水平弯管含砂分散泡状流冲蚀机理分析

目的揭示水平弯管含砂分散泡状流的冲蚀机理。方法构建气液固多相流冲蚀实验环道,研究管道内流体流动状态及管道三维冲蚀速率。采用显微分析方法研究管道冲蚀形貌,并提出基于VOF模型和DPM模型耦合的瞬态冲蚀仿真方法。实验与仿真相结合分析管道内部气液分布、颗粒运动对冲蚀形貌的影响。结果弯管冲蚀最严重区域出现在弯头出口处(θ=90?),而冲蚀最严重位置则出现在该截面φ=45?以及φ=90?两个位置上。仿真可知整个弯管冲蚀严重的区域边界呈现出较为均匀的抛物线形状。砂粒对弯管的冲蚀作用主要以冲击变形和微切削摩擦为主,砂粒的直接冲击碰撞导致试样表面产生密集冲蚀坑,冲蚀坑周围有基体材料外翻形成的"唇片"。分散泡状流中的固体颗粒大部分分散在液相中,弯头处滞止区使得弯头处截面的含液率及颗粒含量大于上下游直管段截面。气体的存在改变了砂粒在管道中的运动状态,大大加剧了弯管的冲蚀。结论水平弯管含砂分散泡状流冲蚀严重区域、冲蚀形貌与管道内部气液分布及砂粒运动直接相关,多相流冲蚀瞬态仿真方法可准确地预测管道冲蚀。     

钛合金深海应力腐蚀研究进展

基于对钛合金应用及研究报道的梳理,综述了钛合金深海应力腐蚀产生原因及机理,探讨了静水压力、溶解氧含量、pH值和温度等深海环境因素对应力腐蚀开裂的影响,以期为今后钛合金深海应力腐蚀开裂等局部腐蚀行为及机制的深入研究提供参考,为优化钛合金组织性能,建立深海先进钛合金材料体系提供支撑。     

Effect of ZnO on the corrosion of zinc,Q235 carbon steel and 304 stainless steel under white light illumination

This paper discusses the effects of the coupling of ZnO–Zn, Q235 carbon steel, and 304 stainless steel on their corrosion in 3.5% NaCl under white light illumination. In the presence of Na₂S, ZnO provided photoelectrochemical cathodic protection for the coupled metals. In the absence of Na₂S, ZnO could only provide photoelectrochemical cathodic protection for 304 stainless steel. Under white light illumination, the open circuit potential of ZnO photoelectrode shifted in the negative direction. ZnO provided photoelectrochemical cathodic protection to the metals only when the open circuit potential of ZnO photoelectrode was more negative than that of the metals.     

In Brief

• United States Patent and Trademark Office
• Datakey
• Sun Microsystems
• Departments of Defense
• Interior
• NASA
• Department of Defense
• Frost & Sullivan
• Transport for London
• Cubic Transportation Systems Ltd
• London Buses
• Transport for London
• EDS
• TranSys
• Microsoft
• Network Associates
• Visa
• Verisign
• Amazon
• eBay
• Coalition on Online Identity Theft
• Federal Trade Commission
• Emosyn
• ATMI
• Bioscrypt
• Little Rock National Airport
• HID’s
• General Services Administration
• BearingPoint
• Marks and Spencer
• Intercede’s
• Infineon Technologies
• Cubic Corporation
• LaserCard Systems Corporation
• Drexler Technology Corporation
• Schlumberger Smart Cards & Terminals
• Visa
• ISO
• ANSI
• Open Security Exchange
• IEEE Industry Standards and Technology Organization
• Computer Associates
• Gemplus
• HID
• Tyco Fire & Security’s Software House
• Hypercom Corporation
• MasterCard’s
• Fazoli’s
• National Bank of Serbia
• Giesecke & Devrient
• GlobalPlatform
• ICC Solutions

     

含砂流动海水中Q235钢冲刷腐蚀行为研究

目的 研究Q235钢在不同流速和不同含砂量环境下的冲刷腐蚀行为。方法 采用旋转冲刷腐蚀试验装置,利用电化学测试手段、表面显微分析以及失重测量等方法分析流速以及含砂量对冲刷腐蚀行为的影响。结果 试样表面主要以腐蚀坑和划痕为主,随流速的增加,试样表面腐蚀坑数目增多,砂粒摩擦造成试样表面有明显划痕。含砂量较小时,试样表面腐蚀坑较大,且比较分散;随着含砂量增加,试样表面腐蚀坑增多,但是腐蚀坑直径减小。随流速的增加,试样表面腐蚀产物膜变得更加致密。随含砂量的增加,试样表面的腐蚀产物膜变厚,出现更加稳定的Fe2O3。海水流速和含砂量均较小时,Q235冲刷腐蚀电化学表征为单层结构腐蚀产物层。随流速和含砂量的增加,电化学表征转变为双层结构的腐蚀产物层,砂粒无法直接作用于基体表面。冲刷流速从1 m/s增加到5 m/s时,冲刷腐蚀速率由0.0113 mm/a增加到0.0309 mm/a,Q235钢最大腐蚀坑深度由34.47 μm增大到281.94 μm。含砂量从0.15%增加到1%时,冲刷腐蚀速率从0.0113 mm/a变为0.0107 mm/a,最大腐蚀坑深度由34.47 μm变化为16.41 μm。结论 Q235钢的腐蚀速率及腐蚀坑深对冲刷流速较为敏感,而对含砂量变化敏感性较小。     

紫外光对铝合金焊接接头腐蚀行为的影响

通过光学显微镜分析研究了6061铝合金熔化极惰性气体保护焊(metal inter gas welding, MIG焊)和搅拌摩擦焊(friction stir welding, FSW)对接头组织的影响.结合极化曲线测试，比较了紫外光照射与暗态对预沉积NaCl的基材及焊接接头腐蚀行为影响的差异.结果表明，MIG焊接头组织均匀性较差，焊缝Mg含量远高于母材，使得表现出较差的热力学稳定性.紫外光照射加速了铝合金焊接接头的腐蚀，尤其是明显加速了MIG焊接头的腐蚀.30天的紫外光照射对FSW接头的影响与母材相近.这些影响与材料本身的耐腐蚀性能及铝合金表面形成的半导体性质腐蚀产物密切有关.     

High-energy mesoscale strips observed in two-dimensional atomistic modeling of plastic deformation of nano-polycrystal

Plastic deformation of two-dimensional polycrystal with nano-size grains is investigated by means of molecular dynamics simulations. High-energy mesoscale strips are revealed and their properties are studied. It is demonstrated that the atoms within the mesoscale strips have higher potential energy and smaller mean interatomic distance than the rest of the atoms with ideal coordination number.     

不锈钢表面聚苯胺基复合涂层的制备与防腐蚀性能研究

目的 制备一种新型复合防腐涂层,增强316L不锈钢在中高温硫酸溶液中的耐蚀性.方法 首先使用化学氧化法在石墨(G)颗粒表面原位聚合聚苯胺(PANI),制得PANI/G复合材料,再使用环氧树脂(EP)作为粘结剂,制备PANI/G/EP复合涂层.对比了PANI/G/EP复合涂层与PANI/EP复合涂层及添加氧化石墨烯(GO...     

Room temperature solid–solid reaction preparation of ironboron alloy nanoparticles and Mössbauer spectra

The amorphous ironboron alloy can be prepared very easily by a room temperature solid–solid reaction of the FeCl₃·6H₂O, CrCl₃·6H₂O and KBH₄ powders. The characterizations show that the product is mainly composed of amorphous ironboron alloy nanoparticles. ⁵⁷Fe Mossbauer spectra at 84 and 295 K show that there are three kinds of Fe-containing components in the sample. There are the superparamagnetic relaxation in Mössbauer spectra and the continuous distribution of internal magnetic field in the ironboron alloy.