Sequentially reinforced additive coating for transparent and durable superhydrophobic glass

Now that there are various routes to prepare superhydrophobic surfaces for self-cleaning, anti-icing, liquid collecting, etc., attentions are moving toward low-cost upscaling of routes and increasing the reliability for actual applications. However, the required micro–nano structures for superhydrophobicity are light scattering and very vulnerable to abrasion. This intrinsically conflicts with the transparency and durability of superhydrophobic glass, which are the major barriers for its commercialization. In this study, we present a novel sequentially reinforced additive coating (SRAC) process to realize robust and transparent micro–nano structured film with tough intergranular sintering. A benign aqueous-based ink with poly(furfuryl alcohol) (PFA) and silica species is carefully designed and sprayed on glass to enable self-phase separation and morphology construction. The coatings reach the static contact angle (SCA) for water over 166° and withstand a 6H pencil scratching, the cross-cut test, and sand abrasion. Moreover, we also performed a 90 day outdoor performance test and the glass maintained superhydrophobicity with an SCA of 154°. These results provide a low-cost waterborne ink formula, and the high throughput and upscalable SRAC process could be a convenient technology for the fabrication of large area, robust superhydrophobic coatings

The refractive and diffractive contributions to GPS signal scintillation at high latitudes during the geomagnetic storm on 7-8 September 2017

Different indices have been used to reflect, or monitor the ionospheric scintillation, e.g. the detrended carrier phase, σφ, S4, the rate of change of the vertical total electron content index (vROTI), as well as the ionosphere‐free linear combination (IFLC) of two carrier phases. However, few studies have been performed to investigate the refractive and diffractive contributions to these indices, especially during geomagnetic storms. In this study, we analyze the high-resolution (50 Hz) phase and amplitude measurements from four high-latitude stations in Svalbard, Norway during the geomagnetic storm on 7–8 September 2017. Our results show that at high latitudes, the high-pass filter with a standard cutoff frequency of 0.1 Hz sometimes cannot effectively remove the refraction-driven phase variations, especially during the geomagnetic storm, leading to a remaining refraction contribution to the detrended carrier phase and σφ when scintillation happens. In the meanwhile, as vROTI is sensitive to the TEC gradients, regardless of small- or large-scale ionospheric structures, both refraction and diffraction effects can cause visible fluctuations of vROTI. For most of the scintillation events, the phase indices (including detrended carrier phase, σφ, and vROTI), IFLC, and S4 show consistent fluctuations, indicating that diffraction usually occurs simultaneously with refraction during scintillation. One interesting feature is that although the IFLC and S4 are thought to be both related to the diffraction effect, they do not always show simultaneous correspondence during scintillations. The IFLC is enhanced during the geomagnetic storm, while such a feature is not seen in S4. We suggest that the enhanced IFLC during the geomagnetic storm is caused by the increased high-frequency phase power, which should be related to the enhanced density of small-scale irregularities during storm periods.publishedVersio