Advanced Materials Research Vols. 652-654

Abstract: Li1+xMn2O4 prepared by solution combustion synthesis method has a strong exothermic peak at 282.1 °C, which is believed that the reaction of LiNO3, LiAc2•2H2O with Mn(NO3)2 and MnAc2•4H2O occurs in this region. So products were calcined at 500 °C would got fine crystalline. Pure phase LiMn2O4 can be prepared with x(Li)=0.16 and 0.24 without impurity. Li-rich samples for x(Li)=0.16 and 0.24 has nanoparticles of which the surface area will be more and can lead to better electrode performance. The initial discharge capacity of Li1.16Mn2O4 was the highest of 116.4mAh•g-1, with a 15 % loss of the initial capacity after 40 cycles, which is much better than bare LiMn2O4. Excess Li+ is beneficial to formation of pure phase of spinel LiMn2O4 and Li1.16Mn2O4 has best electrochemical performance in the method of solution combustion synthesis.

Abstract: Lithium bis(oxalato)borate (LiBOB) and lithium oxalyldifluroborate (LiODFB) are promising boron-based lithium salts for lithium ion batteries. Advantages, disadvantages, and recent developments of each lithium salt were introduced respectively in this article. In addition, ionic conductivities and compatibilities with electrode materials were emphatically reviewed.

Abstract: The effective minority carrier lifetime (τ_eff) depends upon the quality of surface passivation, which by means of the microwave photoconductance decays (μPCD) method. The effective minority carrier lifetime (τ_eff) cannot reveal the real bulk lifetime of minority carriers (τ_b) . We have applied iodine-ethanol (I-E) treatment to silicon surface at different molar concentrations and shown that the effective concentrations ranges was 0.08mol/L~0.16 mol/L, the maximum The effective minority carrier lifetime (τ_eff) of n-type monocrystalline and p-type monocrystalline was 973.71μs and 362.6μs, respectively. We also accurately evaluate the bulk lifetime of minority carriers by measured with different thickness of silicon substrate.

Abstract: The primary purpose of this research is to establish the optimal alloy design and microstructure for achieving the desired mechanical properties (tensile strength, yield strength, elongation and low temperature impact value) of key components used in large-scale windmills. In order to meet the impact requirement (I-40°C≥10J) of spec. EN-GJS-350-22U-LT, the Si content should be kept below 1.97%, and also the maximum pearlite content shouldn’t exceed 7.8%. On the other hand, the optimal alloy designs that can comply with specification EN-GJS-700-2U include 0.25%Mn+0.8%Cu+0.01%Sn , 0.25%Mn+0.6%Cu+0.05%Sn and 0.45%Mn+0.6%Cu+0.01%Sn. Furthermore, based upon the experimental results, multiple regression analyses have been performed to correlate the mechanical properties with chemical compositions and microstructures. The derived regression equations can be used to attain the optimal alloy design for castings with targeted specifications. Furthermore, by employing these regression equations, the mechanical properties can be predicted based upon the chemical compositions and microstructures of cast irons.

Abstract: This paper focus on the development of low-alloy anti-corrosion steel for the upper deck of COT(cargo oil tank), and the corrosion behavior of Cr-containing low-alloy steels in O₂-CO₂-SO₂-H₂S moisture were studied using homemade COT corrosion simulation device. After the corrosion experiment, related corrosion data was measured, and macro morphology and structure of corrosion scale were observed by SEM(Scanning Electron Microscope). The phase and chemical composition of corrosion product film were analyzed by XRD(X-ray diffraction) and EDS(energy dispersive spectroscopy). The effect of misorientation distribution on anti-corrosion property of steel was investigated by EBSD(electron backscattered diffraction). Based on the results, corrosion scale of COT on the upper deck consist of α-FeOOH, γ-FeOOH, FeS₂, S and Fe_1-xS, and the type of corrosion is mainly general corrosion. Cr enrichment was found on the inner corrosion product film, the addition of Cr leads to the increasing of low-angle grain boundaries and sub-grain structure which is conducive to the improvement of corrosion resistance.

Abstract: Uniaxial hot compression simulation experiment at 700°C with different true strain was carried out to study the microstructure evolution of medium carbon steel, the predominant mechanism on the cementite softening has been explored, the experimental results show that the volume fraction of deformation induced ferrite (DIF) increased with increasing true strain and even exceeds the equilibrium content. With the increase of DIF, more and more carbon atoms congregated in the boundaries such as the interface of DIF and the interphase of DIF/deformation austenite. Carbon congregation provides the right carbon content and the optimized microstructure for divorced decomposition during the process of controlled cooling. Therefore spherical or rod-like cementite and degenerated pearlite can be obtained.

Abstract: The effect of phosphorus contents on texture and grain boundaries character for the high strength Ti-IF annealed for 120sec at 810oC are researched by electron backscatter diffraction technique（EBSD）. The recrystallization texture is approximated by the γ-fiber texture whose components are {111} and {111} orientation texture. The highest volume fraction of //ND texture is almost 80% for the sample containing 0.056%P. A large amount of coincidence site lattice(CSL) grain boundaries ∑3，∑5, ∑7，∑9，∑11 and ∑13b are obtained.

Abstract: The original austenite grain size, the inclusions and the isothermal annealing microstructure of 20MnCrNi2Mo wear-resistant cast steel without and with Rare Earth were observed by metallographic microscope and QUANTA-400 environmental scanning electronic microscope. The effect mechanism of Rare Earth in 20MnCrNi2Mo wear-resistant cast steel was investigated. The results show that adding Rare Earth in 20MnCrNi2Mo wear-resistant cast steel can refine the original austenite grains. Meanwhile, it can reduce the inclusions size and change the inclusions shape from irregular to nearly spherical. In addition, the Rare Earth in 20MnCrNi2Mo wear-resistant cast steel can increase the amount of ferrite, reduce that of pearlite in the isothermal annealing microstructure and refine the microstructure of pearlite.

Abstract: The feature, structure and composition of oxide films of a TP304H steel oxidized under 650°C and 25MPa water vapor for 1~50h were analyzed by SEM, EDS and XRD. The oxidizing dynamic curves were measured by discontinuous weighing method. The results indicated that the oxidation kinetics was agreement with the parabolic law. At the beginning of the oxidation, the formation of oxide was Fe2O3, while Fe3O4 and FeCr2O4 were formed with the increasing of oxidation time, without independent Cr2O3.

Abstract: Caustic calcined dolomite based compound desulfurizer by the aluminum thermal reduction was taken as study object. Effect of fluxing agent, reaction time and experimental temperature on the weightlessness of compound desulfurizer was studied. The result showed that the weightlessness of compound desulfurizer decreases slightly with the increase of fluxing agent CaF₂ content. When the content of SiO₂ changes from 12% to 20%, the weightlessness of compound desulfurizer which is basically about 27.5% changes a little. With the increase of experimental temperature and reaction time, the weightlessness of compound desulfurizer is gradually increased. When the reaction time and temperature is respectively 20min and 1300°C, the weightlessness of compound desulfurizer is 31.80%.