Ordered mesoporous silica were synthesized under different conditions: hydrothermal synthesis in basic medium, room temperature synthesis in acid medium and sol-gel synthesis in neutral medium, and pore structure, specific surface area and pore size distribution of samples were studied and compared in detail by means of SAXRD, HRTEM, BET, FT-IR. The results show that the mesopores in the samples obtained via above three methods all possess uniform hexagonal arrays in short range. Mesoporous silica obtained in acid medium possesses narrow pore size distribution centered around 1.24 nm with specific surface area of 1220 m2·g−1; Mesoporous silica obtained in basic medium by hydrothermal synthesis at 160°C possesses narrow pore size distribution centered around 1.90 nm with specific surface area of 542.8 m2·g−1; and mesoporous silica obtained in neutral medium by sol-gel synthesis possesses broader pore size distribution centered around 4.01 nm, specific surface area of 485.0 m2·g−1. Therefore, ordered mesoporous silicas with different pore sizes can be prepared using various synthetic methods and conditions. After heat treatment, Si-O-Si bending vibration strengthens and the adsorption peak of asymmetrical Si-O-Si stretching vibration broadens, and the crosslinking and condensation reaction of silica skeleton strengthen, meanwhile the amount of active centers of hydroxyl group on the surface of mesopores may be influenced, thus chemical assembly activity of mesopores may also be influenced.
Two structure types of LiMnO2 were synthesized by sol-gel method and ion-exchange method respectively. The results indicate that orthorhombic phase LiMnO2 is more stable than layered LiMnO2, o-LiMnO2 can be synthesized directly by sol-gel methods followed by heat-treated in argon, but layered LiMnO2 was obtained only by indirect methods such as ion-exchange method. In this paper, we first synthesized layered NaMnO2 by the sol-gel method, and then obtained layered LiMnO2 by the ion-exchange method. The phase, constitution, chemical composition, and images of the products were tested by XRD, AAS (atomic absorption spectroscopy) and SEM. The electrochemical performances of the two structural types of LiMnO2 are obviously different during the initial few cycles, but later they both have a good capacity-retaining ability. The capacity of layered structure LiMnO2 is higher than that of o-LiMnO2.
An investigation was performed on the effects of semi-solid compression parameters, such as strain rate, compression temperature and heating time at these temperatures on deformation behaviors of two kinds of ZA27 alloys, one was modified by Zr and the other was unmodified. The results indicate that with the increasing of the strain, the stress of the modified composite first sharply increases to a peak value, then dramatically decreases to a peakeau value, and again increases till the end of deformation. But for the unmodified, after being up to a peak value, the stress only decreases slowly. As the compression temperature or the heating time decreases, or the strain rate increases, the stress level and the cracking degree of these two kinds of alloys increase. Under the same deformation conditions, the stress level and the cracking degree of the unmodified alloy are higher than those of the modified one. But there is an exception that the stress level of the unmodified alloy is minimum and smaller than that of them modified one when deformed at the low temperature of 450°C. These phenomena were mainly discussed through analyzing the microstructures under different conditions and the deformation mechanisms at different deformation stages.
The supported membranes of Al2O3 and its modification membranes were prepared. Al2O3, Al2O3-SiO2-TiO2 and Al2O3-SiO2-TiO2-ZrO2 membranes were manufatured by the slip-casting process using mixing boehmite, silicate, titania and zirconia sols under proper conditions, then the composite membrane was prepared. The structure and characteristics of the membrane were determined by XRD, SEM and AFM measurement. The conditions of preparation of the membrane are discussed. The thickness of the layer is about 1–2 μm, the diameter of an average pore is 200–300 nm and has a narrow pore distribution without crack forming. By changing the ratios of Al∶Si∶Ti∶Zr (mol), variations of surface pore size of Al2O3-SiO2-TiO2-ZrO2 membrane can be gained.
Large-quantity growth of ZnO nanorods is achieved by oxidation of Zn powders with catalystfree method. The products are characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy. The as-grown nanorods are structurally uniform with diameter ranging from 60 to 150 nm and lengths of up to 5–8 μm, and they are single crystalline in nature with growth direction parallel to [0001]. Room-temperature photoluminescence spectrum of the nanorods shows a strong and sharp UV emission band at 385 nm and a weak and broad green emission band at 495 nm. The vapor-solid model is also proposed to explain the growth behavior of ZnO nanorods in our synthesis process.
Through measuring the alkali resistance of the invert glass and the quanity of SiO2 and TiO2 migrating fron the glass into the solution, the influence of TiO2 on the alkali resistance of the glass is discussed and its structure is also analyzed by infrared spectroscopy. It is concluded that TiO2 has double functions for the alkali resistance of the invert glass. On the one hand, both TiO2 polarizing the secondary ions in glass and TiO2 isomorphism replacement of SiO2 make the alkali resitance of the glass decrease. On the ther hand, TiO2 patching network and anti-erosion covering help to increase the alkali resistance.
The V2O5 sol was fabricated by ultra-fast quenching. The vanadium with low valence (V4+) was found in V2O5 xerogel films by XPS analysis. The technology of oxygen top-blown was applied to analyze the XPS spectrum difference of V2O5 xerogel when the powder of V2O5 was melting in air or in oxygen atmosphere. The results show that the different melting atmosphere has certain influences on the chemical valence of V2O5 xerogel.
The solidification features, micro-segregation, and fracture characteristics of cobalt-based alloy on the substrate of 20 CrMo steel by laser cladding were studied by using electron microscopy. Experimental results show that the fine columnar grains and cellular dendrite grains are obtained which are perpendicular to the coating/substrate interface; the primary arms are straight while the side branches are degenerated; the microstructure consists of primary face-centered cubic (fcc) Co dendrites and a network of Cr-enriched eutectic M23 C6 (M=Cr, W, Fe) carbides; the micro-segregation is severe for the rapid heating and cooling of laser cladding; the typical brittle intergranular fracture occurs in cobalt-based laser cladding layer.
By means of chemical reduction, nanoparticles of platinum were deposited on the surface of multi-walled carbon nanotubes (MWCNTs). The performance of hydrogen storage of as-prepared MWCNTs decorated with platinum was investigated. The results indicate that: (1) Hydrogen uptake is more quick and intense for decorated MWCNTs than that for not decorated ones at 10.931 MPa and room temperature. The saturation of hydrogen uptake of the former only lasts about 30 min, while the latter needs about 150 min; (2) The amount of hydrogen uptake of decorated MWCNTs is about 1.13wt%, which is larger than that of not decorated ones (about 0.54wt%); (3) However, more than 37% hydrogen absorbed by decorated MWCNTs is chemisorbed.
TiO2 fims have been deposited on glass substrates using DC reactive magnetron sputtering at different oxygen partial pressures from 0. 10 Pa.to 0.65 Pa. The transmittance (UV-vis) and photoluminescence (PL) spectra of the films were recorded. The results of the UV-vis spectra show that the deposition rate of the films decreased at oxygen partial pressure P(O2)≥0.15 Pa, the band gap increased from 3.48 eV to 3.68eV for direct transition and from 3.27 eV to 3.34 eV for indirect transition with increasing the oxygen partial pressure. The PL spectra show convincingly that the transition for films was indirect, and there were some oxygen defect energy levels at the band gap of the films. With increasing the O2 partial pressure, the defect energy levels decreased. For the films sputtered at 0.35 and 0.65 Pa there were two defect energy levels at 2.63 eV and 2.41 eV, corresponding to 0.72 eV and 0.94 eV below the conduction band for a band gap of 3.35 eV, respectively. For the films sputtered at 0.10 Pa and 0.15 Pa, there was an energy band formed between 3.12 eV and 2.06 eV, corresponding to 0.23 eV and 1.29 eV below the conduction band.
The frost durability of concrete is considered from structural engineering points of view. Specific failure process is analyzed and a damage model is established, which can describe the deterioration of concrete during the whole freeze-thawing process. The model is verified by test data. The parameters of model can explain the effect of pore structures or water to binder ratio on frost durability of concrete.
The homogenous glass samples of the (1−x) As2S3−xCdCl2 where x=0 and 0.05 were prepared by the conventional melt-quenched method. The addition of 5 mol% CdCl2 enhanced the glass transition temperature of pure As2S3 glass sample by about 30°C. Based on the experimental data, the microstructure is considered to be that the discrete molecule species of AsCl3 and nanocrystal CdS is homogeneously dispersed in the disordered polymer network formed by AsS3 pyramids interconnected by sulfur bridges.
Vickers indentation test, a simple method for the toughness determination, is used to test the fracture toughness of Al59 Cu25.5 Fe12.5 B3 polycrystal’s modulus E, cracking threshold, and fracture toughness have been evaluated. The results show that the Young’s modulus of Al-Cu-Fe-B polycrystalline quasicrystal is evaluated as 134 GPa, and the fracture toughness is about 1.36 MPaom−1/2. For the Vickers indenter, the cracking threshold is in the range of 250MN−500MN. Moreover, the surface morphology of the indentations and the cracks are observed by means of Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The relationship between the microstructure of quasicrystal and crack initiation and propagation is discussed in detail.
Al2 O3/Al composite was fabricated by the reaction between SiO2 and molten aluminum. The microstructures of the composite obtained under different reaction conditions were analyzed. The formation mechanism of the composite microstructure was discussed. Results show that the reaction kinetics is influenced remarkably by the reaction temperature, reaction time and the quantity of SiO2. The morphologies of Al2O3 have different features, depending on the reaction temperature. The composite has equaxed Al2O3 grains when materials reacted below 1200°C, and the composite is composed of a large number of fine Al2O3 grains and aluninum. The composite has a frame-shaped Al2O3 microstructure at the reaction temperature of above 1250°C.
Electrical conductivity and seebeck coefficient at different temperatures, and thermal conductivity at room temperature for various doped polyaniline (PAn) samples were measured, and the thermoelectric figure of merit ZT was calculated. The effects of preparation methods and temperature on thermoelectric properties were discussed. The results show that the electrical conductivity and the seebeck coefficient of PAn are strongly dependent on the preparation conditions and temperature. The electrical conductivity becomes larger and the seebeck coefficient becomes smaller as PAn molecular weight increase. Redoping by organic acid and HCl results in an increase in both electrical conductivity and Seebeck coefficient of PAn, and therefore ZT value. The electrical conductivity increases and the seebeck coefficient decreases as the temperature increases when T<Td (dedoping temperature). The decreasing of the electrical conductivity and increasing of the seebeck coefficent take place by dedoping when T>Td. The thermal conductivity is lower, and insensitive to the sample preparation conditions.
Quantitative phase analysis of Portland cement clinker samples was performed using an adaptation of the Rietveld method. The Rietveld quantitative analysis program, originally in Fortran 77 code, was significantly modified in visual basic code with windows 9 X graph-user interface, which is free from the constraint of direct utilizable memory 640 k, and can be conveniently operated under the windows environment. The Rietveld quantitative method provides numerous advantages over conventional XRD quantitative method, especially in the intensity anomalies and superposition problems. Examples of its use are given with the results from other methods. It is concluded that, at present, the Rietveld method is the most suitable one for quantitative phase analysis of Portland cement clinker.
The selective laser sintering (SLS) was used to prepare components from modified polyamide (PA) powder. The behaviour of the sintering process was analyzed. The influences of the fill laser power, powder bed temperature and powder thickness were discussed in detail. By means of SEM, the morphology and the heat influence were analyzed. Results show that the powders were fused thoroughly which allowed a more dense structure to be built at a powder bed temperature of 98°C, fill laser power 12W, slice thickness of 0.10 mm and a default scanning speed of 1700 mm/s.
Silicon-iron-peach pigment 510B in Mossbauer spectra was analyed, the results show that there are mainly two kinds of iron phase mineral existing in 510B pigment, α-FeO(OH) and γ-FeO(OH). The Mossbauer spectra of 510B sample after being calcined in 1200°C was also analyzed.
Stable and single-dispersed HAP nanoparticles were synthesized with chemical method assisted by ultrasonic treatment. HAP nanoparticles were surveyed by AFM and Zataplus. The effect on the Bel-7402 human hepatoma cell lines treated with HAP nanoparticles was investigated by the MTT methods and observation of morphology, and the mechanism was studied in changes of cell cycle and ultrastructure. The result shows that inhibition of HAP nanoparticles on the Bel-7402 human hepatoma cell lines is obviously in vitro. HAP nanoparticles the entered cancer cytoplasm, and cell proliferation is stopped at G1 phase of cell cycle, thus, cancer cells die directly.
Denture base made from acrylic resin (polymethyl methacrylate, PMMA) was reinforced by different contents of ultrahigh-modulus polyethylene fiber (UHMPEF). The flexural strength of the denture base was tested, the failure modes and microstructures were investigated with a scanning electron microscope (SEM). The results indicate that 3.5wt% UHMPEF increased the ultimate flexural strength of the denture base.
The visualization experiments were carried out to investigate the permeability of the high-permeable medium (HPM) and the roles of the peel ply and the HPM in the mold filling. The influence of process parameters on mold filling is discussed. Furthermore, the whole vacuum infusion molding process (VIMP) procedure is introduced in detail taking the manufacture of a model boat for example.
A non-contacting electrical resistivity measurement device was used for measuring the electrical resistivity of cement paste incorporated with retarder. The hydration process was divided into dissolving period, setting period, hardening period. With the increase of the retarder, the dissolution time will increase. The setting time happens between minimum point time and inflexion point time based on the electrical resistivity curve. The strength isoline was proposed to predict the strength trend.
A new type of concrete expansion agent has been successfully developed for the first time in the world by utilizing an industrial waste residue-soda residue and an industrial wasteliquor. Adding 3%–6% of the agent into Portland cement enables a shrinkage-compensating concrete to be prepared. Mortar and concrete containing this expansion agent have better shrinkage-compensating and mechanical properties. The raw materials component, production process, technical properties, micro-analysis of mortar made with this expansion agent, mechanism of expansion and research results are described in this article. The experimental results show that the new type of concrete expansion agent accords with the standard and its main mineral component is xCaO−ySO3−zAl2O3.
The epoxy resin polymer cement mortars with excellent performances were made up through modifying ordinary Portland cement with emulsified epoxy and micro-fine slag. The microstructure of the epoxy resin polymer cement materials was studied and their hydration and hardening characteristics were discussed by means of modern analysis measures such as SEM, XRD and Hg-intrusion micromeritics. The experimental results indicate that the series effects of water-reducing, density, pozzolanicity, filling and solidification crosslinking through the action together with epoxy organism and micro-fine slag endowed cement-based materials with perfect performances. The main hydration products in the system are C-S-H gel and hydrated calcium aluminate. At later age, AFt can be in existence, and no Ca(OH)2 is found. When epoxy resin is solidified, the organism is in a network structure. In the micro-pore structure of hydrated cement with modified epoxy and fine slag, big harmful pores were fewer, more harmless abundant micro pores were and the possible pore radius was smaller than that of ordinary Portland cement.
On the basis of the characteristics of high rigidity and excellent friction resistance, a new kind of steel slag SMA (stone matrix asphalt) concrete was designed and prepared. The main processes include aggregate gradation, performance analysis of steel slag before and after aging, preparation methods and properties test of steel slag SMA. The experimental results indicate that the index of steel slag's activation is less than 1 percent, the dynamic stability is 5699 times/mm, and both the residual stability and ratio of frozen splitting strength are more than 80 percent; the friction factor and structure depth are 67.1% and 0.7 mm respectively. These results show the steel slag SMA is superior to the common asphalt concrete and SMA that uses common aggregate.
Experimental investigation was conducted on the effects of gypsum types and SO3 content on the fluidity and strengths of different cementitious systems. The experimental results show that influences of gypsum in various cementitious materials are different. For cementitious materials blended with various proportions of slag-fly ash and 5% gypsum content, influences of gypsum and calcined gypsum on the fluidity and flexural/compressive strength are similar. It is revealed that “combination effect” and “synergistic effect” of slag and fly ash play an important role during hydration. For cementitious materials with 45% clinkers, 30% slag, 20% fly ash and 5% limestone, the optimized SO3 contents in gypsum and calcined gypsum are 3.13% and 3.51% respectively and the optimized gypsum content is 6.5%. While both of them are blended, the optimum ratio of gypsum to calcined gypsum is 40%:60% (total gypsum content 6.5%), correspondingly the optimum ratio of SO3 is 19.3%:32. 4%.
Based on the basic theory of the fiber Bragg grating sensor, a kind of stickup FBG sensor is developed, which is applied in the structure strengthening. With the experiment of the FBG senor and the common electricity sensor stuck on the reinforced structure, the result shows that the FBG sensor not only has a high performance, but also can realize the control on the spot and on the line.
The using of the iron to extract reduced iron with TFe≥69.5% Al2O3+SiO2<0.3% was studied. Preparation of reduced iron powder in this experimental research can produce ultra-pure magnetite concentrate. The quality of the final product reaches the product standard of SC 100.26 and NC 100.24.
The permeability, alkali-silica reaction, workability and strength of GHPC (green high performance concrete) were studied in this paper. The results show that GHPC has an excellent durability and the effects of mass ratio of flyash to high calcium slag, water-binder ratio, content of water reducer, and crushed coarse aggregate type on the workability and strength of GHPC were considerably evident. A new path for the concretes continuous development was put forward.