南极菲尔德斯半岛岛弧火山岩中的辉石

菲尔德斯半岛岛弧火山岩中的辉石有贫钙和富钙两类,前者由古铜辉石、紫苏辉石和易变辉石组成,后者包括透辉石、顽透辉石、次透辉石及普通辉石,以普通辉石为主。辉石的化学成分及其变化与寄主玄武岩浆的演化有密切联系。其端元组分呈有规律变化,基质中辉石微晶,Fs明显高于斑晶,Wo低于斑晶。其稀土元素含量与寄主岩的稀土总量呈正相关,轻稀土亏损,重稀土较富集,Eu具较小的负异常,δEu约为0.6。热力学计算表明结晶时的平衡温度为1053—1150℃,平衡压力为0.25—1.03GPa,氧逸度为10~(-6.3)—10~(-8.9)atm,斑晶晶出深度多数在10—25km,岩浆房可能位于下部地壳。     

西藏冈底斯中段晚侏罗-早白垩世花岗岩特征

对西藏冈底斯中段1∶25万措麦区幅区域地质调查中新发现的侵入于晚古生代地层中被古近纪林子宗群火山岩喷发沉积不整合覆盖的尼雄超单元、许如错超单元进行了解体,划分了7个单元。许如错超单元同位素年龄值154.2 Ma±3.8 Ma(锆石U-Pb)、141 Ma(锆K-Ar),时代为晚侏罗世,尼雄岩体中获锆K-Ar法年龄值114 Ma、106 Ma,时代为早白垩世,其地球化学及同位素特征反应两岩体为过铝型高钾钙碱性壳幔混合型花岗岩,形成于活动陆缘火山弧构造环境,为大陆弧花岗岩,与雅江洋向北和班-怒洋向南俯冲有关。     

臭氧发生系统中半导体制冷干燥装置的研制

本文介绍了未经过干燥处理的原料气进入电晕放电臭氧发生系统后的危害机理 ,根据半导体的制冷干燥机理 ,开发研制了实验室用半导体制冷干燥装置 ,实验证明该装置的研制是成功的。     

Double-electrode arc welding process: Principle,variants, control and developments

Double-electrode gas metal arc welding (DE-GMAW) is a novel welding process in which a second electrode, non-consumable or consumable, is added to bypass part of the wire current. The bypass current reduces the heat input in non-consumable DE-GMAW or increases the deposition rate in consumable DE-GMAW. The fixed correlation of the heat input with the deposition in conventional GMAW and its variants is thus changed and becomes controllable. At the University of Kentucky, DE-GMAW has been tested/developed by adding a plasma arc welding torch, a GTAW (gas tungsten arc welding) torch, a pair of GTAW torches, and a GMAW torch. Steels and aluminum alloys are welded and the system is powered by one or multiple power supplies with appropriate control methods. The metal transfer has been studied at the University of Kentucky and Shandong University resulting in the desirable spray transfer be obtained with less than 100 A base current for 1.2 mm diameter steel wire. At Lanzhou University of Technology, pulsed DE-GMAW has been successfully developed to join aluminum/magnesium to steel. At the Adaptive Intelligent Systems LLC, DE-GMAW principle has been applied to the submerged arc welding (SAW) and the embedded control systems needed for industrial applications have been developed. The DE-SAW resulted in 1/3 reduction in heat input for a shipbuilding application and the weld penetration depth was successfully feedback controlled. In addition, the bypass concept is extended to the GTAW resulting in the arcing-wire GTAW which adds a second arc established between the tungsten and filler to the existing gas tungsten arc. The DE-GMAW is extended to double-electrode arc welding (DE-AW) where the main electrode may not necessarily to be consumable. Recently, the Beijing University of Technology systematically studied the metal transfer in the arcing-wire GTAW and found that the desired metal transfer modes may always be obtained from the given wire feed speed by adjusting the wire current and wire position/orientation appropriately. A variety of DE-AW processes are thus available to suit for different applications, using existing arc welding equipment.     

电弧炉烟尘治理

某特种钢厂15t电弧炉产生的烟尘污染车间及周围环境。针对电弧炉冶炼的特点选用脉冲袋式除尘器对电弧炉产生的烟尘进行捕集除尘,设计了手动旋转分体捕集罩。使用结果表明:手动旋转分体捕集罩操作灵活方便,除尘效果达到设计要求。     

Modeling and simulation of arc: Laser and hybrid welding process

Welding is a fabrication process to join two different materials. Among the many welding processes, the arc and laser welding processes are the most widely used. Great effort is required to understand the physical phenomena of arc and laser welding due to the complex behaviors which include liquid phase, solid phase and, gas phase. So it is necessary to conduct numerical simulation to understand the detailed procedures of welding. This paper will present the various numerical simulation methods of the arc welding processes such as arc plasma, gas tungsten arc welding, gas metal arc welding, laser welding, and laser–arc hybrid welding. These simulations are conducted by the finite element method, finite differential method and volume of fluid method to describe and analyze the various welding processes.     

Microstructure and mechanical properties of alloy C-276 weldments fabricated by continuous and pulsed current gas tungsten arc welding techniques

Effects of switching over from gas tungsten arc welding (GTAW) to pulsed current gas tungsten arc welding (PCGTAW) on the quality of joints produced in Hastelloy C-276 material were investigated. Welding was carried out both by autogenous mode and using ERNiCrMo-3 filler wire. Microstructures of weld joints produced with and without current pulsing were studied using optical and scanning electron microscopy. Microsegregation occurring in GTAW and PCGTAW joints was investigated using energy dispersive X-ray spectroscopy (EDS). Strength and ductility of weld joints produced with and without pulsing were evaluated. The results show that pulsing results in refined microstructure, reduced microsegregation and improved strength of weld joints. Secondary phase(s) noticed in GTA weldments were found to be absent in PCGTA weldments. Autogenous PCGTA weldments were found to be the best in terms of: (i) freedom from microsegregation, (ii) strength and (iii) freedom from unwanted secondary phases.     

Metal-cored arc welding process for joining of modified 9Cr-1Mo (P91) steel

In the present work, metal-cored arc welding process was used for joining of modified 9Cr-1Mo (P91) steel. Metal-cored arc welding process is characterized by high productivity, slag-free process, defect-free weldments that can be produced with ease, and good weldability. Toughness is essential in welds of P91 steel during hydro-testing of vessels. There is a minimum required toughness of 47 J for welds that has to be met as per the EN1557:1997 specification. In the present study, welds were completed using two kinds of shielding gases, each composition being 80% Argon + 20% CO₂, and pure argon respectively. Microstructural characterization and toughness evaluation of welds were done in the as – weld, PWHT at 760 °C – 2 h and PWHT at 760 °C – 5 h conditions. The pure argon shielded welds (‘A2’ and ‘B2’) have higher toughness than 80% argon + 20% CO₂ shielded welds (‘A1’ and ‘B1’). Pure argon shielded welds show less microinclusion content with low volume fraction of δ-ferrite (<2%) phase. Themo-calc windows (TCW) was used for the prediction of equilibrium critical transformation points for the composition of the welds studied. With increase in post-weld heat treatment (PWHT) duration from 2 h to 5 h, there was increase in toughness of welds above 47 J. Using metal-cored arc welding process, it was possible to achieve the required toughness of more than 47 J after PWHT at 760 °C – 2 h in P91 steel welds.     

天津钢管100t电炉除尘工程

天津钢管100t电炉除尘项目为适应电炉的操作及提高烟气捕集率,减少除尘系统烟气量,采用第四孔捕集一次烟气,电炉跨屋顶罩捕集二次烟气的组合方式,间接水冷,间接风冷,混风降温的干法除尘,效果显著。针对此工程,分析除尘系统在设计、施工、运行中需要注意的关键技术,并对除尘工艺的发展作了前瞻性的探讨。     

直缝埋弧焊管氧化铁及粉尘的吸附处理装置

为了克服氧化铁厦粉尘等杂物滞留在直缝焊管缝内,设计并制作了吸附处理装置。介绍了该装置的结构照成、装置特点厘工作流程等＋实际应用表明,这套装置吸附分离效果良好。