Anticorrosion assessment of Al₂O₃‐TiO₂ composite thin films derived from sol‐gel dipping technique

Abstract

Metal surface protection by means of nanostructured ceramic coatings is considered an issue, which is variously scrutinized, and more efforts are made to improve steel performance in accordance with this method. In this respect, this study sought to examine the protective effects of a nanostructured coating containing TiO2 and Al2O3. The optimization approach for obtaining a coating without any cracks with the highest efficiency of corrosion resistance is reported. The variables under assessment were as follows: weight ratio of the oxides, calcination temperature, and preparation parameters. The synthesized samples were analyzed utilizing XRD, FESEM, AFM, Tafel test, EIS, and microhardness measurement. The results revealed that the optimized conditions were as follows: (i) Ti:Al precursor mixture with a weight ratio of 75:25, (ii) heat treatment at 1000°C. This process yielded a uniform composite coating without any cracks with 5.1 nm roughness, containing crystalline rutile phase and amorphous alumina. Not only the intended coating improves the corrosion resistance of steel up to 97%, but it also increases its surface hardness up to 10 units.

Al2O3–TiO2 composite coatings with enhanced anticorrosion properties for 316L stainless steel

“…To further improve its corrosion resistance in the solutions containing chloride ions, various amounts of TiO 2 are incorporated in the Al 2 O 3 coatings due to the advantageous chemical stability of TiO 2 in such solutions. [41] Figure 3b arising from 316L SS were detected in all samples (43.5°, 50.7°, 74.7°). [42] After coating with the Al 2 O 3 coating, no more diffraction peaks can be observed, suggesting the amorphous nature of Al 2 O 3 coating.…”

High transmittance and excellent hardness TiO2‐SiO2‐Al2O3 nanocomposite thin film for anti‐scratch surface applications

“…In recent years, nanomaterials, especially NCTFs, have been attractive to researchers and widely used in numerous applications such as electrically operating coatings, optical coatings, photovoltaic cells, and protective coatings on low hardness and scratch-resistant surfaces, [1][2][3] or corrosive surfaces such as metal. [4,5] With the purpose of application in several particular fields, such as optical coatings and protective coating for interior decoration surface materials, including natural stone, artificial stone, and glass…., the NCTFs need to meet the requirements such as high transmittance in the visible region (greater than 85% in the wavelength range from 400 to 800 nm), strong absorption in the UV region (250-380 nm), high hardness, excellent anti-scratch, and abrasive resistance. [6,7] For this requirement, NCTFs based on organic polymer matrixes such as Al 2 O 3 -epoxy coating, [8] Al 2 O 3polyurethane, [9] or Al 2 O 3 -polyvinyl coating [10] often cannot meet due to low transmittance, low hardness, and easiness to scratch.…”

“…[6,7] For this requirement, NCTFs based on organic polymer matrixes such as Al 2 O 3 -epoxy coating, [8] Al 2 O 3polyurethane, [9] or Al 2 O 3 -polyvinyl coating [10] often cannot meet due to low transmittance, low hardness, and easiness to scratch. [11] Related to this field, NCTFS-based inorganic matrix containing two or more ceramic materials such as Al 2 O 3 -TiO 2 coating for improving corrosion behavior and gas sensor, [5,12,13] TiO 2 -SiO 2 coating for enhancing hardness, photocatalyst activity [4,[14][15][16] have been reported. Each ceramic material component in NCTFs has a specific property that contributes to the characteristics of obtained NCTFs.…”