 Mg-Li-Ca 合金腐蚀形貌由点蚀向均匀腐蚀转变的影响，提出了基于体积分数的双相 Mg-Li 合金腐蚀表征数学模型。 此项研究同时提出的两个理论，有助于加深腐蚀产物膜对合金腐蚀动力学影响的理解。 此研究受到国家自然科学基金（51241001）等项目资助。论文已经发表在《腐蚀科学》 ( Corrosion Science, 79, 2014: 69-82 .) 。该文在审稿过程中和发表后受到国际同行的关注。近日收到Elesvier通知，该文可以在3月26日前自由获取（ Free access to your article ）。 Share your article with your network! Elsevier is helping you to spread the word about your research. We are providing you with a customized link which will provide temporary free access to your published article on ScienceDirect. Congratulations on publishing your article Corrosion and characterisation of dual phase Mg-Li-Ca alloy in Hank’s solution: the influence of microstructural features in Corrosion Science. We are pleased to offer you a personal link for sharing your article: http://elsarticle.com/1ejEwps This link will provide free access to your article, and is valid for 50 days, until 26th March, 2014. 后记： 2014年3月11日收到通知： We are pleased to present to you as a corresponding author, an overview of the performance of your article in Corrosion Science . With Article Usage Alerts, a free service, you are able to measure the impact of your article via its usage on ScienceDirect. Your article has been downloaded or viewed 407 times since publication (measured through 31 January). For more details, please check here for your Article Usage Dashboard . For best results use Google Chrome or Firefox. Corrosion and characterisation of dual phase Mg–Li–Ca alloy in Hanks solution.pdf
Improving mechanical properties and corrosion resistance of Mg-6Zn-Mn magnesium alloy by rapid solidification H.J. Zhang a , b , D.F. Zhang a , b , , , C.H. Ma a , b , S.F. Guo c , , , a College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China b National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China c School of Materials Science and Engineering, Southwest University, Chongqing 400715, China http://dx.doi.org/10.1016/j.matlet.2012.10.051 Abstract The current work presents the room-temperature mechanical properties and the corrosion resistance in 3.5% NaCl solution of conventional casting and rapidly solidified Mg 6Zn Mn (ZM61) magnesium alloys. It is found that the mechanical properties of rapidly solidified ZM61 alloy are dramatically enhanced, with the ultimate strength increased from 335MPa to 460MPa (37% increment), which can be attributed to the formation of the refined dendrite microstructure and the strengthening MgZn 2 phase distributed within the matrix. Furthermore, the rapidly solidified ZM61 alloy performs better in corrosion resistance than the extruded ZK60 and pure Mg alloys, suggesting that the rapid-solidification technique is a promising way to improve the strength and corrosion resistance of magnesium alloy for the structural and corrosive media utilization. Highlights mechanical and corrosion properties of Mg-6Zn-Mn alloy were investigated. rapid solidification ZM61 alloy possesses an ultimate strength of about 460MPa. corrosion penetration rate of the rapid solidification ZM61 alloy was only 11.2μm/year.
标签: magnesium
