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Development and Characterization of Hot-Pressed Matrices for Engineered Ceramic Matrix Composites (E-CMCs)The present research effort was undertaken to develop a new generation of SiC fiber-reinforced engineered ceramic matrix composites (E-CMCs). In contrast to traditional CMCs with a brittle SiC matrix, an E-CMC is designed to consist of a matrix engineered to possess sufficient high temperature plasticity to minimize crack propagation, relatively high fracture toughness, and self-healing capabilities to prevent oxygen ingress to the BN-coated fibers through surface-connected cracks. The present paper discusses the bend strength, isothermal oxidation, microstructures and self-healing properties of several silicide-behaved engineered matrices. Based on the oxidation tests, where it was observed that some of the matrices exhibited either catastrophic oxidation ("pesting") or spalling of the oxide scale, two engineered matrices, CrSi2/SiC/Si3N4 and CrMoSi/SiC/Si3N4, were down-selected for further investigation. Four-point bend tests were conducted on these two engineered matrices between room temperature and 1698 degrees Kelvin. Although these matrices were brittle at low temperatures, it was observed that the bend strengths and bend ductility increased at high temperatures as the silicide particles became more ductile, which was qualitatively consistent with the theoretically expected behavior that crack blunting at these particles should increase the matrix strength. Additional studies were conducted to study the effects of different additives on the self-healing properties of the engineered matrices, which helped to identify the most effective additives.
Document ID
20190001797
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
External Source(s)
doi:10.1016/j.ceramint.2018.11.021
Authors
Raj, S. V. (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
March 22, 2019
Publication Date
March 1, 2019
Subject Category
Composite Materials
Report/Patent Number
E-19663
GRC-E-DAA-TN65208
NASA/TM-2019-220071
Funding Number(s)
WBS: WBS 109492.02.03.02.02
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
Composite Materials

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