Single fiber push-out characterization of interfacial mechanical properties in unidirectional CVI-C/SiC composites by the nano-indentation technique

• Published in: Applied surface science 2015-12, Vol.357, p.1427-1433
• Main Authors: Zhang, Lifeng, Ren, Chengzu, Zhou, Changling, Xu, Hongzhao, Jin, Xinmin
• Format: Article
• Language: English
• Subjects: Ceramic matrix composites; Debonding; Fiber coatings; Fiber push-out test; Fibers; Interfacial characterization; Mathematical models; Mechanical properties; Nano-indentation; Nanostructure; Plastic deformation; Silicon carbide
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.10.018

In this work, a new model material, the unidirectional CVI-C/SiC was developed to investigate the interfacial mechanical properties of the woven ceramic matrix composites. Single fiber push-out/push-back tests with the Berkovich indenter were conducted on the thin sliced specimens by the nano-indentation technique. In addition, both the neighboring fibers and the distant fibers (fibers surrounded by not-pushed fibers) were tested. And in order to give a detailed illustration of interfacial crack propagation and failure mechanism, each sector of the push-out process was analyzed at length. •The CVI-C/SiC was developed to investigate the interfacial properties of CMCs.•The interfacial debonding strength and friction stress of CVI-C/SiC were obtained.•There is no detectable difference between testing the two typical fibers. The characterization of interfaces in woven ceramic matrix composites is one of the most challenging problems in composite application. In this investigation, a new model material consisting of the chemical vapor infiltration unidirectional C/SiC composites with PyC fiber coating were prepared and evaluated to predict the interfacial mechanic properties of woven composites. Single fiber push-out/push-back tests with the Berkovich indenter were conducted on the thin sliced specimens using nano-indentation technique. To give a detailed illustration of the interfacial crack propagation and failure mechanism, each sector during the push-out process was analyzed at length. The test results show that there is no detectable difference between testing a fiber in a direct vicinity to an already tested fiber and testing a fiber in vicinity to not-pushed fibers. Moreover, the interface debonding and fiber sliding mainly occur at the PyC coating, and both the fiber and surrounding matrix have no plastic deformation throughout the process. Obtained from the load-displacement curve, the interfacial debonding strength (IDS) and friction stress (IFS) amount to, respectively, 35±5MPa and 10±1MPa. Based on the findings, the interfacial properties with PyC fiber coating can be predicted. Furthermore, it is expected to provide a useful guideline for the design, evaluation and optimal application of CVI-C/SiC.