Mariana Fraga - Atomic Layer Deposited TiO2 and Al2O3 Thin Films as Coatings for Aluminum Food Packaging Application

Document created by Mariana Fraga on Feb 26, 2019
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  Dias, V.;   Maciel, H.; Fraga, M.; Lobo, A.O.; Pessoa, R.; Marciano, F.R.   Atomic Layer Deposited TiO2 and   Al2O3Thin   Films as Coatings for Aluminum Food Packaging   Application. Materials 201912,   682.


    Titanium dioxide (TiO2)   and aluminum oxide (Al2O3)   coatings have been investigated in a wide range of   bio-applications due to their biodegradation and biocompatibility   properties, that are key parameters for their use in the food   packaging and biomedical devices fields. The present study   evaluates and compares the electrochemical behavior of the   non-coated, commercial resin-coated, TiO2-coated   and Al2O3-coated   aluminum in commercial beer electrolyte. For this,   TiO2 and   Al2O3 thin   films were deposited on aluminum (Al) substrates using atomic   layer deposition (ALD). The evaluation of the corrosion barrier   layer properties was performed by linear sweep voltammetry (LSV)   during 10 min and electrochemical impedance spectroscopy (EIS).   In addition, profilometry, grazing incidence X-ray diffractometry   (GIXRD), scanning electron microscopy (SEM) and Fourier-transform   infrared spectroscopy (FT-IR) analyses were performed to   investigate the physical and chemical properties of the pristine   and / or corroded samples. TiO2 and   Al2O3 films   presented an amorphous structure, a morphology that follows Al   substrate surface, and a thickness of around 100 nm. Analysis of   LSV data showed that ALD coatings promoted a considerable   increase in corrosion barrier efficiency being 86.3% for   TiO2-coated   Al and 80% for Al2O3-coated   Al in comparison with 7.1% of commercial resin-coated Al. This is   mainly due to the lower electrochemical porosity, 11.4% for   TiO2-coated   Al and 20.4% for Al2O3-coated   Al in comparison with 96% of the resin-coated Al, i.e. an   increase of up to twofold in the protection of Al when coated   with TiO2 compared   to Al2O3.   The EIS results allow us to complement the discussions about the   reduced corrosion barrier efficiency of the Al2O3 film   for beer electrolyte once SEM and FT-IR analyzes did not show   drastic changes in both investigated ALD films after the   corrosion assays. The above results indicate that ALD   TiO2 and   Al2O3 films   may be a viable alternative to replace the synthetic resin   coatings frequently used in aluminum cans of use in the food   industry.

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