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分层微观结构与碳/碳复合材料力学行为之间关系的基本理解。这是通过在纳米到宏观长度尺度上利用基于微观结构和力学表征的多尺度模型来完成的。通过测量各种长度尺度下的力学性能，验证了模型的有效性。参与研究的人员将微观结构和力学性能与化学蒸汽渗透参数联系起来。研究了热解碳纳米结构和复合材料热处理引起的应力集中和断裂。该项目是由新罕布什尔大学（UNH）和德国卡尔斯鲁厄大学（UKA）的研究人员密切合作进行的。材料样品是在UKA受控的加工条件下生产的。这些样品的微观和纳米结构在UKA和UNH使用各种显微镜进行了表征。在UNH使用纳米压痕方法进行微观成分机械行为的测量。研究人员将这些信息整合到复合材料整体力学响应的统一预测模型中。最后，在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。这项研究将导致碳/碳复合材料制造的改进，这将主要通过航空航天工业的技术进步造福社会，尽管复合材料在生物医学设备、加热元件、金属成型和玻璃制造硬件等新兴应用领域也有望产生潜在影响。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广泛复合材料和非均质材料相关，包括高性能陶瓷涂层，纳米结构电磁干扰屏蔽材料，以及由放置在不同陶瓷基体（例如SiC）的热解碳涂层的碳纤维组成的复合材料。来自美国和德国的五名研究生以及来自UNH的两到四名本科生在合作的国际环境中接受教育。他们每个人都会用他们的经验影响他们的同龄人和同事。

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.