Advanced Materials Research Vol. 662

Abstract: By using the density functional theory (DFT), we have investigated CO molecules adsorbed on palladium atom doped (Pd-doped) (5, 5) and (6, 6) boron nitride nanotubes (BNNTs). In order to investigate the electronic and structural properties of all the research objects, we calculated the band gap (Eg), bind energy (Eb), and density of state (DOS). The results show that energy gaps of BNNTs reduced by doped impurity Pd atom, but there are no obvious changes with the tube diameter of Pd-BNNTs change. One impurity Pd atom substituting one B (PdB) or N atom (PdN) of pristine BNNTs can increase the reactivity with CO molecule. The energy gaps for CO molecule adsorption on the tube wall of Pd-BNNTs reduced. This indicates that Pd-doped BNNTs can be considered as nano gas sensitive material.

Abstract: A novel micro-extraction procedure was developed through the use of an electrospun polymer nanofiber as a solid-phase extraction (SPE) sorbent to directly extract benzimidazoles in pork. The target compound was then monitored by a high performance liquid chromatography with ultraviolet detector (HPLC-UV) system. The eluted solvent was investigated meanwhile. Under the optimized conditions, a linear response for benzimidazoles over the range of 20-1000 ng mL−1 was achieved with the γ2 >0.99. The recoveries were in the range of 95.4%~101.2%. RSDs of intra-day and inter-day assays were 3.5%~6.3% and 5.7%~9.9%. The method is simple, sensitive, accurate and repeatable, which can be used for the determination of benzimidazoles in pork.

Abstract: The optical characterization of LaF3 thin film in DUV spectral range was experimental investigated by using a variable angle purged UV spectroscopic ellipsometer. In order to take into account the inhomogeneity, a theory model that dividing the single thin film into several sublayers was adopted. Two kinds of LaF3 thin films fabricated on fused silicate substrate with different substrates temperature were tested. From the obtained optical index and the physical thickness of different sublayer in the two different kinds of LaF3 thin films, it was found that, the inhomogeneity of the LaF3 thin film deposited with substrate temperature at 300°C was stronger than that of the LaF3 thin film deposited with substrate temperature at 250°C, indicating that the substrate temperature has important influence on the optical index and inhomogeneity of LaF3 thin films. For both of the two kinds LaF3 thin films, the agreement between the measured transmittance and the simulated transmittance using the parameters from regression of SE was nice, indicating that the selection of the material dispersion law and regression procedure were successful.

Abstract: 6005A aluminum alloys were welded at different relative humidity conditions. The effects of relative humidity on the salt fog corrosion of the welding joints were researched. The results showed that the weight loss of the joints after 14 days corrosion was higher than that corroded after 7days, but the corrosion rate was lower. The corrosion rate first increased then declined with the increase of environmental humidity for the joints corroded for 7days. However, when the environmental humidity was 80%, corrosion rate achieved the maximum, when environment humidity was 70%, corrosion rate was the lowest. After corroded for 14 days, corrosion rate was the maximum when the environmental humidity was 50%, and it was the lowest when the environmental humidity was 90%. The tensile strength declined obviously after corrosion.

Abstract: The corrosion resistance of Ultra-fine grain (UFG) chromium bronze, prepared by Equal-channel angular pressing (ECAP) processing, was investigated in HCl solution at room temperature and atmospheric pressure by electrochemistry technique and immersion experiment. The results shows that the corrosion potential of chromium bronze is decreased with ECAP processing. But the corrosion resistance is deteriorated slightly. According to the immersion tests, the weight-loss of UFG chromium bronze, compared with its counterpart, is higher in the initial stage and lower in the later stage, and the gap is in the range of 5%-15%. The corrosion mechanism on the UFG chromium bronze is deduced from the experiment data and corrosion morphology.

Abstract: Based on the general mathematical formulation under unidirectional solidification with mushy layer developed in Ref.[13], leading approximation of solution in mushy layer is obtained for the case that the inverse Lewis number is small parameter. For the steady state of solidification, concentration field in the mushy region is given as function of a solid volume fraction. Mushy layer width and solid volume fraction at the solid-mush interface are obtained. Effects of temperature gradient on mushy layer width and solid volume fraction at solid-mush interface are presented.

Abstract: As the fabrication technology of the composite electrode becomes sophisticated, the understanding of the detailed knowledge of the microstructure’s effect on the electrochemical process is essential for the commercializing of the solid oxide fuel cell (SOFC). In this paper, an equivalent circuit for the SOFC structure is proposed to clearly describe the electronic electric current transfer process, ionic electric current transfer process and the charge transfer process at the electrochemical reaction interface between electronic and ionic conducting materials. And types of the boundary condition setting constraints for the developing of the multi-physics coupling numerical model of SOFC are obtained basing on the electrochemical kinetic analysis.

Abstract: The orthogonal experiments of end milling were designed. Workpiece surfaces hardening were studied in high-speed milling. The results indicate that the degree of surface work-hardening in high-speed milling 8407 mold-steel is lower than that in conventional speed milling;By choosing the appropriate cutting parameters, to improve the surface quality of the workpieces and the processing efficiency is beneficial;Through changing the high-speed milling parameters to control the work hardening, the effect is not so obvious.

Abstract: The Interfacial layer has an important influence on the optical performance of the deep ultraviolet (DUV) coatings. The variable angle Spectroscopic ellipsometry measurements of three kinds of DUV coating samples were performed in the wavelength range 150-500nm using a purged variable angle Spectroscopic ellipsometer. The samples include the single layer sample, double layers sample, and three layers sample. The thickness and optical index of the MgF2 layer and LaF3 layer as well as those of the interfacial layer between them were obtained by successful regression of the SE measurements. For the single layer, the agreement of the results between the SE and the spectrophotometic techniques was very good. The obtained thickness of the two kinds of interfacial layer was in consistent with the RMS results of the single layer obtained by AFM, indicating the obtained results were reliable.

Abstract: Ka-band radio-frequency(RF) performance of a InAlN/GaN/AlGaN HFET on SiC was reported. Based on a detailed delay analysis,a maximum drain current density of 1.12 A/mm was obtained. Power measurements were performed, the maximum output power density is 2.1 W/mm and a power-added efficiency (PAE) is 22.3% at 29 GHz. The current gain cut-off frequency (fT) is 60 GHz, and the power gain cut-off frequency (fMAX) is 105 GHz.