Environmental mud adhesion on optical glass surface: Effect of mud drying temperature on surface properties

Mud formation in humid air ambient from dust particles on the glass surfaces is investigated. Mud drying temperature and the characteristics of mud liquid created at the interface between wet mud and the glass surface are examined. Effects of dried mud liquid layer on the glass surface are assessed using analytical tools including scanning electron and atomic force microscopes, energy dispersive spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Dry mud adhesion on the glass surface is evaluated incorporating the micro-tribometer and UV visible transmittance tests are carried out to determine optical properties of the glass substrate after dry mud removal. It is found that mud drying temperature has significant effect on the glass surface chemistry and topology; in which case, increasing mud drying temperature increases OH− and KOH attack on the glass surface while forming cavities-like structures and randomly distributed few micro-cracks. The tangential force required for dry mud removal from the glass surface increases with increasing mud drying temperature. Transmittance of UV visible spectrum is suppressed by the mud residues on the glass surface, which is more pronounced at high temperatures.