Fabrication of exfoliated graphite nanoplatelets-reinforced aluminum composites and evaluating their mechanical properties and corrosion behavior

Aluminum composites with different amounts of exfoliated graphite nanoplatelets particles were fabricated by powder metallurgy method. The mixture powders were consolidated at 520 MPa for 5 min and followed by pressureless sintering at 600 degrees C for 6 h. The mechanical properties of composites were evaluated by compression and hardness tests. The corrosion behavior in 3.5% NaCl solution was investigated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements. The mechanical testing results showed that the maximum strength and Vickers hardness increase as a function of exfoliated graphite nanoplatelets content. Corrosion data indicated that the presence of exfoliated graphite nanoplatelets and the increase of its concentration raise the corrosion rate and reduce the polarization resistance of AI. SEM/EDX investigations revealed that the presence of exfoliated graphite nanoplatelets activates the corrosion of Al clue to the occurrence of galvanic corrosion. SEM/EDX investigations confirmed the electrochemical measurements showing that the increase of exfoliated graphite nanoplatelets content increases the corrosion of Al. (C) 2011 Elsevier B.V. All rights reserved.