Prickly structure of multi-walled carbon nanotube reinforced mesocarbon microbead composite with high strength at elevated temperature

摘要

High-density carbon blocks are extensively applied in bearing and sealing structures of some advanced aero-engines. Mesocarbon microbead (MCMB) based material, as a kind of high-density carbon, can potentially possess high mechanical strength at high temperature. Multi-walled carbon nanotube (CNT) reinforced mesocarbon microbead composite blocks were in situ fabricated with different amounts of incorporated CNT and further carbonized at 1500 ℃. High-temperature compressive strength testing of the composite blocks was performed on a thermal-mechanical system at 700 ℃ in vacuum. The results indicated that addition of CNTs up to 5 wt.% effectively improves the high-temperature compressive strength of CNT/MCMB composite. Morphology characterization showed that some CNTs are embedded beneath the microbead surface, creating a novel prickly structure which contributes to reinforcement. Moreover, excessive addition of CNTs leads to formation of large fragile hybrid spheres and consequently lowers composite strength at high temperature. The effect of CNTs on sphere structure along with the structure-property relationship revealed in this work would be helpful to further study of high-strength CNT/MCMB composite fabrication and prospective application.