Advanced Materials Research Vols. 750-752

Abstract: The modified sizing nozzle with excellent performances was successfully prepared by using of Mg,Y-PSZ as aggregates, Mg,Y,Ca-PSZ as fines, adding a certain amount of Al₂O₃-ZrO₂ composite powders prepared by sol-gel. Effects of magnesium aluminate spinel in-situ synthesized in modified sizing nozzle on its performances were studied in this experiment. The results show that, the content of cubic zirconia in the sizing nozzle was decreased with the increasing of Al₂O₃-ZrO₂ composite powders; the samples of modified sizing nozzle have no diameter-expanded after 30 hours service. The use effects are obviously better than that of Al₂O₃-ZrO₂ composite powders free. The main reason is that a new bond phase magnesium aluminate spinel was in-situ generated through the reaction between Al₂O₃ in Al₂O₃-ZrO₂ composite powders and the stabilizer MgO from partially stabilized zirconia in the sintering process at high temperature. The spinels embedded in the substrate of zirconia grow further and fill between zirconia particles. This prevents the stabilizer of CaO further desolventizing and also stop losing the eutectics formed by the reaction with compositions of molten steel. Therefore, the stability of zirconia and the corrosion resistance of the sizing nozzle were improved.

Abstract: To improve corrosion rates and activation properties of AZ91 magnesium alloy anode, effects of additives (propargyl alcohol) on electrochemical behaviors of AZ91 magnesium alloy in 3.5% NaCl solution have been examined by studying corrosion rate, polarization, open circuit potential (E_ocp) and transfer resistance values (R_t) of electrochemical impedance spectroscopy(EIS). The results show that propargyl alcohol not only decreases corrosion rate of AZ91 magnesium alloy anode, corrosion-inhibition ratio is 64.6%, but also increases activation properties of AZ91 when 1.0 % propargyl alcohol added into 3.5% NaCl solution. The current density of AZ91 reaches 9.46 mA.cm^-2 at-1.35V. Its active potential (E_act ) is-1.527 V , and E_ocp is-1.556 V.

Abstract: We investigate the thermodynamic properties of superhard w-BC2N by using ab initio plane-wave pseudopotential density functional theory method within local density approximation (LDA). Through the quasi-harmonic Debye model, we investigate the thermodynamic properties of w-BC2N. The variation of the thermal expansion, the heat capacity and the Gruneisen parameter γ with pressure P and temperature T, and many other thermodynamic parameters of w-BC2N are obtained systematically.

Abstract: A lithium iron phosphate composite LiFePO₄/C as cathode material for lithium ion battery was synthesized by sol-gel and high temperature solid state reduction method. The crystalline structure, morphology of particles and electrochemical performances of the sample were investigated by X-ray diffraction, scanning electron microscopy and charge-discharge test. Crystal structure and electrochemical performances of the composite relates to the heat treatment temperature. The composite synthesized under 700°C is simple pure olive-type phase structure with relative uniformly distribution of particle size. Also high charge-discharge capacity and efficiency, good cycle ability and high rate capability were observed in electrochemical tests for the composite. However, the capacity loss under high temperature, which may be the main content of further study.

Abstract: In this study, a novel phase change material was prepared by coordinating rare earth Tb³⁺ ions to the carboxylate groups of a poly (ethylene glycol).The properties of the material were characterized by differential scanning calorimetry (DSC), infrared spectroscopy (IR) and fluorescence spectroscopy. The synthesis and characterization a novel phase change luminescent Tb-PEG/SA material were described in this paper. The result show that this modified PEG material show both good phase change properties and excellent luminescent properties.

Abstract: Fluorinated acrylate emulsion was prepared in the presence of TPG as co-solvent, effects of TPG content to the polymerization stability and monomer conversion of the prepared emulsion was studied by the coagulation ratio and conversion rate, respectively. The hydrophobicity and oleophilicity of the polymer film was studied by water/oil contact angle. The chemical structure and morphology of the latexes was studied by FTIR and TEM observation, respectively. The results show that TPG has great impact on the stability of emulsion polymerization and morphology of the latex particles. The prepared fluorinate poly-acrylate emulsion has excellent water/oil repellency and thermal stability.

Abstract: F-TiO₂ nanosheets were synthesized by alcohothermal method. Surface fluorination enhances the absorption of TiO₂ in the visible region. Meanwhile, the strongest electronegativity of the fluorine reduces recombination of electrons and holes. Thus compared with the naked TiO₂, the F-TiO₂ has excellent photocatalytic properties in oxidation of benzene to phenol. The results suggest that benzene conversion and phenol selectivity are up to 35.6% and 93.8%, respectively.

Abstract: In this study, a novel flame retardant 1,2-bis (dimelaminium of 1-nitro-3,5-diphospha-4-oxa-3,5-dihydroxy cyclohexane) ethane (EAPM) was synthesized by ethylene diamine tetra (methylene phosphonic) acid (EDTMPA) and melamine in two steps. Meanwhile, its molecular structure was determined by Fourier-transform infrared spectroscopy (FT-IR), elemental analysis, ¹H-NMR. The thermal properties were characterized by TG and DTG, which indicated the good thermostability of EAPM for processing and the considerable residual char in the final stage of combustion. The fire performance of composites blended by the novel flame retardant and polypropylene waere investigated by limiting oxygen index (LOI) and vertical burning test. The results demonstrated the treated PP with the optimal flame retardant formulation of 15 w% EAPM, 5 w% charring agent and 10 w% MEL-APP was attached with an LOI of 33.3% and UL-94 V-0 rating.

Abstract: Magnetorheological (MR) elastomers are a new type of MR material. At present, most studies in this field are at laboratory stage, and practicability was rarely considered preparation of MR elastomer materials. Consequently, the existing materials with low overall properties cannot be applied in engineering. In this paper, the performance requirements for MR elastomers to be used in isolators were proposed. Then a type of practical MR elastomers for isolators was prepared, and its mechanical performance and MR effect were tested. The results show that the designed MR elastomers have high mechanical performance and high MR effect, and thus can be used in isolators.

Abstract: Air permeability and acoustical behavior of nonwovens are two properties which are correlated with each other. And both are determined by the structural parameters of nonwovens. However, the structure of nonwovens is nonlinear, and the influences of parameters are out-of-order, that traditional methods can hardly characterize it. In this paper, the rank method is implemented to investigate the influence of structural parameters on acoustical property. Thus the mechanism of acoustical property of nonwovens is studied.