Low-temperature formation and oxidation resistance of ultrafine aluminide coatings on Ni-base superalloy

Ultrafine aluminide coatings were successfully produced on Ni-18Fe-17Cr superalloy at 540-600 °C in a modified pack-aluminizing process. Repeated ball-impacts accelerated the formation of the aluminide coatings by a surface refining process, resulting in atomic diffusion occurring at a relatively low temperature. The effects of the operation temperature and the treatment duration on the formation of the coatings have been investigated. The coatings possessed a two-layer structure. The top layer, approximately 5 µm in thickness, exhibited equiaxial coarse grains and was dominated by NiAl₃, with small amounts of Fe₂Al₅ and CrAl₅. The bottom layer showed high density, homogeneous, ultrafine grains with diameters approximately 30-50 nm. High-temperature oxidation tests were carried out at 1000 °C. The oxidation kinetics and microstructure of the oxide scale were studied. The experimental results indicated that the coatings greatly enhanced the high-temperature oxidation resistance of Ni-18Fe-17Cr superalloy.     

Ways of improving the high-temperature work service of vanadium and some alloys used in reactors

We present new evidence for the high-temperature strength of vanadium and low-alloyed (up to 15 at.%) vanadium-based alloys under conditions of prolonged (up to 5000 h) high-temperature (973-1173 K) exposure to vacuum, helium, lithium and sodium melts, modeling reactor heat-transport media (10 Pa). The kinetics of phase transformations in alloys of the systems V-Zr-C, V-Nb-Zr-C, V-Mo-Zr-C, and V-Ti-O in the process of prolonged aging under stress is analyzed. It is established that the process of pre-decay of a solid solution has many stages and is intensified by the action of stresses. The corresponding isothermal diagrams of the decay of VTsU (V-Zr-C) alloy are constructed. We give recommendations as to the choice of alloying elements with the aim of enhancing the high-temperature strength of vanadium and vanadium alloys used for reactors. New alloys developed on the basis of the systems V-Ti-O, V-Nb-Zr, V-Ta-Hf, V-Cr-Sc, and V-Cr-Nd and a new method of strengthening thermochemical treatment of vanadium-titanium alloys with the use of oxygen from air have found application in pilot-engineering developments for high-temperature nuclear power plants.     

MgO和STO基片上制备YBCO高温超导薄膜生长研究

用AFM和XRD研究在MgO和STO基片上外延生长2-200nm的YBCO高温超导薄膜的生长机制。采用倒筒式直流溅射装置,首次实现单轴驱动双轴旋转技术,本质上实现同时在MaO基片和STO基片上沉积同一均匀厚度的YBCO薄膜。     

High-temperature oxidation and aqueous corrosion performance of ferritic, vacuum-sintered stainless steels prealloyed with Si

The corrosion behavior at high-temperature and the aqueous corrosion behavior of sintered stainless steels manufactured from non-commercial prealloyed powder (434L with 2% Si) are studied and their results are compared with those of sintered stainless steels manufactured from commercial 434L powder, that has lower Si content. Both types of powders have been sintered in vacuum at three different temperatures, so materials with different porosity levels have been obtained. Several oxidation tests have been carried out from 700 to 1000 °C. Long-term experiments have proven the better oxidation resistance of 434L + 2% Si steels. Electrochemical measurements of the corrosion rate show a decrease on this parameter caused by the increase of Si-content on powders.     

高温应变计焊接技术

结合合山电厂7号发电机组汽包高温应力测试,介绍了高温应变计焊接方法.利用旧变压器改装成一台高温应变计电焊机,试验结果表明该设备能够满足高温应力测试的应变计焊接要求,介绍的方法同样适合于将电弧焊机改装成高温应变计点焊机.     

（YBa2Cu3O7—y）1—xAgx体材料的超导性质

本文从混合硝酸盐水溶液出发制备Y、Ba、Cu氧化物粉体。在通氧、960℃×61小时烧结和550℃×45—60小时退火的条件下,大截面块状样品的临界电流(Ic)随加1-2wt%Ag_2O迅速升高,出现一极大值,然后随增加Ag_2O量至10wt%而显著下降。加入1.2—1.5wt%Ag_2O的小截面样品的临界电浇密度(Jc)达到1457安/厘米~2(78K、零场、判据1微伏/厘米)。对加入少量Ag_2O提高YBCO体材料Jc的问题作了讨论。     

高温耐磨蚀涂层在循环流化床锅炉水冷壁中的应用研究

本文综述了目前国内外常用的几种循环流化床锅炉水冷壁用高温耐磨蚀涂层,并对各种涂层的应用现状、性能作了简要分析,提出高速电弧喷涂镍基高铬合金涂层和Fe3Al金属间化合物涂层具有良好的发展前景。     

HTR-10控制棒磁涡流阻尼器研究

高温气冷堆控制棒磁涡流阻尼器是控制棒传动机构中的重要部件，其主要作用是利用磁涡流阻尼效应来降低事故落棒过程中的落棒速度，养活事故落棒对传动机构所造成的冲击。本文采用有限元分析方法，对磁涡流阻尼器的磁场进行了模拟和计算，分析了阻尼器的内部结构尺寸和环境温度对其工作特性的影响。并通过传动机构的性能试验，验证了有限元模拟计算以及阻尼器设计的合理性和可靠性，同时证明了从理论上对阻尼器进行前期设计的可行性。