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Photoactive TiO2–SiO2 Thin Films on 316L Stainless Steel for Self-Cleaning Application, Tribological Properties and Corrosion Protection

Shayegh Boroujeny, Behrooz | 2012

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 43258 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Afshar, Abdollah; Dolati, Abolghasem
  7. Abstract:
  8. In this study, TiO2-SiO2 nanocomposite films with different amount of SiO2 were prepared by sol-gel process and were coated onto stainless steel 316L. The effect of addition of various amounts of SiO2 in the precursor solution on the structure, morphology, photocatalysis, photo-generated hydrophilicity, self-cleaning property and mechanical properties of TiO2 thin films and corrosion behavior of AISI 316L stainless steel substrate, was investigated. For this purpose, X-ray diffraction, Fourier transform infrared spectroscopy, water contact angle measurements, UV spectroscopy, field-emission scanning electron microscopy, atomic force microscopy, depth-sensing indentation technique supporting microscratch mode and potentiodynamic polarization test were employed. It was observed that appropriate amount SiO2 addition into TiO2 film not only decreased the particle size of TiO2–SiO2 crystal but also could help to improve the surface quality. In the tested ranges of SiO2 content and sintering temperature, the highest photocatalytic activity and self-cleaning property were observed in the 15 mol% SiO2 sample sintered at 750°C. It was found that the mechanical and tribological properties of the films became better in the range of 10–15% mol SiO2 addition compared with the pure TiO2. In addition, the corrosion behavior of AISI 316L stainless steel was improved by adding 15 %mol SiO2. Under UV illumination conditions, photogenerated electrons accumulated in this film could perfectly protect the substrate photocathodically. Addition of less than 30 %mol SiO2 had a suppressive effect on the transformation of anatase to rutile and on the crystal growth of anatase in the sintering heat treatment. Phase separation occurred in the composite films for SiO2 content of 30 %mol or more
  9. Keywords:
  10. Photocatalyst ; Hydrofilicity ; Photocathodic Protection ; Self-Cleaning ; Titanium Oxide

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