Strengthening of C/SiC Composites by Electrophoretic Deposition of CNTs on a SiC Coating
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The current study reports the enhancement of mechanical properties of carbon fiber-reinforced silicon carbide ceramic matrix composites (C/SiC CMCs) by the application of a carbon nanotube/silicon carbide (CNT/SiC) coating. CNTs were deposited on the surfaces of C/SiC composites using electrophoretic deposition (EPD), after which infiltration by SiC was achieved through a chemical vapor infiltration process. An EPD duration of 5 min was associated with a 40% increase in the ultimate flexural strength relative to that of composites with a pure SiC coating. The observed enhancement was rationalized by the microstructural observations of SiC infiltration into the porous CNT morphology and the subsequent formation of CNT/SiC layers on the surfaces of the composites and by the inherent toughness of the SiC whiskers. The flexural strength decreased with EPD durations greater than 5 min due to the formation of thick CNT meshes, which decreased the open porosity and thereby obstructed further SiC infiltration. This is a viable methodology for the improvement of mechanical properties of CMCs by the introduction of a ceramic coating containing CNT.
Keywordsceramics matrix coatings composites electrical inorganic mechanical static
This work had been financially supported by Natural Science Foundation of China (51272210 and 50902112), Program for New Century Excellent Talents in University (NCET-13-0474), Foreign Talents Introduction and Academic Exchange Program of China (B08040), and Northwestern Polytechnical University (NPU) Foundation for Fundamental Research (NPU-FFR-JC201135).
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