【作者】 王建新；

【导师】 张瑞军；

【作者基本信息】 燕山大学 ， 材料物理与化学， 2013， 博士

【摘要】 高能球磨极易在材料中引入大量的应变、缺陷以及纳米级微结构，目前已成为调控材料微观结构及性能乃至获得各种纳米结构的有效方法之一。碳纳米结构因其独特的结构、优异的性能及巨大的应用前景一直是材料学界的研究热点之一。研究表明：高能球磨天然石墨是制备碳纳米结构的有效技术手段。至今，人们通过对天然石墨进行高能球磨已成功制备出碳纳米弧、碳纳米卷（CNSs）、类洋葱、碳纳米管等多种碳纳米结构。膨胀石墨（Expanded Graphite，简称EG）是天然石墨经插层、水洗及高温膨化制得的一种新型碳材料。EG基本保持着天然石墨原有的层状结构特征，但是其中的石墨片厚度更薄，而且表现出特殊的柔性和弹性。迄今为止，有关EG的高能球磨处理及其结构演化的研究尚处于初级阶段，而通过高能球磨EG制备碳纳米结构的工作更是鲜见报道。鉴于此，本学位论文以EG为对象，研究其在高能球磨期间的结构演化并探索碳纳米结构的形成过程与形成机理以及球磨态EG在复合材料领域中的应用。主要研究工作和结果如下：以EG为原料，采用振动球磨的方法制备出石墨纳米片及其衍生结构-柱状CNSs。柱状CNSs是由双层石墨烯卷曲形成的。研究了球磨过程中石墨纳米片和柱状CNSs的形成过程与形成机理，并进一步分析了片层结构特点（如厚度、面内缺陷等）对柱状CNSs形成的影响。结果表明：片层厚度与球磨过程中产生的面内缺陷对柱状CNSs的形成起了决定性作用；相比片状结构和管状结构的碳纳米结构，柱状CNSs具有较差的柔韧性。以球磨态EG和电解铜粉为原料，采用粉末冶金的方法制备出新型球磨态EG-Cu自润滑复合材料。研究了球磨态EG含量与复合材料的硬度、弯曲强度及摩擦学性能的关系，并分析了其减摩耐磨机制。结果表明：球磨态EG因纳米级尺度的片层厚度而具有高效的润滑性能；随着球磨态EG含量的增加，复合材料的硬度和弯曲强度均降低，摩擦学性能先提高后略有降低。因此加入适量石墨烯纳米片，能够有效提高铜-碳自润滑复合材料的摩擦学性能，并兼顾最大限度地抑制复合材料弯曲强度因球磨态EG的引入而导致的恶化，提高复合材料的综合性能。将EG与Sn粉混合球磨并退火处理，制备出新型球磨态EG-SnOx（x=0,1,2）复合材料。研究了不同制备工艺（球磨时间和退火温度）对复合材料成分种类与微观结构的影响，并进一步研究了退火温度对复合材料电化学性能的影响。结果表明：球磨时间能有效控制球磨态EG的孔隙率、微晶厚度与含氧量；退火温度能有效改善球磨态EG结构的有序度，控制碳热反应的进程。通过控制球磨时间和退火温度可以制备出含不同成分种类、微观结构的球磨态EG-SnOx复合材料。电化学性能方面，相比球磨18h未退火和800℃退火4h制备的球磨态EG-SnOx复合材料，球磨18h600℃退火4h制备的球磨态EG-SnOx复合材料具有更好的电化学性能。更多还原

【Abstract】 It is extremely easy to introduce a lot of strain, defects and nanoscale microstructuresin materials during high-energy ball milling process. Therefore, high-energy ball millinghas become an effective method to control nanostructures and properties of materials andproduce various nano-materials. Carbon nanostructure is always the research focus ofmaterial fields due to its unique structure, outstanding performance and huge applicationprospect. Investigations show that high-energy ball milling is an effective method toproduce carbon nanomaterials. Up to now, many carbon nanostructures have beenproduced by ball milling of natural graphite, such as carbon nano-arc, carbon nanoscroll,carbon onion and carbon nanotube etc.Expanded graphite (EG) is a novel carbon material which is produced by naturalsquama graphite through oxidation, intercalation, washing, dryness and expansion. EGkeeps the layered structure of natural graphite mainly, but its carbon nanosheets possess athinner thickness and show excellent flexibility and elasticity. Up to now, bothhigh-energy ball milling and microstructure evolution of EG have just been receivedattention. The carbon nanostructures produced by ball milling EG has been barely reported.Therefore, this dissertation takes EG as the object of study. The microstructure evolutionof EG and the formation mechanism of carbon nanostructures during ball-milling processwere studied. In addition, the applications of ball milled EG-metal (oxide) composites intribology and energy fields were also investigated. The main research works and resultsare listed below.Graphite nanoshteets and their derived structure-columnar carbon nanosrolls (CNSs)are produced by vibratory milling of EG. The columnar CNSs are formed by bilayergraphenes. The formation mechanisms of graphite nanoshteets and columnar CNSs arestudied. The effect of the characters of nanosheets (thickness and intralayer defects) on theformation of columnar CNSs is also investigated. Results show that the ultrathin lamellarthickness and the intralayer defects play a decisive role of the formation of columnarCNSs. On the other hand, compared with the lamellar and tubular carbon nanostructures, columar CNSs has a lower flexility.Ball milled EG-Cu self-lubricating composites are fabricated by powder metallurgyusing ball milled EG and electrolytic copper powders as raw materials. The effect of theEG nanosheets on the hardness, bending strength, and tribological properties of ball milledEG-Cu composites are investigated. The abrasion mechanism of the ball milled EG-Cucomposites is also investigated. Results show that the ultrathin thickness of carbonnanosheets determines it has excellent tribological properties. With the content of EGnanosheets increasing, the hardness and bending strength of ball milled EG-Cu compositesgradually decrease, and the tribological properties are first improved and then deterioratedslightly. Adding a proper amount of carbon nanosheets can improve the tribologicalproperties of ball milled EG-Cu composites efficiently, and reduce the drop of the bendingstrength of ball milled EG-Cu composites.Ball milled EG-SnOx(x=0,1,2) composites are produced by ball milling andannealing of EG and Sn powder mixture. The effect of ball milling time and annealingtemperature on the component kinds and microstructures of ball milled EG-SnOxcomposites is investiagated. The effect of annealing temperature on the electrochemicalperformance of ball milled EG-SnOxcomposites is also investigated. Results show thatmilling time has the ability to control the porous rate, the microcrystal thickness and thecontent of oxide of ball milled EG. Annealing temperature has the ability to improve thedisordered structure of ball milled EG, and to control the process of carbothermic(reduction) reaction. Ball milled EG-SnOxcomposites with various component kinds andmicrostructures can be produced by controlling ball milling time and annealingtemperature. Compared with the ball milled EG-SnOxcomposites produced by18h ballmilling unanealed and annealed at800℃for4h, the ball milled EG-SnOxcompositeproduced by18h ball milling and annealed at600℃for4h has a better electrochemicalperformance.更多还原