Our earlier studies have shown that the use of high temperature pressurised steam treatment on aluminium surfaces results in the formation of nano-scale needle structured boehmite,which exhibited good barrier properties against corrosion in NaCl
solution [5,20,21]. Further enhancement in performance is possible by the use of various chemical agents together with high pressure steam treatment. The present study deals with the effect of using oxidative agents with steam namely nitric acid and potassium permanganate, and detailed investigation of the oxide layer formed
on the surface of aluminium alloys. Microstructure, surface morphology, and composition of the oxide layers were investigated as a function of additive concentration using glow discharge optical emission spectroscopy (GD-OES), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and focused ion beam scanning electron microscopy (FIB-SEM) analysis. Chemical composition analysis was carried out using Fourier transform infrared spectroscopy (FT-IR) and the surface composition of the coating was analysed using X-ray photoelectron spectroscopy (XPS). Part II of this paper will describe the detailed investigation of corrosion performance of the coatings developed using similar
additives.