In-situ Growth Of Carbon Nano-fibers,coiled Carbon Fibers On The Surface Of Carbon Fibers And The Mechanism Research

Owing to its high specific strength and modulus, advanced mechanical behavior under high temperature, carbon fiber is used to fabricate high-performance composite which widely employed in aerospace and other high-tech fields. Carbon nano-fibers or coiled carbon fibers in-situ growth on carbon fiber can farther improve the properties of composite and also endow with peculiar function. Up to present, however, there never has a publication of in-situ growth of coiled carbon fibers on carbon fiber. In this paper, by catalytic chemical vapor deposition, carbon nano-fibers were in-situ grown on the surface of carbon fiber with nature gas or propylene as carbon source , and coiled carbon fibers were in-situ grown on the surface of carbon fiber with acetylene as carbon source. Effect of parameters of chemical vapor deposition on growth of carbon nano-fibers or coiled carbon fibers with different carbon source gas were investigated in detail.1) Nature gas can be used as carbon source for carbon nano-fibers to grow on the surface of carbon fiber, then the cost of growth carbon nano-fibers couled be reduced. The carbon nano-fibers with relatively high purity and uniform diameter could be obtained at 750℃with a flow rate of nature gas 0.8 l/min, and hydrogen gas 1.0 l/min, for 45min.2) On condition of propylene flow rate of 0.3 l/min and hydrogen gas flow rate of 1.5 l/min, growth time of 30 min, much smaller, more uniform and pure plate-like carbon nano-fibers can be obtained by adding thiophene at a content of 4% and by controlling growth temperature of 650℃.3) The micro-helix carbon fibers were grown on the surface of carbon fiber for the first time. The relatively better parameters of chemical vapor deposition are as follws: temperature of 680℃, acetylene flow rate of 1.0 l/min, hydrogen gas flow rate of 2.0 l/min, nitrogen gas flow rate of 1.0 l/min, thiophene concentration of 16%, Ni(NO3)2 concentration of 0.1 mol/l, growth time of 60min. The as-arrayed coiled carbon fibers grown on the surface of carbon fiber could be farther obtained by using the process of different acetylene flow rate at different growth stages.4) The coiled carbon nano-fibers were growth on the surface of carbon fiber for the first time. The proper parameters of chemical vapor deposition are as follws: 650℃of temperature, acetylene flow rate of 0.8 l/min, hydrogen gas of 1.2 l/min, thiophene concentration of 16% , growth time of 60min.The mechanism of carbon nano-fibers and coiled carbon fibers in-situ growth on the carbon fiber were discussed.Both carbon nano-fibers and coiled carbon fibers were grown on the surface of carbon fiber according to the top growing model. The growing of coiled carbon fibers relate to the formation of polyhedral shapes of catalyst particles during CVD processes.