水泥砂浆衬里在输水钢管内壁防腐中的应用

结合工程实例,阐述了在输水水质腐蚀性不大的情况下,输水钢管的内壁防腐采用水泥砂浆衬里的必要性和优点,并介绍了设计要点和安装施工注意事项。     

Improving Short-Circuit Current Capacity, Resistance, and Breaking Load of OPGW Constructions by Modifying Aluminium Alloy With AlB2

This article presents a method that can be applied to molten AA-6101 alloy to improve electrical properties of the aluminium part of the optical ground wire (OPGW) used in overhead transmission lines to protect phase conductors from lightning strike and to transmit signals and data. AA-6101 alloy in casting of the log as 6 m length and 178 mm diameter for extrusion has been inoculated by AlB₂ to decrease detrimental effects of Cr, Ti, V, and Zr on the conductivity of the material. After inoculation, improved billets were extruded as 9.5 mm diameter feedstock. Required wires drawn from the feedstock according to the construction types of OPGW to be tested were exposed to aging at 175°C, 6 h (T-8). Upon completion of the back-twist and performing-type stranding process, resistance, and short-circuit current capacity and breaking load of the OPGW 88/44 constructions with other metal combinations have been examined and tested to show improvement. Results are summarized in tables and graphically.     

Vapor absorption by LiBr aqueous solution in vertical smooth tubes

Heat and mass transfer in a falling film vertical in-tube absorber was studied experimentally with LiBr aqueous solution. The presented results include the effect of solution flow rate, solution subcooling and cooling water temperature on the absorption in a smooth copper tube 16.05 mm I.D. and 400 mm long. The experimental data in the previous report for a 1200-mm-long tube was also re-examined and compared. It was demonstrated by the observation of the flow in the tube that the break down of the liquid film into rivulets leads to deterioration of heat and mass transfer at lower film Reynolds number or in longer tubes. An attempt to evaluate physically acceptable heat and mass transfer coefficients that are defined with estimated temperature and concentration at the vapor–liquid interface was also presented.     

Determining the Instantaneous Effective Energy of x-Ray Tube Bremsstrahlung

A method is described for determining the instantaneous effective energy of x-ray tube brehmsstrahlung by means of two semiconductor detectors employing epitaxial GaAs structures and a measurement circuit, which together determine the effective energy with an error of 5% in the range 20–80 keV in the presence of nonlinearity in the detector response.     

魏氏组织对20#碳钢H2S应力腐蚀开裂性能的影响

文章对H₂S-CO₂-H₂O腐蚀环境下发生H₂S应力腐蚀的20^＃碳钢弯管（无缝钢管）进行了成分、组织、拉伸、硬度和应力腐蚀开裂等性能的试验研究，并与同材质、同时投产、腐蚀环境基本相似而未发生应力腐蚀开裂的在役弯管及未使用的新弯管作对比，结果表明魏氏组织是引起20^＃钢发生应力腐蚀开裂的主要原因；正火能消除魏氏组织，降低钢的应力腐蚀开裂敏感性。     

大功率半导体激光熔覆高速钢研究

使用2kW半导体激光在工具钢表面熔覆高速钢粉末。在同轴送粉的粉末汇聚点与激光的聚焦点可获得无裂纹的熔覆层。随着激光功率的增加,熔覆层厚度和粉末利用率增加,同时基体对熔覆层的稀释率下降。获得的熔覆层的硬度达到800Hv0.3,基体硬度200Hv0.3,表明大功率半导体激光在表面熔覆领域具有很好的应用前景。     

基于PDP机理的两种超大屏幕显示

超大屏幕显示系统优点甚多，正越来越受到各行各业的关注。近年来，若干种超大屏幕显示已在市场出现，但各有利弊。本文介绍基于PDP工作机理开发成功的两种新型超大屏幕显示器件，包括其结构、性能、特点，以及在超大屏幕显示系统中的应用。     

珠光体球化的分形研究

珠光体球化反映到金相上，是一种不规则图像的变化，并且具有分形的特征，可望用分形几何的方法来进行描述。以Cr-Mo钢的珠光体球化为例，用分形维数来描述珠光体球化程度；用小岛法对15CrMo钢的珠光体球化图谱进行了测量。实验表明，珠光体球化从1级到6级，其相应的分形维数范围为1.3156-1.9282。从电厂运行了10^5h的15CrMo钢管上取样，实测了该试样的珠光体球化等级，结果表明，以分形维数表示的球化程度与按图谱评定的球化等级完全吻合。     

热作模具钢表面激光堆焊耐磨合金层的研究

本文主要通过在H13钢上用大功率CO_2激光束进行堆焊,阐述了激光堆焊工艺变化对堆焊组织和性能的影响,在本试验条件下,得到了高密度弥散金属化合物组织的激光堆焊层,平均硬度为HV800,与基体呈冶金结合,耐磨性比H13模具钢提高149%。     

薄壁圆筒试样的扭转断裂曲线

通过比较多种材料的光滑薄圆筒和切口薄壁圆筒试样的扭断裂曲线，测向两种试验的断裂韧性ＫＩＩＣ相同，从而间接证实了利用光滑薄壁筒测定延性金属断裂韧性ＫＣ方法的正确性。