苏拉马都跨海大桥主桥尾梁段及端横梁施工

介绍了苏拉马都跨海大桥主桥尾梁段及端横粱的安装施工工艺,尾梁段端部设现浇预应力混凝土端横粱,端横梁采用C60混凝土,在端横梁箱内堆放压重铸铁块,并浇注填充混凝土填实.在钢主梁端部外侧设现浇混凝土伸臂.     

摩托车和轻便摩托车轻合金车轮新老标准分析(2)

(上接2011年第11期)2径向冲击试验不同之处原QC/T211 1996和QC/T 212 1996标准规定单锤冲击,冲击锤质量为m=k×W/g,其中k为系数,前轮1.8,后轮1.2;冲击锤坠落高度不分前后轮都是100 mm。GB/T 22435 2008参照ISO 8644:2006,将冲击锤为m k×F_v/g,其中k为系数,前轮和后轮均为1;冲击锤坠落高度,前轮180 mm,后轮120 mm。从表面看二者的势能一致,但实际上是不一样的。根     

世博园直饮水采用世界领先的“活性炭+PVC合金超滤膜+紫外线”处理工艺

<正>上海世博园区直饮水采用了世界领先的"活性炭+PVC合金超滤膜+紫外线"处理工艺,超滤膜和直饮台均由国内著名膜企——立昇企业提供。该技术细菌去除率达到99.9999%,病毒去除率达到99.99%,水资源利用率达99%,水质卫生标准优于欧盟标准。     

双层Ni-P合金镀层制备及耐蚀性

为研究双层Ni-P合金镀层的高耐蚀性,通过改变络合剂组分和控制化学镀工艺条件,制备了3种不同磷含量的镀层.用XRD,EDS和SEM方法,对镀层的成分、结构和形貌进行表征,并用电化学方法和腐蚀膏法,分别测定了镀层的腐蚀电位和耐蚀性.结果表明:不同的镀液成分和化学镀工艺使镀层的磷含量和组织结构发生变化.随镀层中磷含量上升,镀层组织的变化从晶态到晶态+非晶态,最后到非晶态,使镀层的自腐蚀电位及自腐蚀电流分别增加和下降.在外层为低电位层(-550 mV),内层为高电位层(-295 mV),内外层厚度比为2∶1时,镀层的耐腐蚀性最好.     

Fe-Mn-Al-Cr合金双极板在模拟PEMFC环境中的电化学性能

采用电化学方法测定一种Fe-Mn-Al-Cr合金在模拟PEMFC环境中的极化曲线以及在PEMFC工作电位下的电流密度随时间变化的曲线.结果表明,Fe-Mn-Al-Cr合金在0.05 mol/L H2SO4＋2 mg/L F-溶液中呈现明显的活化-钝化转变.在恒电位极化过程中,阴极一侧表面能够形成稳定的钝化膜,钝化电流密度低于l6μA.cm-2.而在阳极一侧则产生了大量溶解的金属离子.     

Recycling of aluminum from fibre metal laminates

Recycling of aluminum alloy scrap obtained from delaminated fibre metal laminates (FMLs) was studied through high temperature refining in the presence of a salt flux. The aluminum alloy scrap contains approximately mass fraction w(Cu) = 4.4%, w(Mg) = 1.1% and w(Mn) = 0.6% (2024 aluminum alloy). The main objective of this research is to obtain a high metal yield, while maintaining its original alloy compositions. The work focuses on the metal yield and quality of recycled Al alloy under different refining conditions. The NaCl-KCl salt system was selected as the major components of flux in the Al alloy recycling. Two different flux compositions were employed at NaCl to KCl mass ratios of 44:56 and 70:30 respectively, based on either the eutectic composition, or the European preference. Different additives were introduced into the NaCl-KCl system to study the effect of flux component on recycling result. Although burning and oxidation loss of the alloying elements during re-melting and refining take place as the drawbacks of conventional refining process, the problems can be solved to a large extent by using an appropriate salt flux. Experimental results indicate that Mg in the alloy gets lost when adding cryolite in the NaCl-KCl salt system, though the metal yield can reach as high as 98%. However, by adding w(MgF₂) = 5% into the NaCl-KCl salt system (instead of using cryolite) all alloying elements were well controlled to its original composition with a metal yield of almost 98%.     

Formation of nanometer coherent structures during spinodal decomposition and ordering coexistence phase transformation in Fe-24Al alloys

The nanometer coherent structure evolution of spinodal decomposition and ordering coexistence phase transformation in Fe-24Al alloys is investigated by the microscopic phase field kinetic model. The results show that the concentration and long-range order parameters all continuously change towards to their equilibrium values during phase transformation. With the increase of elastic interaction energy, the anisotropy along [01] or [10] elastic soft direction is more obvious and the time reaching equilibrium state is also shortened. According to the results, the formation of nanometer coherent structures during phase transformation is composed of the initial decreasing stage of order degree stage, the incubation stage, the continuous increasing stage of concentration order parameter and long-range order parameter, and the later stable stage. The spinodal decomposition and ordering is interaction; the initial ordering stage is a necessary condition of the coexistence phase transformation. The nanometer coherent structures are not found to grow during the whole phase transformation. The simulation results are in accordance with the results in experiment obtained by the aging treatment in Fe-24Al alloys.     

Ni-Mn合金的去合金化

在氩气保护下,应用真空熔炼炉分别制备了Ni30Mn70与Ni55Mn45合金.测定了这两种合金在(NH4)2SO4溶液中的圾化曲线,然后对其进行去合金化实验.结果显示,Ni30Mn70合金在1M(NH4)2S04溶液中去合金化后,试样表面呈现“泥裂”结构.Ni55Mn45在1M(NH4)2S04溶液中不同电位下去合金化...