Stability of alumina- and mullite-based fibers by thermal exposure: experimental study and phase-field modeling

氧化铝和莫来石基纤维的热暴露稳定性：实验研究和相场建模

• 批准号: 327298888
• 负责人: Dr. Julia Kundin
• 金额: --
• 依托单位: Fachgebiet Keramische Werkstoffe und Bauteile
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/327298888?language=en
• 关键词: Stability; alumina; mullite; based; fibers

The efforts to achieve high strength and damage tolerant oxide-based ceramic matrix composites (Ox-CMCs) were, for a long time, focused on searching for new matrix systems and proceeding routes, as well as on the adjustment of the fiber-matrix-interface. Nowadays, such "conventional" methods seem to have reached the limits of their capacity.In the last decade, several studies on oxide fibers and composites revealed another way to enhance the performance of Ox-CMCs by optimal utilization of the oxide fibers. Being used as reinforcements, these fibers are responsible for the mechanical performance of the composites. As it is well-known, oxide fibers present an excellent strength and stiffness in as received conditions. However, commercially available polycrystalline fibers show strength loss when they are exposed to elevated temperatures due to grain growth. Thus, attention has been given to this subject, since such temperatures can be easily reached during processing and application of Ox-CMCs.The goal of the present proposal is to understand the mechanisms and to successively predict microstructural changes of alumina- and mullite-based fibers embedded in ceramic matrices depending on the matrix composition, the processing conditions, and additional heat treatments performed. This will be achieved by combining experiments and phase-field modeling as necessary to bridge the different effects that are involved. Furthermore, the effect of the microstructural changes on the quasi-static and long-term performance of the fibers at high temperatures should be evaluated.For that, minicomposites comprised of one fiber bundle are to be manufactured under different conditions. The grain size distribution and morphology of the fibers in dependency on the matrix composition will be experimentally investigated after exposure to elevated temperatures and mechanical load. The corresponding changes of the strength and the creep performance will be investigated by means of mechanical characterization techniques and correlated to the microstructure evolution. In parallel, the effective growth mechanisms will be studied through phase-field modeling combined with the feedback from the experimental results. The model will take into account the anisotropy of crystal growth, the grain boundary diffusion, the formation and evolution of impurities and pores. Special attention will be given to the abnormal grain size distribution and possible diffusion mechanisms between fiber and matrix.As a main result, it is expected that the enhanced predictability of the fiber properties (in composites) will show a way to determine the matrix composition used. By doing so, it will be possible to reduce the strength loss of the ceramic fibers during composites lifetime. Consequently, an adjusted matrix composition will provide flexibility in the tailoring of composite properties to the target application in terms of strength and durability.

氧化物基陶瓷基复合材料（Ox-CMC）的制备一直致力于寻找新的基体体系和工艺路线，以及纤维-基体界面的调整。在过去的十年中，一些关于氧化物纤维和复合材料的研究揭示了另一种通过优化利用氧化物纤维来提高Ox-CMC性能的方法。作为增强体，这些纤维负责复合材料的力学性能。众所周知，氧化物纤维在原样条件下具有优异的强度和刚度。然而，市售的多晶纤维在暴露于高温时由于晶粒生长而显示出强度损失。因此，注意力已被给予这个问题，因为这样的温度可以很容易地达到在处理和应用Ox-CMCs.The本建议的目标是了解的机制，并连续预测嵌入陶瓷基质中的氧化铝和莫来石基纤维的微观结构的变化取决于基质组合物，处理条件，和额外的热处理进行。这将通过结合实验和相场建模来实现，以弥合所涉及的不同效果。此外，还应评估纤维在高温下微观结构变化对纤维准静态和长期性能的影响。为此，需要在不同条件下制造由一束纤维组成的微型复合材料。在暴露于高温和机械负荷后，将实验研究依赖于基质组合物的纤维的粒度分布和形态。强度和蠕变性能的相应变化将通过力学表征技术进行研究，并与微观结构演变相关联。与此同时，有效的生长机制将通过相场模型结合实验结果的反馈进行研究。该模型将考虑晶体生长的各向异性、晶界扩散、杂质和孔隙的形成和演化。将特别注意异常的晶粒尺寸分布和纤维与基体之间可能的扩散机制。作为主要结果，预计纤维性能（在复合材料中）的增强的可预测性将显示出一种确定所用基体成分的方法。通过这样做，可以减少陶瓷纤维在复合材料寿命期间的强度损失。因此，调整后的基质组成将在强度和耐久性方面为目标应用定制复合材料性能提供灵活性。

项目成果

Phase-field modeling of grain growth in presence of grain boundary diffusion and segregation in ceramic matrix mini-composites

• DOI: 10.1016/j.commatsci.2021.110295
• 发表时间: 2021-04
• 期刊: Computational Materials Science
• 影响因子: 3.3
• 作者: J. Kundin;Hedieh Farhandi;Kamatchi Priya Ganesan;Renato S. M. Almeida;K. Tushtev;K. Rezwan

Joining oxide ceramic matrix composites by ionotropic gelation

• DOI: 10.1111/ijac.13507
• 发表时间: 2020-04
• 期刊: International Journal of Applied Ceramic Technology
• 影响因子: 2.1
• 作者: Renato S. M. Almeida;Hedieh Farhandi;K. Tushtev;K. Rezwan

Obtaining complex-shaped oxide ceramic composites via ionotropic gelation

通过离子凝胶化获得复杂形状的氧化物陶瓷复合材料

• DOI: 10.1111/jace.15990
• 发表时间: 2019
• 期刊: Journal of the American Ceramic Society
• 影响因子: 3.9
• 作者: Almeida RSM;Pereira TFS;Tushtev K;Rezwan K
• 通讯作者: Rezwan K

Numerical investigation of the recrystallization kinetics by means of the KWC phase-field model with special order parameters

• DOI: 10.1088/1361-651x/aa6a2a
• 发表时间: 2017-04
• 期刊: Modelling and Simulation in Materials Science and Engineering
• 影响因子: 1.8
• 作者: J. Kundin

Phase-field simulation of abnormal anisotropic grain growth in polycrystalline ceramic fibers

• DOI: 10.1016/j.commatsci.2020.109926
• 发表时间: 2020-12
• 期刊: Computational Materials Science
• 影响因子: 3.3
• 作者: J. Kundin;Renato S. M. Almeida;Hesham Salama;Hedieh Farhandi;K. Tushtev;K. Rezwan