不锈钢管道坡口加工的新方法

对于不锈钢管及合金钢管坡口的加工,采用以往的加工方法切割出来的坡口一般参差不平、比较粗糙,难于打磨平整。使用LGK空气等离子切割机和磁力管道切割机的组合加上一定的辅助手段,改善了不锈钢管及合金钢管的坡口加工效果,使加工出来的坡口像碳钢管一样平整,更加容易打磨组焊。文章介绍了这一新方法所用的设备、材料、切割原理以及操作过程。     

Improving narrow bandgap a-SiGe:H alloys grown by hot-wire chemical vapor deposition

We have improved the electronic properties of narrow-bandgap (Tauc gap below 1.5 eV) amorphous-silicon germanium alloys (a-SiGe:H) grown by hot-wire chemical vapor deposition (HWCVD) by lowering the substrate temperature and deposition rate. Prior to this work, we were unable to grow a-SiGe:H alloys with bandgaps below 1.5 eV that had photo-to-dark conductivity ratios comparable with our plasma-enhanced CVD (PECVD) grown materials [B.P. Nelson et al., Mater. Res. Soc. Symp. 507 (1998) 447]. Decreasing the filament diameter from our standard configuration of 0.5 mm to 0.38 or 0.25 mm provides first big improvements in the photoresponse of these alloys. Lowering the substrate temperature from our previous optimal temperatures (T_sub starting at 435 °C) to at 250 °C provides additional photo-to-dark conductivity ratio increasing by two orders of magnitude for growth conditions containing 20–30% GeH₄ in the gas phase (relative to the total GeH₄+SiH₄ flow).     

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.     

Al-10Mg型固溶合金自然时效稳定性研究

测定了ZL30 5合金自然时效 33年的力学性能变化 ,观察了晶界的析出相 ,研究了组织和性能的关系 ,从而确定了ZL30 5合金具有长期自然时效稳定性。     

Effect of Stoichiometry on Properties of Rare-Earth-Based Hydrogen Storage Alloy for Nickel-Metal Hydride Secondary Battery

Effect of stoichiometry on microstructures, electrochemical properties and PCT characteristics of the alloys MI(Ni0.71Co0.15-Al0.06Mn0.08)x (MI=Lanthanum-rich Michmetal, x=4.6~5.2) have been investigated. The lattice constants a, c, and cellvolumes of non-stoichiometric alloys are bigger than those of the stoichiometric alloy. With the increasing stoichiometry x,the value of a decreases, and the value of c and cell volume increases except for those of the stoichiometric alloy; the plateaupressure of PCT curve, discharge capacity and cycling stability all increase. The alloy with x=5.2 shows the highest dischargecapacity and the best cycling stability among the studied alloys.     

机械合金化Fe-Ni粉末的相结构

使用XRD和Moessbauer等方法，研究了在Ar气氛下机械合金化Fe—Ni粉末相结构的变化．结果表明，在机械合金化Fe64-Ni36粉末过程中，fcc相的数量随着球磨时间的增加先增加然后减少，与加乙醇球磨Fe64-Ni36的情形相同．当Ni的含量(原子分数)大于50％时，有fcc相、顺磁相和FeNi3形成，当Ni的含量低于50％时，bcc相的数量随着Ni含量减少而增加．Moessbauer谱的结果表明，因球磨时间或Fe、Ni比例的不同，Fe—Ni球磨粉末固溶体具有不同结构的原子配比。     

大块非晶合金的性能、制备及应用

综述了大块非晶合金的性能、制备方法及应用，对比了吸铸法制备的棒状Zr41.2Ti13.8Cu12.5Ni10Be22.5,Zr57Cu20Al10Ni8Ti5,Zr52.5Ti5Cu17.9Ni14.6Al10(原子分数)大块非晶样品的过冷温度区间宽度(△Tx)，给出了3种大块非晶合金系列的热稳定性参数Tg、Tx及△Tx，提出了大块非晶合金领域存在的问题及发展方向．     

Finite element analysis of femoral components paper III – hip joints

Finite element analysis of the hip implant is conducted in this paper for representative femoral cross-section geometries and development of stress in the presence of bone cement is elucidated. Differences in cement stresses generated by varying implant cross-sections were compared with conventional features derived from representative implants. The analysis was performed under idealized implant assemblies by constraining the implant movement in the assembly. The cross-sections and implant geometries used are generic and intended to be representative of available geometries. This paper is a part of student research projects, prepared from a series of activities in biomedical implant research currently underway at Ohio Northern and Arkansas Tech Universities.     

Intergranular corrosion of a light aircraft aluminum alloy propeller

Examination of the wreckage of a light aircraft revealed that approximately 20 cm was missing from one tip of the aluminum alloy propeller. Fractographic and metallographic examination of the remaining portion of the propeller revealed extensive grain-boundary separation in the vicinity of the fracture, and grain edges and corners rounded by corrosion on the fracture surface. Energy dispersive X-ray analysis (EDXA) revealed fluorine on, and in the vicinity of, the fracture surface. In the ensuing litigation, it was asserted that the crash occurred because the propeller fractured in flight as the result of intergranular attack caused by the use of a fluorine-bearing cleaner.     

激光熔覆专用铁基合金粉末的研究进展

指出了目前防止熔覆层开裂所采取的主要措施中存在的问题,阐述了激光熔覆和热喷涂对于所用合金粉末性能要求之异同,评述了激光熔覆专用铁基合金粉末的研制现状,提出了成分与组织设计的新思想。