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，将重点研究金刚石-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备的金刚石基复合材料具有硬度高、耐磨性好等特点。将研究在生产方案中加入纳米级金刚石对复合材料结构和性能的影响。超硬金刚石复合材料可应用于许多行业；一种可能的应用是在石油和天然气勘探中，金刚石复合材料可以用作钻头的切削刀片。钻头寿命的延长将降低油气钻井的成本。通过减少更换钻头的频率来降低潜在井喷期间的环境污染风险，很难用货币来衡量，但这将是巨大的。该项目正在与匈牙利布达佩斯的Eotvos大学和波兰华沙的波兰科学院高压研究中心合作进行。学生们将在这些机构进行长时间的访问，并在匈牙利和波兰顶尖科学家的指导下工作。匈牙利和波兰的科学家也将访问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晶粒尺寸和尺寸分布以及晶体缺陷引起的晶格应变来描述。最可能的缺陷是晶体之间的层错和界面。重点是了解纳米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。该方法将指导前驱体的最佳制备工艺和烧结超硬金刚石-碳化硅纳米复合材料的工艺条件的选择。新的缺陷表征方法，即通过x射线和中子衍射图确定纳米晶体的晶粒尺寸和原子结构，将进一步发展和完善，并应用于纳米材料的表征。当它们发展起来时，可以用来表征其他金属、电介质或半导体纳米晶体和纳米复合材料。具体来说，检查在晶体表面/界面形成的结构将能够评估这些材料的化学反应性，纳米结构基体中的晶界结构及其与材料性能的关系。对纳米晶体中原子排列的基本理解，特别是在界面附近的原子排列，对于纳米技术的进一步发展是绝对必要的。关于复合材料结构的补充信息将从其他技术中获得。纳米技术相关研究的跨学科性质和拟议的教育活动将为学生和年轻的专业人员准备未来的挑战。国际合作、研究活动的整合、知识和实践技能的分享、研究生和博士后的交流以及访问的高级研究员提供的一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.