Key Engineering Materials Vols. 480-481

Abstract: Five-period hydrogenated silicon carbide (SiC) multiple quantum wells with silicon dioxide (SiO2) or silicon nitride (SiN) dielectric that were synthesized by high density plasma chemical vapor deposition were studied using photoluminescence (PL) spectroscopy to understand its blue shift. Rapid thermal annealing induced significant blue shifting in the PL spectra after fluorine ion implantation due to crystallization. The thinning of the SiC causes blue shift due to the quantum confinement effect. The higher PL intensity of the amorphous SiC:H in SiO2 than in SiC/SiN may be attributed to the high number of non-radiative sites on its surface. Annealing with nitrogen may cause impurities in SiC/SiO2, thereby broadening the PL peak.

Abstract: In this study AZ31 sheet with a thickness of 1.2mm and diameter of 52mm was simulated to press into a dish by a finite element method(FEM) software, which to obtain better processing of plastics forming of magnesium alloy by varying die parameters. In order to find the way of development on drawing property and to formulate the rational stamping processing, simulations have been applied on the maximum principal stress various with round radius of dent die and round radius of punch and die gap. Simulation results show that: to obtain a dish of 29mm diameter, a sheet of AZ31 magnesium with a thickness of 1.2mm and diameter of 52mm has been drawn, the fracture occurring at the corner of dish wall bottom. the ability of drawing varies with the round radius of dent die, which better radius is 3.8 mm. In the same way better round radius of punch is 3.0 mm, while better half gap is 1.8mm. Experiments also show that high diameter ratio has been increased with the various of die parameters and forming ability of material has been developed. It is reliable of simulation of finite element method.

Abstract: The Bi2Mn0.1V0.9O5.35-δ (BIMNVOX.10) thin films have been successfully deposited on the LaNiO3(LNO)/Si (100) substrates by chemical solution deposition process. The phases, morphology and electrical properties of samples have been studied. The BIMNVOX.10 films show a (00l)-preferred orientation and have a homogeneous distribution of grains. A low frequency dielectric dispersion observed in the films may be originated from the short distant diffusion of oxygen vacancies. The Cole-Cole plots of dielectric constant for the BIMNVOX.10 films appear semicircular arc with the center off the x-axis and deviate from the ideal mono-dispersive Debye model. The frequency dependent of ac conductivity for BIMNVOX.10 films follows the Joscher’s power law, mainly contributed to the grain resistivity and predicts the nature of an oxygen vacancies conduction process. The complex impedance spectra reveal that electrical process arises due to contribution from the grain interior and grain boundary effects.

Abstract: The Laser Metal Deposition Shaping (LMDS) is a state-of-the-art technology which correlates the Rapid Prototyping and Manufacturing (RP&M) and laser processing. During this process, a certain alloy is fused onto the surface of a substrate. Laser deposition devices, namely powder feeder, CNC worktable, and laser shutter, are integrated to automatically make any cladding profile possible. Material is deposited by scanning the laser across a surface while injecting metallic powders into the molten pool at the laser focus. The metal part is then fabricated layer by layer. The LMDS system consists of four primary components: energy supply module, motion control module, powder delivery module, and computer control module. These modules of LMDS system individually perform the specified functions, but coordinate with each other. One of them, the control module plays an important role in causing the LMDS system automatic and intelligent. The control module can be divided into hardware and software components. The hardware structure mainly includes industrial computer, motors, and motion control card, which build the overall framework, and are driven by software structure. The software structure, namely the system application program with GUI, can instruct every module of LMDS system to finish the motion cooperatively adjust the processing parameters freely, and fulfill the LMDS technology automatically and intelligently. The hardware and software structures work in harmony with each other, thus flexibly controlling the LMDS system.

Abstract: We have proposed a three-dimensional sand table based on the video see-through tabletop augmented reality (VSTAR) system. The hybrid registration algorithm is used combining marker-based OI iterative computer vision method and photoelectric encoders mechanical tracking method instead of computer vision method only, which makes tracking does not dependent on markers, so that the tracking field of vision is not limited to the scope of markers. The system is of high precision and can be used for architecture design show, military topography simulation, museum exhibition and other virtual sand table applications.

Abstract: The super high-quality zirconium alloys thin walled pipe is an important part in the nuclear power station to transmit nuclear fuel, and it should be possessed higher quality in diameter error and straightness and be required to measure on-line. A super high-quality zirconium alloys thin walled pipe automatic comprehensive measuring system had been proposed according to the relative two sensor method, and the system can perform the measurement of 9 sections’ diameter error, straightness, ellipse error on the zirconium alloys thin walled pipe, with the measuring time shorten to 25s, and distinguish the reject part from the detected parts, which had been applied in the zirconium alloys thin walled pipe manufacturing pipeline. Two measurement results to the on-line multiple sample 50 parts randomly can coincide better between manual operations and the automatic comprehensive measuring system.

Abstract: A mechanical model of coating-substrate specimen is developed that allows us to derive analytical solution to quantify the residual stress and yield strength gradient effect resulting from surface heat treatment on energy release rate of the coating on its substrate. Using a Micro-Composite-Double-Cantilever–Beam Model (MCDCBM), the analytic solutions can be derived, and they can be used to characterize the fracture toughness of the inhomogenous coatings on substrates in terms of the critical energy release rate. Finally, a numerical example is presented to show how the critical energy release rate is obtained.

Abstract: College of chemistry is the required course of every non-liberal arts students, how to teach them with green chemistry concepts is a key question. America Chemistry Society presents 12 guide linesof green chemistry. Based on these guide lines, thispaper introduces the significance of green chemistry, the principle and the concrete measures and means of education.

Abstract: In order to produce paper from agricultural residues such as wheat straw, it is necessary to delignify the wheat straw. Ethanol cooking is a novel process for the fractionation of biomass components. This study evaluated the effectiveness of sulphate acid catalyzed ethanol pulping on pulp yield, chemical composition of wheat straw, strength properties of the resulted paper sheet. The raw wheat straws, which were impregnated with 1.0% sulphate acid for about 12 h at room temperature, were subjected to ethanol cooking. The results showed that total pulp yield and kappa number decreases while screened pulp yield and brightness increases as the cooking severity increases. The optimal conditions of pulping were determined. Under the optimal condition, the screened pulp yield was up to 55.4%, with the kappa number of 66.35, brightness of 16.1 SBD, and the maximum paper sheet strength.

Abstract: The CIMS development and the high-speed cutting has given a higher demands on cutter performance. It is an tremendous tendency of studying excellent wearing resistance and high stability. PCD (polycrystalline diamond) and PCBN (poly cubic boron nitride) can obtain more higher finished surface quality, which cannot acquire by regular cutting process. This study introduces super-hard cutters materials (PCD and PCBN) development, and discusses two kinds of material properties, The features of them used in different cutting fields are given.