HARDNESS AND STRUCTURAL PROPERTIES OF MULTIWALL CARBON NANOTUBES AND ALUMINUM-BASED COMPOSITES.

Abstract

Powder Metallurgy was used for the preparation of aluminum composite reinforced with multiwall carbon nanotubes (MWCNTs). The MWCNTs were synthesized by Chemical Vapor Deposition (CVD), using C2H2 as precursor gas, Ar as a carrier gas, and Fe-Co / CaCO3 as a catalyst. The powder aluminum was mixed with MWCNTs in a planetary ball milling device for different weight ratios, from 0% to 2%, and different times stages in the mixing process (3 min and 60 min). The powders compounds were doubled hot-pressed and sintering and analyzed using a Field Emission Scanning Electron Microscope, X-ray powder diffraction, and Vickers Hardness. A total of 80 samples were examined to evaluate the effect of the MWCNTs on the hardness. Results showed a hardness-increasing for the compounds from ~15 % to 24 %. The standard deviation of hardness measures was considered to evaluate the dispersion of MWCNTs in the composites. We applied a linear fit to the hardness data to assess the influence of temperature in the grain consolidation process and variance analysis of data. Results exhibited a substantial dispersion of hardness from 13.13% to 24.57% of error. The analysis of the results obtained at several conditions suggested an optimal setting involving a mixing time of 3 min and a sintering temperature of 760 °C.