Applied Mechanics and Materials Vol. 692

Abstract: The object of this work was to determine the solubility and stability of the synthetic Sr₅(AsO₄)₃OH solid solution at 25°C and the different initial pHs (pH at 2, 6 and 9) by batch dissolution experiments. The results indicated that with the initial pH value of 2, 6 and 9, the reaction system reached equilibrium after 2880h, and by that time the pH value of the solution reached, 7.90, 8.74 and 8.27 respectively. The concentration of strontium and arsenic in the initial solution pH at 2 are higher than that of solutions pH at 6 and 9. While the concentration of strontium in neutral or alkaline solutions is low and stays unchanged.

Abstract: β-Sialon/Si₃N₄ composite ceramic were prepared from starting materials of α-Si₃N₄, AlN and Al₂O₃ by pressureless sintering. The physical properties, phase composition and microstructure were tested by modern testing technology. The effect of different additives such as Y₂O₃, La₂O₃ and borax on the sintering temperature and physical properties was studied. The results show that D3 is the best formula, firing shrinkage rate of the sample is 14.14%, water absorption 3.16%, porosity 9.02%, bulk density 2.85g·cm^-3 and bending strength 193.87MPa after firing at 1580°C. XRD analysis indicates that the main phases of D3 are β-Sialon, β-Si₃N₄ and corundum. SEM analysis shows that the microstructure of D3 sample is quite dense and the pores distribution is uniform, the diameter of the pore is about 1~5μm. β-Sialon/Si₃N₄ composite ceramic has high bulk density, bending strength and fine microstructure, which is a new choice of the heat absorb material for solar thermal power generation system.

Abstract: A series of transition metal alanine-salicylaldehyde Schiff base chromium (III) complexes immobilized on MCM-41 were prepared and characterized by various physico-chemical measurements such as FIIR, XRD, HRTEM, N₂ sorption and elemental analysis. The immobilized complexes were effective and stable catalysts for the epoxidation of styrene and cyclohexene with 30% hydrogen peroxide. Moreover, the metal centers were found to play important roles in the catalytic performance of immobilized complex catalysts.

Abstract: Depolymerization of DGEBA/EDA Epoxy Resin was carried out in a microwave reactor, heated for definitized time. Experimental results showed that the products obtained are phenol, bisphenol A, isopropyl phenol. Liquid products were analyzed by high performance liquid chromatography (HPLC) and the standard curve was established by the pure samples and used it to quantify. The results show that the maximum yields of phenol, bisphenol A, isopropyl phenol are 81%,50%,12%.The residual solid after depolymerization were analyzed by infrared spectroscopy and confirmed that it was residual epoxy resin solid. Depolymerization ratio and yields of main products increase with the increase of reaction temperature and time. The most effective medium is BmimCl and the depolymerization ratio can reach 92%, and the test by infrared spectroscopy shows that BmimCl is stable , It can be used for many times.

Abstract: The aqueous dispersion of MAH-g-PP and KH-550 solution are used in the pretreatment of GF. The effects of pretreatment of the aqueous dispersion of MAH-g-PP and KH-550 solution on the interface crystallization of PP/GF, the suitable temperature and time of the pretreatment of the aqueous dispersion of MAH-g-PP on GF are studied by scanning electron microscope (SEM) and polarized light microscope (PLM). Finally, PLM is used to study the effects of the aqueous dispersion of MAH-g-PP on the crystallization of PP.

Abstract: The Polarized light microscope and DSC are used to study the influence of the nucleation agents’ type (The aqueous dispersion of isotactic polypropylene wax and the commercial nucleating agent TMB-5), nucleating agents’ content on the β-crystal content, melting points of α-crystal and β-crystal are studied in the paper. The difference of their capacities of inducing the crystallization of polypropylene are compared and analyzed. The foundation of the treatment of the aqueous dispersions of isotactic polypropylene wax on the reinforcements to induce crystallization on the surfaces of the reinforcements is laid.

Abstract: The organosilicone gel material for large-power LED packaging was prepared through Si-H addition reaction of hydrogen-silicone with vinyl-silicone catalyzed by Pt coordination compound in the paper. The effect of Si-H/C=C ratio on thermal stability, shore hardness, visible light transmittance and tensile properties were investigated by FTIR, UV-vis spectrometer, etc., which supplied the basic data for the preparation and application of organosilicone materials for large-power LED packaging.

Abstract: Three typical solution schemes of adjoint problems of heat transfer, phase transformations and chemical reaction at the forest fuel material surface were analyzed in this work. Characteristic times of thermal decomposition reaction suppression of forest fuel materials (needles of pine and fir-tree, leaves of birch) were presented for concerned heat transfer models. Effective heat exchange conditions which are characterized by minimal times of chemical reaction suppression in forest fuel materials and minimal extinguishing agent's expenditure were established.

Abstract: The transparent epoxy molding compound (EMC) for integrated circuits (IC) packaging was prepared by using tetrahydromethyl-1,3-isobenzofurandione as curing agent, respectively using 2-methyl imidazole and triphenyl phosphine as curing accelerator. The effect of curing accelerator type on curing behavior of EMC was investigated by non-isothermal DSC method in this paper. Based on Kissinger method, Crane method and Ozawa method, the kinetic parameters such as activation energy and reaction order of the curing reaction were obtained. The characteristic temperatures of the curing process such as gel temperature, curing temperature and post-curing temperature were calculated by extrapolation. The results showed that EMC with 2-methyl imidazole had a lower activation energy compared to EMC with triphenyl phosphine, which provided the basic data for the optimal recipe of EMC and the determination of IC packaging technologies.

Abstract: Composite coatings of PTFE/PEEK (Polytetrafluoroethylene/Polyetheretherketone) were prepared by electrostatic powder spraying method. The frictional coefficient were investigated by the orthogonal experimental method. The results show that 250°C preheating temperature and 150°C working temperature are better conditions for frictional coefficient.