Although in-situ growing carbon nanotubes(CNTs) on carbon fibers could greatly increase the matrix-dominated mechanical properties of carbon/carbon composites(C/Cs),it always decreased the tensile strength of carbon fibers.In this work,CNTs were introduced into unidirectional carbon fiber(CF) preforms by electrophoretic deposition(EPD) and they were used to reinforce C/Cs.Effects of the content of CNTs introduced by EPD on tensile property of unidirectional C/Cs were investigated.Results demonstrated that EPD could be used as a simple and efficient method to fabricate carbon nanotube reinforced C/Cs(CNT—C/Cs) with excellent tensile strength,which pays a meaningful way to maximize the global performance of CNT—C/Cs.
In-situ growing carbon nanotubes(CNTs)directly on carbon?bers(CFs)always lead to a degraded tensile strength of CFs and then a poor?ber-dominated mechanical property of carbon/carbon composites(C/Cs).To solve this issue,here,a novel carbon?ber-based multiscale reinforcement is reported.To synthesize it,carbon?bers(CFs)have been?rst grafted by graphene oxide(GO),and then carbon nanotubes(CNTs)have been in-situ grown on GO-grafted CFs by catalytic chemical vapor deposition.Characterizations on this novel reinforcement show that GO grafting cannot only nondestructively improve the surface chemical activity of CFs but also protect CFs against the high-temperature corrosion of metal catalyst during CNT growth,which maintains their tensile properties.Tensile property tests for unidirectional C/Cs with different preforms show that this novel reinforcement can endow C/C with improved tensile properties,32% and 87%higher than that of pure C/C and C/C only doped with in-situ grown CNTs.This work would open up a possibility to fabricate multiscale C/Cs with excellent global performance.
Yunyu LiLing-jun GuoYa-wen WangHe-jun LiQiang Song
Carbon nanotubes(CNTs) were deposited uniformly on carbon cloth by electrophoretic deposition(EPD). Thereafter, CNT-doped clothes were stacked and densified by pyrocarbon via chemical vapor infiltration to fabricate two-dimensional(2 D) carbon/carbon(C/C) composites. Effects of EPD CNTs on interlaminar shear performance and mode Ⅱ interlaminar fracture toughness(GⅡc) of 2 D C/C composites were investigated. Results showed that EPD CNTs were uniformly covered on carbon fibers, acting as a porous coating. Such a CNT coating can obviously enhance the interlaminar shear strength and GⅡc of 2 D C/C composites. With increaing EPD CNTs, the interlaminar shear strength and GⅡc of 2 D C/C composites increase greatly and then decrease, both of which run up to their maximum values, i e, 13.6 MPa and 436.0 J·m-2, when the content of EPD CNTs is 0.54 wt%, 2.27 and 1.45 times of the baseline. Such improvements in interlaminar performance of 2 D C/C composites are mainly beneficial from their increased cohesion of interlaminar matrix, which is caused not only by the direct reinforcing effect of EPD CNT network but also by the capacity of EPD CNTs to refine pyrocarbon matrix and induce multilayered microstructures that greatly increase the crack propagation resistance through "crack-blocking and-deflecting mechanisms".
