Advanced Materials Research Vols. 228-229

Abstract: The new generation TMCP process based on ultra fast cooling has recently developed rapidly. In order to develop the low yield ratio constructional steel, the effects of cooling finishing temperature on microstructure and yield ratio of steels were studied primarily. The results show that the high strength and low yield ratio can be achieved by multiphase including M-A hard second phase and bainite ferrite soft matrix. When UFC final temperature is 521°C, the uniform M-A phases with volume fraction of 22.5% are distributed on bainite ferrite matrix, and then the yield strength is 570MPa, tensile strength 760MPa, yield ratio 0.75, and percentage elongation 22% with the Charpy impact energy 284J at -40°C. All these indexes come up to the relevant standards. The steel with lower yield ratio can be subjected to larger plastic deformation before the necking instability.

Abstract: The nano-SiC whisker reinforced Cu-matrix composites (SiCw/Cu) were obtained by powder metallurgy processes. The electrical arc ablation performance of composite SiCw/Cu was compared with copper H62 through stagnation-point ablation experiments. The results indicated that the qualities of copper H62 samples decreased with the increasing of ablating current; and the qualities of SiCw/Cu samples firstly increased and then decreased with the increasing of ablating current. Ablation mechanism research indicates the ablation hole of SiCw/Cu is smaller than copper H62, but it produced micro cracks because of different thermal expansion coefficients between nano-SiC whisker and Cu-matrix. At the same time, nano-SiC whisker happens to intricate oxidation reaction during arc ablation, it can reduce Cu-matrix smelts and sprays by absorbing arc energy. The anchoring effect and protection for the copper matrix of the uniformly dispersing nano-SiC whiskers have been considered to contribute the excellent arc ablation performance of composite SiCw/Cu.

Abstract: ZnO-coated LiNi0.5Mn1.5O4 cathode materials for Li-ion batteries have been synthesized. Samples were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and charge-discharge tests. The results of XRD and scanning electron microscopy (SEM) showed the ZnO-coating was nano-sized, and the LiNi0.5Mn1.5O4 powder exhibits a typical cubic spinel structure with a space group of Fd3m. Electrochemical tests demonstrate that the ZnO-coated sample obtained possesses high capacity and excellent cycling stability compared with the as-prepared LiNi0.5Mn1.5O4. When being discharged at a rate of 1C after 50 cycles, the ZnO-coated LiNi0.5Mn1.5O4 powders can still deliver a capacity of 115.5 mAh•g-1, with nearly no capacity fading, which shows to be a potential cathode material for high-energy density power batteries.

Abstract: Aiming at the evaluation and optimization of urban rail transit network scheme, the optimization decision-making model based on group TOPSIS was advanced in this paper. The multi-attribute evaluation index system of urban rail transit network was established. Then the decision-making’s position matrix and the attribute weights were determined using the idea of group decision-making on the basis that group rationality was guaranteed , which aimed at the phenomenon that preference of decision-making existed and the reduction of decision-maker’s preference had influence on the result of decision-making. The network scheme was ranked based on TOPSIS method to arrive at a decision. The example in this paper has verified the effectiveness and practicability of the model.

Abstract: This paper describes the basic concept of the new technique for the modeling of the structural-acoustic coupling between the pressure field in an acoustic cavity with arbitrary shape and the out-of-plane displacement of a flat plate with arbitrary shape. It is illustrated through a three-dimensional validation example that the new prediction technique yields a high accuracy. The effect of the cavity depth and the coupling interface area on the strength of mutual coupling interaction are discussed in detail.

Abstract: This paper has analyzed key techniques in foam mold development for Lost Foam Casting for different types of casting, which are complex box, pipe faucet junction ,wear-resisting and refractory alloy steel casting, Focused on complex castings with free-form surface, key points during whole technical route, which includes three-dimensional modeling, foamed pattern design, mold design and CNC program, have been discussed by utilizing modeling & manufacturing module on Unigraphics. Because of its perfect free-form surface functions and plentiful toolpath operations in CNC programming, Foam mold of complex casting with free-form surface has been designed, manufactured and assembled successfully for LFC, Qualified foamed pattern of vortical shell has been produced successfully. Several effective methods and experiences have been achieved by utilizing CAD/CAM technology.

Abstract: Nano NiO is prepared by Parallel Dropping Concentration Gradient method(PDCG)with nickel nitrate hexahydrate,ammonia and Tween-80.The structures and morphology of Ni(OH)2•nH2O and NiO are characterized by DSC,XRD,SEM and FTIR.The results shows that because of the desorption of solvent and physical adsorbed water, the weight of precursor changes slowly during 40-280°C, while the weight of compound material changes quickly during 280-480°C because of the loss of chemical adsorbed water and the decomposition of Ni(OH)2. Above 480°C,the weight of sample changes unobviously. SEM shows that nano NiO soft gathered to form particles under the effection of surfactant. XRD shows that nano NiO prepared by PDCG was cubic crystal and with an average particle size of 3.8 nm.

Abstract: Based the CAE technology, the paper introduced the application of Moldflow Insight in injection mold design of mobile phone cover. First, we must preprocess the finite element model, including importing three-dimensional model, meshing, and process setting. And then, we can use preliminary simulation analysis to determine the number and location of the gate. Finally to filling, cooling, packing and warpage analysis for part which can help us to find the causes from warpage generated. By optimizing the molding process parameters, adjusting the dwell pressure and the dwell time we can get less warpage, which can meet the precision demand of parts, consequently, the result can provide gist for the mold designers to design and for the injection molding technologist to process parameter adjustment.

Abstract: The wire was made by Tungsten Carbide(WC) particles as core. MIG welding was used to surface iron-based WC wearable composite coating of different size and content of WC particles on mild steel. Microstructure was investigated. Surface rigidity and wear resistance were tested. The results indicate that the small particles are dissolved seriously, which separate out with reticulation. The hardness and wear resistance of the matrix are relative higher. The big particles are dissolved less, tree crystal separates out along particles. The particles are easy to fall off when wearing. So the hardness and wear resistance of the substrate are relative lower. The admixture with 80% big particles and 20% small particles has the best wear resistance, its wear resistance can achieve quintupling of quenching 45 steel. The hardness and wear resistance increase with content of WC increasing.

Abstract: With the development of global economy, energy situation has been more and more severe. The shortage of energy will no doubt be one of the bottlenecks, which restricts the social progess. Iron and steel industry is an important energy intensive industry, whose use of energy plays an important role in the national energy situation. Therefore, energy optimization is a serious topic for the iron and steel enterprises. Based on the systematic energy conservation, this paper raised the importance and necessity of Energy Management System for energy saving and optimization dispatching in Iron and Steel enterprises. It also describes its present situation and basic functions, in which general ways to the domestic construction of EMS are included. There is the analysis of the difficulty of its construction and solutions to it.