Advanced Materials Research Vols. 233-235

Abstract: In this paper, TiO₂ crystallines doped with transition metal ions have been prepared by sol-gel method. The UV-visible spectra indicated that the doping with transition metal ions (especially Cu²⁺, Mn²⁺ and Cr³⁺ ions) could effectively improve the absorption of TiO₂ crystals in the visible-light range. The XRD results showed that the doping does not affect the anatase phase of TiO₂. The band structure and the UV-vis absorption spectrum of Mn²⁺ ions doped-TiO₂ were also calculated by DFT (density function theory) method, which indicated that the doping with transition metal ion could make the band gap of TiO₂ smaller and a red shift in optical absorption.

Abstract: In this paper, a virtual prototype of the shovel loader with four tracks was established, and the tension adjustor’s F-t curve under driving conditions was obtained by the simulation. Then, the finite element analysis and the dimension optimal design of the tension adjustor which is an important part of the tracked vehicles were carried out so as to find out its best bearing structure. At last, the new model after optimization was analyzed again. According to the comparison between the finite element analyze results before and after the optimization, the finite element model’s maximum strain and stress under working condition after the optimal design were greatly cut down. As a result the using safety of the tension adjustor and its service life were greatly improved.

Abstract: Directional solidification and single crystal technology reduces material defects, improves material mechanical property and improves resistances to the high temperature fatigue, creep and corrosion. Accumulation of fatigue damage is a method of life prediction analysis and many fatigue damage models are proposed. Based on foregone research achievements, this paper presents a fatigue damage model, which could reflect material anisotropy and thermomechanical coupling effect. Based on equivalent strain, a fatigue damage evaluation method of directionally solidified and single crystal superalloy is presented and by this method, the linear fit of published fatigue experiment data is proceeded. Directionally solidified and single crystal superalloy is of strong anisotropy and crystal orientation has strong effect on component mechanical response. Comparative life of different location on component could be analyzed.

Abstract: Elastic and electronic properties of Mg₂Ca and Mg₂Y phases were investigated from first-principles calculations based on density functional theory. The optimized lattice parameters were found to be in excellent agreement with the available experimental value, and the structural stability was also studied from the energetic point of view. The five independent elastic constants were calculated, then the bulk modulus B, shear modulus G, Young’s modulus E and Poisson’s ratio ν of polycrystalline aggregates were derived, and the relevant mechanical properties Mg₂Ca and Mg₂Y phases were also further discussed. The elastic anisotropy of the two phases was also discussed in details. Finally, the electronic density of states and charge density distribution were also calculated to reveal the underlying mechanism of structural stability and mechanical properties.

Abstract: Ordered nanoporous carbon (ONC) was synthesized by adopting sucrose as precursor and SBA-15 as template. The thermal stability of sucrose and its SBA-15 composite were detected by thermogravimertic analysis. Transmission Electron Microscope, X-ray diffraction and nitrogen adsorption technology were used to characterize the morphology, microstructure and specific surface area of resultant ONC. The effects of carbonization temperature and pre-carbonization on the microstructure of ONC were investigated. The results have shown that SBA-15 is a kind of ideal template for preparing ONC, from which ONC with the diameter around 8 nm was obtained. When carbonized at 700 °C, the specific surface area of ONC derived is 2884.05 m²/g.

Abstract: The reaction between Si₃N₄ and AlF₃ had been investigated in CO atmosphere at high temperature. Experimental results are shown that the reaction between Si₃N₄ and AlF₃ is accelerated with the rise of temperature. At the temperature of 950 (aluminum electrolytic operation temperature is 935±15), there is obvious reaction between Si₃N₄ and AlF₃; under this experiment condition, Si₃N₄ converted into Si₂N₂O partly, Si₂N₂O can also react with AlF₃. The reaction products of Si₃N₄ with AlF₃ are SiF₄ (g) and AlN, while the reaction products of Si₂N₂O with AlF₃ are SiF₄ (g) and Al₈O₃N₆. So, during the usage of Si₃N₄-bonded SiC sidewall brick in aluminum electrolysis cells, the content of Si₃N₄ in Si₃N₄-SiC block are reduced which can bring down the corrosion of aluminum electrolyte to the sidewall materials.

Abstract: Mn₂O₃ Nanorods have been successfully synthesized under mild conditions by hydrothermal route following by thermal treatment at different calcination temperatures. Techniques of XRD, TEM, HRTEM, ED and XPS have been used to characterize the nanorods. The magnetic properties of the Mn₂O₃ nanorods synthesized at different calcination temperature have been studied using electron paramagnetic resonance (EPR) technique. And the evolved different EPR signals have also been discussed.

Abstract: This paper aims to characterize Baoluo kaolin and investigate its chemical composition. The Baoluo kaolin was characterized by XRD and SEM. The XRD pattern revealed that the Baoluo kaolin was composed of kaolinite, quartz, little feldspar and mica. Its chemical composition was determined by volumetric method, titration method and flame photometer method. The weight percentages of Al₂O₃, SiO₂, Fe₂O₃, Na₂O and ignition loss in the Baoluo kaolin are 36%, 46%, 0.56%, 1.21% and 12.76%, respectively. The results in this paper would be benefit to industry utilization of the Baoluo kaolin.

Abstract: Eu(DBM)₃•phen complexes have been Successfully synthesized by the sonication of an Ethanol solution of europium chloride and dibenzoylmethanide (DBM) in the presence of 1,10-phenanthroline(phen). The properties of the Eu(DBM)₃•phen complexes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform Infrared spectroscopy (FT-IR) and fluorescence spectrometry (FS). Reaction conditions, such as ultrasonic power and the concentration of complexing reagent, were found to have close relation with the morphologies of final products. The formation mechanism of Eu(DBM)₃•phen complexes with ultrasonic irradiation is discussed in the context.

Abstract: China is rich in CBM resources, but so far, some production wells present low production and rapid decline trend. In addition to these objective factors such as low permeability and complexity of geological structure of CBM reservoir, there is still the most important problem during the exploitation techniques that is the lack of understanding to dynamic variation character of CBM reservoir permeability, which leads to the unreasonable work of depletion for coalbed methane.Using P&M model and parameters from 3# coal seam of Shanxi Formation, Permian system in Qinshui basin, the permeability variations of this block (first decline, then ascend, reaching 2.8 times of initial permeability at the end) were analyzed, revealing good depletion prospect of this CBM field, and pointed that the higher Young's modulus is, the more obvious matrix shrinkage is and the higher gas saturation is, the more favor for permeability improvement through sensitivity analysis. Finally, two suggestions were proposed, (1) add the 'permeability variations' to the parameters for CBM block select, which may find the "innate" in the late development of the poor condition of properties easy to improve, develop potential for larger blocks. (2) Adjust and optimize the depletion method (amplitude and frequency of bleeding, pressure reduction) according to the permeability variation characters discussed in this paper