Corrosion behavior of Graphene reinforced Al-12Si coated 7075 Aluminium alloy

Abstract

This paper aims at investigating the effect of graphene reinforced Al-Si coatings on the corrosion behavior of AA7075 aluminium alloy. Al - 12Si alloy powder reinforced with 0.5 and 1 wt.% graphene was plasma sprayed on AA7075 substrate. Potentiodynamic polarization measurements were performed using CHI660E-CH electrochemical workstation. It was observed that 0.5 wt.% graphene reinforced Al-Si coating enhanced the corrosion potential from –0.893 to –0.761 V and reduced the corrosion current density from 1.3×10-4 to 9.78×10-6 A/m2. The atmospheric galvanic corrosion was simulated using COMSOL Multiphysics finite element package. It was observed that AA7075 aluminium electrode potential with respect to AISI 4340 steel increased from –0.76 to –0.59 V. The least average current density of 0.95 A/m2 was observed at 95 % relative humidity and 0.0035 kg/m2 salt load density indicating the minimum corrosion rate for 0.5 wt.% graphene reinforced Al-Si coated AA7075 substrate. The simulation also confirmed that 0.5 wt.% graphene reinforcement in Al-Si coatings enhanced the corrosion behavior of AA7075 when compared with 1 wt.% graphene reinforcement.