1. Transmission electron microscopy study of the microstructure of unidirectional C/C composites fabricated by catalytic chemical vapor infiltration
- Author
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Liu, Yequn, He, Lianlong, Lu, Xuefeng, and Xiao, Peng
- Subjects
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TRANSMISSION electron microscopy , *MICROSTRUCTURE , *CHEMICAL vapor deposition , *CARBON compounds , *NICKEL catalysts , *ELECTROLESS plating , *GRAPHITIZATION - Abstract
Abstract: Unidirectional carbon/carbon (C/C) composites were fabricated by catalytic chemical vapor infiltration, using electroless Ni–P as catalyst. Transmission electron microscopy (TEM) investigations indicate that the catalyst particles (100–800nm) in the pyrocarbon (PyC) matrix are composed of Ni3P and Ni phases, but only the Ni3P phase was observed in the tiny catalyst particles (<50nm) in carbon fibers. The catalyst particles in the matrix were encapsulated by high-textured PyC shells, in which openings were observed. The thicknesses of the medium-textured PyC in the composites (720–850nm) are greater than in conventional C/C composites (660–740nm), but have no significant difference in texture degree. Catalysts were partially extruded out of the PyC shells and migrated into the carbon fibers, leading to the catalytic graphitization of the carbon fibers, and their structural homogeneity was destroyed. Based on the TEM observation, a dissolution/precipitation mechanism was proposed for the catalytic graphitization of carbon fibers, and a dissolution/precipitation/encapsulation/fracture/extrusion mechanism was proposed for the encapsulation of catalyst particles. [Copyright &y& Elsevier] more...
- Published
- 2013
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