Advanced Materials Research Vols. 295-297

Abstract: Nano- and micro-scaled LiFePO₄ was synthesized by hydrothermal synthesis method using disodium ethylenediamine tetraacetate (Na₂EDTA)-assisted to avoid the Fe(II) ions from oxidation and control the growth of the crystal. The as-synthesized samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), The SEM showed that the pH value of the synthesis solution played a key role in the formation of the final products with different morphologies. Charge–discharge cycling performances were used to characterize its electrochemical properties. The results indicated that the nano-sized LiFePO₄ presents enhanced discharge capacities (148 mAhg⁻¹ at 0.1C-rate) and stable cycling performance. This study offered a simple method to design and synthesis nano-sized cathode materials for lithium-ion batteries.

Abstract: Cold-formed steel structure dwelling system is becoming the major development trend of steel structure for its lightweight, long durability and quick construction. In this paper, the development process of technology and application of cold-formed steel structure dwelling system in China and abroad is introduced. Compared with developed countries there is great disparity in this area.

Abstract: The degassing and dedusting mechanism of La and Ce during non-vacuum melting process of Cu-Cr-Zr alloy were analyzed by thermodynamics. The gibbs free energy changes of reactions of La and Ce with some impurties such as O2, H2, S, P and Si, were calculated to discriminate the possibility of reaction during the melting process, respectively. In addition, the effect of La and Ce on microstructure and properties were studied. The results show that La and Ce can react with O2, H2, S, P and Si, which improves the effect of degassing and dedusting remarkably; the addition of La and Ce can eliminate pine-tree crystal, fine grain and clear grain bourdary.

Abstract: In the aerospace test, Signal source is the core component. It provides various signals what are needed by test. However signal transmission’s reflections and noise always cause interference. It will impact the accuracy of signal. Therefore, the precision, stability and reliability of signal source in space telemetry experiment are very important. This paper adopts FPGA + AD768 to achieve a precision, stability signal source. By the assessment test, this system is proved to be feasible and stable.

Abstract: High-g accelerometer and storage test system is designed for the measurement of multi-layer steel targets penetration. The penetration test of the double layer steel target is performed, and the verload acceleration is obtained when the projectile penetrates the steel target. According to the overload data, the effective overload accelerations are concluded. The effective overload accelerations gained when projectile penetrates the double steel targes are 81078g and 152061g respectively. Also from the calculation, it can be concluded that the test errors are all less than 10%, which can meet the requirement of penetrating multi-layer steel targets.

Abstract: Mg-5Y-3Nd-Zr-xGd (x=0 and 4 wt.%) alloys were prepared by metal mould casting, and aging behavior, mechanical properties and fracture morphology were investigated. The result shows that after T6 treatment, the massive eutectic phase in as-cast alloys dissolved and finer Mg5RE phase precipitated dispersively in the matrix, and mechanical properties were improved simultaneously. Mg-5Y-3Nd-4Gd-Zr alloy exhibits good age hardening behavior and the peak hardness is about 20% higher than the Gd-free alloy. Gd addition can significantly improve mechanical properties of the alloy especially at the elevated temperature. The ultimate tensile strength and yield strength of Mg-5Y-3Nd-4Gd-Zr alloy at 250°C, with the value of 276 and 168 MPa, respectively, are over 20% higher than those of the Gd-free alloy. It is mainly attributed to the increase and homogeneous distribution of the fine heat-resistant Mg5RE precipitate in the matrix.

Abstract: With the continuous development of science and technology, the method of using the pre-stressed carbon fiber on the concrete structure, in particular on the bridge structure has become a research direction by the domestic and foreign scholars. In this paper, it has done the long-term test for the civil carbon fiber in the library on the base of the research of reinforced concreted beams with pre-stressed CFRP plate, and has observed the slip of the carbon fiber fixed on the side of the tension anchor. The results showed that: when put 50% of the ultimate stress of the carbon fiber on the carbon fiber, under the action of long-term tension, the variation of carbon fiber and the slip of the carbon fiber fixed on the side of tension anchor can all achieve intended purpose of the experimen ,which provides the theoretical data on the long-term performance research of the civil carbon fiber reinforced on the concrete structures.

Abstract: The synthesis of thermo-responsive hydrogels poly(N-isopropylacrylamide )(PNIPAm) by frontal polymerization (FP) was carried out in four mixed solvents, i.e. dimethylsulfoxide (DMSO) mixing with water, ethanol, tetrahydrofuran (THF) and acetone, respectively. The influences of mixed solvent on frontal parameters, pore morphologies, swelling behavior of PNIPAm hydrogels were investigated. The pore of PNIPAm hydrogel synthesized in THF/DMSO was observed a big honeycomb cells, others were channel-like cells. Furthermore, the sample obtained in THF/DMSO had higher swelling ratio as compared to others, and the one synthesized in Water/DMSO showed the lowest. Above results indicated that fine-tuned poly(N-isopropylacrylamide) hydrogels can be prepared in short time and with easy protocol by adjusting mixed solvents in frontal polymerization process.

Abstract: This paper developed a kind of concrete with coal gangue as coarse aggregate in order to solve the environmental pollution problem and meet the requirement of filling material in gob-side entry retaining. Firstly physical properties and chemical properties of coal gangue were analyzed, and then several schemes of mix proportion were designed, according to which new product was trial-produced in the laboratory. The optimal mixing ratio was selected by testing the performance of trial-product. Industrial test indicate that the coal gangue concrete can be used as filling material for the gob-side entry retaining, which not only solve the problem of ecological environment and resource shortage, but also reduce the cost of filling material and increase the economic benefit of coal mine enterprise.

Abstract: Effects of various types and amounts of plasticizer on the moisture sorption and mechanical properties of gelatin-chitosan composite films were investigated. The films were plasticized with glycerol, polyethylene glycol 400 (PEG 400), polyethylene glycol 800 (PEG 800), and sorbitol, respectively. With increasig the amount of plasticizers in the composite films plasticized with the fromer three plastizers, the equilibrium moisture sorption ratio increases. For the last one, however, it decreases with increasing the plastizers content. Increasing the plasticizer content decreases the tension strength and increases the elongation at break of the samples, and the type and amount of the plasticizers affect the mechanical properties of the composite films. PEG 400 is the most effective plasticizer in the plastizers studied.