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Study of Hydrophobic Properties of SiO2/SiC Nanocomposite Coating Synthesized by Sol Gel Method

Sabetkar, Ashkan | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57505 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): dolati, Abolghasem; Mohammadi, Mohammad Reza
  7. Abstract:
  8. This project focuses on developing a hydrophobic coating with enhanced hardness and adhesion on a glass substrate using the sol-gel method. To achieve hydrophobic properties, modified SiO2 nanoparticles were incorporated, while nitrocellulose resin was employed as a binder to improve the adhesion of the coating to the substrate. SiC nanoparticles, with an average particle size of 20 nanometers, were added to enhance the coating’s hardness. The silica nanoparticles were synthesized through Stöber method using tetraetthy orthosilicate (TEOS), and functionalized with hexadecyltrimethoxysilane (HDTMS) to impart hydrophobicity. Additionally, 3-glycidoxypropyltrimethoxysilane (GPTMS) was used as a coupling agent to bond the nanoparticles to the nitrocellulose resin. The prepared sol, containing the modified nanoparticles, was mixed with the nitrocellulose resin solution, and the coating was applied via dip-coating. Dynamic light scattering (DLS) analysis revealed that the average size of the synthesized silica particles was approximately 16 nanometers. Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) were performed to confirm the functionalization of the nanoparticles. The coating morphology was examined using scanning electron microscopy (SEM), while atomic force microscopy (AFM) was employed to assess the surface topography. SEM images of the optimized coating showed a crack-free surface with well-dispersed silica nanoparticles within the nitrocellulose matrix. AFM analysis indicated that the addition of modified silica nanoparticles increased the average root mean square (RMS) surface roughness from 1 nanometer to 10.5 nanometers. Furthermore, water contact angle measurements demonstrated that incorporating modified silica nanoparticles into the nitrocellulose resin increased the contact angle from 76° to 113°, indicating improved hydrophobicity. The pencil hardness test results showed a significant improvement in coating hardness, from HB to 2H with the addition of modified silica nanoparticles, and further increased to 3H with the inclusion of SiC nanoparticles. Adhesion tests conducted on the optimized coatings confirmed strong adhesion to the substrate, with no significant reduction in contact angle after two adhesion tests cycles
  9. Keywords:
  10. Hydrophobic Materical ; Sol-Gel Method ; Silica Nanoparticles ; Nitrocellulose Resin ; Coupling Agent ; Hydrophobicity

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