石墨烯薄膜的原子氧效应研究

发布时间：2018-02-19 21:00

本文关键词： 石墨烯薄膜原子氧效应 sp~2杂化　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,空间环境及其效应对航天器的严酷性已被逐步认识。低地球轨道(距地面高度200km-700km)是空间站、飞船、航天飞机以及一些应用卫星的主要运行轨道。原子氧(AO)是低地球轨道环境大气的主要成分,含量约占气体总量的80%,作为低地球轨道环境中含量最高的粒子,其对航天器的危害也是巨大的。造成原子氧危害的原因主要有以下两个方面:其一,原子氧的化学活性极强,极易与材料发生反应;其二,航天器在其轨道上的运行速度极高,可以达到8km/s,原子氧作用于航天器材料的动能可以达到4e V,当具有强氧化性、高通量、高能量的原子氧与材料相互作用时,会对材料的性能和表面形貌产生影响,致使在航天器的正常运行和使用寿命方面有不良影响。到目前为止,人们对原子氧效应的机理理解还不是很充分,研究人员们关心的问题主要有以下几个方面:材料的质损是由于剥落还是更复杂的化学反应;材料表面退降与碰撞角度的依存关系;材料表面温度对反应的影响;退降产生的反应产物是什么;原子氧效应局限在材料表面还是能扩展到材料体内。石墨烯的研究价值主要体现在两个方面,一是作为sp~2杂化碳材料的基本结构单元,可被当作模型材料使用;另一方面,石墨烯拥有众多的优异特性,如高比表面积、高载流子迁移率、高电导率、高热导率、高透光率、高强度等,因此在许多领域中具有巨大的应用潜力。石墨烯作为sp~2杂化碳材料的基本结构单元,其原子氧反应规律对于其它种类碳膜传感器的原子氧反应状况也具有指导作用;同时,由于石墨烯具有确定的结构和性质,也非常适合作为模型碳材料首先进行原子氧反应规律的研究。本文第一部分工作,采用氧化还原法制备了两组不同还原程度的石墨烯薄膜,并且薄膜含氧基团的含量在制备过程中可控。对制得的薄膜进行了不同原子氧通量的辐照,对样品的质量损失、剥蚀率进行了计算分析,结果表明石墨烯薄膜具有较低的原子氧剥蚀率,相比碳、石墨、Kapton、Teflon、环氧树脂等常用空间材料,具有更好的抗原子氧性能。并且不同还原程度的石墨烯薄膜展示出了不同程度的抗原子氧性能,还原程度高的薄膜具有更好的抗原子氧性能,因此可以通过调控制备过程中薄膜的还原程度来制备具有适当抗原子氧性能的石墨烯薄膜。为了研究原子氧辐照环境下石墨烯薄膜的导电性能的变化,采用导电粘结剂将铂丝连接到石墨烯薄膜的两端,形成了石墨烯薄膜电阻,在原子氧辐照环境下考察薄膜电阻的导电性能变化情况,实验结果显示薄膜电阻稳定时间高达149h,对应的原子氧通量为1.3x10~(21)atom/cm2,并且其有效工作时间可以随石墨烯薄膜电阻的还原程度在制备过程中进行调控。本文第二部分工作,通过一系列测试方法对石墨烯薄膜物理化学性质进行表征,对比不同原子氧通量辐照下石墨烯薄膜的变化情况,分析石墨烯与原子氧作用情况,测试结果表明原子氧对石墨烯薄膜的作用既有对其表面的物理溅射还有与材料表面的化学反应,作用过程中,物理溅射导致石墨烯薄膜表面被剥蚀,二维平面结构逐渐出现孔洞,表面呈现凹凸不平,化学反应导致薄膜表面氧元素含量逐渐增加,原子氧与石墨烯发生化学反应,逐渐破坏原有的sp~2杂化碳碳键,与石墨烯逐渐形成C=O、环氧键,碳原子杂化方式逐渐变成sp~3。
[Abstract]:In recent years, severe space environment and its effects on the spacecraft has been recognized gradually. The low earth orbit (altitude 200km-700km) is a space station, spacecraft, space shuttle and satellite orbit. The main application of atomic oxygen (AO) is the main component of the low earth orbit environment atmosphere, the total gas content of about 80%, as the particle content in low earth orbit spacecraft to the highest, its harm is enormous. The cause of atomic oxygen hazards are mainly in the following two aspects: first, the chemical activity of atomic oxygen is extremely strong, react easily with the material; second, the speed of the spacecraft orbit high that can reach 8km/s. The kinetic energy of atomic oxygen on spacecraft materials can reach 4E V, when has strong oxidation, high throughput, interaction of atomic oxygen with high energy materials, performance and surface morphology of the material. Have an impact, resulting in adverse effects on the normal operation of the spacecraft and service life. So far, the mechanism of understanding on the atomic oxygen effects is not good, the researchers are concerned about the problems mainly in the following aspects: the mass loss of materials is due to the peeling or more complex chemical reactions; surface degradation and the collision angle dependency relation; influence of surface temperature on the reaction; what is the reaction product of degradation generated; atomic oxygen effects on the surface of the material or limitations can be extended to materials in vivo. The research value of graphene is mainly reflected in two aspects, one is as the basic structural unit of sp~2 hybrid carbon material, can be as a model of material use; on the other hand, graphene has many excellent features, such as high specific surface area, high carrier mobility, high conductivity, high thermal conductivity, high light transmittance, high strength and so on, because of This has great potential applications in many fields. Graphene as the basic structural unit of sp~2 hybrid carbon material, the atomic oxygen reaction rules for other kinds of carbon film sensor atomic oxygen reaction condition also has a guiding role; at the same time, because graphene has determined the structure and properties, also very suitable for the study as a model of carbon the material first reaction of atomic oxygen. In the first part of this work, the oxidation of two groups of different levels of reduction of graphene thin films were prepared by reducing the content of the film, and the oxygen containing groups in the preparation process of controllable. The prepared films were irradiated by different atomic oxygen flux, mass loss of the samples. The denudation rate was calculated and analyzed. The results show that the graphene films with atomic oxygen in low rate, compared with carbon, graphite, Kapton, Teflon, epoxy resin and other commonly used materials in space, has better The atomic oxygen resistance. And the reduction degree of graphene films showing the atomic oxygen resistance in different degree, high degree of reduction film has better atomic oxygen resistance, so the reduction degree of the film can be controlled by adjusting the preparation process for the preparation of graphene films with appropriate atomic oxygen resistance. In order to change the conductive properties of graphene films of atomic oxygen irradiation environment, the conductive adhesive platinum wire connected to both ends of the graphene films, formed graphene thin film resistor, the conductive properties of thin film resistor to investigate the changes in atomic oxygen irradiation environment. The experimental results show that the thin film resistor stable time up to 149h atoms the oxygen flux corresponding to 1.3x10~ (21) atom/cm2, and the degree of reduction of the effective working time with the graphene film resistance regulation in the preparation process of the second part of this. Work to characterize the physical and chemical properties of graphene films through a series of test methods, the changes of graphene films between different atomic oxygen flux under irradiation, analysis of graphene and atomic oxygen effects, test results show that the effect of atomic oxygen on graphene thin film sputtering on the surface of both the physical and chemical reaction the surface of the material, process, physical sputtering surface resulting in graphene film was eroded, planar structure has holes, showed uneven surface, chemical reaction causes the surface oxygen content of the film increased gradually, atomic oxygen and graphene chemical reaction, the gradual destruction of the original sp~2 hybridized carbon carbon bond, gradually formed C=O. With graphite epoxy bond, carbon atom hybridizationway gradually become sp~3.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TB383.2

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