Computer Simulation of the Process of Quenching Large-Size Parts in Water and Aqueous Solutions

DESPITE of the rapid development of computerfacilities and numerical methods of computing thestress-strain state of large-size parts,the accuracy ofcomputations is not sufficient because of the lack ofaccurate input data.For this reason,heat treatingengineers do not trust computations and are afraid ofquenching of large-size parts in water,in particular,when Bi—>°°.There are some causes of suchsituation:1)Because of inaccurate boundary conditions andincomplete information on mechanical p…     

多孔材料:现状和发展趋向

本文评论了近半个世纪以来有关多孔材料的现状和发展趋向。指出了利用多孔材料的孔隙度、孔径分布、渗透性及缓冲能力、毛细管引力、电阻、耐磨性、高的比表面及表面张力等性质,而在可渗透材料、轴承、蓄电池、燃料/空气电池、医学领域、密封圈、灯芯、发散冷却、振动缓冲、模的润滑、原子能工业等方面的应用。较为详细地叙述了多孔材料在过滤、轴承、碱性蓄电池电极板三方面的应用。同时也指出了多孔材料     

PROPERTIES, WELDABILITY AND APPLICATIONS OF ADVANCED WROUGHT SUPERALLOYS FOR GAS TURBINE ENGINES

Alloy selection and alloy design both require consideration of an array of material attributes, including in-service properties, weldability and fabricability. Critical properties of advanced wrought superaUoys for gas turbine applications include high temperature strength, thermal stability, oxidation resistance and fatigue resistance. In this paper, the properties of twelve wrought solid-solution-strengthened and six age-hardenable superalloys are compared. Weldability is an important attribute and can be a major limiting factor in the use of certain alloys. Weldability test methods are discussed and the resistance of alloys to solidification cracking and strain-age cracking is compared. The use of weldability testing in the development of modern wrought superalloys is discussed with several examples cited. Finally, alloy selection for gas turbine components is outlined, taking into account both alloy properties and fabricability.     

A302B类钢室温疲劳试样的断口组织照片和显微组织分析

<正> 本文通过对A302B类铁素体压力容器钢室温试验的试样显微镜分析,描述材料的断裂过程并确定它与疲劳裂纹扩展数据的关系。断裂试样用了扫描电镜(SEM)、电子照相技术和能散X射线显微分析作检查。对切自T-L方向的试样的断面所作的扫描电镜检查披露了存在着在所观察倒的ΔK临界值以上时夹杂物带。随后所进行的X射线影象扫描以及目对应的能谱表明带区是硫化锰夹杂。这些试样在夹杂物带区上的裂纹扩展速度与L-T向试样相仿。产生夹     

热载荷下A1203—球铁、ZrO2—A1—Si合金，以及ZrO2球铁热障涂层中热应力的产生的比较

表面处理技术如等离子喷涂、物理气相沉积、化学气相沉积已经被方便得用来制备用于高科技应用方面的复合涂层。高温涂层的目的主要有两点，第一是保护基体材料免受侵蚀，第二是提高耐磨性，另外对于热障涂层还有第三个功能就是使基体材料免受高温。在本研究中，用有限元方法对A1203—球铁、ZrO2—A1—Si合金，以及ZrO2球铁热障涂层在热载荷下的热应力产生和发展进行了分析，涂层与基体的厚度比为1／10，ZrO2球铁之间的梯度层为NiAl，NiCrAlY和NiCoCrAlY，这些因素都考虑到模型中去，计算了关键的界面区域(涂层/中间层/基体)的名义应力和剪切就布告并进进行了比较，结果表明ZrO2球铁的抗热冲击性能最好。此外，梯度层对热应力的产生程度有显著影响。本研究也表明，有限元方法可以用于优化陶瓷涂层的设计和生产。     

MODELING OF CONTROLLED THERMO-MECHANICAL PROCESSING OF TUBES FOR ENHANCED MANUFACTURING AND PERFORMANCE

1.IntroductionApproximately15milliontonsofsteeltubeandpipeproductsareconsumedintheUnitedStatesannually.Mechanicaltubesarethefeedstocksusedinthemanufactureofrollingelementbearings,hydrauliccylinders,alldagreatvarietyofpowertransmissioncomponents.Steeltubesarealsoemployedinthedrillstringsforoilandnaturalgasexplorationandrecovery.Steelpipesareusedinthetransportofgas,oilandotherfluids.ControlledThermal--MechanicalProcessing(CTMP)involvesprecisecontroloftemperature,mechanicaldeformation,andmicr…     

Nd_xB_（20－x）Fe_（78）Cu_（0．3）Co_（1．7）系非晶合金

本文测量了经不同温度和时间真空退火的非晶合金带Ｎｄ_ｘＢ_（２０－ｘ）Ｆｅ_（７８）Ｃｕ_（０．３）Ｃｏ_（１．７）（ｘ＝０．１，２，３，４，５），在１ｋＨｚ交流电下的磁化曲线，发现含少量Ｎｄ的非晶合金带在晶化温度附近真空退火后、起始导磁率减小，饱和场增大，使材料从软磁性向硬磁性转化；随着Ｎｄ含量的增加，这种转化重明显．Ｘ射线衍射透射电镜观察及电子衍射分析表明，材料在初期晶化时能析出颗粒大小为５－１００ｎｍ的针状纳米晶，且随着Ｎｄ含量增加，针状纳米晶的数量增多，这一现象与材料磁性测量的结果吻合．     

设计电解槽阳极时应考虑的因素

序言铝工业趋向采用低电流密度的大型多爪头阳极,所以考虑对使用中阳极有影响的起作用的机械应力和热应力的设计因素变得更加重要。设计时应该使合成应力不超过碳块的机械强度极限,同时要使钢爪和碳块间的接触电压降为最小。     

光解制氢材料的构筑及其性能

探讨了利用太阳能光解水制氢的有关材料和技术,概述了本文作者及其合作者近几年来在新型高效光解水制氢材料的设计和制备方面取得的研究进展.以雀巢结构、层间插入、桥架构筑以及氮化掺杂等技术为手段,研制了多种纳米复合半导体光催化材料,探讨了材料的组成、结构以及添加正孔捕捉剂对光解水性能的影响.研究结果表明:通过表面雀巢结构和层间复合物修饰能使助催化剂和基体紧密结合,有利于自由电子的快速迁移和自由电子与正孔的有效分离.采用层间插入CdS和氮掺杂等手段优化了能带结构,吸收边延伸至550 nm以上.NaS2的添加起到正孔捕捉剂的作用,促使自由电子连续产生,从而显著提高了产氢率.     

Ultra-low noise single-photon detector based on Si avalanche photodiode

We report operation and characterization of a lab-assembled single-photon detector based on commercial silicon avalanche photodiodes (PerkinElmer C30902SH, C30921SH). Dark count rate as low as 5 Hz was achieved by cooling the photodiodes down to -80 °C. While afterpulsing increased as the photodiode temperature was decreased, total afterpulse probability did not become significant due to detector's relatively long deadtime in a passively-quenched scheme. We measured photon detection efficiency >50% at 806 nm.