2VQS发动机气缸罩冲压成形数值模拟分析

本文应用Ｌｓ－Ｄｙｎａ３ｄ非线性有限元件对桑塔纳２０００型轿车ＶＱＳ发动机气缸罩冲压成形过程进行了详尽的有限元模拟分析，通过与实测结果的比较、表明有限元预测结果可靠的。     

微液滴现象与大气腐蚀——Ⅰ.微液滴的形成与扩展

采用改变相对湿度、无机盐粒/金属组合和环境气氛等参数的方法研究了微液滴形成、生长的特征及其与大气腐蚀过程的关系.结果表明,微液滴形成和生长与气氛中氧和相对湿度及盐粒/金属组合密切相关.在大气环境中,微液滴形成和生长需要两个前提条件:第一,环境相对湿度须高于盐粒水解液滴液面的饱和蒸气压;第二,水解液滴下的金属应能被液滴腐蚀.     

Formation and growth model of B-Al permeation layer of Steel 45

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｓＢ Ａｌｐｅｒｍｅａｔｉｏｎｅｆｆｅｃｔｉｖｅｌｙｄｅｔｅｒｓｔｈｅｆｏｒｍａ ｔｉｏｎｏｆＦｅＢ ,ｔｈｅｂｒｉｔｔｌｅｎｅｓｓ[1～ 4 ] ,ｈａｒｄｎｅｓｓ ,ｔｈｅｒｍａｌｓｔａｂｉｌｉｔｙａｎｄｗｅａｒｉｎｇａｂｉｌｉｔｙｏｆ     

咪唑啉表面活性剂的合成及用于制备ZnSe纳米材料

合成了两种咪唑啉型双子表面活性剂二（2-十一（十七）烷基-1-甲酰胺乙基咪唑啉）己二胺季铵盐（SUAEIHDI、SHAEIHDI），并进行了红外表征；然后以Zn（Ac）2-2H20为锌源，硒粉为硒源，水合肼为还原剂，SUAEIHDI为表面修饰剂，采用水热法于150℃反应24h，制得球形ZnSe纳米材料，用TEM、SEM、IR、UV-vis和XRD等手段对ZnSe纳米材料进行了表征，并对球形ZnSe的形成机理进行了初步探讨。结果表明：该咪唑啉型双子表面活性剂对于纳米材料具有良好的形貌控制作用和表面修饰作用。     

Application of multiscale modeling in the coating formation simulation of APS PYSZ TBCs

The process parameters of atmospheric plasma spraying (APS) influence the coating formation and properties of partially yttria stabilized zirconia (PYSZ) thermal barrier coatings (TBC). Simulations can be used to investigate this dependency and to design the coating process for a targeted production of TBCs. A whole process simulation was realized by modeling the linked subprocesses: plasma torch, plasma free jet, powder particles characteristics, and coating formation. The coating formation can be described by model approaches with different physical assumptions and geometric scales. One approach is the simulation of single powder particles hitting the substrate surface. An alternative macroscale finite element model (FEM) model approach is applied in the coating formation simulation. A group of particles is pooled in a splash that is dependent on the precalculated particle distribution in front of the substrate. A third modeling approach is applied to calculate effective mechanical and thermodynamical properties of coatings dependent on the experimentally obtained or calculated microstructure of the PYSZ TBC, which is based on different homogenization methods. The application of three simulation approaches in the whole process simulation of APS is discussed; advantages and disadvantages are elucidated. Results based on simulation and experiments are presented for a variation of process parameters. Missing links in the multiscale approach are detected to make suggestions for future modeling and simulation work. This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.     

大块非晶合金的形成能力及研究进展

综合评述了大块非晶合金形成的控制因素，从热力学、动力学和结构三个方面讨论了大块非晶合金的形成机理；并简介了大块非品合金的制备技术和研究现状。     

STUDY ON NON-SINUSOIDAL OSCILLATION FOR SLAB CONTINUOUS CASTING MOLD WITH HIGH CASTING SPEED Ⅰ. Mechanism of Oscillation Marks Formation

通过分析2.0 m/min拉速稳定浇铸时振动周期内弯月面初凝坯壳的受力情况,阐述了高拉速连铸坯表面振痕形成过程,给出振动参数与最大液体摩擦力和最大保护渣渣道动态压力关系;结合振动参数对振动过程参数的影响和实际设备状况,提出了振动参数优化方向,确定了拉速升至2.2 m/min时的振动参数值.结果表明,弯月面初凝坯壳在钢水静压力、摩擦力和保护渣渣道压力作用下随凝固进程形成振痕,振痕生成位置取决于初凝坯壳糊状区固相分率;随拉速提高,应降低振频、增大振幅和非正弦振动因子,以改善振动效果和振痕形貌;拉速升至2.2 m/min时的适宜振频、振幅和非正弦振动因子分别为145 min-1,±5.0 mm和0.25.     

螺旋焊管成型辊的分析

为了消除螺旋焊管成型过程中压痕等缺陷,提高焊管质量,延长成型辊寿命,分析了螺旋焊管在成型过程中,三辊与管壁不发生相互滑动的情况下,即在纯滚动的理想工作状态下,三辊工况的共性和特性与辊面形状;探讨最接近理想状况的辊面形状,并就目前生产中存在的问题提出解决方案。     

Analytical and experimental study of shear localization in chip formation in orthogonal machining

A simplified theory of instability of plastic flow is applied to analyze the formation of shear localized chips in orthogonal machining. A flow localization parameter is expressed in terms of associated cutting conditions and properties of the workpiece material. The analysis, which indicates the important parameters in the cutting process, is used to investigate the effect of cutting conditions on the onset of shear localization and the formation of adiabatic shear banding in metal cutting. Comparisons are made between the analysis and experiments in which the flow localization parameter is obtained for several workpiece materials. The results of this investigation seem to support the analysis and its potential benefits in analyzing and/or remedying problems associated with chip formation and temperature generated in metal cutting. Presently at Advanced Technology Center, Valenite, Inc., Madison Heights,MI 48071, USA     

Effect of gas composition on cementite decomposition and coke formation on iron

Cementite decomposition and coke formation in the metal dusting process of iron were investigated at 700 °C in CO-H₂-H₂O gas mixtures. The presence of graphite deposited on the surface initiates the decomposition of cementite into iron and graphite. The morphology of the reaction products varies with gas composition. For CO concentrations less than 5 vol%, particles of iron or even closed iron layers have been observed at the cementite/graphite interface. With increasing CO content the amount of iron in the interface decreases. At CO concentrations higher than 30 vol%, iron could not be detected at the interface by optical microscopy. Thermo-gravimetric analysis shows that the rate of carbon take-up increases with increasing CO concentration reaching a maximum at about 60-75 vol%.The morphologies of graphite in the coke layer can be identified as three types: porous graphite clusters with embedded iron-containing particles, compact bulk graphite with a uniform thickness and a columnar layered structure, and filamentous carbon with iron-containing phases at the tip or along its length. For gas mixtures with low CO concentrations, e.g. 5 vol%, porous graphite clusters are the main form of carbon although filamentous carbon can be seen at the early stage of reaction. With increasing CO concentrations to, e.g. 30 vol%, a compact bulk graphite is formed on the top of the surface. Under this compact graphite, there is an inner layer of graphite which is the combination of porous graphite clusters and filaments. These two layers of graphite are clearly distinguishable when CO content reaches more than 75 vol%. In this case, the main form of graphite in the inner layer is filamentous carbon. The compact graphite layer suffers a serious deformation and forms many cracks because of the growth of catalytic filamentous carbon underneath. These filaments grow outside from compact graphite crevices and finally cover the whole surface. The higher the CO content in the gas, the more the tendency of filamentous carbon formation. The interplay between morphologies of carbon formation and metal dusting has been discussed.