Carbon Fiber and Tungsten Disulfide Nanoscale Architectures for Armor Applications

Abstract

The objective of this research was to generate shock-resistant materials based on inorganic fullerene type tungsten disulfide (IF-WS2) and carbon nanocomposite structures for personal protection armor systems. The aim was to develop a new generation of composites that combine the known energy absorbing properties of carbon nanofibers, with the shock absorbing properties reported for IF-WS2 structures. Various methods were explored to generate the desired WS2carbon fiber composite. Experimentation revealed that in situ growth of carbon fibers from a nickel catalyst with tungsten disulfide particulates had to be performed from particular precursors and fabrication conditions to avoid undesirable byproducts that hinder fiber growth. As a result, tungsten oxide was used as tungsten source, nickel as carbon fiber growth catalyst, ethylene as hydrocarbon and fuel rich oxidative conditions for growth, all followed by a sulfurization process. Fabrication of fibers was performed at moderate temperatures (ca. 550 degrees C) with a sulfurization step at 900 degrees C in a tubular furnace. Microstructural characterization of the samples was primarily conducted using X-ray diffraction and electron microscopy. In order to determine more properties of the nanocomposites, the samples were dispersed into an epoxy matrix. Nano-indentation was utilized as a method of determining mechanical properties of the composites while a gas gun was used to determine shock propagation effects. The inclusion of WS2/C nanocomposites into epoxy matrixes showed a significant improvement in modulus and hardness values when compared to bare carbon fiber epoxy composites. WS2/C fiber epoxy nanocomposites preserved their integrity during gas gun tests while samples without WS2 fractured.