Effects of organic additives on alumina coatings on stainless steel obtained by spray pyrolysis

Alumina coatings were obtained by deposition of boehmite sol, with added polyvinyl alcohol or polyethylene glycol, on stainless steel foil by spray pyrolysis method. Characterizations of coatings were performed by SEM, XRD, XPS, AFM and SBET analysis. Alumina coating prepared with polyethylene glycol has improved resistance to surface area loss than coating obtained with polyvinyl alcohol. At elevated temperatures polyethylene glycol has preserved the morphology of alumina coating and prevents the diffusion of Fe from stainless steel substrate. Porous, foam-like aluminium oxide coating, consisted of accidentally distributed rings of alumina, was created from both additives. Such coating morphology, with a hierarchical porosity, has application in numerous catalytic processes.

► Spray pyrolysis represents a reliable method for the preparation of thin alumina coating on SS substrate.
► Porous alumina coatings were obtained by deposition of boehmite sol with added PVA or PEG on SS substrate.
► The open porous structure of aluminium oxide coatings have been obtained with both additives.
► Better thermal stability was determined for PEG alumina coating than PVA coating.