Abstract: Organic-Inorganic hybrid (OIH) derived by sol-gel process have emerged as promising pretreatments alternative to conventional chromate-based systems for aluminum alloys.

In this study novel organo-silane precursor has been synthesized from epoxy resin and amino-silane compound and used as the primary component of OIH film. The effects of epoxy and silane functionality and organic inhibitor used in the composition have been studied on corrosion resistance performance of aluminum alloy (3003-H14). The study also investigates the performance of top coat (powder coating) adhesion onto the pretreatment under different cure conditions. The chemical structure of sol-gel precursor (epoxy silane) and the deposited films have been characterized by FTIR analysis. The corrosion protection performance has been studied by electrochemical impedance spectroscopy (EIS), D.C. electrochemical polarization measurements, and the accelerated neutral salt spray test (ASTM B117). This study shows that by proper choice of precursor structure, functionality, processing conditions, and corrosion inhibitor amount, it is possible to derive OIH films with corrosion resistance performance comparable to conventional Cr (VI) based pretreatments.

Keywords: Sol-gel, organic-inorganic hybrid, epoxy silane, corrosion inhibitor, aluminum alloy.

Abstract: Coalescence of water droplets is an important phenomenon in many industrial applications. One approach for coalescing water droplets is by applying an external voltage across the drops. Coalescence occurs when spreading and motion of the drops due to the electrical field brings the drops into contact. Electrowettable surfaces were prepared with poly(styrene-co-methyl methacrylate) as the dielectric film and Fluropel™ as the hydrophobic surface layer. The surface of a stainless steel disk was coated in a way that the dielectric coating layer thickness varied with radial position with minimum thicknesses at the center and at the outer edge of the disk and a maximum at an intermediate radial position of the disk surface. The thickness gradient influenced the droplet movement and contributed to the coalescence. Two disks were assembled with a thin slit between the disks. Emulsions of water droplets in ultra low sulfur diesel fuel were pumped through the thin slit. Experiments showed significant increase in drop sizes when the disks were electrified compared to non-electrified disks.

Keywords: Electrowetting, Coalescence, Emulsion, Dispersion, Oil-Water.