Catalytic Cvd Of C / C Composite Material Structure And Performance Impact

By isothermal chemical vapor deposition (ICVD), Fe-catalyzed insitu-growth carbon nanofiber on PAN carbon fibers and the application of Fe-catalyzed insitu-growth carbon nanofiber in the fabrication of C/C composites were investigated with ferrocene as catalyst precursor. On this base, the functions of FCN B in the process of ICVD and the effects on the microstructure and properties were studied.PAN carbon fibers soaked in the solution of ferrocene were deposited for 1 > 2 ^ 4> 8 hours at 880 癈 , 920 ℃. Through Scanning Electron Microscopy(SEM) ,it was found there were many vapor-grow carbon nanofibers around PAN carbon fibers at 880癈. But at 920癈, many big particles and short carbon fibers were found. Carbon nanofiber have not been found on nono-catalyzed PAN carbon fibers. With the CaHe-Fe-Na system, Fe-catalyzed instu-growth carbon nanofibers on PAN carbon fibers at 880癈 is possible. The mechanism of Fe-catalyzed insitu-growth carbon nanofiber was discussed.By comparing different optical micrographs and the SEM graphs of pyrolytic carbon of Fe^ B-catalyzed and nono-catalyzed C/C composites, the microstructure has the characteristics of cone. But the microstructure of B-catalyzed and nono-catalyzed C/C composites is smooth lamina. The forming mechanism of pyrolytic carbon and the functions of Fe, B in the process of decomposition of hydrocarbons were proposed.The properties of C/C composites have been investigated. Combined with difference of optical micrograph of C/C composites ,the mechanical properties of C/C composites were studied. The effects of bulk density, microstructure ,degree of graphitization on mechanical properties were discussed. The fracture behavior and toughness of C/C composites were further studied with fracture modes of the materials with different microstructures analyzed. Studied the thermal conductivity of the C/C composites with the values in two directions measured, the effects of bulk density, microstructure, degree of graphitization on the thermal conductivity of C/C composites were discussed, and the essential cause of the lower thermal conductivity was analyzed. The friction and wear properties of C/C composites were studied. The effects of bulk density, microstructure, degree of graphitization, pressure on friction and wear properties were discussed. Combined with the observation of frictionated surface, the reasonable frication and wear mechanism was posed.