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

本研究的目的是加深对碳/碳复合材料复杂的层状微结构与力学行为之间的关系的基本了解。这是通过利用基于纳米到宏观长度尺度的微观结构和机械特性的多尺度模型来实现的。通过测量各种长度尺度上的力学性能，验证了模型的有效性。参与研究的人员将微观结构和机械性能与化学气相渗透参数相关联。还研究了热解碳纳米织构和复合材料热处理引起的应力集中和断裂。该项目是由新汉普郡大学(UNH)和德国卡尔斯鲁厄大学(UKA)的研究人员密切合作进行的。材料试件在英国阿肯色州的受控加工条件下生产。这些样品的微观和纳米结构在UKA和UNH使用不同的显微镜进行了表征。在UNH使用纳米压痕方法测量微组分的机械行为。研究人员将这些信息合并到复合材料整体机械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。研究将导致碳/碳复合材料制造的改进，这将主要通过航空和航空航天工业的技术进步造福社会，尽管潜在的影响也预计在复合材料的新兴应用领域，如生物医疗设备、加热元件、金属成形和玻璃制造的硬件。本研究开发的表征和建模方法也将适用于具有复杂纳米结构的广泛的复合材料和非均质材料，包括高性能陶瓷涂层、纳米结构电磁屏蔽材料，以及由热解碳包裹在不同陶瓷基质(如碳化硅)中的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北卡罗来纳大学的两到四名本科生在合作的国际环境中接受教育。他们中的每一个人都会用他们的经历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.