Materials Science Forum Vols. 663-665

Abstract: Direct at the anticorrosive problem of the pipeline, especially inner wall of the small-caliber pipe, we conceived and designed a new anticorrosion glass fiber powder reinforced plastic (GFRP) coating material. The reinforced material is GFRP powder, but not traditional fiber glass cloth or short glass fiber. This material assures perfect physical and chemical properties of traditional GFRP and ensures good coating fluidity for it at the same time. By experiment, raw materials of GFRP coating, their best formula and the fiber glass’s dispersion technology and parameters were determined. Drying time, thickness, abrasion resistance, adhesion, flexibility, heat resistance, and chemical resistance of coating were tested.

Abstract: Barium-bearing glass samples were fabricated in a laboratory scale using quartz sands that was a by-product of feldspar floatation in Tak Province, northern Thailand, and 30-wt% barite from Loei Province, northeastern Thailand, as the main compositions. Cr2O3 of concentrations ranging from 0.01 to 5.0 wt% was doped into the glass mixture. The dried powders were wellmixed in a ceramic crucible and melted in an electric furnace at 1250°C for 6 hr. Bubble-free glass samples were yielded after cooling down. The glass colors were changed from colorless to green by the addition of Cr2O3. Dielectric property, color, specific gravity, and refractive index of the glass samples were analyzed. It was found that dielectric constant, specific gravity, and refractive index increased with increasing amount of Cr2O3 dopant. Measurements of UV-VIS-NIR spectra and microstuctural analysis using scanning electron microscope were also carried out and discussed.

Abstract: Laser forming process analyzed under thermo-elasto-plastic finite element method can better understand the forming mechanism. However, it is very time consuming. This paper introduced the prediction of the deformation in laser forming based on the theory of inherent strain by finite element method (FEM). The relations between inherent strains and laser forming parameters based on some experimental curves and the thermo-elasto-plastic analysis can be determined, in which the inherent strains are assumed to be distributed in a rectangle shape. This method is much more convenient because only elastic analysis is involved. The effectiveness of the proposed method is demonstrated through the comparison with the experimental data.

Abstract: Ethyl cellulose-graft-poly(N-isopropylacrylamide-co-6-[4-(4-ethoxyphenylazo)phenoxy] hexyl methacrylate) (EC-g-P(NIPAM-co-MAZO)) were synthesized through atom transfer radical polymerization (ATRP). Ethyl cellulose-based macroinitiator was prepared by direct acrylation of ethyl cellulose with excess 2-bromoisobutyryl bromide at room temperature, the bromo-ester groups of which were known to be efficient initiator for ATRP. Statistical copolymerization of N-isopropylacrylamide (NIPAM) and 6-[4-(4-ethoxyphenylazo)phenoxy] hexyl methacrylate (MAZO) onto ethyl cellulose (EC) was achieved using CuCl/Me6TREN as the catalyst system and N,N-dimethylformamide/water mixture (DMF/H2O, v/v = 4:1) as solvent. Appropriate solvent concentration and polymerization temperature can minimize the intermolecular coupling and render the polymerization controllable. The aggregates formed by EC-g-P (NIPAM-co-MAZO) copolymer in aqueous solution were investigated by varying temperature and irradiation under UV/visible light. The results indicated that the copolymer had thermal- and photo- dual-responsive properties. The copolymer formed a comparatively stable suspension in water at room temperature and underwent a hydrophilic-hydrophobic transition when the temperature raised. Furthermore, their aggregates in water were influenced by isomerization of azobenzene groups under UV/visible light irradiation.

Abstract: This paper reports the study on the shape effect of gold nanoparticles on their plasmonic responses to the vapor samples, such as methanol, ethanol and propanol. In typical process, it was observed that the plasmonic of gold nanoparticles was very sensitive to the presences of the vapor samples by giving the change in the absorption as well as the shift in the SPR peaks position. It was also found that the plasmonic responses to the vapor indicated a significant improved if the gold nanoparticles prepared in the form of nanorods morphology. The plasmonic response of the spherical and nanorods gold nanoparicles to the gasses will be discussed.

Abstract: To achieve the welding of the larger copper substrate and iron parts, the new method of laser-TIG (Tungsten-arc Inert-Gas welding) hybrid welding is proposed. Experiment shows that the Ni-Cr alloy cladding layer is firstly prepared by YAG laser on the welding body of copper surface, it is metallurgically combined with copper substrate, and then the 5 mm diameter iron cylinder is welded by TIG welding in the cladding layer. The welding zone is fine, no weld cracks is observed under the microscope, metallographic analysis shows that copper and iron is the metallurgical bond.

Abstract: TiO2/Ga2O3 nanowires were successfully prepared by a sol–gel-solvothermal method using tetrabutyl titanate as precursor, alcohol as solvent, Ga2O3 as templet and dopants, alginate as dispersant. The structures, morphologies,compositions and catalytic activity of products have been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy ( FESEM ), nitrogen adsorption test, ultraviolet-visible near-infrared spectroscopy (UV–vis–NIR ),energy dispersive X-ray (EDX) analysis and spectrophotometer. The results revealed that the as-synthesized TiO2/Ga2O3 nanowires grew along [001] direction,which is reported for the first time, and the as-prepared product had better optical activity than TiO2 nanoparticles. Finally, the nanowires have a good adsorption capacity of 128.2 m2/g tested through nitrogen adsorption.

Abstract: Single-layer silica films modified with polytetramethylene glycol (PTMEG) were prepared via sol-gel process in the presence of NH4OH as catalyst. Compared with the pure SiO2 coating, the hybrid films possessed higher lased-induced damage threshold (LDT). The characterization results from AFM and TEM indicated that the introduction of PTMEG molecules changes the structure of the colloidal silica matrix, which directly resulted in the improvement of the transparency and LDT.

Abstract: The stability of μc-Si:H materials for solar cells was well researched. The light induced degradation of intrinsic μc-Si:H single layer material with different crystal volume fraction deposited were studied. The dependence of light-sensitivity as well as sub gap absorption on light soaking time was monitored. The results clearly showed that the magnitude of relative light induced degradation is closely related to material structure. Amorphous fraction is the key determining factor to light induced degradation. The results showed clearly that the magnitude of relative efficiency degradation is increase with amorphous fraction. The more amorphous fraction located in material, the more degradation was been found. With better structure and optical properties, microcrystalline silicon with transition region is more suitable for the manufacturing of stable Microcrystalline silicon solar cells due to the structure and optical properties.

Abstract: A theoretical model to study Hanle effect for materials with weak spin-orbit coupling is developed. It considers the contributions from not only the drift current but also the diffusion part, which pronouncedly enlarges the application scope of the model. The spin lifetime in spin drift diffusion equation is also corrected by considering the thermal effect and the influence of external electrical field.