Abstract: Nanosilica was extracted from iron tailing by the chemical deposition method, involving pickling, filters washing, alkali dissolving of pickling dregs in high temperature, precipitating silica controlled by diluted acid and so on. The product has been studied by SEM, XRD, FT-IR, and thermal analysis techniques, etc. These study shows that the nanosilica is a kind of amorphous matter consists of hydrous silicon dioxide (97.076%) with small amount of sodium and aluminum trapped inside the Si–O network. The diameter of globular silica particles is 30-50 nm.
Abstract: Hydrophilic polyvinylidene fluoride (PVDF) flat ultrafiltration membranes were prepared by wet-spinning method. The effects of technical parameters of maleic anhydride grafted onto PVDF on the performance of hydrophilic PVDF membranes were investigated, the preparation technical parameters were determined, and the hydrophilic PVDF flat membranes were prepared. Then, hydrophilic PVDF membranes were characterized in terms of pure water flux, contact angle, infrared spectroscopic analysis and scanning electron microscope(SEM). The results showed that maleic anhydride had been grafted onto PVDF, and the hydrophilic performance of the modified membrane was better than the traditional one.
Abstract: In order to restrain the lateral expansion and splitting of GFRP, and accordingly heighten its axial compressive bearing capacity, a project that to confine GFRP column with surrounding CFRP sheet is suggested in the present study. Experiment on the CFRP sheet confined GFRP column shows that a combined structure of high bearing capacity is attained. Basing on the experiment research a theoretical iterative calculation approach is suggested to predict the ultimate axial compressive stress of the combined structure, and the predicted results agree well with the experimental results. Then the influences of geometrical parameters on the ultimate axial compressive stress of the combined structure are also analyzed basing on this approach.
Abstract: In order to study the evolution of Ti-Si-N film growth, the total energies and absorption energies of the Ti-Si-N islands on TiN(001) surface and the activation energy of the configuration evolution have been calculated with the first principle method. Four configurations of Si-2Ti-2N island have been studied, which are a silicon atom in a 2Ti2N island (Si-in-2Ti2N), a silicon atom by a 2Ti2N island (Si-by-2Ti2N), a titanium atom by a 2N1Ti1Si island (Ti-by-2N1Ti1Si), and a nitrogen atom by a 2Ti1N1Si island (N-by-2Ti1N1Si), respectively. The investigation presents some results. In the growth process of Ti-Si-N film, (1) the Ti and N atoms bonding together to form islands and Si atoms staying outside of TiN islands will lead to the most stable configuration; (2) the Si atom tends to separate from TiN phase, but the configuration evolution is not very easy, the activation energy of the transition from Ti-by-2N1Ti1Si to Si-2Ti2N is about 1.94eV; (3) it shows a tendency for Si atoms to bond with N atoms, rather than with Ti atoms.
Abstract: The AlMn and AlMnSi foils were fabricated by rapid solidification technology. The microstructures of the foils with various Si content were studied by transmission electron microscope (TEM). The phases of the foils were indentified by X-ray diffractometer (XRD); the phase transformation temperatures of the foils measured by differential scanning calorimeter (DSC). The results showed that addition of Si in the AlMn foil can improve the heat stability (phase transformation temperature) from 543K to over 873K. The addition of Si can change the phase structure of the foils. The phases of AlMn foil conclude Al and Al6Mn while the phases of AlMnSi foils with 3% Si or 5% Si addition become Al and Al4.01MnSi0.74. The addition of Si can also change the microstructure morphology of the foils from the rod, block and petal-like to the homogeneous globular. With the increase in Si content, the grain sizes of the foils were refined.
Abstract: Mullite- corundum insulation material with nano crystals in matrix was fabricated by gel-casting process. The results showed that the volatilization temperature of organisms is 285°C- 600°C, there is no glass phase appeared in specimens; The mullitization begin at 1000°C, along with the raise of temperature, the quantity of mullite phase increases, especially during 1200°C- 1400°C; when the temperature is up to 1550°C, mullite becomes the main crystal phase and there are also some corundum crystals in the specimens; The specimen matrix sintered at 1550°C is consisted of nano crystals 80nm in length and 10-20nm in diameter.
Abstract: This Montmorillonite modified by melamine (MA-MMT) was prepared via cation exchange reaction by using melamine salt as intercalation reagent. MA-MMT and Na-MMT was combined with intumescent flame retardant (IFR) to be adopted into polypropylene (PP), respectively. The synergistic effect between MA-MMT and IFR and the influence of melamine in MMT layers on fire-resistant performance was evaluated. Results of limited oxygen index (LOI) tests and UL-94 tests indicate that melamine salts in MMT layers behaved better than Na-MMT in PP/IFR system. According to the results of cone calorimeter tests and scanning electron microscope (SEM), it concludes that melamine salts act as gas agent to provide migration impetus and expanded power, which caused a well-structured and strong char that had better ability to endure heat erosion. A good synergistic effect between MA-MMT and IFR is constructed.
Abstract: The oxidation of binary Co-5Al alloys in 1 atm of pure O2 at 700 and 800°C was investigated. Oxide scales generally showed good adherence to alloys during oxidation process, although scale spallation on cooling was observed inevitably due to difference in the thermal expansion coefficients between oxides and alloys. It indicated that oxidation of the two alloys approximately obeyed parabolic rate law (n=2). The parabolic rate constants as functions of temperature at 700 and 800°C were 8.38×10-11, 3.45×10-10 g2cm-4s-1, respectively. The binary Co-5Al alloys presented a non-protective oxidation behavior because the Al content was not enough to support the growth of a dense, stable Al2O3 layer. The scales were mainly composed of oxides of cobalt, coupled with a little Al2O3 present at the inner part of the scales.
Abstract: Four up-flow anaerobic sludge blanket reactors (UASB) filled with oyster shell (R1), activated carbon (R2), quartz sand (R3), zeolite (R4), respectively had been selected to inspect their effects on the COD removal efficiency, and to compare with the traditional UASB reactor (R0). System stability and pH variation were also inspected. All the reactors were inoculated with sludge from a local sewage treatment plant, and fed with the synthetic wastewater. The organic load rate was 0.96 kgCOD.m-3.d-1 during 1-20 days (StageⅠ), 1.86 kgCOD.m-3.d-1 during 21-57 days(StageⅡ), and 5.32 kgCOD.m-3.d-1during 58-97 days(StageⅢ), the system temperature was controlled at 35 °C. The influent pH was 7-8. The results reveal that: (1) The average removal rate was 94.5%, 78.0%, 91.4% for R1; 93.6%, 87.7%, 92.5% for R2 in the three stages, respectively. R1 and R2 reactors are suitable to treat low organic load wastewater( 0.96 kgCOD.m-3.d-1) to high organic load wastewater(5.32 kgCOD.m-3.d-1). R3, R4 and R0 are not suitable for high organic load wastewater. (2) R1 and R2 reactors can resist the continuous organic shock load, and the system can recover in a short time; R3, R4and R0 reactors could not recover during StageⅢ. (3) The system was sensitive to temperature variation, so temperature was an important factor to the system. (4) Anaerobic granular sludge were formed in R1, R2, R3, R4 reactors, the amount of granular sludge sequencing was 89.02%, 82.46%, 16.44%, 36.54%, respectively. Compared to the support material size which was 0.15-0.20 mm; the size of granular sludge larger than 0.90mm was 41.5% in R1 reactor, and 28.8% in R2 reactor. (5) All the reactors had the ability of pH value moderation, so the pH value of all the system were stable. Since oyster shell is a solid waste, oyster shell powder used as the immobilization material not only has good effects of immobilization, but also has a strong economic competitiveness.
Abstract: TiO2-pillared montmorillonite is successfully synthesized via sol-gel method, which is used to remove blue-green algae from water. The composite was characterized by X-ray diffraction and Scanning electron microscope. The analysis results shows that TiO2 has entered into the interlayer of montmorillonite and the d001 increases from 1.27639 nm to 1.64437 nm, and the surface charge of montmorillonite was recyanobacteriarkably raised from -41.5 mV (Fig. 1a) to +12.21 mV (Fig. 1b) mV at pH =6～8. The results of algae adsorption experiments displays the positive surface charge of modified montmorillonite was thus expected to induce the electrostatic neutralization between TiO2-pillared montmorillonite and Microcystis aeruginosa (CYANOBACTERIA) cells. When the cyanobacteria concentration is 12100 number/μL, chlorophyll content is 2.831883 mg/L, turbidity of the water is 44.2%, and TiO2-pillared montmorillonite is 0.5 g/L, the removing rate of chlorophyll and microcystis exceeds 90%, and the turbidity reduces from 44.2% to 19.1%.