This work investigates polyester powder coatings containing graphene on aluminium alloy AA6060. The coatings were developed with a multifunctional approach in order to combine efficient barrier properties and high electrical and thermal conductivity. Graphene contents up to 10 wt% were introduced in the composite powder coatings. The barrier properties were investigated by means of electrochemical impedance spectroscopy (EIS) in 0.1 M NaCl solution. This technique was also employed to obtain information about the electrical parameters of the coatings. Although barrier properties remain high over immersion times up to 35 days, a strong increase of coating capacitance and a decrease of coating resistance were observed by EIS for the coatings with graphene content above 1 wt%. Impedance data were interpreted on the base of the electrical percolation theory in order to correlate the increase of capacitance and the decrease of the resistance to the existence of graphene-rich agglomerates in the composites coatings. Moreover, the thermal behaviour of the composite powder coatings was preliminarily evaluated indicating that the introduction of graphene can improve heat dissipation.
