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In the present research, automotive windshield samples were successfully coated with SiO 2-TiO 2 nanostructure layer using the sol-gel technique for self-Cleaning and photocatalytic applications. This procedure resulted in transparent, crack-free, self-cleaning, nanostructure SiO 2-TiO 2 films. To prevent the thermal diffusion of the sodium ions from the glass substrate to TiO 2 layer, the SiO 2 layer was pre-coated on the glass by the sol-gel method. The coated samples were dried for 48 hour at room temperature to allow slow solvent evaporation and condensation reactions due to rapid sol-gel reaction of titania precursor. Then, the samples were annealed at 100℃ for 30 min and at the final temperature (500℃ and 700℃) for 30 min immediately. The crystalline structure, surface morphology, photocatalytic activity and hydrophilic properties of the films were investigated using XRD, SEM, FE-SEM, UV-Vis spectrophotometer and contact angle measurement, respectively. The FE-SEM surface morphology results indicate that the particle size increases from 19 to 42 nm by increasing the annealing temperature from 500℃ to 700℃. Likewise, XRD illustrate the crystal anatase and rutile as main phases for SiO 2-TiO 2 films annealed at 500℃ and 700℃, respectively. Increasing heat treatment temperature from 500 to 700℃, decreases the photocatalytic activity and inversely increases of the contact angle of the films.

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Chromate conversion coatings (CCCs) were synthesized on AA7075 alloy. The effects of sodium saccharin as a grain refining agent (GRA) and coating time on the coating morphology, topography, and alloy corrosion resistance were studied in this work. Morphologies and topographies of CCCs were examined using optical, scanning electron and atomic force microscopes. The corrosion behaviour was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy in 0.5 M NaCl solution. Major decreases in both coating grain size and corrosion rate occur at a GRA concentration of 1 g/l. Coating roughness increased to a limited nano-scale extent with increasing immersion time.Hardened aluminium alloys are extensively used in aerospace industries because of their excellent mechanical properties such as toughness and high strength due to presence of second-phase particles in the alloys. 1 In alloy group of 7xxx, the primary alloying elements including Zn, Mg and sometimes Cu are used for age hardening and damage tolerance, but they form a range of second phase particles that make them sensitive to localized corrosion. 2 Applying protective conversion coatings onto the alloy surface is one approach to improve the environmental performance as well as to increase paint adhesion. 3 Chromate coating is a extremely effective and widely-used type of conversion coating for high strength Al alloys in aerospace applications due to advantages such as like high corrosion resistance, good paint adhesion, low costs, simple application process and low dimensional changes. 4-12 A combination of pressures, including environmental regulations on the use and handling of chromates, increased service-life requirements of the fleet of airplanes, and the cost of preventive maintenance, has motivated aerospace industries to invest in efforts to find improved and environment-friendly methods of corrosion protection.

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