Materials World Network: Multi-Scale Study of Chemical Vapor Infiltrated Carbon/Carbon Composites

本研究的目的是加强对复杂的分级结构和碳/碳复合材料的力学行为之间的相关性的基本理解。这是通过利用多尺度模型的基础上微观结构和机械特性在纳米到宏观长度尺度。通过测量所有长度尺度上的力学性能来验证该模型。参与的研究人员将微观结构和机械性能与化学气相渗透参数相关联。研究了热解碳纳米织构和热处理对复合材料应力集中和断裂的影响。该项目由新罕布什尔州大学（UNH）和德国卡尔斯鲁厄大学（UKA）的研究人员密切合作进行。材料样本在UKA在受控的加工条件下生产。在UKA和UNH使用各种显微镜对这些样品的微观和纳米结构进行表征。在UNH使用纳米压痕法进行微观组成的机械行为的测量。研究人员将这些信息整合到复合材料整体机械响应的统一预测模型中。最后，UNH和UKA使用标准测试方法对材料进行宏观力学表征，以验证模型。该研究将导致碳/碳复合材料制造的改进，主要通过航空航天工业的技术进步造福社会，尽管预计在复合材料的新兴应用领域也会产生潜在影响，如生物医学设备，加热元件以及金属成型和玻璃制造用五金件。本研究中开发的表征和建模方法也将与具有复杂纳米结构的复合材料和异质材料的广泛类别相关，包括高性能陶瓷涂层，纳米结构电磁干扰屏蔽材料，以及由置于不同陶瓷基质（例如SiC）中的热解碳涂层碳纤维组成的复合材料。来自美国和德国的五名研究生和来自UNH的两到四名本科生在合作的国际环境中接受教育。他们每个人都将用自己的经验影响同行和同事。

The objective of this research is to enhance fundamental understanding of the correlation between complex hierarchical microstructure and the mechanical behavior of carbon/carbon composites. This is done by utilizing a multiscale model based on microstructural and mechanical characterization at nano to macro length scales. The model is validated by measuring the mechanical properties on all length scales. Participating investigators correlate microstructure and the mechanical properties with chemical vapor infiltration parameters. Stress concentrations and fracture induced by nanotexture of pyrolytic carbon and by thermal treatment of the composite are also investigated. The project is conducted in close collaboration by researchers from the University of New Hampshire (UNH) and the University of Karlsruhe (UKA), Germany. Material specimens are produced at UKA under controlled processing conditions. The micro and nanostructure of these specimens is characterized at UKA and UNH using various microscopies. Measurements of the micro-constituent mechanical behavior is performed at UNH using nanoindentation methods. Researchers incorporate this information in a unified predictive model of the overall mechanical response of the composite. Finally, macro-mechanical characterization of the material is conducted at UNH and at UKA using standard testing methods to validate the model.The research will result in improvements in manufacturing of carbon/carbon composites that will benefit society mainly through technological advances in aeronautics and aerospace industries, although potential impact is also anticipated in emerging areas of applications of the composites such as biomedical devices, heating elements, and hardware for metal forming and glass making. The characterization and modeling approaches developed in this research will also be relevant to a wide class of composite and heterogeneous materials having complex nanostructures, including high performance ceramic coatings, nanostructured electromagnetic interference shielding materials, and composites consisting of carbon fibers coated by pyrolytic carbon placed in a different ceramic matrix (e.g. SiC). Five graduate students from the US and Germany and two-to-four undergraduate students from UNH are educated in a collaborative, international setting. Each of them will impact their peers and colleagues with their experience.