Advanced Materials Research Vols. 308-310

Abstract: The micron expanded graphite is prepared by the method of chemical oxidation. Sulfuric acid and ice acetic acid are used as inserting reagent, potassium dichromate is used as an oxidizing agent. The optimum mass ratio is as follows: mC: mH2SO4:mCH3COOH:mK2CrO7=1:5:3:0.5. The reaction time is 60 min and the temperature is at room temperature. The measured result of FTIR, SEM and Laser Particle Size Analyzer show that target product is successfully prepared. Its expanded volume is up to 8.0mlg-1. At the same time, the static and dynamic infrared extinction properties of micron expanded graphite are measured. Results show that the micron expanded graphite has stronger Infrared extinction ability than the raw graphite. The cause is that the surface of micron expanded graphite has some open or semi-open small holes which can obviously absorb infrared radiation.

Abstract: Copper oxide was prepared via the calcination of copper oxalate precursor. By using high-temperature solvent method, the precursor decomposed under nitrogen atmosphere and copper nanoparticles were obtained. The microstructure and properties of the products were characterized by scanning electron microscopy, X-ray diffraction, UV-Vis spectroscopy, Fourier transform infrared spectroscopy and other analysis methods. The results show that the obtained copper oxide is constructed by nanoparticles. The sample is porous and has a good catalytic activity. Three copper samples were obtained by controlling the reaction time. The particle size of the samples was calculated to be about 44.3 nm, 17.1 nm and 9.9 nm respectively.

Abstract: A research is made on the different influence on frame structure stiffness between straight board stairs and fold board stairs. The research is divided into two circumstances: independent framework unit and the overall framework. in each circumstance, there are four cases: frame without stairs, frame with straight stairs, frame with fold board stairs whose slow bedplate is located in the floor place, frame with fold board stairs whose slow bedplate is located in the middle platform, the horizontal floor displacement of four kind of frames in transverse and longitudinal direction under the same force. By comparing the four displacements, the influence of three different forms of stairs on frame structure stiffness can be got; the result shows that fold board stairs whose slow bedplate is located in the middle platform are better than straight stairs in seismic performance.

Abstract: During electrodepositing pure lead dioxide, the electrocatalytic activity of PbO₂ electrodes, as well as their stability, can often be considerably enhanced by the incorporation of some fine particles added to the electrodeposition. The morphology, crystal phase, surface composition, microstructure, of the electrode were characterized by means of SEM, XRD and EDS. SEM-EDS analysis showed the addition of solid particles could inhibit the growth of α-PbO₂ unit cells, improving the specific surface areas of coating surface.Under all condition, the matrix was highly oriented α-PbO₂. The electrocatalytic activity of the prepared materials has been tested in Zn2+ 50g L-1, H2SO4 150g L-1 solution. It showed that the electrocatalytic activity of the A1/conductive coating/α-PbO₂-3.71 wt.% TiO₂-2.12 wt.% CeO₂ anode is the best.

Abstract: Aiming at the problem of more difficult and low efficiency to assembly 63PF2 conveying chain, the work measurement, action research and production line balancing method are studied, and the data of 63PF2 conveying chain assembly lines is obtained. Taking 63PF2 conveying chain assembly lines for example and using industrial engineering foundation of stopwatch time study, two-handed operation analysis, process flow analysis and quality management of fishbone diagram, the problems existing in 63PF2 conveying chain assembly process are analyzed. And then the work site preliminary optimization is carried out. The bottleneck process of assembly process is optimized and improved. And the balance of assembly line is optimized, so as to improve the transmission chain assembly efficiency.

Abstract: The Quality Function Deployment (QFD) model and the optimal decision-making model is applied to the design of special-shaped stone Machining Center. Through the establishment of Design of house of quality of Machining Center, it can convert the users' needs and requirements of improvement on machining center into engineering measures of shape design of machining center in manufacturing engineering and at the same time combine resource consumption of various engineering measures implemented and resources of enterprises together. In the constrains of limited resource, in order to make the design of machining center meet the customers’ needs to the maximum extent and enhance the competitiveness of machine tool in the market, the optimal decision model can be used to select the vital engineering measurement on re-designing machining tool.

Abstract: Recently, polyethylene coating steel pipe has been extensively applied to water delivery in south-east China. However, similar applications in the north-west district where is severely cold and salty are seldom reported. This paper designed the refrigeration experiment, the freeze-thaw cycle experiment and the chemical immersion experiment after freeze-thaw, to test the PE coating steel pipe's reliability in the severely cold and salty region. The result showed that, after freeze-thaw or a period of refrigeration, a small number of dark spots appeared in the coating but didn’t change with the increase of freeze-thaw cycle times and the erosion of salt. The compositions were proved to be carbon and oxygen which indicated that the spots might be relative to the cryogenic stability of the coating rather than the corrosion of matrix steel. A crack and corrosion spot also appeared in test due to the excessively thick coating and the burr in steel substrate which can be eliminated by manufacturers through improving the coating formulas, surface pretreatment and coating process.

Abstract: The wave character of atoms can produce Casimir-like size effects in gases confined in a narrow box. A general micro/nano scaled model of the Otto engine cycle working with an ideal gas is used to discuss the Casimir-like size effects. Based on the model, expressions of the work output and efficiency are derived analytically. By means of numerical calculation and illustration, the influence of the surface areaon the performance of the cycle are discussed and evaluated in detail. Furthermore, some optimal operating regions including those for the work output, efficiency and the optimal region of the volume ratio and the surface area ratio are determined and evaluated. The results attained here are useful for designing of a micro/nano scaled heat exchange device.

Abstract: The state study on mechanical properties’ changes of X80 steel at different quenching temperature. The results showed that the quenching temperature is 1000 °C, X80 Austenite grain coarsening is serious, leading to the production of coarse lath bainite ferrite, resulting in increased strength of X80 steel, toughness and hardness of a serious reduction; When the quenching temperature is 930 °C, and assisted by the appropriate temperatures, can make the X80 steel the small needle-like ferrite-based organizations, to obtain good hardness, strength, ductility and toughness of the match.

Abstract: Four-wheel steering (4WS) is an advanced vehicle control technique which can improve steering characteristics. Compared with traditional two wheel steering (2WS) vehicles, 4WS vehicle can steer the front wheels and the rear wheels individually when cornering, according to the vehicle motion states such as vehicle speed, yaw velocity and lateral acceleration. Therefore, 4WS can enhance the handling stability and improve the active safety for vehicle. In this paper, the motion characteristics of 4WS vehicle are analyzed. The steering dynamics model of vehicle is established, and the transfer function of deflection angle of mass center to steering angle of 4WS vehicle is deduced. The handling stability of 4WS vehicle is researched by virtue of Matlab/simulink, Simulation results show that the 4WS vehicle is agile to and consistent with steering input and the transient handling stability is improved distinctly without increasing driver’s handling burden.