A nanoindentation based study to evaluate the effect of carbon nanofibers on the mechanical properties of SiC composites
Shaik Mubina, P Sudharshan Phani, Asit Kumar Khanra, Bhaskar Prasad Saha
An advanced high-speed nanoindentation technique is employed to analyze the combined benefit of the particulate and continuous fiber’s reinforcing effect of carbon fibers in the SiC matrix. Spray freeze granulated well-dispersed carbon nanofibers (CNF) containing precursor SiC-CNF (1 wt%) composite powder was used as a base matrix in which continuous carbon fibers were introduced in a systematic laying pattern to produce hybrid composite tubes with 10–12 mm wall thickness. Thin tubes with a wall thickness of 1–2 mm were produced with SiC, SiC-CNF composite powder. The two types of tubes with various lengths were cold isostatically pressed and pressureless sintered at 2150°C/1hour under Argon (Ar). The surface properties of the sintered tubes were further enhanced by coating with a dense SiC layer by adopting a CVD technique. The properties of the fiber-matrix interface and coating-matrix interfaces of the tube samples were evaluated using conventional processes as well as the nanoindentation techniques and compared at different length scales. Attempts have been made to correlate the structure-property relations of complex multi-phase of SiC composites employing high-speed nanoindentation mapping as well as XRD, Digital optical, SEM, and TEM analysis.