The growth of carbon filaments onto the surfaces of primary fibers by catalytic decomposition of a hydrocarbon offers the potential of producing a new generation of composites with unique physical, chemical and mechanical properties. Filaments can be formed in three basic conformations: (i) whisker-like, (ii) branched, and (iii) multidirectional. The material chemistry on and within the catalyst particle which causes carbon filaments to grow in these various conformations will be investigated. A combination of techniques will be used to study various aspects of the proposed filament-growing process, including controlled atmosphere electron microscopy, HRTEM/in-situ electron diffraction, surface spectroscopy, C13NMR, micro-calorimetry and bulk kinetic studies. Also to be studied are the fundamental relationships between filament morphology and mechanical behavior of the X-D composites containing such filaments. The micromechanics physical and chemical characteristics of the filaments will be established. These data will then be used to select catalytic chemistry and whiskerization process variables to produce desirable filament morphology. The multidirectional filaments will provide the continuous fiber composites with through thickness reinforcement, improved interlaminar shear strength, enhanced delamination resistance and damage tolerance.
