透明超疏水疏油涂层的制备及性能

以纳米SiO2和聚合物为原料,采用喷涂的方法,在不同基材的复杂工件表面形成均一涂层,并研究了SiO2含量对涂层性能的影响。结果表明,所得涂层与水接触角>150°,与油的接触角超过90°,具有超疏水性和疏油性。此外,涂层具有很好的透明性,涂层硬度高达6H,附着力达到5B。适当添加纳米SiO2,涂层的疏水性、疏油性以及透过率均得到增强。     

Sol-gel法制备耐蚀涂层的技术及应用

Sol-gel法制备耐蚀涂层对提高基材的化学耐久性、防止氧化、控制腐蚀有显著的效果,有望完全替代传统材料表面腐蚀控制处理使用的毒性物质铬酸盐处理工艺,可以减轻对环境的污染,是一项可持续发展的表面处理技术.为了阐述该项技术的工艺方法及特点,综述了Sol-gel法制备技术在不同的金属基体--不锈钢、铝合金和铜合金表面中的应用现状和最新研究进展.分析了采用Sol-gel法制备耐蚀涂层可以有效地阻止腐蚀介质对基体金属材料的破坏,延长材料在实际应用环境中的使用寿命等方面的作用原理,从理论上对Sol-gel耐蚀涂层的形成机制和耐蚀机理进行了初步讨论,并对Sol-gel技术的应用前景作一简要展望.     

Preparation of highly hydrophobic and oleophobic textile surfaces using microwave-promoted silane coupling

The wetting behavior of a solid surface is controlled by the geometric structure as well as the chemical composition of the material. In this study, highly hydrophobic and oleophobic materials were prepared by microwave-assisted cross-linking of perfluoroalkoxysilane onto nylon and cotton-blended fabric. Surface roughness was controlled by choice of the catalyst. Water catalysis resulted in a smooth coating deposition of the perfluoroalkoxysilanes on the fiber surface, while base catalysis resulted in a micro and nano scale rough surface on the fibers. Both water and base-catalyzed materials were superhydrophobic, but creating multi-scale geometric structure via base catalysis was required to improve oleophobicity. A series of experiments explored the parameters of fluorosilane concentration, base catalysis, curing time, and the number of cures. The apparent contact angles of the fabric samples treated in a multiple dip-and-cure sequence averaged 135° (hexadecane) and 148° (water) with no absorption of either within 60 h (hexadecane) or until complete evaporation (water).     

PECVD法制备微晶硅薄膜的研究

对等离子体增强化学气相沉积技术(PECVD)制备的微晶硅(μc-Si)薄膜的电导率、光学带隙和晶化率随温度和功率的变化规律进行了研究.从拉曼谱中可以明显看出,随着功率的增大,N型材料的非晶肩逐渐减小,材料的晶化率增大.随着温度的升高,P型材料的暗电导率和激活能都是先升高后降低.     

电泳沉积制备BG／BG—FHA复合涂层

采用电泳沉积在Ti6A14V钛合金表面制备了以生物玻璃（BG）为中间层,BG与氟取代磷灰石（FHA）复合粉末为表层的BG／BG—FHA涂层。通过XRD、SEM、EDS和电子万能力学试验机对BG／BG—FHA复合涂层的物相结构、微观形貌和涂层结合力进行了分析,优化了涂层的热处理制度,并通过模拟体液浸泡实验研究了涂层的体外...     

Negative photoconductivity in silver nanocubes prepared by simple photochemical method

Silver nanocubes embedded in polyvinyl alcohol matrix have been synthesised by photoirradiation technique. The composite films are characterised by FESEM, XRD, UV-Visible absorption and photoluminescence. These show characteristics of silver nanoparticles with FESEM showing the cubic shape. The photoconductivity study of these films shows decrease in photocurrent with light irradiation. Such negative photoconductivity behaviour may be attributed to dominant scattering of electrons by excited surface plasmon polaritons in nanoscale.     

Structural and gas-sensing properties of nanometre tin oxide prepared by PECVD

A low-temperature plasma-enhanced chemical vapour deposition (PECVD) technique has been employed to produce ultrafine tin oxide powders. The structural features and phase transition of this material have been characterized using differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction, infrared spectroscopy (IR) and transmission electron microscopy (TEM). The oxygen absorption behaviour and gassensing properties have been investigated by electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS) and electrical measurements. Thick film gas sensors made from such ultrafine SnO₂ powders yield better sensitivities than those of normal undoped SnO₂ gas sensors. A gas-sensing reaction mechanism is also proposed.     

Titanium and zirconium hard coatings on glass substrates prepared by the sol-gel method

In this work innovative antiscratch sol-gel coating films deposited on a soda-lime glass substrate are examined. Sol-gel coatings of different composition (TiO₂, TiO₂/B₂O₃, ZrO₂ and ZrO₂/B₂O₃) were prepared starting from Titanium, Zirconium and Boron alkoxides and from boron oxide. Coatings were obtained at room temperature and at atmospheric pressure by dip-coating using common soda lime silicate glass slides as substrates. Densification was carried out at 550 °C for 2 h in air. The morphology of the coatings has been studied by Atomic Force Microscopy, Scanning Electron Microscopy, and with a profilometer. Roughness grows with thickness and with boron addition. The mechanical properties of the films were evaluated by micro scratch at fixed and variable load. The scratch hardness numbers of ZrO₂ and ZrO₂/B₂O₃ coatings reach 6 GPa (glass value = 1.9 GPa), whereas the best value for the critical load is 16.7 N (glass value = 9 N).     

High-strength reduced graphene oxide paper prepared by a simple and efficient method

Journal of Materials Science - Excellent mechanical and electrical properties of graphene-based paper-like materials are essential for applications in flexible conductors, energy-storage devices,...     

Evaluation and characterization of nanostructure hydroxyapatite powder prepared by simple sol-gel method

Many attempts have been focused on preparing of synthetic hydroxyapatite (HA), which closely resembles bone apatite and exhibits excellent osteoconductivity. Low temperature formation and fusion of the apatite crystals have been the main contributions of the sol-gel process in comparison with conventional methods for HA powder synthesis. This paper describes the synthesis of nano-HA particles via a sol-gel method. Nanocrystalline powder of hydroxyapatite (HA) was prepared using Ca(NO₃)₂·4H₂O and P₂O₅ by a simple sol-gel approach. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for characterization and evaluation of the phase composition, morphology and particle size of products. The presence of amorphous and crystalline phases in the as-dried gel precursor was confirmed by the evaluating technique. Single phase of HA was also identified in the heat treated powder by XRD patterns. SEM and TEM evaluations showed that the obtained powder after heat treatment at 600 °C was agglomerated and composed of nanocrystalline (25-28 nm) HA particles. Increasing the sintering temperature and time could cause decomposition of HA into β-tricalcium phosphate and calcium oxide. The prepared nanocrystalline HA is able to improve the contact reaction and the stability at the artificial/natural bone interface for medical applications.     

简单醇热法制备ZnO纳米棒及其抗菌性能研究

通过Zn(NO3)2.6H2O和NaOH的醇溶液制备ZnO,利用XRD和TEM对产物进行表征,产物为具有较高的结晶度和纯度的ZnO纳米棒,直径约为30nm,长度约为130～500nm。取市售ZnO和产物,采用抑菌圈法对3种常见致病菌作药物敏感试验,并测定了产物对金黄色葡萄球菌的最小杀菌浓度(MBC)。结果表明,产物与市售ZnO试剂均对大肠杆菌不敏感,对金黄色葡萄球菌和白色念珠菌有不同程度的敏感,且产物比市售试剂抑菌效果更为明显,产物对金黄色葡萄球菌的最小杀菌浓度(MBC)为1.5%。     

Spectroscopic studies on Zn-doped CdS nanopowders prepared by simple coprecipitation method

Abstract  

A series of Zn-doped cadmium sulfide (CdS:Zn) nanopowders were prepared by a simple coprecipitation method at room temperature, mixing the stoichiometric amount of reactants in a Milli-Q water solvent. The composition of nanopowders was accurately adjusted by controlling the molar ratio of Cd, Zn acetate in the mixed reactants. Spectroscopic studies on as prepared nanopowders were investigated by using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy, Raman, UV–Vis absorption, Field emission–scanning electron microscope–energy-dispersive X-ray analysis, and photoluminescence. Broad nature of XRD peaks confirms that as prepared powders are in nanosize and cubic structure at room temperature. Doping with Zn in CdS does not lead to any structural phase transformation but introduces a decrease in the lattice constants. Raman spectrum of Zn-doped CdS nanopowders shifts slightly toward higher energy side compared with their pure CdS nanopowders. Exciton–phonon confinement factor (S) varies in between 0.3 and 0.4. At lower wavelength excitation, we observed a broad emission peak maximum centered at 404 nm is attributed to localized band edge emission.     

Low refraction properties of F-doped SiOC:H thin films prepared by PECVD

Low refractive index materials which F-doped SiOC:H films were deposited on Si wafer and glass substrate by low temperature plasma enhanced chemical vapor deposition (PECVD) method as a function of rf powers, substrate temperatures, gas flow ratios (SiH₄, CF₄ and N₂O). The refractive index of the F-doped SiOC:H film continuously decreased with increasing deposition temperature and rf power. As the N₂O gas flow rate decreases, the refractive index of the deposited films decreased down to 1.378, reaching a minimum value at an rf power of 180 W and 100 °C without flowing N₂O gas. The fluorine content of F-doped SiOC:H film increased from 1.9 at.% to 2.4 at.% as the rf power was increased from 60 W to 180 W, which is consistent with the decreasing trend of refractive index. The rms (root-mean-square) surface roughness significantly decreased to 0.6 nm with the optimized process condition without flowing N₂O gas.     

Boron carbide coatings prepared by cathodic arc deposition

Boron carbide films are attractive materials for use as tribologcal coatings for low and high operating temperatures, especially for applications that require high hardness. The properties of boron carbide films prepared by cathodic arc using a heated B₄C cathode are investigated. The B:C ratio in the film was about 3, and the only detected impurity was oxygen with a content below 5%. The effect of substrate bias on the film characteristics was studied. A direct correlation between hardness and elastic modulus and bias voltage applied to the substrate was observed for bias voltages in the interval of 0–500 V. Microstructure and chemistry of the films were investigated using X-ray diffraction, electron microscopy and X-ray absorption spectroscopy.     

Metal chalcogenide-oxide composite coatings prepared by spray pyrolysis

The spray pyrolysis technique has been employed to deposit composite coatings of chalcogenides of cadmium, zinc, lead and cobalt with oxides of aluminium, tin, lead, zinc and cobalt. Widely varying microstructural, electronic, optical and chemical properties have been obtained for such layers by monitoring the oxide composition, its spatial distribution and profile along the thickness. The large area chalcogenide-oxide composite films prepared by this technique are eminently suited for photovoltaic energy conversion, photothermal energy conversion and voltage-dependent resistor (Varistor) applications.In this paper we report our studies on co-pyrolytically deposited CdS:Al₂O₃ and CdS:SnO₂ layers and their application to improved thin film solar cells. Each of the oxides is insoluble in CdS and is segregated at the grain boundaries in the deposited films. Small amounts (less than 10%) of oxide in CdS are found to reduce its grain size negligibly and to make the film more compact, hard, adherent and less susceptible to chemical attack. The altered microstructure modifies the surface topography of the CdS film from a pebble-like roughness to an improved void-free serpentine texture. Segregated oxide in CdS does not affect the optical band gap of the films, although the composites exhibit enhanced diffuse optical scattering.Large area CdS films with a gradient profile of oxide have been utilized to fabricate thin film CdS/Cu₂S solar cells. The growth (length and distribution) of Cu₂S fingers and/or curtains deep into the top CdS layers during the topotaxial conversion reaction of chemiplating is controlled by the presence of oxide along the grain boundaries. This has not only resulted in improved interface topography for better carrier collection and reduced shunt losses but has also enabled us to decrease drastically the CdS film thickness necessary for the solar cells. Furthermore, the subsequent degradation of the junction via the well-known mechanism of the loss of copper from the Cu₂S layer by diffusion into CdS is expected to be considerably reduced by the presence of the oxide gradient in the CdS layer.