NIRT: Tough Nanocomposite Coatings using New Self-Organized Carbon Forms

使用新型自组织碳形式的韧性纳米复合涂层，W.A.Curtin，B.W.Sheldon，R.Hurt和G.Crawford工程系，布朗大学，普罗维登斯，RI 02912Y。-T·程通用汽车研究和开发，沃伦，密歇根高模和高强度碳纳米管(CNT)的出现引发了人们对基于纳米管的材料和相关新形式碳的极大兴趣。我们建议开发新型的碳纳米纤维增强陶瓷和金属，作为用于接触和磨损应用的坚韧、耐损伤涂层，以取代传统的硬涂层。含有新型工程碳纳米纤维的纳米复合材料将被制造、评估和优化，以触发纳米级的增韧。我们建议(I)使用Brown特有的盘状自组装路线和CVD方法来控制纳米纤维增强材料和所产生的纳米复合材料的结构/性能，来合成一系列全新的纳米复合材料，(Ii)在这些复合材料系统中展示韧性和损伤容忍度，(Iii)阐明这些纳米复合材料的增韧机理，(Iv)研究这些材料的一系列制造路线，以及(V)在现实磨损条件下评估用于汽车零部件和机械加工的铝和钢合金的新材料。由于我们最近观察到碳纳米管/陶瓷复合材料的增韧机制，以及我们可以通过各种方法来产生和控制碳结构来设计各向异性性能，所以我们将重点放在纳米复合涂层中的碳基增强上。由于传统的碳纳米管可能不是实现纳米级增韧所必需的，我们将开发包含全新类别纳米碳纤维体的复合材料，这些纳米碳纤维体是通过低成本的聚芳烃介晶前体的表面介导的低温组装合成的，这种组装允许对性能的各向异性以及控制纤维/基质结合的表面进行分子工程。碳/陶瓷纳米复合材料的整体合成将涉及到我们新颖的定向聚芳烃组装和几种在纳米通道氧化铝阵列模板中形成纤维状碳材料的沉积方法，从而生成一系列具有不同纤维结构(纳米管、固体石墨纤维、“开放”结构的纤维和管)、纤维尺寸、界面粘附性、残余应力、各向异性热/弹性/强度性能、摩擦系数和几何有序的纳米陶瓷复合材料。纳米金属基复合材料的制造将通过金属沉积到通过CVD形成的独立的纤维结构或通过对模板陶瓷基质的刻蚀来实现。重点机械测试将测量韧性和抗损性，分析将确定增韧机制，并确定在多个尺度上的结构/化学细节如何控制增强的韧性和磨损性能。私人投资促进机构致力于通过整合研究和教育、工业推广和人力资源开发来提高技术工作的影响力。该项目将通过培训研究生加强科学和教育的基础设施，通过建立针对代表性不足群体的暑期实习计划，通过将创新研究活动纳入课程，通过为研究生提供在转基因研发部门工作的机会。我们将与妇女科学与工程协会、全国黑人工程师协会和新科学家计划合作，广泛传播纳米技术的科学和应用，并招募活跃的研究人员。我们将把纳米技术概念整合到现有的NSF MRSEC计划和我们的创业计划中。

Tough Nanocomposite Coatings using New Self-Organized Carbon Forms W. A. Curtin, B. W. Sheldon, R. Hurt, and G. CrawfordDivision of Engineering, Brown University, Providence, RI 02912Y.-T. ChengGeneral Motors Research and Development, Warren, MIABSTRACTThe advent of high modulus and strength carbon nanotubes (CNT) has sparked tremendous interest in nanotube-based materials and related new forms of carbon. We propose to develop novel carbon-nanofiber-reinforced ceramics and metals as tough, damage-tolerant coatings for contact and wear applications to replace traditional hard coatings. Nanocomposites containing new engineered carbon nanofibers will be fabricated, evaluated, and optimized to trigger nanoscale toughening. We propose to (i) synthesize a set of wholly new nanocomposite materials using discotic self-assembly routes unique to Brown, and CVD methods to control the structure/properties of the nanofibrous reinforcements and resulting nanocomposites, (ii) demonstrate toughness and damage tolerance in these composite systems, (iii) elucidate toughening mechanisms in these nanocomposites, (iv) investigate a range of fabrication routes for these materials, and (v) evaluate the new materials under realistic wear conditions for aluminum and steel alloys used in automotive components and machining. We focus on carbon-based reinforcements in nanocomposite coatings due to our recent observations of toughening mechanisms in CNT/ceramic composites and because of the myriad ways in which we can produce and control carbon structures to engineer anisotropic properties. Because conventional CNTs may not be necessary to achieve nanoscale toughening, we will develop composites containing an entirely new classes of nanoscale carbon fiberous bodies synthesized by surface-mediated, low-temperature assembly of low-cost polyaromatic mesogenic precursors, which allows molecular engineering of anisotropy in properties, and of the surfaces that control fiber/matrix bonding. The overall synthesis of carbon/ceramic nanocomposites will involve our novel directed polyaromatic assembly and several deposition approaches for forming fiberous carbon materials in nanochannel alumina array templates so as to generate an array of nanoceramic composites with varying fiberous structure (nanotubes, solid graphitic fibrils, "open" structure fibrils and tubes), fiberous dimensions, interfacial adhesion, residual stresses, anisotropic thermal/elastic/strength properties, friction coefficients, and geometric order. Fabrication of nanometal-matrix composites will be performed by metal deposition into free-standing fiberous structures formed via CVD or via etching of the template ceramic matrix. Focused mechanical testing will measure toughness and damage resistance, and analysis will determine the toughening mechanisms and identify how structural/chemical details at multiple scales control enhanced toughness and wear performance. The PIs are dedicated to enhancing the impact of the technical work through integration of research and education, industrial outreach, and human resource development. The project will enhance the infrastructure for science and education by training graduate students, by establishing a summer internship program targeted at under-represented groups, by integrating innovative research activities into the curriculum, and by providing opportunities for graduate students to work at GM R&D. We will cooperate with local chapters of the Women in Science and Engineering, National Society for Black Engineers, and New Scientist Program to broadly disseminate the science and application of nanotechnology and to recruit active researchers. We will integrate nanotechnology concepts into existing NSF MRSEC programs and our entrepreneurship program.