Advanced Materials Research Vols. 239-242

Abstract: The B-F codoped nano-TiO₂ powders were prepared by the sol-gel method. The surface of powders was modified by stearic acid. The visible light photodegradable PVC/B-F codoped nano-TiO₂ composite films were prepared by tape casting processing. Solid-phase visible light photocatalytic degradation of the films were investigated with a 1000W xenon lamp and a ZJB 420 filter glass was used to cut off light of wavelength <420 nm. The weight-loss measurement, SEM, DSC of films were detected. Results showed that the weight loss of PVC/B-F codoped nano-TiO₂ composite film (2%TiO₂ w/w) is 16.9% after 120h UV irradiation, which is notably higher than that of both the pure PVC film and the PVC/nano-TiO₂ composite film. Glass transition (Tg) is appeared for samples after 72h irradiation, and the Tg of PVC/B-F codoped nano-TiO₂ composite film is the lowest of all samples. The surface of PVC/B-F codoped nano-TiO₂ composite film was destroyed obviously by SEM photo.

Abstract: The mechanical properties of the extruded profiles depend on the final microstructure distribution in the extrusion process. To investigate the effect of the stain-rate and temperature on the microstructure distribution of the aluminum profiles, the aluminum profile with different wall thickness was studied by metallographic experiment and numerical simulation. The result showed that the distribution of fine equiaxed grain developed by the complete process of primary recrystallization and coarse grain developed by secondary recrystallization was consist with the distribution of temperature and strain-rate. The variation gradient of the strain-rate was the key factor which determines the distribution of microstructure in thick wall section. Compared with thick section, the higher strain-rate is the key factor that leads to secondary recrystallization, but lower temperature prevents complete process of recrystallization. in thin wall section.

Abstract: The environment-friendly hydrochloric acid pickling inhibitor was extracted from distiller's grains (DG). By comparing a variety of extraction methods of DG, the effect of different extraction method on inhibition efficiency of extraction was investigated, and the inhibition efficiency for Q235 steel in hydrochloric acid medium was studied by weight loss measurements, electrochemical measurements and SEM. The results show that the distiller's grains extract (DGE) acts as an excellent acid pickling corrosion inhibitor for the corrosion of Q235 steel in hydrochloric acid. The studies of inhibitor preparation methods show that the ultrasonic technology is the best method. The effective constituent of DGE is a mixed-type inhibitor in hydrochloric acid medium.

Abstract: A secondary dendrite arm spacing coarsening model for multi-component alloy is proposed, where the back diffusion flux in solid is simplified by introducing the parameter of solute boundary layer,δi . The simplified model was applied to the predication of the secondary arm spacing of directional solidified Al-Cu-Mn alloy. The good agreement between the experimental results and the calculated lines shows that this simplified model is satisfactory for the prediction of dendrite arm coarsening during solidification in multi-component alloys.

Abstract: Surface morphologies of sealed films on anodized aluminum alloy extraordinarily affect on their corrosion resistance. Two-dimensional surface morphologies and three-dimensional surface morphologies of sol sealing, sodium dichromate sealing, boiling water sealing and unsealed films were obtained by OLS3100 laser scanning confocal microscope (LSCM). The three-dimensional surface morphologies show that the amounts of pores are greatly reduced when anodized aluminum 2024 are sealed by these methods. Surface roughness of sealed anodized aluminum 2024 films is increased comparing with the unsealed films, especially the boiling water sealing film. The results of two-dimensional surface morphologies show that unsealed films have plenty of spherical particles; there are raised blocks on sol film; there are much round or chrysalis cavities inside sodium dichromate sealing and boiling water sealing film. Especially there are the most and the deepest cavities with the largest diameter on the boiling water sealing film.

Abstract: Dynamic mechanical behavior of materials, which is the response under cyclic stress(cyclic strain/force) in vibration condition, is different from its static behavior. The latter is the behavior of material in a monotonic increasing stress(strain/force). Dynamic mechanics analysis (DMA) is a method to measure the dynamic stiffness and damping in a lower stress level(linear elastic and lower than its yield strength). In the paper, dynamic mechanical experiments of filled polymer materials, polysulfone(PSU) and polyurethane(PUR), were performed on EPLEXOR 500N which manufacturing by GABO of Germany, the relationship of storage modulus E', loss modulus E" and loss tangent to pre-static load and frequency were systemically analyzed.

Abstract: Cobalt oxide-Polyaniline (Co₃O₄/PANI) nanocomposites were prepared via inverted emulsion polymerization. The structure of the obtained composites were characterized by X-ray diffraction (XRD). The electrochemical behavior was studied by cyclic voltammetry(CV) and electrochemical impedance spectrometry(EIS) experiments. The Co₃O₄/PANI(1:2) composite calcined at 400°C exhibits the highest capacitance value of 357 F/g at the scan rate of 5mV/s.

Abstract: A simple and reliable method for electrochemical determination of nitrite based on Gd doped nano titanium dioxide (Gd-nano-TiO₂) modified gold electrode was well developed in this paper. Using cyclic voltammetry, the modified electrode shows electrocatalytic activity for oxidation of nitrite in 0.10 mol×L^-1 sulfuric acid solution (pH=0.70). The catalytic peak current was found to be linear with nitrite concentration in the range of 2.0´10^-6 ~ 2.0´10^-4 mol×L^-1, with a detection limit of 1.1´10^-6 mol×L^-1 (S/N=3). Compared with spectrophotometry, the Gd-nano-TiO₂ modified Au electrode could be used for the determination of nitrate in the ham sausage samples with a satisfactory recovery of 95.9 ~ 103.2%, showing its promising application in safety evaluation for food.

Abstract: The adsorption characteristics of four calixarene supramolecular compounds, like RCT, PCT, MRCT, and TBCA, as coating materials of quartz crystal microbalance sensors responding to isopropanol vapor have been investigated in this paper. The results showed that the RCT was the best coating material for isopropanol vapor when the coating mass reached 20.41 μg. The frequency shift of RCT coated QCM and the concentration of isopropanol vapor had a good linear relationship and sensitivity. Comparing with the gas chromatography, the QCM sensor could be well used for the determination of isopropanol vapor with a recovery rate of 95.22~108.1 %, and the two methods showed a well consistent examination result. Also, the sensor possessed good reversibility, reproducibility and stability, indicating that the RCT coated QCM sensor can be applied for the detection of the atmospheric polutant of isopropanol vapor in practice. The mechanism of the calixarene derivative for recognition of the isopropanol molecule has been preliminarily discussed.

Abstract: Four calixarene supramolecular compounds, RCT, PCT, MRCT, and TBCA as active materials, were immobilized on gold substrates of quartz crystal microbalance (QCM) sensors by using L-cysteine self-assembled monolayer (SAM) as a linker. The RCT immobilized QCM sensor possessed the best response characteristics for methanol molecule when the assembling concentration of RCT reached 1.0 mg/mL. The frequency shift response value of the RCT immobilized QCM sensor was in direct proportion to the concentration of methanol vapor with a range of 0 ~ 6000 ppm. Comparing with a gas chromatography, the proposed QCM sensor could be well used for the determination of methanol vapor with a recovery rate of 98.01 ~ 103.9 %, and the two methods showed a well consistent examination result. Also, the sensor possessed good reproducibility and stability, showing that the RCT immobilized QCM sensor can be applied for the detection of the methanol vapor of atmospheric polutants in our living environment.