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首页> 外文会议>High temperature ceramic matrix composites 8 >ANALYSIS AND MOLECULAR MODELING OF PYROLYTIC CARBONS NANOTEXTURES
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ANALYSIS AND MOLECULAR MODELING OF PYROLYTIC CARBONS NANOTEXTURES

机译：热解碳纳米结构的分析和分子建模

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摘要

Pyrolytic carbons are critical components of CMCs and C/C composites; their nanotexture is widely variable, and so are their mechanical and thermal properties. It is thus of high interest to understand their spatial organization, especially at the nanometer scale. Several known nanotextural types of pyrocarbons have been prepared and studied by numerous experimental techniques, and particularly by HRTEM lattice fringe imaging. Indeed, micrographs are the basis for an original approach to the construction of atomic scale models, called Image-Guided Atomistic Reconstruction (IGAR). Starting from an HRTEM LF micrograph with high- and low-frequency filtering, a set of 2D image statistical descriptors is collected. This set is imposed as a constraint to a random 3D image generator, assuming transverse isotropy. The generated 3D blocks are then used as templates in Molecular Dynamics simulations of liquid carbon quenching. The obtained sets of up to 80,000 C and H atoms may be used for the evaluation of several properties. Structural properties like simulated LF images and pair distribution functions are compared to experimental HRTEM and neutron diffraction data, with an excellent agreement. We confirm that the "Rough Laminar" and "Regenerative Laminar" are two distinct nanotextures, though often indistinctly called "Highly Textured". A virtual mechanical testing of the structure is presented and discussed.
机译：热解碳是CMC和C / C复合材料的关键成分。它们的纳米结构变化很大，其机械和热性能也变化很大。因此，非常有必要了解它们的空间组织，特别是在纳米尺度上。已经通过多种实验技术，特别是通过HRTEM晶格条纹成像，制备并研究了几种已知的纳米结构的热解碳。实际上，显微照片是构建原子尺度模型的原始方法的基础，这种方法称为图像引导原子重建（IGAR）。从带有高频和低频滤波的HRTEM LF显微照片开始，收集了一组2D图像统计描述符。假设横向各向同性，则将该集合作为对随机3D图像生成器的约束。然后将生成的3D块用作液态碳淬灭的分子动力学模拟中的模板。所获得的最多80,000个C和H原子的集合可用于评估几种性能。像模拟LF图像和成对分布函数这样的结构特性与实验HRTEM和中子衍射数据进行了比较，具有很好的一致性。我们确认“粗糙层流”和“再生层流”是两个截然不同的纳米纹理，尽管常常被模糊地称为“高度纹理化”。提出并讨论了结构的虚拟机械测试。

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