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A method for forming electromagnetic waves with a tunable nonzero orbital angular momentum (OAM) is proposed. The approach is based on transforming an incident plane wave into a helical one using an electrically tunable ferroelectric lens. It uses high-resistive thin/thick film electrodes with a special discrete topology. The correlation between film electrodes topology and the highest order of OAM modes that the lens can form is described. A lens prototype based on Ba0.55Sr0.45TiO3 ferroelectric material and operating at a frequency of 60 GHz was designed, manufactured, and tested. The amplitude and phase distribution of the OAM wave with l = +1 formed by prototype were measured to confirm the effectiveness of the proposed method. The proposed lens has a combination of advantages such as low dimensions, electrical control over the OAM modes, and the possibility to operate in the millimeter wavelength range.

To prolong the lifetime of hydraulic cylinders, a wear-resistant low-friction surface is required. Until now, hard Cr coatings were the best materials for this. However, in recent years, there has been an increasing pressure on the manufacturing of hard Cr plating and plated products, because of environmental and health hazards. The replacement of these coatings by alternatives has not been highly successful yet, because it requires extensive component testing, which is costly and time-consuming and thus not appropriate for material development. For this reason, there is a high need to develop tribological methods that simulate hydraulic cylinders’ component-testing closely. In addition, these new methods should also provide additional information (e.g., friction evolution) that can assist in the further development and optimization of alternative coatings. Having the above in mind and building on an existing method from the American Society for Testing and Materials (ASTM G133), a new test method that allows users to test directly on hydraulic cylinders was developed. This method can provide a relative ranking of both the wear resistance and frictional performance of alternative coatings in direct comparison to state-of-the-art hard Cr. Importantly, the method is repeatable and has a much shorter test duration than full-scale component tests, thereby accelerating material development significantly. ispartof: Coatings vol:11 issue:12 status: published

An oxidation resistant coating on cemented tungsten carbides is characterised in this work. Cemented tungsten carbides (cWCs) are routinely used in mining and manufacturing but are also candidate materials for compact radiation shielding in fusion power generation. In both environments, cWCs will suffer significant degradation due to oxidation at relatively low temperatures. In a recent study, a Si-deposition coating method was demonstrated to improve the oxidation resistance of cWCs by up to a factor of 1,000. This work focusses on the growth kinetics, phase composition, and mechanical properties of these coatings. By combining quantitative X-ray diffraction, electron microscopy and nanoindentation, we show that the coating layer has a 20 % higher hardness than the substrate, which was explained on the basis of a previously-unknown presence of a fine distribution of very hard SiC laths. To interpret the coating stability, a coating growth map is developed. The map shows the structure is stable under a broad range of processing temperatures and composite compositions, demonstrating the potential application of these coatings in a variety of nuclear shielding cWCs.

We present organic, diamagnetic materials based on structurally simple (hetero-) tolane derivatives. They form crystalline thin-film aggregates that are suitable for Faraday rotation (FR) spectroscopy. The resulting new materials are characterized appropriately by common spectroscopic (NMR, UV-Vis), microscopy (POM), and XRD techniques. The spectroscopic studies give extremely high FR activities thus makes these materials promising candidates for future practical applications. Other than a proper explanation, we insist in the complexity of designing efficient FR materials starting off from single molecules.

This study focused on the deposition of indium-doped zinc oxide (IZO) films at high growth rates by ultrasonic spray pyrolysis. We investigated the influence of processing parameters, such as temperature and solution flow rate, on the structural, optical, and electrical film properties. For all depositions, low-cost and low-toxicity aqueous solutions and metal salt precursors were used. Through the optimization of the spraying parameters and pattern, a spatially homogeneous IZO layer with transparency greater than 80%, resistivity of 3.82 &times, 10&minus, 3 Ω&middot, cm for a thickness of 1800 nm (sheet resistance of 21.2 Ω/sq), Hall carrier density of 1.36 &times, 1020 cm&minus, 3, Hall mobility of 12.01 cm2 V&minus, 1 s&minus, 1, and work function of 4.4 eV was obtained. These films are suitable for implementation in optoelectronic and photovoltaic devices.

This paper presents the influence of an inorganic Al2O3 layer over MoS2 particles on the tribological performance of electroless Ni&ndash, P&ndash, MoS2/Al2O3 composite coatings fabricated without using surfactants. The Al2O3-coated MoS2 particles were prepared by a heterogeneous nucleation process. The dry sliding tests of the composite coatings were tested against a WC ball. SEM was used to observe the surface morphology of particles, composite coatings, and worn surfaces. The results indicate that the coverage of an Al2O3 coating on MoS2 particles significantly affects the surface morphology, frictional coefficient and wear loss of the composite coatings. The incorporation of Al2O3-coated MoS2 particles with lower coverage (up to 7% of Al2O3) could obtain compact surface structure of composite coatings, which contribute to reduced wear loss. However, higher coverage would lead to loose surface structure of the composite coatings, and thus increase their wear loss.