CERAMIC COMPOSITE INTERFACES Properties and design KT Faber Department of Materials Science and Engineering, Robert R. McCormick School of Engineering and Applied Science, Northwestern University, Evanston, Illinois 60208 KEY WORDS: ceramic-matrix composites, interfaces, interphases, residual stress, roughness ABSTRACT Optimal design of the fiber-matrix interface in ceramic-matrix composites is the key to achieving desired composite performance. In this paper the interface controlling parameters are described. Techniques for measuring interfacial prop- erties are reported. Examples of interface design of both oxide and non-oxide types are illustrated INTRODUCTION It is well established that the fiber-matrix interface is the dominant design pa- ameter in ceramic-matrix composites. The characteristic that sets brittle ma- trix composites apart from ductile composites, either metal or polymer, is the reliance on a relatively weak fiber-matrix interface for enhanced mechanical be- havior. Recognition of this phenomenon came as early as the early 1970s when Sambell et al (1)noted enhanced work of fracture in carbon fiber-reinforced glass and glass-ceramics where no chemical bond existed between fiber and matrix. In contrast, carbon fibers in magnesia and zirconia fibers in magnesia and glass were found to be chemically bonded and demonstrated little, if an The chemistry of interfaces was the sole design parameter over much of the ext 25 years. More recently, physical parameters, such as the thermal sion mismatch and fiber surface roughness(both relieved through cor oatings), were found to be equally important in interfacial design. The contained herein describes the interface controlling parameters, measurement 084-6600/97/0801-049990800P1: ARK/MBL/rkc P2: MBL/vks QC: MBL/agr T1: MBL May 16, 1997 13:47 Annual Reviews AR034-16 Annu. Rev. Mater. Sci. 1997. 27:499–524 Copyright c 1997 by Annual Reviews Inc. All rights reserved CERAMIC COMPOSITE INTERFACES: Properties and Design K. T. Faber Department of Materials Science and Engineering, Robert R. McCormick School of Engineering and Applied Science, Northwestern University, Evanston, Illinois 60208; email: k-faber@nwu.edu KEY WORDS: ceramic-matrix composites, interfaces, interphases, residual stress, roughness ABSTRACT Optimal design of the fiber-matrix interface in ceramic-matrix composites is the key to achieving desired composite performance. In this paper the interface￾controlling parameters are described. Techniques for measuring interfacial prop￾erties are reported. Examples of interface design of both oxide and non-oxide types are illustrated. INTRODUCTION It is well established that the fiber-matrix interface is the dominant design pa￾rameter in ceramic-matrix composites. The characteristic that sets brittle ma￾trix composites apart from ductile composites, either metal or polymer, is the reliance on a relatively weak fiber-matrix interface for enhanced mechanical be￾havior. Recognition of this phenomenon came as early as the early 1970s when Sambell et al (1) noted enhanced work of fracture in carbon fiber–reinforced glass and glass-ceramics where no chemical bond existed between fiber and matrix. In contrast, carbon fibers in magnesia and zirconia fibers in magnesia and glass were found to be chemically bonded and demonstrated little, if any, toughening. The chemistry of interfaces was the sole design parameter over much of the next 25 years. More recently, physical parameters, such as the thermal expan￾sion mismatch and fiber surface roughness (both relieved through compliant coatings), were found to be equally important in interfacial design. The review contained herein describes the interface controlling parameters, measurement 499 0084-6600/97/0801-0499$08.00