Comparison of structural, mechanical and corrosion properties of thin TiO2/graphene hybrid systems formed on Ti-Al-V alloys in biomedical applications
Comparison of structural, mechanical and corrosion properties of thin TiO2/graphene hybrid systems formed on Ti-Al-V alloys in biomedical applications
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DOI：
10.1016/j.surfcoat.2015.08.011
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发表时间：
2016-03
影响因子：
5.4
通讯作者：
M. Kalisz;M. Grobelny;M. Świniarski;M. Mazur;D. Wojcieszak;M. Zdrojek;J. Judek;J. Domaradzki;D. Kaczmarek
中科院分区：
文献类型：
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作者：
M. Kalisz;M. Grobelny;M. Świniarski;M. Mazur;D. Wojcieszak;M. Zdrojek;J. Judek;J. Domaradzki;D. Kaczmarek
在本文中，基于二氧化钛薄膜（200 nm）和石墨烯单层的混合涂层系统的机械和腐蚀性能的比较研究进行了研究。采用传统的磁控溅射工艺和所谓的“调制等离子体磁控溅射”工艺在Ti6 Al 4V合金表面沉积纯二氧化钛层。使用“PMMA介导的”方法将石墨烯单层转移到钛合金基底上。通过拉曼光谱、X射线衍射（XRD）、扫描电子显微镜（SEM）和原子力显微镜（AFM）测量来检查所获得的薄膜的结构特征。机械性能，即硬度，通过使用纳米压痕测试进行测试。通过伏安曲线的分析，确定了涂层的腐蚀性能，用常规磁控溅射法制备的TiO 2薄膜由可见的晶粒组成，晶粒大小约为100 μ m。50-100 nm，具有纳米晶TiO 2（a）相。用等离子体调制溅射法制备的TiO 2薄膜具有纳米晶金红石结构TiO 2（r），其表面由大的、不规则的晶粒组成，不像用常规方法制备的薄膜那样均匀。转移到二氧化钛薄膜表面的石墨烯是没有缺陷的单层。不幸的是，用于测量二氧化钛/石墨烯涂层系统的硬度的纳米压痕法对沉积在涂层结构顶部上的石墨烯的一个或几个原子层不敏感。因此，与未涂覆的TiO 2薄膜如TiO 2（a）和TiO 2（r）薄膜相比，测量没有揭示石墨烯沉积后二氧化钛薄膜硬度的变化。此外，石墨烯单层可以很容易地从二氧化钛薄膜表面去除（例如通过刮擦）。涂覆有TiO 2（a）薄膜的样品Ti6 Al 4V获得了最好的腐蚀性能（较低的腐蚀电流密度值）。在所有测试的薄膜的顶部上的沉积石墨烯单层提高了腐蚀电位（Ecorr）值，其比其他样品的Ecorrregistered正得多。腐蚀电位的正值是具有低电化学活性的材料的特征，因此具有非常好的耐腐蚀性。此外，这些涂层系统在腐蚀过程中保持机械性能的稳定性。
In this paper, comparative studies on the mechanical and corrosion properties of hybrid coating systems based on titanium dioxide thin films (200 nm) and graphene monolayers have been investigated. The pure titanium dioxide layers were deposited on a Ti6Al4V alloy surface using the conventional magnetron sputtering process and the so-called “magnetron sputtering with modulated plasma” process. A graphene monolayer was transferred to a titanium alloy substrate using the “PMMA-mediated” method. The structural characteristics of the obtained thin films were examined by using Raman spectroscopy, X-ray diffraction (XRD), a scanning electron microscope (SEM) and atomic force microscopy (AFM) measurement. The mechanical properties, i.e. hardness, were tested by using a nanoindenter test. The corrosion properties of the coatings were determined by analysis of the voltammetric curves.The deposited TiO2thin film prepared by the conventional magnetron sputtering process consisted of visible grains with the size of ca. 50–100 nm and had a nanocrystalline anatase phase (TiO2(a)). The TiO2thin film deposited by plasma-modulated sputtering had a nanocrystalline rutile structure TiO2(r) and its surface consisted of big, irregular grains and was not as homogeneous as the coating prepared by the conventional method.The hardness of TiO2(a) and TiO2(r) thin films was equal: 7.59 GPa and 14.2 GPa, respectively.Graphene transferred to a titanium dioxide thin film surface was a single layer without defects. Unfortunately, the nanoindentation method, used to measure the hardness of the titanium dioxide/graphene coating systems, is not sensitive to one or few atomic layers of graphene deposited on the top of the coating structures. Therefore, the measurement did not reveal changes of titanium dioxide thin film hardness after graphene deposition, in comparison with uncoated TiO2thin films such as TiO2(a) and TiO2(r) thin films. Futhermore, the graphene monolayer can be very easily removed from the titanium dioxide thin film surface (e.g. by scratching).The best corrosion properties (the lower value of corrosion current density) were obtained for sample Ti6Al4V coated with a TiO2(a) thin film. A deposition graphene monolayer on the top of all tested thin films improves the corrosion potential (Ecorr) value, which is much more positive than Ecorrregistered for the other samples. A positive value of the corrosion potential is characteristic of materials with low electrochemical activity and thereby very good corrosion resistance. Moreover, these coatings systems maintain stability of the mechanical properties during the corrosion process.