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Surface roughness analysis of hydrophilic SiO2/TiO 2/glass nano bilayers by the level crossing approach

Daryaei, E ; Sharif University of Technology | 2013

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  1. Type of Document: Article
  2. DOI: 10.1016/j.physa.2012.11.058
  3. Publisher: 2013
  4. Abstract:
  5. The effect of etching time on the statistical properties of hydrophilic surfaces of SiO2/TiO2/glass nano bilayers has been studied using atomic force microscopy (AFM) and a stochastic approach based on a level crossing analysis. We have created rough surfaces of the hydrophilic SiO 2/TiO2 nano bilayer system by using 26% potassium hydroxide (KOH) solution. Measuring the average apparent contact angle allowed us to assess the degree of hydrophilicity, and the optimum condition was determined to be 10 min etching time. A level crossing analysis based on AFM images provided deeper insight into the microscopic details of the surface topography. With different etching times, it has been shown that the average frequency of visiting a height with positive slope behaves in a Gaussian manner for heights near the mean value and obeys a power law for heights far away from the mean value. Finally, by applying the generalized total number of crossings with positive slope, it was found that the both high heights and deep valleys of the surface have a great effect on the hydrophilic degree of the SiO 2/TiO2/glass nano bilayer investigated system
  6. Keywords:
  7. AFM image ; Etching ; Etching process ; KOH ; SiO2/TiO2 ; Stochastic analysis ; Atomic force microscopy ; Contact angle ; AFM images ; Glass ; Potassium hydroxide ; Railroad crossings ; Stochastic systems ; Surface roughness ; Titanium dioxide ; Hydrophilicity
  8. Source: Physica A: Statistical Mechanics and its Applications ; Volume 392, Issue 9 , 2013 , Pages 2175-2181 ; 03784371 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0378437112010515