用于AGS结构分析的混合法

结合均匀化模型和加筋单元模型构造了一种混合模型用来分析复合材料格栅加筋板/壳结构（AGS）。所构造的加筋单元模型是一种高性能协调转角独立加筋板壳单元,保持了肋骨和蒙皮位移场的协调性,同时还满足肋骨和蒙皮具有独立转动条件,该单元中肋骨的方向和位置任意。混合法具有精度高、速度快等特点。通过典型算例讨论了肋骨间距和高度对均匀化模型计算结果精度的影响,通过对带孔复合材料AGS板孔边特殊点应力值的分析证明了混合法的有效性。      

Fabrication of titania/hydroxyapatite composite granules for photo-catalyst

The titania/hydroxyapatite composite granular photo-catalyst with novel microstructure was fabricated by the process based on the liquid immiscibility effect and followed by precalcination and hydrothermal treatment from commercially available powders of α-Tri-calcium phosphate and TiO₂. XRD, SEM, BET, optical microscopy and UV-vis spectrophotometer were applied to characterize the prepared photo-catalyst. Microstructure analysis indicated that the granule was weaved by rod-shaped hydroxyapatite crystals whose surface was covered by nano-sized TiO₂. In the composite granules, the active surface of anatase was retained effectively. With the hybridization of TiO₂ and HAp, a 16-nm blue-shift of absorption edge could be observed and the crystallinity of anatase could be enhanced by precalcination. The granules with the rod-shaped hydroxyapatite crystals performing as scaffold work as three-dimensional high porous, size-controllable small reactor. The phase and microstructure transformation of the granule before and after hydrothermal treatment was investigated and its decomposition ability was evaluated by using Methylene blue as a target pollutant compound.     

An aggregate fuzzy hazardous index for composite wastes

In this paper, a fuzzy waste index for evaluating the hazard posed by composite wastes generated from industrial processes is proposed. Within this methodology, a fuzzy index as a measure of hazardousness of a given composite waste is derived from the crisp inputs of its component's flammability, corrosivity, toxicity and reactivity attributes based on the National Fire Protection Association (NFPA) hazard rankings. The novelty of this work lies in establishing an integrated fuzzy hazardous waste index (FHWI) which provides a single-value representing the hazard ranking of a composite waste. This is contrary to current techniques which do not provide a final aggregated hazard index. The efficacy of the new proposed approach is illustrated through several worked examples. The results demonstrate that the fuzzy algorithm can be useful in aiding policy and decision-makers in conducting comprehensive initial evaluation of the status of waste hazardous status without the need for costly laboratory experiments. As such, the approach offers a robust and transparent decision-making methodology.     

Formation and properties of porous silicon/titania nanostructures

Porous silicon/titania structures have been prepared for the first time by a sol-gel process in which a porous silicon layer was produced on single-crystal p-type silicon wafers and the titania was obtained from Ti-containing sol. The formation of TiO₂, predominantly in the form of anatase, on the porous silicon surface was demonstrated by X-ray diffraction and energy dispersive X-ray analysis. The porous layers were found to contain carbon in addition to the host elements (Si, Ti, and O). Increasing the pore volume through the thermal oxidation of the porous silicon and dissolution of the oxide layer had little effect on the final Ti content, whereas the average pore diameter increased twofold, and the photoluminescence intensity in the porous silicon increased by 20 times.     

Visible-light responsive zinc ferrite doped titania photocatalyst for methyl orange degradation

Visible-light responsive zinc ferrite doped titania (ZFDT) photocatalysts were prepared by sol-gel method. Diffuse Reflectance Spectroscopy (DRS) result shows that the absorption edge of ZFDT has moved to the visible spectrum range and a very large redshift occurs in comparison with the undoped titania. X-ray diffraction (XRD) results show that zinc ferrite can prevent the transformation of titania from anatase to rutile when the content of zinc ferrite is above 1.5%; while the phase transformation is promoted when its content is below 1.5%. In the latter case, zinc ferrite was assumed to exist as separate zinc and ferric cations in the lattice of titania in the form of oxides, both of which promote the phase transformation as previously reported in other literatures. Field emission scanning electron micrography (FE-SEM) shows that the average particle size of 1.5%ZnFe₂O₄/TiO₂ calcined at 500 °C is about 70 nm. The photocatalytic experimental results exhibit that ZFDT powders can effectively photodegrade methyl orange under visible light irradiation and the maxium photoactivity is achieved when the amount of zinc ferrite is 1.5%.     

Fabrication of homogeneous titania/MWNT composite materials

MWNT/titania nanocomposites were prepared by an impregnation method and subsequent heat treatment at 400 °C. Precursor compounds such as titanium (IV) propoxide and titanium (IV) ethoxide were used to cover the surface of CNTs under solution conditions. Electron microscopy and X-ray diffraction techniques were carried out to characterize the as-prepared titania layers.     

Hydrothermal preparation of neodymium oxide coated titania composite designer particulates and its application in the photocatalytic degradation of procion red dye

Nd₂O₃ coated onto titania composite designer particulates using 1M NaOH at 250°C and P~80 bars with an experimental duration of 5–72 h were obtained under hydrothermal conditions. Different weight % of Nd₂O₃ (1–9%) was used for coating in order to reveal the role of Nd₂O₃. Characterization of the Nd₂O₃ coated titania composite designer particulates obtained was carried out using XRD and FTIR spectroscopy techniques. Photocatalytic reactivity of Nd₂O₃ coated titania composite designer particulates was evaluated by studying the degradation of procion red dye. The effect of various kinetic parameters like initial dye concentration, catalyst amount, pH of the medium, temperature of the medium, light source and catalyst reusability on the photodegradation of procion red dye has been discussed in detail. The thermodynamic parameters like energy of activation, enthalpy of activation, entropy of activation and free energy of activation were estimated.     

Composition parameters for hybrid composite materials

The ‘rule-of-mixtures’ is frequently invoked to compare the properties of hybrid composites with those of related single-fibre materials. If this is to be done, it is essential that the correct value for hybrid composition be employed. Some ways of expressing hybrid composition are defined, the relationships between them given, and the implications of incorrect usage discussed.     

Synthesis of porous micro-sized titania cages and their photocatalytic property

Micro-sized TiO₂ cage consisted of anatase nanoparticles on the edges of each cube, was synthesized using TTIP as the reagent and NaF submicrometer sized cubes as the template. When a salt of cube was adopted as the template, the reactants prefer to grow on the active sites, edges and corners of the cube, after removing the NaF template, the skeleton of the cube remain as the cage-shaped materials. The hierarchical structures with nano-sized anatase particles and micro scaled cage architecture markedly enlarge the surface area and enhance the light harvesting by light scattering of TiO₂ frame, resulting in great photo-catalytic performance, which leads to the photo-degradation of methylene blue by 40% higher than that was achieved by crushed nanoparticles.     

Nanoarchitectonics of nitrogen-doped porous carbon derived from leather wastes for solid-state supercapacitor

Journal of Materials Science: Materials in Electronics - Leather solid wastes not only endanger the environment, but also lead to a significant waste of biomass resources. The efficient utilization...     

Formation mechanism of biomedical apatite coatings on porous titania layer

A titania containing calcium and phosphate with rough and porous structure was prepared by microarc oxidation. The in vitro bioactivity was examined by immersing the samples into the simulated body fluid (SBF). And the mechanism was also discussed. The results show that only 3 days of immersion in SBF, apatite was formed on the surface, and after 6 days, nearly all the surface covered by apatite. This indicates that the layer can induce the formation of apatite in simulated body fluid. It is analyzed that the key factors of the apatite formation are the hydrolysis of the CaTiO₃ and special structure.     

EDTA-directed synthesis of highly active porous titania with bicrystalline framework

Porous titania with bicrystalline (anatase and rutile) framework was successfully synthesized by a facile hydrothermal process using inexpensive and nontoxic organic molecules, EDTA (ethylenediamine-tetra-acetic acid) or its sodium salts as a template, which could be removed from porous titania by the extraction with sodium hydroxide aqueous solution and then easily recovered by acidification. XRD investigation suggested that the ratio of anatase to rutile could be readily tuned by employing different sodium salts of EDTA. All of as-prepared porous titania showed higher activities than the commercial photocatalyst P25 for the degradation of methyl orange (MO), because of the high surface area, bicrystalline phase composition and bimodal porous structures.     

Synthesis of organic–inorganic hybrid composite and its thermal conversion to porous bioactive glass monolith

We report the synthesis and bioactivity studies of 3-dimensional macro-porous material produced by thermal treatment of organic–inorganic hybrid composite. This is prepared by sol–gel processing of co-poly(methylmethacrylate (MMA)-vinyltriethoxysilane (VTS)) with tetraethoxysilane (TEOS), calcium nitrate and zinc nitrate, ([CH₂C(CH₃)(CO₂CH₃)]_0.8n-[CH₂-CH(Si(OEt)₃]_0.2n-SiO₂-CaO-ZnO) (1). Thermal treatment of this polymer at 600 °C yielded macro-porous bioglass monolith, with pore size distribution between 1 and 5 μm and showed excellent bone bonding ability in simulated body fluid. The ratio of VTS:MMA in the organic polymer can easily be controlled. Since the VTS is the bonding agent, the amount of VTS in the co-polymer can be utilized to increase or decrease the porosity of the hybrid composite. This may be a convenient approach for preparation of bioglass scaffolds especially in tissue engineering of bone.     

Synthesis and characteristics of polyimide/titania nano hybrid films

Polyimide/titania (PI/TiO₂) nano hybrid films are synthesized by sol-gel technology. [4,4′-(4,4′-Isopropylidenediphenoxy) bis (phthalic anhydride)] (IDPA), 4,4′-diaminodiphenyl ether (ODA) and 3-aminopropyltrimethoxysilane (APrTMOS) mixed entirely and reacted at room temperature to form the polyamic acid (PAA). Tetraethyl orthotitanate (Ti(OEt)₄) and actylacetone, the latter one is used as chelating agent, are then added to the polyamic acid. After imidization at high temperature, PI/TiO₂ hybrid films with different block chain length, 5000 of PAA and 15000 g mol^− 1, and a cross-linked structure are formed. The resulting hybrid films, containing relatively small amounts of titania, exhibit higher transparency and flexibility. Moreover, as compared with pure PI, the hybrid film formed from APrTMOS has better ability to form a film with a higher titania content. Due to the high and low refractive index (RI) of TiO₂ and APrTMOS, their introduction may lead to the change of the RI of hybrid films. From the transmission electron microscope (TEM) images; the particle size of titania decreases with increasing APrTMOS content. Thermal decomposition temperatures (T_d), with a 5% weight loss, are in the range of 400-540 °C. The dynamic mechanical thermal analysis showed a systematic increase of glass transition temperature, along with a broader and weaker tan δ peak with increasing titania content.     

Optimum bolted joints for hybrid composite materials

The optimum bolted joints for hybrid composite materials composed of glass-epoxy and carbon-epoxy under tensile loading were investigated. The design parameters considered for the bolted joints were ply angle, stacking sequence, the ratio of glass-epoxy to carbon-epoxy, the outer diameters of washers and the clamping pressure. As bearing failure was desirable for bolted joints, the geometry of the bolted joint specimen was designed to undergo bearing failure only.

By inspecting the fracture surfaces of the specimens it was found that delamination on the loaded periphery of the holes and extensive damage on the edge region constrained by a washer occurred. To assess the delamination of the hybrid composite materials, three-dimensional stress analysis of the bolted joint was performed using a commercial finite-element software and compared with the experimental results.     

Biomass-derived nitrogen-rich porous carbon composite for supercapacitor application

In this study, egg proteins are used as a nitrogen source for the synthesis of nitrogen-rich carbonaceous material through hydrothermal carbonization (HTC) for the electrochemical energy storage application. The composite of activated carbon with egg-derived protein (AC/EDP) is prepared by mixing untreated egg proteins in the aqueous dispersion of activated carbon, followed by HTC at 220 °C for 12 h in a Teflon-lined autoclave. The resultant composite is then directed to chemical activation with KOH and thermal activation at a temperature ranging from 500 to 700 °C. The nitrogen-doped activated carbon exhibited a microporous and mesoporous structure with a high specific surface area of 1660 m² g^?1, confirmed through BET analysis. The composite morphology was analyzed through scanning and high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy indicates the presence of a considerable amount of pyrrolic, pyridinic, and quaternary nitrogen in AC/EDP, which improved the electrochemical performance. The composite activated at 700 °C exhibited the highest capacitance of 263 F g^?1 at a current density of 0.2 A g^?1. The highest energy density and power density values are 32 Wh kg^?1 and 7920 W kg^?1, respectively. The AC/EDP exhibited high cyclic stability, and the capacitance retention observed after 10,000 cycles is 98%.

     

Microwave glazing of alumina–titania ceramic composite coatings

The application envelop of atmospheric plasma sprayed ceramic composites can be widened considerably by reducing/eliminating inherent surface defects by treating them through techniques like microwave irradiation. In microwave processing, microwave energy is directly applied to the material. High-frequency microwaves (>1 GHz usually) penetrate into the bulk of the material and the volumetric interaction of the electromagnetic fields with the material results in dielectric (volumetric) heating. This leads to higher heating efficiency with faster processing. Ceramics are transparent to microwaves at low temperatures, however, start absorbing microwaves at higher temperatures resulting change in microstructure and material characteristics. This paper presents microwave processing of atmospheric plasma sprayed alumina–titania ceramic composite coatings in conventional microwave heating system and evaluation of the processed materials through XRD, SEM, microhardness survey and surface finish with illustrations. Results indicate microwave irradiation induces densification of the material and possible flow of dominant gamma-alumina phase that leads to glazing of coated surface. Glazed surfaces exhibit enhanced microhardness as well as surface finish.     

核壳结构TiO2光催化剂的制备和性能

统一尺寸、结构上有序包覆的核壳型复合材料,具有高折射率以及独特的电磁、光学和机械性质.结构上的独特性可能导致其在近红外和可见光区有完整的带隙,利用核与壳之间的相互作用,以及核对降解物的吸附等作用,可提高复合体的光催化性能.本文着重介绍核壳型TiO2的几种类型、特点及其性能,并提出其今后的发展方向.     

Synthesis, characterization and photocatalytic activity of porous manganese oxide doped titania for toluene decomposition

The present study describes the photocatalytic degradation of toluene in gas phase on different porous manganese oxide doped titanium dioxide. As synthesized birnessite and cryptomelane type porous manganese oxide were doped with titania and tested for photocatalytic decomposition of toluene in gas phase. The effects of the inlet concentration of toluene, flow rate (retention time) were examined and the relative humidity was maintained constantly. Thermal and textural characterization of manganese oxide doped titania materials were characterized by X-ray diffraction (XRD), thermogravemetry (TG), BET and TEM-EDAX studies. The aim of the present study is to synthesize the porous manganese oxide doped titania and to study its photocatalytic activity for toluene degradation in gas phase. Cryptomelane doped titania catalyst prepared in water medium [K-OMS-2 (W)] is shown the good toluene degradation with lower catalysts loading compared to commercial bulk titania in annular type photo reactor. The higher photocatalytic activity due to various factors such as catalyst preparation method, experimental conditions, catalyst loading, surface area, etc. In the present study manganese oxide OMS doped titania materials prepared by both aqueous and non-aqueous medium, aqueous medium prepared catalyst shows the good efficiency due to the presence of OH bonded groups on the surface of catalyst. The linear forms of different kinetic equations were applied to the adsorption data and their goodness of fit was evaluated based on the R2 and standard error. The goodness to the linear fit was observed for Elovich model with high R2 (>or=0.9477) value.     

Synthesis of porous titania microspheres for HPLC packings by polymerization-induced colloid aggregation (PICA)

Porous titania microspheres with a very narrow particle size distribution (PSD) were synthesized by polymerization-induced colloid aggregation (PICA). After being sintered, the titania microspheres that are obtained have an average diameter of 3.5 microm, a surface area of 36.7 m2/g, an average pore volume of 0.30 mL/g, and an average pore diameter of 32.2 nm. The microspheres possess enough rigidity to withstand high packing pressure and are very useful as a new kind of chromatographic packing material for high performance liquid chromatography (HPLC).