Facile method to prepare stable superhydrophobic Co3O4 surface

A facile and novel method was developed to fabricate rough Co₃O₄ surface with hierarchical micro- and nanostructures by the combination of simple solid state reactions and coating process. After modification with stearic acid, a superhydrophobic surface with water contact angle of 155 ± 1.8° and sliding angle of 2° was obtained. The superhydrophobic Co₃O₄ surface remained superhydrophobic property in a wide pH range from 3 to 14. The superhydrophobic Co₃O₄ surface also showed excellent self-cleaning property and high stability in ambient environments.     

Synthesis and characterization of superhydrophobic functionalized Cu(OH)2 nanotube arrays on copper foil

Superhydrophobic functionalized cupric hydroxide (Cu(OH)₂) nanotube arrays were prepared on copper foils via a facile alkali assistant surface oxidation technique. Thus nanotube arrays of Cu(OH)₂ were directly fabricated on the surface of copper foil by immersing in an aqueous solution of NaOH and (NH₄)₂S₂O₈. The wettability of the surface was changed from surperhydrophilicity to superhydrophobicity by chemical modification with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS). The morphologies, microstructures, crystal structure, chemical compositions and states, and hydrophobicity of the films on the copper foil substrates were analyzed by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. It was found that the rough structure of the surface helped to magnify the wettability. The static contact angle (CA) for water is larger than 160° and the contact angle hysteresis (CAH) is lower than 5° on the modified surface. The high roughness of the nanotube arrays along with the generated C-F chains by chemical modification contributed to the improved superhydrophobicity. The present research is expected to be significant in providing a new strategy for the preparation of novel multifunctional materials with potential industrial applications on copper substrates.     

Porous ceramic membrane with superhydrophobic and superoleophilic surface for reclaiming oil from oily water

A porous ceramic tube with superhydrophobic and superoleophilic surface was fabricated by sol-gel and then surface modification with polyurethane-polydimethysiloxane, and an oil-water separator based on the porous ceramic tube was erected to characterize superhydrophobic and superoleophilic surface's separation efficiency and velocity when being used to reclaim oil from oily water and complex oily water containing clay particle. The separator is fit for reclaiming oil from oily water.     

Fabrication of superhydrophobic copper surface with ultra-low water roll angle

Binary geometric structures at the micro- and nano-scale are fabricated on copper surfaces via simple sandblasting and surface oxidation process. The rough surfaces show excellent superhydrophobicity and ultra-low water roll angle (RA) after fluorination. The structure effect is deduced by comparing it with those of a single micro- or nano-scale structure. Such superhydrophobic copper surfaces can be widely used in many fields such as corrosion protection, liquid transportation without loss. Such a facile technique is expected to offer a feasible avenue for the industrial fabrication of superhydrophobic surfaces.     

A novel method to fabricate superhydrophobic surfaces based on well-defined mulberry-like particles and self-assembly of polydimethylsiloxane

A superhydrophobic surface was obtained by combining application of CaCO₃/SiO₂ mulberry-like composite particles, which originated from violent stirring and surface modification, and self-assembly of polydimethylsiloxane. Water contact angle and sliding angle of the superhydrophobic surface were measured to be about 164 ± 2.5° and 5°, respectively. The excellent hydrophobicity is attributed to the synergistic effect of micro-submicro-nano-meter scale roughness (fabricated by composite particles) and the low surface energy (provided by polydimethylsiloxane). This procedure makes it possible for widespread applications of superhydrophobic film due to its simplicity and practicability.     

Mechanically stable and corrosion resistant superhydrophobic sol-gel coatings on copper substrate

Development of the anticorrosion coatings on metals having both passive matrix functionality and active response to changes in the aggressive environment has raised tremendous interest in material science. Using a sol-gel deposition method, superhydrophobic copper substrate could be obtained. The best hydrophobic coating sol was prepared with methyltriethoxysilane (MTES), methanol (MeOH), and water (as 7 M NH₄OH) at a molar ratio of 1:19.1:4.31 respectively. The surface morphological study showed the ball like silica particles distributed on the copper substrate with particle sizes ranging from 8 to 12 μm. The coatings showed the static water contact angle as high as 155° and the water sliding angle as low as 7°. The superhydrophobic nature was maintained even though the deposited copper substrate was soaked for 100 h in 50% of HCl solution. The coatings are stable against humidity and showed superhydrophobic behavior even after 90 days of exposure. The coatings are mechanically stable and water drops maintained the spherical shape on the bent copper substrate, which was bent more than 90°.     

Guiding of 150 keV O6＋ ions through nanocapillaries in an uncoated Al2O3 membrane： special time dependence of the transmission profile width

<正>This paper reports that the transmission of O⁶⁺ ions with energy of 150keV through capillaries in an uncoated Al₂O₃ membrane was measured,and agreements with previously reported results in general angular distribution of the transmitted ions and the transmission fractions as a function of the tilt angle well fitted to Gaussian-like functions were observed.Due to using an uncoated capillary membrane,ourψ_c is larger than that using a gold-coated one with a smaller value of（?）,which suggests a larger equilibrium charge Q_∞in our experiment.The observed special width variation with time and a larger width than that using a smaller（?） were qualitatively explained by using mean-field classical transport theory based on a classical-trajectory Monte Carlo simulation.     

Microstructure and corrosion resistance behavior of ceramic coatings on biomedical NiTi alloy prepared by micro-arc oxidation

In this paper, ceramic coatings were prepared on biomedical NiTi alloys by micro-arc oxidation (MAO) in constant voltage mode. The current density-time response was recorded during the MAO process. The microstructure, element distribution and phase composition of the coatings prepared at different MAO treatment times were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), thin-film X-ray diffraction (TF-XRD) and X-ray photoelectron spectroscopy (XPS). The corrosion behavior of the coatings in 0.9% NaCl solution was evaluated by the potentiodynamic polarization test. It is found that the coatings become more compact with increasing the MAO treatment time, and the growth rate of coating decreases. The results of TF-XRD, EDS and XPS indicate that the coatings are composed of a large amount of γ-Al₂O₃ and a little α-Al₂O₃, TiO₂ and Ni₂O₃. The Ni content of the coatings is about 3 at.%, which is greatly lower than that of NiTi substrate. The bonding strength of coating-substrate is higher than 40 MPa for all the samples in this study. The corrosion resistance of the coatings is about two orders of magnitude higher than that of the uncoated NiTi alloy.     

One-step electrodeposition process to fabricate cathodic superhydrophobic surface

In this work, a rapid one-step process is developed to fabricate superhydrophobic cathodic surface by electrodepositing copper plate in an electrolyte solution containing manganese chloride (MnCl₂·4H₂O), myristic acid (CH₃(CH₂)₁₂COOH) and ethanol. The superhydrophobic surfaces were characterized by means of scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The shortest electrolysis time for fabricating a superhydrophobic surface is about 1 min, the measured maximum contact angle is 163° and rolling angle is less than 3°. Furthermore, this method can be easily extended to other conductive materials. The approach is time-saving and cheap, and it is supposed to have a promising future in industrial fields.     

The resistance to wear and corrosion of laser-cladding Al2O3 ceramic coating on Mg alloy

The paper presents a study on the preparation of Al₂O₃ ceramic coating on AZ91HP Mg alloy by laser remelting plasma-sprayed coating. It was found that after laser remelting, the coating exhibited obvious layer-like characteristics due to influence of temperature distribution, thermophysical parameters and layer thickness. According to the microstructural difference, the coating can be divided into the melted zone with the α-Al₂O₃ column-like crystal, the sintered zone with flock-like structure, the residual plasma-sprayed zone with loosened structure. Because of the dense column-like crystal, the hardness, wear and corrosion resistance of the laser remelted coating are much higher than those of the plasma-sprayed coating and as-received Mg alloy.     

Improvement in the properties of plasma-sprayed metallic, alloy and ceramic coatings using dry-ice blasting

Dry-ice blasting, as an environmental-friendly method, was introduced into atmospheric plasma spraying for improving properties of metallic, alloy and ceramic coatings. The deposited coatings were then compared with coatings plasma-sprayed using conventional air cooling in terms of microstructure, temperature, oxidation, porosity, residual stress and adhesion. It was found that a denser steel or CoNiCrAlY alloy coating with a lower content of oxide can be achieved with the application of dry-ice blasting during the plasma spraying. In addition, the adhesive strength of Al₂O₃ coating deposited with dry-ice blasting exceeded 60 MPa, which was nearly increased by 30% compared with that of the coating deposited with conventional air cooling. The improvement in properties of plasma-sprayed metallic, alloy and ceramic coatings caused by dry-ice blasting was attributed to the decrease of annulus-ringed disk like splats, the better cooling efficiency of dry-ice pellets and even the mechanical effect of dry-ice impact.     

Fabrication of two biomimetic superhydrophobic polymeric surfaces

Two biomimetic superhydrophobic polymeric surfaces were obtained by a simple approach under ambient atmosphere. Water and ethanol were used as the nonsolvents in the method of phase separation in different systems. The influences of various factors in the process were investigated. Both of the as-prepared films showed excellent superhydrophobicity, depending on the high contact angle and the low contact angle hysteresis. Moreover, the classic and a new modified Cassie-Baxter relation were used on the polystyrene and poly-α-methyl styrene films to confirm the superhydrophobic performance.     

Chemical quenching of positronium in Fe2O3/Al2O3 catalysts

Fe₂O₃/Al₂O₃ catalysts were prepared by solid state reaction method using α-Fe₂O₃ and γ-Al₂O₃ nano powders. The microstructure and surface properties of the catalyst were studied using positron lifetime and coincidence Doppler broadening annihilation radiation measurements. The positron lifetime spectrum shows four components. The two long lifetimes τ₃ and τ₄ are attributed to positronium annihilation in two types of pores distributed inside Al₂O₃ grain and between the grains, respectively. With increasing Fe₂O₃ content from 3 wt% to 40 wt%, the lifetime τ₃ keeps nearly unchanged, while the longest lifetime τ₄ shows decrease from 96 ns to 64 ns. Its intensity decreases drastically from 24% to less than 8%. The Doppler broadening S parameter shows also a continuous decrease. Further analysis of the Doppler broadening spectra reveals a decrease in the p-Ps intensity with increasing Fe₂O₃ content, which rules out the possibility of spin-conversion of positronium. Therefore the decrease of τ₄ is most probably due to the chemical quenching reaction of positronium with Fe ions on the surface of the large pores.     

Wetting mode transition of nanoliter scale water droplets during evaporation on superhydrophobic surfaces with random roughness structure

During evaporation, shape changes of nanoliter-scale (80-100 nL) water droplets were evaluated on two superhydrophobic surfaces with different random roughness (nm-coating, μm-coating). The square of the contact radius and the square of the droplet height decreased linearly with evaporation time. However, trend changes were observed at around 170 s (nm-coating) and around 150 s (μm-coating) suggesting a wetting mode transition. The calculated droplet radii for the wetting mode transition from the average roughness distance and the average roughness height of these surface structures were approximately equal to the experimental values at these trend changes. A certain level of correlation between the roughness size and droplet radius at the wetting mode transition was confirmed on surfaces with random roughness.     

注入Ar+的蓝宝石晶体退火前后光致发光谱的分析

对注入Ar⁺后不同晶面取向的蓝宝石晶体在不同退火条件下的光致发光谱进行了分析.分析结果表明:三种晶面取向的蓝宝石样品经Ar⁺注入后,其光致发光谱中均出现了新的位于506nm处的发光峰;真空和空气气氛下的退火均对样品在506nm处的发光有增强作用,不同晶面取向的样品发光增强程度不同,且发光增强至最大时的退火温度也不同,空气气氛下的退火使样品发光增强程度更为显著.由此可以看出,退火气氛、退火温度和晶面取向均对样品发光峰强度有影响. 关键词： 2O₃')" href="#">Al₂O₃ 离子注入 退火 光致发光谱     

Structural and phase transition of α-Al2O3 powders obtained by co-precipitation method

Aluminium oxide has been synthesized by co-precipitation technique at different annealing temperature. Powder XRD confirms the formation of α-Al₂O₃ with rhombohedral crystal structure having lattice constant a = 4.76 Å and b = 12.99 Å by the Scherer formula, the average crystallite size is estimated to be 66 nm. The scanning electron microscope results expose the fact that the α-Al₂O₃ nanomaterials are seemingly porous in nature and highly agglomerated. Chemical composition of aluminium oxide is confirmed by energy dispersive spectroscopy. The molecular functional group is confirmed by FTIR. Optical absorption of α-Al₂O₃ has been studied in the UV–vis region and its direct band gap is estimated to be 5.97 eV. This study involves the structural and phase transition of Al₂O₃ and also indicates that α-Al₂O₃ has considerable properties, deserving further investigation for the energetic materials with excellent properties for the possibility of using thin-layer α-Al₂O₃ as a thermo luminescence material.     

Al2O3绝缘层的AlGaN/GaN MOSHEMT器件研究

在研制AlGaN/GaN HEMT器件的基础上,采用ALD法制备了Al₂O₃ AlGaN/GaN MOSHEMT器件.通过X射线光电子能谱测试表明在AlGaN/GaN异质结材料上成功淀积了Al₂O₃薄膜.根据对HEMT和MOSHEMT器件肖特基电容、器件输出以及转移特性的测试进行分析发现：所制备的Al₂O₃薄膜与AlGaN外延层间界面态密度较小,因而MOSHEMT器件呈现出较 关键词： 2O₃')" href="#">Al₂O₃ ALD GaN MOSHEMT     

Substrate effects on V2O3 thin films

We apply density functional theory and the augmented spherical wave method to analyze the electronic structure of V₂O₃ in the vicinity of an interface to Al₂O₃. The interface is modeled by a heterostructure setup of alternating vanadate and aluminate slabs. We focus on the possible modifications of the V₂O₃ electronic states in this geometry, induced by the presence of the aluminate layers. In particular, we find that the tendency of the V 3d states to localize is enhanced and may even cause a metal-insulator transition.     

Electrical and structural properties of a stacked metal layer contact to n-InP

In this study, we found that the double metal contact structure in Pt/Al/n-InP diodes provides better rectification characteristics than conventional single-metal/n-InP Schottky diodes. The effective barrier height was measured to be 0.67 eV for a 400 °C-annealed Pt/Al/n-InP diode sample. The increase in the barrier height is attributed to the formation of Al₂O₃ at the metal/n-InP contact interface during thermal annealing. The formation of the phase Al₂O₃ phase was monitored by X-ray diffraction (XRD) analysis. The corresponding element profiles of Al and O were also confirmed at the metal/n-InP contact interface using secondary ion mass spectrum (SIMS) analysis. The lowering of the Schottky barrier height due to the inhomogeneity at the metal/n-InP junction is also discussed on the basis of the TE theory. The distribution of local effective Schottky barrier heights was explained by a model incorporating the existence of double Gaussian barrier heights, which represent the high barrier and low barrier of the full distribution in the temperature ranges of 83-198 and 198-300 K.