Advanced Materials Research Vols. 148-149

Abstract: After TiO2/SPAN (Sulfonated Polyaniline) complex prepared by the reverse-microemulsion method was calcinated, C, S & N-doped TiO2 was successfully synthesized with C/S/N/Ti atomic ratio of 12.5/12.2/1.3/100 and formaldehyde-degradation ratio of 58.5%. Its excited wavelength was red-shifted to 433.5 nm and its band gap was degraded to 2.87 eV. XPS analysis proved that C, S & N was doped into TiO2 lattice to form TiC, Ti(CO)n, Ti(CO3)2, Ti(SO3)2, TiS2, TiN and Ti(NO2)n.

Abstract: A facile method capable of preparing CuO nanocrystals has been developed in a water-isopropanol system. The different shapes of CuO nanocrystals can be obtained simply by adjusting the amount of adding water in the reaction system. Rod-like CuO nanocrystals with diameters of 5 nm and lengths of 20 nm, and spherical CuO nanoparticles with sizes of 5-8 nm can be formed. Furthermore, the obtained CuO product has a high surface area of 128 m2/g, which is very important for its applications especially in catalysts.

Abstract: (Ba0.7Ca0.3)TiO3 (BCT) powders and ceramics have been prepared by sol-gel technique. Structural evolution of the BCT dry gels are investigated by thermal gravimetric analysis–differential scanning calorimetry. It is found that BCT crystallites can be formed before 800 . Well-sintered samples are synthesized at 1260 for 2h. The crystal structure of the BCT powders is studied by XRD and ferroelectric properties of the ceramics are characterized by TF analyzer 2000. The Curie temperature Tc of the BCT ceramics is at about 125 . The maximum dielectric constant (εr) reaches about 4851 at 125 and hysteresis loops are measured with the temperature range from 25 to 150 .

Abstract: The fibular PANI/ nano-CeO2 composites were synthesized via chemical oxidation of aniline using nano-CeO2 as an oxidant, and nano-CeO2 was prepared by hydrothermal treatment. Sphere-like morphology and fibers of PANI/ nano-CeO2 composites were obtained. The resulting composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FT-IR). The results showed that chemical bonds existed between two phases. The acid concentration and nano-CeO2 particles affected the crystallinity of PANI fibers. The morphology of PANI was formed from the ball gradually developing into the fibular with rising of acid concentration. The regular crystalline structure of fibular was easy to form with a reducing CeO2 particle size.

Abstract: Controlled grafting of S-naproxen-imprinting polymer layer on the poly(vinylidene fluoride) (PVDF) microporous was carried out by the surface-initiated atom transfer radical polymerization (ATRP). Polymerization time was used as the independent variable to manipulate the amount of grafted imprinting polymer on the membrane surface. SEM, SPM and UV spectrum were used to study the structural morphology and selectivity of membranes and probe the incorporation of imprinted polymer layer on the surface of PVDF membranes . Results indicate that the integration of ATRP and molecularly imprinted polymeriaztion realize preparation of molecular selective membranes and it is possible to tune selectivity and morphology in rational way by changing polymerziton times.

Abstract: With the development of the embedded microcapsule concept for self-healing material, the preparation of microcapsule has been paid more attentions. A new series of microcapsules were prepared by in situ polymerization technology in an oil-in-water emulsion with polyoxymethylene urea (PMU) as shell material and a mixture of epoxy resins as core material. The PMU microcapsules were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), particle size analyzer and thermo gravimetric analyzer (TGA) to investigate their chemical structure, surface morphology, size distribution and thermal stability, respectively. The results indicate that PMU microcapsules containing epoxy resins can be synthesized successfully. The optimized reaction parameters were obtained as follow: agitation rate 600 rpm, 60°C water bath, pH=3.5, core material 20ml and hot water dilution by in-situ polymerization. The size is around 116 μm. The rough outer surface of microcapsule is composed of agglomerated PMU nanoparticles. The microcapsules basically exhibit good storage stability at room temperature, and they are chemically stable before the heating temperature is up to approximately 200°C.

Abstract: Based on Monte Carlo (MC) simulation, the magnetization behavior of mixed ferrimagnetic spin system with single-ion anisotropy under external field is investigated. It is assumed that the element of the mixed system is composed of spin-1 and spin-3/2 by turns. The simulated results indicate that there exist the magnetization curves at the ground state on the one-dimensional spin chain, two-dimensional spin system as well as three-dimensional spin system. It found that the size, anisotropy constant and spin configurations influence evidently the magnetic properties of the mixed system. Moreover, the magnetic plateaus and the phase diagrams of the systems can be well interpreted in terms of the simple calculation of energy.

Abstract: Novel tungsten oxide sensors were fabricated based on Hall Effect and their NO2 gas sensing properties were examined. Tungsten trioxide was grown by vapor evaporation of metal tungsten filament in an oxygen atmosphere. A WO3 thick film was deposited on the four Au electrode to be a WO3 sensor. The sensor was tested between magnetic field in a plastic test chamber. The gas sensing experiment revealed that at the NO2 concentration of 40 ppm, a sensitivity of 3.27, a response time of 36 s, and a recovery time of 45 s were observed at room-temperature. The effect of WO3 based on Hall Effect on the sensing characteristic is discussed.

Abstract: To develop a potential substitute for conventional lubricant additive, pure calcium borate nanoparticles (PCBN) and calcium borate nanoparticles modified with oleic acid (MCBN) were prepared. The microstructures of the as-obtained samples were characterized using X-ray power diffraction (XRD), transmission electron microscope (TEM) and infrared spectra (IR), and the dispersing stability of oil containing nanoparticles was also evaluated. Tribological properties of MCBN used as lubricating additive were evaluated using four-ball tribometer and compared with that of PCBN. The results indicate that MCBN show better antiwear and friction-reducing property than PCBN. The worn surface of the steel ball lubricated with MCBN was investigated by Polarized microscope (PM) and X-ray photoelectron spectroscopy (XPS), and the action mechanism of MCBN during friction process was preliminarily discussed.

Abstract: The mathematical model of probabilistic optimization is established for diaphragm spring. The process and the method of design with an example are presented. The result shows the model and the method of design are feasible, and perfect optimal result is attained. Vehicle has mass production and its conditions of use are changeable, which determine design parameters and operating parameters of its parts have complex randomness. Diaphragm spring clutch is now widely used by many kinds of vehicles. Research of diaphragm spring parameters’ probabilistic and statistics model and the study of its optimal design have great significance for the design, R & D, manufacturing and use of automotive products and parts. Studies in the references[1,2,3] have shown that the root cause of diaphragm spring’s fatigue fracture is the original crackles near the concave inner edge point, so there is a need to do probabilistic optimal design for diaphragm spring’s structural parameters to improve the fatigue life.