湿硫化氢环境下换热器管束的防腐改造

针对原有管束使用周期短、腐蚀现象严重的情况进行了综合分析,将原管束材质由10号碳钢更换为抗湿硫化氢应力腐蚀效果明显的08Cr2AlMo材质。在随后的设备运行周期内延长了管束的使用期限,降低了修理费用,具有良好的社会效益和经济效益。     

SF6/O2气氛中SiC ICP刻蚀的微沟槽效应

本文采用SF6 + O2作为刻蚀气体,对单晶6H-SiC 材料的感应耦合等离子体( ICP) 刻蚀工艺进行了研究。着重分析了ICP 功率、偏置电压、气体混合比等工艺参数对微沟槽效应的影响。结果表明,O2的加入对于微沟槽的形成起到了极其重要的作用,微沟槽是加入氧气后形成的SiFxOy中间层的充电造成的。ICP功率与偏置电压的增大会增强微沟槽效应,进一步促进微沟槽的形成,另外入射离子的角度分布也会影响微沟槽的形成.     

Three-dimensional numerical study on thermal performance of a super large natural draft cooling tower of 220m height

Based on the heat and mass transfer theory and the characteristics of general-purpose software FLUENT, a three-dimensional numerical simulation platform, composed of lots of user defined functions（UDF）, has been developed to simulate the thermal performance of natural draft wet cooling towers（NDWCTs）. After validation, this platform is used to analyse thermal performances of a 220m high super large cooling tower designed for inland nuclear plant under different operational conditions. Variations of outlet temperature of the cooling tower caused by changes of water flow rates, inlet water temperatures are investigated. Effects of optimization through non-uniform water distributions on outlet water temperature are discussed, and the influences on the flow field inside the cooling tower are analyzed in detail. It is found that the outlet water temperature will increase as the water flow rate increases, but the air flow rate will decrease. The outlet water temperature will decrease 0.095K and 0.205K, respectively, if two non-uniform water distribution approaches are applied.     

Preparation and characterization of Z-type hexaferrites, Ba3(1−x)Sr3x Co2Fe24O41 with x = 0–0.5, via a two-step calcination with an intermediate wet milling

Z-type hexaferrites (Ba_{3(1 − x)}Sr_3x Co₂Fe₂₄O₄₁with x = 0–0.5, Z-hex) were prepared in a nearly phase pure state by a two-step calcination with an intermediate wet milling. The first calcination of the starting mixture comprising oxides or hydroxides at temperatures below 1100^∘C brought about a mixture of layer-structured M and Y-type hexaferrite phases, together with a spinel phase of Co ferrite. Z-hex was fully crystallized after the second calcination up to 1230^∘C. Wet milling between the two calcination steps was decisive for the phase purity. Emphasis was laid on the quantitative analyses of Z-hex, together with the evaluation of anisotropic growth of the crystallites. Sr addition stabilizes Z-hex, while decreases degree of anisotropy simultaneously.     

过孔刻蚀工艺优化对过孔尺寸减小的研究

为了适应TFT-LCD小型化与窄边框化以及在面板布线精细化的趋势,提高工艺设计富裕量以及增加面板的实际利用率,之前做过钝化层沉积工艺优化来减小液晶面板阵列工艺中连接像素电极与漏极的过孔尺寸的研究。本文在此基础上进行过孔刻蚀工艺的优化,从而最终达到进一步减小过孔尺寸实现TFT-LCD小型化与窄边框化的趋势。通过设计实验考察了影响过孔大小刻蚀主要影响因素(功率、压强、气体比率、刻蚀速率选择比)。实验结果表明,在薄膜沉积优化的基础上可使过孔的尺寸再降低10%~20%。对其进行了良率检测与工艺稳定性评价,最终获得了过孔尺寸减小的方案,并成功导入到产品生产中,从而提高了产品品质。     

高能球磨制备NdFeB纳米晶粉末

利用湿法球磨制备了NdFeB纳米晶粉末,并通过对比发现湿法球磨比干法球磨效果好。研究结果表明,当湿法球磨超过210h,粉末变成细小、均匀的圆球状的小颗粒,颗粒直径在80～120nm之间,在本实验条件下颗粒尺寸已经趋向极限。粉末最终变成以Nd2Fe14B为基体相的合金。     

一种具有应力隔离结构的扭摆式电容加速度计

基于硅-玻璃键合工艺的扭摆式加速度计,其信号输出对扭转梁上的应力极敏感,而微加工过程中由于硅、玻璃两种材料热膨胀系数不匹配,会在扭转梁上引入较大的热应力,进而引起加速度计温度漂移。为此,提出一种具有应力隔离结构的扭摆式电容加速度计。通过缓冲折叠梁和内支撑框架的优化组合,使热应力难以传递到扭转梁上,从而有效降低加速度计的温度漂移。使用ANSYS软件对加速度计进行了模态和热应力分析,结果表明:工作模态的固有频率为1 352 Hz,远小于其他干扰模态的频率;加速度计的灵敏度为0.386pF/g(g=9.8m/s2);相同条件下,不带隔离结构的扭摆加速度计的热应力主要集中在扭转梁的末端,其最大应力约100 MPa;具有应力隔离结构的加速度计,其热应力主要集中在缓冲折叠梁上,而扭转梁上的应力约为1.7 MPa,仅为前者的1.7%。采用硅-玻璃键合和电感耦合等离子体(ICP)刻蚀工艺,完成了加速度计芯片的制作。     

石灰石-石膏湿法脱硫系统的经济运行

介绍台山电厂2×600 MW机组石灰石-石膏湿法烟气脱硫系统实现经济运行的经验,给出了降低电耗、水耗、石灰石耗量的具体措施。两年多的运行实践表明,机组在额定工况下,在保证脱硫效率达95%的前提下,台山电厂脱硫系统多项运行指标均优于设计值。     

RESEARCH ON DESIGN METHOD OF A MULTIPLE DISC WET BRAKE IN LUBRICATED ENVIRONMENT

The rmomechnical phenomena occurring between friction pairs greatly change the distributions oflining pressure and friction surface temperature of a multiple disc wet brake. It has become one of the maincauses of brake failure. In order to understand these thermomechanical phenomena, several design and mate-rial factors tha have great influence on thermomechanical phenomena, such as heat transfer coefficient, fric-tion factor, sliding velocity initial lining pressure and so on, are analyzed. An isothermal design method isproposed for designing a multiple disc wet brake.     

Safety assessment aspects of type B(U) packages containing wet intermediate level waste

Abstract

In Germany, the mechanical and thermal safety assessment of approved packages for the transport of RAM is carried out by BAM as the competent authority according to the International Atomic Energy Agency regulations. BAM was involved in several approval procedures with ductile cast iron containers containing wet intermediate level waste. These contents, which are not dried, only drained, consist of saturated ion exchange resin and a small amount of free water. Compared to the safety assessment of packages with dry content, attention must be paid to some more specific points. The physical and chemical compatibility of the content itself and of the content with materials of the package must be shown. From the mechanical resistance point of view, the package has to withstand the forces resulting from the freezing liquid. The most interesting point, however, is the pressure build-up inside the package due to vapourisation. This could be caused by radiolysis of the liquid and must be taken into account for the storage period. The paper deals primarily with the pressure build-up inside the package caused by the regulatory thermal test (30 min at 800°C) as part of the cumulative test scenario under accident conditions of transport. To determine the pressure, the temperature distribution in the content must be calculated for the whole period from the beginning of the thermal test until cooling down. In this case, calculating the temperature distribution requires, besides the consideration of conduction and heat radiation, consideration of evaporation and condensation including the associated processes of transport.