NSF-Europe Materials Collaboration: Atomic Structure of Nanosize Crystalline Grains in Diamond-SiC Composites

非技术描述：该研究项目由材料研究部和国际科学与工程办公室共同资助，重点研究金刚石-碳化硅（SiC）复合材料的合成、结构和性能之间的关系。 在高压和高温条件下制造的金刚石基复合材料具有高硬度和非常好的耐磨性的特点。 将研究生产方案中包含纳米级金刚石如何影响复合材料的结构和性能。 超硬金刚石复合材料可应用于多种行业；一种可能的应用是石油和天然气勘探，其中金刚石复合材料可用作钻头的切削刀片。 钻头使用寿命的延长将降低天然气/石油钻井的成本。 通过减少钻头更换频率来减少潜在井喷期间的环境污染风险，很难用货币价值来衡量，但它的价值是巨大的。 该项目是与匈牙利布达佩斯 Eotvos 大学和波兰华沙波兰科学院高压研究中心合作开展的。 学生将长时间参观这些机构，并在匈牙利和波兰顶尖科学家的监督下工作。 同样，匈牙利和波兰科学家将访问 TCU 并在国家实验室进行高压实验。 技术细节：复合材料的微观结构可以通过表征金刚石和碳化硅相的微晶尺寸和尺寸分布以及晶体缺陷引起的晶格应变来描述。 最可能的缺陷是堆垛层错和微晶之间的界面。 重点是了解纳米结构碳化硅基体的形成机制、其结构和机械稳定性以及其机械和物理性能的表征。 这种组合方法将指导选择最佳的前驱体制备程序和烧结超硬金刚石-SiC纳米复合材料的技术条件。 缺陷表征、通过 X 射线和中子衍射图确定纳米晶体晶粒尺寸和原子结构的新方法将得到进一步开发和完善，并应用于表征纳米材料。 开发完成后，它们可用于表征其他金属、电介质或半导体纳米晶体和纳米复合材料。 具体来说，检查微晶表面/界面处形成的结构将能够评估这些材料的化学反应性、纳米结构基质中的晶界结构及其与材料性能的关系。 对纳米尺寸晶体中原子排列（尤其是界面附近的原子排列）的基本了解对于纳米技术的进一步发展是绝对必要的。 有关复合材料结构的补充信息将从其他技术中获得。 纳米技术相关研究和拟议的教育活动的跨学科性质将为学生和年轻专业人员应对未来的挑战做好准备。 国际合作、研究活动的整合、知识和实践的分享、研究生和博士后的交流以及访问高级研究人员的系列讲座将为学生提供新的教育体验。

NON-TECHNICAL DESCRIPTION:This research program, co-funded between the Division of Materials Research and the Office of International Science and Engineering, will focus on relationship between synthesis, structure and properties of diamond-silicon carbide (SiC)composites. Diamond-based composites manufactured under high-pressure and high-temperature conditions are characterized by high hardness and very good wear resistance. How the structure and properties of the composites are influenced by inclusion of nanosize diamonds in the production protocol will be examined. Superhard diamond composites can be applied by many industries; one possible application is in oil and gas exploration where diamond composites could be used as cutting inserts in drill bits. An increase in the lifetime of drill bits will lower the cost of gas/oil drilling wells. It is difficult to assign the monetary value to the diminished risk of environmental pollution during potential blowouts by reduced frequency of drill bits replacements, but it would be substantial. This project is being carried out in collaborations with Eotvos University, Budapest, Hungary and High Pressure Research Center of Polish Academy of Sciences, Warsaw, Poland. Students will visit these institutions for extended periods of time and work under supervision of the leading Hungarian and Polish scientists. Likewise, Hungarian and Polish scientists will visit TCU and conduct high-pressure experiments at national laboratories.TECHNICAL DETAILS: The microstructure of composites can be described by characterizing diamond and silicon carbide phases in terms of their crystallite size and size distribution, and lattice strain caused by crystal defects. The most likely defects are stacking faults and interfaces between the crystallites. The emphasis is on understanding the formation mechanism of the nanostructured silicon carbide matrix, its structural and mechanical stability, and on characterization of its mechanical and physical properties. This combined approach will guide in selection of the optimum preparation procedures of precursors and technological conditions leading to sintering of superhard diamond-SiC nanocomposites. Novel methodologies of defects characterization, determination of grain sizes and atomic structure of nanocrystals from x-ray and neutron diffractograms, will be further developed and refined, and applied to characterize nanomaterials. When developed they could be used to characterize other metal, dielectric, or semiconductor nanocrystals and nanocomposites. Specifically, examination of the structures formed at the crystallite surfaces/interfaces will enable assessing chemical reactivity of these materials, and the structure of grain boundaries in nanostructured matrix and its relation to the material properties. Fundamental understanding of the atomic arrangements in nanosize crystals, especially near the interface, is absolutely necessary for further progress in nanotechnology. Supplementary information on structure of composites will be obtained from other techniques. The interdisciplinary nature of the nanotechnology-related research and proposed education activities will prepare students and young professionals for future challenges. International collaboration, integration of research activities, sharing of knowledge and practical know-how, the exchange of graduate students and post-doctoral fellows, and series of lectures offered by visiting senior researchers will offer students a new educational experience.