Hierarchically porous N-doped carbon nanofibers derived from ZIF-8/PAN composites for benzene adsorption

Coupling with electrospinning technique, metal–organic-frameworks (MOFs)-derived porous carbon fibers exhibit a great potential application in the adsorption of volatile organic compounds (VOCs) because of their huge surface area, high porosity, as well as sufficient heteroatom-doped active sites. In this work, the hierarchically porous N-doped carbon nanofibers are obtained after the pyrolysis of zeolite imidazole framework-8 and polyacrylonitrile (ZIF-8/PAN) composite fibers synthesized by electrospinning method. The N-doped carbon nanofibers fabricated in N₂ atmosphere (N-CF-N₂) present an enhanced adsorption capacity of 694 mg/g for benzene because of the synergistic effect of the hierarchically porous structure and the abundant N-species-containing active sites. It is also interesting that the N-doped hierarchical carbon nanofibers fabricated in Ar atmosphere (N-CF-Ar) exhibit a low benzene adsorption as compared with the N-CF-N₂, which can be attributed to the porous structure damage caused by the bombardment of heavy Ar atoms on the pore shells during the pyrolysis. These results not only show a promising application of the as-fabricated N-CF-N₂ in adsorption of VOCs for air purification due to its merit of cost-efficient, large-scale production, and excellent adsorption capacity, but also expand the potential of electrospinning technology and composite fibers in volatile organic gas adsorption.     

变质Mn8Crl耐磨钢弥散组织的形成机制

研究了变质Ｍｎ８Ｃｒｌ耐磨钢弥散处理过程中显微组织、物相硬度及成分的变化。结果表明，通过热处理获得理想弥散组织的条件：首先是奥氏体锰钢中含有适量的强碳化物形成元素，其次是使奥氏体尽可能充分地发生珠光体转变，三是适当控制高温阶段等温温度和时间。     

Al5TiB对Mg-8Zn-4Al-0.3Mn镁合金阻尼性能的影响

研究了变质剂Al5TiB对Mg-8Zn-4Al-O．3Mn镁合金阻尼性能的影响。结果表明：Al5TiB的加入显著细化了Mg-8Zn-4Al-O．3Mn镁合金晶粒，增大了界面面积，提高了合金的界面阻尼。但是，Al5TiB的加入又促进了Al、Zn原子向基体中的扩散，降低了合金的位错阻尼。加入变质剂Al5TiB后Mg-8Zn-4Al-O．3Mn镁合金的阻尼机制主要是界面阻尼和位错阻尼。二者迭加的结果决定了ZA84镁合金的宏观阻尼行为。     

Fe3Al/18-8扩散焊接头的组织特征分析

采用扫描电镜，X射线衍射仪和透射电镜分析了Fe3Al／18-8扩散焊接头的显微组织特征。结果表明，加热温度1040℃、保温时间60min、焊接压力15MPa时获得的Fe3Al／18-8扩散焊接头抗剪强度达226MPa。接头处形成具有三个扩散反应层的过渡区，其相结构依次由(FeAl Fe3Al)、Ni3Al相和α-Fe(Al)固溶体组成。显微硬度峰值为610HM，不存在FeAl2(820HM)、Fe2Al5(990HM)和FeAl3(1030HM)等脆性相，有利于保证Fe3Al／18-8扩散焊接头的组织性能。     

Flow behavior and microstructure evolution of TB8 alloy during hot deformation process

Hot compression tests of metastable β titanium alloy TB8 were carled out using a Gleeble-1500 thermal simulation testing machine in the temperature range of 750-1 100 ℃, at constant strain rate from 0.01 s^-1 to l S^-1 and with height direction reduction of 60%. Flow stress behavior and microstructure evolution during hot compression of TB8 alloy were investigated. The hyperbolic-sine-type constitutive model of TB8 alloy was obtained to provide basic data for determining reasonable forming process. The results indicate that hot deformation behavior of TB8 alloy is highly sensitive to the temperature and strain rate. An analysis of the flow stress dependence on strain rate and temperature gives a stress exponent of n=3.416 19 and a deformation activation energy of Ω=227.074 4 kJ/mol. According to the deformation microstructure, no dynamic recrystallization happens below r-phase transus temperature and as a result dynamic recovery is the predominant softening mechanism. On the other hand, the main softening mechanism is characterized as dynamic recrystallization at a slow strain rate above r-phase transus temperature.     

净化对非晶形成能力和非晶热稳定性的影响SCIEI

采用玻璃熔体净化法和电磁悬浮循环过热法消除Ni_(75),B_(17)Si_R合金液内的异质核心,研究了净化对该合金液非晶形成能力和所形成的非晶合金热稳定性的影响。采用净化和忽冷相结合的工艺制备出了20×10×0.5mm的Ni_(75)B_(17)Si_8非晶试样,试样的厚度较净化前提高了4倍。     

原位生成TiC对Al-8Fe合金显微组织的影响

通过XRD，SEM，TEM等手段研究了Al-8Fe常规铸态合金原位生成不同TiC粒子含量时相组成及显微组织的变化，以及Ti同α（Al）基体及Al3Fe相之间的界面关系。结果表明：随着TiC含量的增加，Al-8Fe合金中Al3Fe相及缩松的形貌及尺寸明显发生了变化，TiC与α（Al）基体之间界面干净，而与Al3Fe之间则存在一过渡层。     

再加热对Fe3A1/18-8扩散焊界面附近组织结构的影响

Fe3A1/18-8扩散焊界面不均匀地分布着第二相析出物,特别是交界面处连续分布的析出相族可能直接诱发裂纹,是引起接头失效的重要因素.对Fe3A1/18-8扩散焊接头进行再加热,采用扫描电镜、能谱分析、X射线衍射等对析出相及界面相结构进行分析.结果表明,再加热后界面析出相细化且形状规则,均匀分布于Fe3A1/18-8界面,析出相族消失.界面附近的显微硬度降低,不存在高硬度脆性相.     

T8钢淬火热处理组织的计算机模拟研究

利用有限差分法计算了T8钢二维温度场，研究了T8钢淬火热处理温度场的变化对组织的影响。根据试样任意一点的温度和冷却速度对该点的组织进行预测，实现了T8钢淬火组织的计算机模拟。     

金属型铸造Mg-8Zn-4Al-0.25Mn合金的凝固行为及组织特征

研究了金属型铸造Mg-8Zn-4Al-0．25Mn合金的凝固行为及组织特征。结果表明：合金的铸态组织主要由初生α-Mg、Mg32（Al，Zn）49相和Al2Mg5Zn2相组成，其中Mg32（Al，Zn）49相主要呈连续状和／或半连续状分布，Al2Mg5Zn2相主要呈孤岛状分布。此外，根据DSC结果还确定了合金的凝固温度范围、液相线及固相线温度，并阐明了合金凝固过程中的相变。