激光快速原位制备石墨烯及其耐腐蚀性研究

发布时间：2018-12-11 01:33

【摘要】：石墨烯是由碳原子紧密排列成的二维蜂窝状结构,其厚度仅为一个原子层或几个原子层厚,是构成其他维数碳材料的基本结构单元。石墨烯具有优异的电学、光学、热学、力学等特性,可被应用于微电子、柔性显示、储能器件和复合材料等方面。其中,石墨烯的抗透性、高导电性和化学稳定性,使其成为一种优异的抗腐蚀保护材料。然而目前对石墨烯在金属防护方面的研究远远不足,在制备方法上也缺乏一种块体金属表面制备石墨烯的有效方法。本论文提出一种金属表面制备石墨烯的新方法,利用激光辐照预置的固体碳源在Ni金属、45#钢和Ni/Cu合金表面快速原位地制备出较大面积的石墨烯,制备过程在开放环境中完成,不涉及可燃性气体的排放,是一种工程化的、环境友好的石墨烯制备方法。利用宽光斑的半导体激光(光斑尺寸16 mm×1 mm)进行单道扫描可制备宽为16 mm的石墨烯宽带,最高生长速度可达28.8 cm2/min;利用聚焦的光纤激光(光斑直径为3 mm或者1 mm)在无需任何掩膜等辅助设施的条件下制备任意图案的石墨烯。系统研究了激光加工工艺、激光光斑能量分布的均匀性、冷却速度及碳涂层厚度对石墨烯生长的影响规律。此外还分析了激光快速加热过程中固态碳源在激光所形成金属熔池中的溶解行为以及快速凝固过程下石墨烯的形成,该过程与CVD气态碳源的扩散与析出过程明显的不同。利用激光合金化引入Ni原子,实现了在45#钢和Ni/Cu合金上生长石墨烯。Fe作为45#钢的主要成分,容易与C形成碳化物,是一种不适合石墨烯生长的金属基底。在Fe中加入Ni后,为石墨烯提供生长所需的催化剂,随着Ni含量的增加,所制备石墨烯的缺陷减少,石墨烯层数增加。通过调控Ni/Cu合金中Ni和Cu的比例,实现了石墨烯层数的初步控制。采用化学浸泡腐蚀和电化学腐蚀等手段系统研究了金属表面激光方法制备的石墨烯的抗腐蚀性能。结果表明,在纯Ni表面用激光原位生长石墨烯后,在海水中的腐蚀速率降低了1000倍;在45#钢表面用激光原位生长了石墨烯后,其抗腐蚀性能甚至超过了超级耐蚀不锈钢904L。激光原位生长石墨烯的优异抗腐蚀性能源于石墨烯的抗透性、化学稳定性和高导电性以及与金属基体的天然良好结合。该方法在金属抗腐蚀防护领域中具有良好的潜在应用价值。
[Abstract]:Graphene is a two-dimensional honeycomb structure composed of carbon atoms. The thickness of graphene is only one atomic layer or several atomic layers. Graphene is the basic structural unit of other dimensional carbon materials. Graphene has excellent electrical, optical, thermal and mechanical properties, and can be used in microelectronics, flexible display, energy storage devices and composite materials. Among them, graphene is an excellent anticorrosive material due to its high permeability, high conductivity and chemical stability. However, the research on the metal protection of graphene is far from enough, and there is also a lack of an effective method for the preparation of graphene on the surface of bulk metal. In this paper, a new method for the preparation of graphene on metal surface is proposed. A large area of graphene is rapidly prepared on the surface of Ni metal, 4steel and Ni/Cu alloy by laser irradiation of solid carbon source. The preparation process is completed in an open environment and does not involve the discharge of combustible gases. It is an engineering and environmentally friendly method for the preparation of graphene. Using semiconductor laser with wide spot size (spot size 16 mm 脳 1 mm), the graphene wideband with width of 16 mm can be prepared by single channel scanning. The highest growth rate can be up to 28.8 cm2/min;. Graphene with arbitrary patterns was prepared by focusing fiber laser (spot diameter 3 mm or 1 mm) without any mask and other auxiliary facilities. The effects of laser processing technology, uniformity of laser spot energy distribution, cooling rate and thickness of carbon coating on the growth of graphene were systematically studied. In addition, the dissolution behavior of solid carbon source in the molten metal pool formed by laser and the formation of graphene during rapid solidification are also analyzed. The process is different from the diffusion and precipitation process of CVD gaseous carbon source. The growth of graphene on 4steel and Ni/Cu alloy was realized by introducing Ni atom into laser alloying. As the main component of 4steel, Fe is easy to form carbides with C and is a kind of metal substrate unsuitable for graphene growth. The addition of Ni to Fe provides the catalyst for the growth of graphene. With the increase of Ni content, the defects of graphene are decreased and the number of graphene layers increases. By adjusting the proportion of Ni and Cu in Ni/Cu alloy, the initial control of graphene layer number was realized. The corrosion resistance of graphene prepared by laser on metal surface was studied by means of chemical immersion corrosion and electrochemical corrosion. The results show that the corrosion rate of graphene in seawater decreases by 1000 times after in situ growth of graphene on the surface of pure Ni, and the corrosion resistance of graphene on the surface of 4steel is even better than that of super corrosion resistant stainless steel 904L. The excellent corrosion resistance of graphene grown by laser in situ can be attributed to its permeability, chemical stability and high electrical conductivity, as well as its natural combination with metal matrix. This method has good potential application value in the field of metal corrosion protection.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG174.45

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