Growth of carbon nanotubes on silicon carbide fabric as reinforcement for SiC/C composites.

Carbon nanotubes (CNTs) have been grown on conventional silicon carbide (SiC) fabric by the catalytic chemical vapour deposition (CCVD) technique. These hybrid reinforcements have been used to develop Silicon carbide-carbon nanotube-carbon matrix mini-composites (SiC/CNTs/C) by chemical vapour infiltration (CVI) method. The microstructures of these hybrid materials and their composites have been studied using scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscope. The microstructure of the carbon matrix has been compared with the silicon carbide-carbon matrix composites (SiC/C) made with SiC fabric alone. It has been found that the carbon matrix exhibit orientation circumferentially around the SiC fibers. In case of composites with CNTs coated SiC fibers, the carbon matrix is found to get infiltrated within the bundles of CNTs whereas at distance away from the CNTs, the matrix is found to be oriented circumferentially around the SiC/CNT bundles. SiC/CNT/C composites are found to exhibit inherent intrabundle porosity and lower density.

Development of carbon/carbon composites with carbon nanotubes as reinforcement and chemical vapor infiltration carbon as matrix.

Carbon nanotubes based carbon/carbon composites were prepared by infiltration of purified ACNTs film with pyrolytic carbon. Densification was performed by filling the space between the CNTs through by deposition of the pyrocarbon on the nanotubes surface. It comprised of (i) Synthesis and purification of aligned carbon nanotubes films by CCVD process and (ii) Infiltration of CNTs film by pyrocarbon using CVI method at 950 degrees C. SEM studies showed that the film was well infiltrated using methane. The density of film increased to 1.4 gm/cm3 from 0.4 gm/cm3 of as purified ACNTs film. The I(D)/I(G) ratio for CNTs film is 0.67 and 0.80 for the CVI deposited pyrocarbon. The lower I(D)/I(G) ratio from Raman microscopy shows fine graphitic nature of carbon nanotubes and nanocomposites films.

Development of composites incorporating carbon nanofibers and nanotubes.

Nanocomposites provide significantly increased modulus, thermal, and electrical properties when compared to traditional reinforced composites. Present work was undertaken to study the microstructure, thermal, and electrical properties of carbon nanostructured reinforced polymer matrix composites. Composites were made with carbon nanofibers and nanotubes (produced by CVD method) as reinforcement with thermoplastic polymers as matrices. The amount of nanoreinforcements was varied between 1 to 5 wt% in different matrices. The problems associated with dispersion of reinforcing materials have been studied. Dispersion of nanofillers in thermoplastics, microstructures, and thermal stability of the reinforced thermoplastics have been studied using SEM, DSC, and TGA. Experimental results show that small amount of carbon nanofillers present in thermoplastic matrix systems enhance the thermal, mechanical, and electrical properties of the composites.