Effects of CNF dispersion on mechanical properties of CNF reinforced A7xxx nanocomposites

Abstract

Carbon nanofiber (CNF) reinforced A7xxx nanocomposites were fabricated by a liquid process, and the effect of CNF dispersion on the mechanical properties of the CNF/A7xxx nanocomposites was investigated. To enhance the dispersion of CNFs in the A7xxx matrix, we reduced their aspect ratios by vibration milling, and used surfactants and ultrasonication. A Cu layer was coated on the surface of CNFs to enhance the wettability of Al on CNF, to reduce the difference in specific gravity between CNFs and the Al melt, and to suppress the formation of brittle Al4C3 phase. Also, a button-shaped feedstock was fabricated with a mixture of Cu coated CNFs and Al powers to overcome the difficulty in direct injection of CNFs into the Al melt. As a result, CNF/A7xxx nanocomposites were successfully fabricated by a liquid process. The variations in the mechanical properties of the CNF/A7xxx nanocomposites according to the concentration of CNFs were analyzed. The yield strength, ultimate tensile strength, and elastic modulus of the nanocomposites for CNF of 0.76 wt% increased by 33%, 55%, and 17%, respectively, in comparison to those of the A7xxx matrix. The CNF dispersion increased the strength of the CNF/A7xxx nanocomposites by about 38%. (c) 2012 Elsevier B.V. All rights reserved.