石墨烯—纳米晶镍基复合材料的制备及性能研究

发布时间：2018-03-21 15:53

本文选题：纳米晶金属　切入点：石墨烯　出处：《吉林大学》2015年硕士论文　论文类型：学位论文

【摘要】：纳米材料指的是在三维空间的某一个维度上处于纳米尺度的材料，而特异的结构使得纳米材料具有普通材料所不具备的特殊性能。纳米晶金属材料作为纳米材料的一种，，即是晶粒尺寸达到纳米级别(10-9m)的金属材料。相较于普通粗晶材料，纳米晶材料的特殊结构使得其在许多方面都展现出了优异的性能，比如超高的屈服强度和硬度，更好的耐磨性与耐蚀性。另一方面，纳米复合材料由于其优异的综合性能，在过去多年一直是材料科学的一个研究热点。碳纳米管、陶瓷纳米颗粒等材料的引入可以将金属基体与第二相粒子的独特性质结合在一起，从而大大地提高复合镀层的性能。然而，过去却很少有将纳米颗粒第二相与纳米晶金属基体结合在一起的研究。假设能够在现有的研究基础上制备出纳米颗粒-纳米晶金属基体的复合材料，将有望能够获得超高强度的纳米复合材料。石墨烯作为一种新兴的二维材料，由于其特殊的结构(超高的比表面积~2600m2g-1和很低的密度~2.2gcm-3)和优异的力学性能(杨氏模量可以达到1TPa，拉伸强度可以达到130GPa)，正是一种理想的第二相材料。将石墨烯与纳米晶金属的优点结合起来，制备出具有优异性能的复合材料正是本文的研究重点。本文以电沉积方法制备纳米晶金属材料的技术理论为基础，在Watts镀液中加入各种添加剂和第二相RGO-Ni纳米复合物，通过复合电沉积的方法将石墨烯引入到纳米晶金属镍中。通过控制RGO-Ni的浓度和电沉积过程中的工艺参数，最终获得了复合电沉积的最佳工艺参数。利用X射线衍射仪(XRD)，透射电子显微镜(TEM)和扫描电子显微镜(SEM)等仪器对实验过程各个阶段产物的成分，微观组织和表面形貌进行了系统的观察与分析。然后利用电化学分析仪对复合镀层的耐蚀性进行了表征，最后对制得样品的力学性能进行了纳米压痕测试研究。本工作的研究结果如下： 1.利用改进Hummer法制备了氧化石墨；改变氧化石墨烯与硫酸镍的重量配比，通过水热还原法制备了Ni纳米粒子浓度不同的RGO-Ni纳米复合物。通过形貌观察与分析，最终选取4:1为硫酸镍与氧化石墨烯质量的最佳配比，并将在该条件下制备的RGO-Ni纳米复合物作为引入到纳米晶Ni中的“第二相”。 2.改变瓦特镀液中RGO-Ni纳米复合物的含量，在电沉积制备纳米晶金属技术的基础上，将RGO-Ni作为第二相材料加入到纳米晶镍镀层中，成功制备出了石墨烯-纳米晶镍基复合镀层。 3.根据扫描电镜的结果，当镀液中RGO-Ni纳米复合物浓度从0.1mg/mL提升到0.5mg/mL时，复合镀层的表面形貌粗糙度会明显地增加。而当镀液中RGO-Ni纳米复合物的浓度相同时，增大超声波的功率会明显地引起复合镀层表面粗糙度的增加。另外，在搅拌条件下制备的复合镀层表面形貌比超声波下制备的材料要更加平整。 4.极化曲线实验和电化学阻抗谱分析表明，镀层中石墨烯的引入影响着镀层的腐蚀行为，它的浓度决定着镀层中的缺陷密度。纯镍镀层在NaCl和NaOH溶液中可以形成有效的钝化膜，增大了Ni2+和电子向表面迁移并参加化学反应的难度，因此具有着更高的耐蚀性。然而，石墨烯的引入使得镀层内的缺陷大量增加，从而形成了很多的微电池，加快了镀层的腐蚀。所以，石墨烯的引入降低了镀层的耐蚀性能，且RGO-Ni纳米复合物浓度越高复合镀层的耐蚀性能也就越低。 5.纳米压痕研究表明，在搅拌条件下与超声条件下制备的纯镍镀层与复合镀层的硬度值和弹性模量值差别很小。纯镍镀层的硬度值在6.9~7.0GPa之间，弹性模量值则在120~121GPa之间。向镀液中直接加入GO对复合镀层的力学性能有一定的提高，复合镀层(镀液中GO浓度为0.5mg/mL时)的硬度值最高可以达到7.4GPa，弹性模量最高值则在130GPa左右。而当镀液中加入RGO-Ni时，复合镀层力学性能的提升更为明显，硬度值最高(镀液中RGO-Ni浓度为0.5mg/mL时)可以达到8.0GPa，而相应的弹性模量最高值达到了177GPa。相比较之下，镀液中直接加入GO对复合镀层力学性能的提升作用并不明显，而向镀液中加入RGO-Ni复合物则能够更加明显地提高镀层的硬度和弹性模量。而且随着镀液中RGO-Ni纳米复合物浓度的增大，镀层硬度值和弹性模量值提高的幅度也有明显的增大。
[Abstract]:Nano material refers to a certain dimension in three-dimensional space in nanoscale materials, and specific structure of the nano materials with special properties of conventional materials do not have. Nanocrystalline metallic materials is a kind of nano material, which is the grain size of nanometer metal materials don't (10-9m). Compared with the conventional coarse-grained materials, the special structure of nanocrystalline materials makes it in many ways to show excellent performance, such as high yield strength and hardness, wear resistance and corrosion resistance is better. On the other hand, nano composite materials due to its excellent performance, in the past years has been a a focus of material science. The introduction of carbon nanotubes, ceramic nano particles and other materials can be the unique properties of the metal matrix and the second phase particles together, thus greatly improve the performance of the coating. However, too However, there are few studies on the combination of second phase and nanocrystalline metal matrix. It is expected that the composite materials with nano particle and nanocrystalline matrix will be able to obtain ultra-high strength nanocomposites on the basis of existing research.
Graphene as a new two-dimensional material, because of its special structure (high ~2600m2g-1 surface area and low density ~2.2gcm-3) and excellent mechanical properties (Young's modulus can reach 1TPa, the tensile strength can reach 130GPa), is an ideal second phase material. The advantages of graphene and nanocrystalline metal combined to prepare composite material with excellent performance is the focus of this paper.
Based on the theory of technology of electrodeposition of nanocrystalline metal materials as the basis, adding various additives and the second phase of RGO-Ni nanocomposites in Watts plating solution, the graphene into nanocrystalline nickel by composite electrodeposition process parameters. By controlling the concentration of RGO-Ni and electrodeposition process. The optimum parameters of composite electrodeposition. By using X ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and other components of instrument experimental process in each stage of product, microstructure and surface morphology were observed and analyzed. Then the electrochemical analyzer system on corrosion resistance of composite coatings were characterized, the mechanical property of the prepared samples were studied. Nano indentation test
The results of this work are as follows:
1. using the improved Hummer method to prepare graphite oxide; change of graphene oxide and nickel sulfate weight ratio of RGO-Ni nanocomposites with different concentrations of Ni nanoparticles were prepared by hydrothermal reduction. Through the observation and analysis of morphology, finally selects the optimal ratio of 4:1 to nickel sulfate and graphene oxide quality, and in this condition preparation of RGO-Ni nanocomposites as into Ni nanocrystals in the "second phase".
2., changing the content of RGO-Ni nanocomposite in watt bath, and based on the technology of electrodeposited nanocrystalline metal, RGO-Ni was added into nanocrystalline nickel coating as the second phase material, and graphene nanocrystalline nickel based composite coating was successfully prepared.
3. according to the results of scanning electron microscope, when RGO-Ni bath nanocomposites concentration increased from 0.1mg/mL to 0.5mg/mL, the morphology of the composite coatings roughness will increase obviously. But when the concentration of RGO-Ni in the bath of nanocomposites is the same, the ultrasonic power increases significantly due to the increase of surface roughness of composite coating. In addition, more smooth than ultrasonic prepared materials, surface morphologies of composite coatings were prepared under stirring.
The 4. polarization curves and electrochemical impedance spectroscopy analysis showed that the introduction of graphene in the coatings affects the corrosion behavior of the coating, its concentration determines the density of defects in the coating. The nickel coating in the NaCl and NaOH solution to form an effective passivation film, increased Ni2+ and electron transfer to the surface and participate in chemical reactions the difficulty, so it has a higher corrosion resistance. However, the introduction of graphene makes the coating defects increase, thus forming a lot of micro cell, accelerate the coating corrosion. Therefore, the introduction of graphene decreased the coating corrosion performance and corrosion resistance properties of RGO-Ni nanocomposites and the higher the concentration of compound the coating is also lower.
5. nanoindentation studies showed that the preparation of pure nickel coating and composite coating prepared under stirring and ultrasonic conditions, the hardness and elastic modulus of the difference is small. The pure Ni coating hardness between 6.9~7.0GPa, elastic modulus is between 120~121GPa. To the bath directly into the mechanical properties of the composite coatings GO has been improved to a certain extent, composite coating (plating GO concentration is 0.5mg/mL) the maximum value of hardness can reach 7.4GPa, the highest modulus value is about 130GPa. When adding RGO-Ni in the plating solution, mechanical composite coating performance improvement is more obvious, the maximum value of hardness (RGO-Ni concentration in plating liquid 0.5mg/mL) can reach 8.0GPa, while the elastic modulus corresponding to the maximum value reached 177GPa. by contrast, plating liquid directly into the effect of GO on the mechanical properties of the composite coating is not obvious, while adding RGO-Ni compound to the bath The hardness and elastic modulus of the coating can be increased more obviously. Moreover, with the increase of the concentration of RGO-Ni nano composite in the bath, the hardness and elastic modulus of the coating will also increase obviously.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

【共引文献】