Materials Science Forum Vols. 704-705

Abstract: This paper presents a study of the temperature fields of steel slab in a walking beam furnace. To simulate the temperature distribution in the slab of heating-up process in heating furnace, a two-dimensional mathematical model was developed. The heat transfer in the furnace was very complex, so the model was developed on the assumptions that the temperature of each section of the furnace was unchangeable, the slab moved in the furnace in even velocity, the heat transfer between the slab and the walking beam was out of consideration, the longitudinal heat conduction of the slab and the effect of the scale on the heat conduction were neglected. The equations were calculated by the finite difference method. A black box experiment research was carried out to measure the temperature history of the slab as it passed through the furnace. The comparison of the calculated results with the measured results showed that the model worked well for simulating the temperature distribution of the slab in walking beam furnace. With this developed model, the optimizing of hot rolling and heating processes of steel slab can be investigated in the future.

Abstract: Bamboo is so easy to get mildewed that bamboo products are still low value added. Therefore, the effect of red extractives from 28 tree leaves on bamboo biology mildewing was studied basing on full-factor test. The result was as follows: (1) most red extractives of tree leaves can inhibit the growth of P. expansum, but a few can inhibit the growth of A. alternate; (2) The red extractives from tree leaves of Deodar cedar, Eucalyptus grandis, Eucalyptus dunnii and pear were the most effective to control spore germination of P. expansum, and those of Manglietia glauca, Osmanthus fragrans, and Melia toosendanin were the most effective to control spore germination of A. alternata; (3) The effect of the red extractives from Pinus taeda, Eucalyptus grandis and Santalum album on bamboo biomass mildewing was highly remarkable on mildew-proof by outdoor test. Our result pointed out the direction for the development of the biological mildew inhibitor from tree leaves. Key words. tree leaves, bamboo biomass, benzene/alcohol extractives

Abstract: To study the impact of VDP on the bending process of fiberboard, this paper deeply researched into the dynamic changes of section stress distribution of fiberboard during the process of loading and bending and built a static bending strength predicting model, which is based on the piecewise function by simulating fiberboard VDP, theory of elasticity and plasticity, lamella inter-bedded theory and VDP model. The results show: The bending process of fiberboard can be divided into two stages which are elasticity period and elasticity-plasticity period. The latter includes both elasticity region and plasticity region, and compression region comes to elasticity bending before pulling region. The curve of bending section stress distribution is nonlinear and affected by loads and VDP. Critical section stress distribution of bending breakage and breakage load can be predicted by VDP with other condition unchanged. The value of static bending strength predicted by model is basically consistent with testing data. And the static bending strength is closely related to qualification factors of VDP. Fiberboard with high average density doesn’t always contain high static bending strength. VDP is a significant physical parameter which has impact on the bending process and performance of fiberboard, so it must be optimized and controlled in production according to for specific purpose. Key words: fiberboard, vertical density profile, section stress distribution, bending strength, predicting model

Abstract: It is shown that application of graphic techniques and CAD/CAM systems for solving problems of metal forming makes it possible to obtain satisfactory results. Using well known COMPAS graphical system, it is possible to plot diagrams of contact pressures for some special cases. PARSHTAMP software developed by authors enables to calculate boundary dividing lines of metal flow during deformation of flat preforms.

Abstract: Composite electrodeposition is one of the most important metallic material surface finishing technology and metal-based composite material preparation technology. Electric field and flow field are the two main influence factors during electrodeposition process of composite coatings. In this paper, numerical simulation of flow-field of zinc-silica composite electrolyte is finished by FLUENT software and the actual flow state is recorded by Particle Image Velocimetry (PIV). The research work is also focused on influence of current and stirring intensity on flow character of electrolyte. The electrolyte composition and plating conditions are: ZnCl₂ 80 g/L, KCl 220 g/L, H₃BO₃ 25 g/L, brightening agent 0.5 g/L, pH value of electrolyte 5.5, temperature 25°C, mass concentration of SiO₂ particles in electrolyte 1 g/L. The average particle size of SiO₂ particle is 11.07 μm. The stirring intensity is controlled between 0 and 3000 rpm, and current is controlled between 0 and 0.5 A. The results show that influence degree of stirring on flow field is much greater than current, and the numerical simulation of flow field finished by FLUENT software is approximately similar to the actual flow charactor recorded by PIV.

Abstract: the moisture distribution in untreated and esterified poplar with Maleic anhydride was studied in the present paper employed nuclear magnetic resonance (NMR). The results show that relaxation times decrease with the the fall of moisture content, and there is a linear equation between the moisture content and transverse relaxation time in esterified wood. The content of bonding water and free water in the esterified wood decreased simultaneously during the drying.

Abstract: This paper comprehensively uses a combination of methods of theoretical analysis, numerical simulation as well as the model test to do the structural analysis to some type of the passenger cabin doors, so as to set up the model for the descriptions of the part subjected to explosion impact loading; Through the tests, we gets the explosion impact loading and other important physical parameters. Aimed at the material of the door as well as the simplified models subjected to the explosion impact loading, the numerical simulation is put up by the finite element software ABAQUS. The necessity of the reinforcement is deeply analyzed as well as the difficulties during the process of the reinforcement, furthermore, the reinforcement measures are proposed to the airliner door. Keywords: Numerical simulation; Explosion impact loading; Explosion-combustion power equipments

Abstract: We use neutron total scattering measurements with reverse Monte Carlo analysis methods incorporating an atom-swapping algorithm to investigate the short-range Zr/Ti cation ordering at the perovskite crystalloraphic B sites and micro structure within PbZr_0.5Ti_0.5O₃ solid solution at different temperature. Our results show that there is no Zr/Ti ordering at the B sites. TiO₆ and ZrO₆ units are rotated and distorted. The amplitude of rotations of the TiO₆ units is larger than that of the ZrO₆ units, accompanied by more distortions of the angles within the TiO₆ units.

Abstract: Heat transfer in wood particle controls the process of the pyrolysis. This paper makes a 2-D transient heat transfer model in cylindrical to predict the thermal behavior of wood particle in the process of fast pyrolysis. Wood anisotropy and thermophysical properties are considered in this model, as well as the influence of heat reaction on temperature distribution in wood particle. Based on the calculation of transient temperature in wood particle, and analysis of the temperature distribution during the process of wood fast pyrolysis at different time, this paper preliminarily discusses the optimization of parameters in wood particle fast pyrolysis. Keywords: pyrolysis, heat transfer, particle, wood

Abstract: Fast pyrolysis is cracking process in which macromolecule of biomass is broken into small molecular under moderate temperature and at high heating speed. Bio-oil produced by the process can be used as potential alternatives of diesel oil and other chemicals. By investigate different kinds of reactor, a new type reactor called vacuum paddle fast pryoysis reactor is developed with low manufacture cost and operating fee and more stable performance. Two stage condensing system composed of 1^st quench stage and 2^nd cooling heat exchanger is designed, which is proven effective in avoiding secondary cracking of biomass oil and eliminating block of equipment by tar. At same time, a model describing heat transfer in new reactor is established and solved by unsteady heat conduction equation, which give conclusion on minimum agitating speed and therefore, provide basic theoretical foundation. Keywords: fast pyrolysis, vacuum paddle reactor, condenser, heat transfer