金属有机骨架材料MOF-235的合成及其对甲基橙吸附性能的研究

对金属有机骨架材料MOF-235的合成、表征及其对甲基橙染料的吸附性能进行研究.采用水热法合成MOF-235材料,通过X-射线衍射、IR、SEM验证并表征其结构特点.运用动力学模型和热力学模型,研究MOF-235对甲基橙溶液的吸附性能.结果显示,该材料对甲基橙的吸附可在极短的时间内达到平衡,温度对吸附效果的影响不大.对实验结果进行吸附等温线和动力学方程拟合,结果表明,MOF-235材料吸附甲基橙的Langmuir等温方程拟合效果更好,吸附过程更符合二级动力学模型.     

加工尺寸分布对零件合格率和装配合格率的影响

建立了零件合格率和装配合格率的计算公式 ,定量分析了零件总体平均尺寸与公差中心不重合对零件合格率和装配合格率的影响 ,分析表明总体平均尺寸与公差中心偏离越大 ,零件合格率和装配合格率尤其是零件合格率降低越多。因此 ,用调整方法进行加工时应彻底纠正传统的调整法———加工尺寸为包容尺寸时靠下差 ,为被包容尺寸时靠上差的做法 ,要加强对小样本的检查 ,发现样本平均尺寸偏离零件公差中心时 ,及时进行调整 ,以期提高合格率 ,降低成本     

Effects of doping in 25-atom bimetallic nanocluster catalysts for carbon–carbon coupling reaction of iodoanisole and phenylacetylene

A trio of thiolate-protected atomically precise gold nanoclusters, [Au_(23)(S-c-C_6H_(11))_(16)]~–, Au24(SCH_2pH~tBu)_(20)and [Au_(25)(SCH_2CH_2pH)_~(18)]~–, are utilized as catalysts for 4-nitrophenol(4-NP) reduction to 4-aminophenol(4-AP).Despite nearly identical sizes(~1 nm), the three nanoclusters possess distinctly different atomic packing structures and surface ligand binding modes, which contribute to different catalytic performance. The [Au_(23)(Sc-C_6H_(11))_(16)]~–nanocluster shows the highest activity with a kinetic rate constant of 0.0370 s~(-1), which is higher than those of Au24(SCH_2pH~tBu)_(20)(0.0090 s~(-1)) and [Au_(25)(SCH_2CH_2pH)_~(18)]~–(0.0242 s~(-1)). Such a trio of gold nanoclusters indicate that the atomic packing mode and electronic structure play a crucial role in determining their catalytic performance.     

Room-temperature NH3 sensors with high sensitivity and short response/recovery times

Micro-sensors are fabricated by co-electrospin- ning In203 and SnO2 nanofibers on the substrates of SiO2/Si with interdigitated Pt signal electrodes. The total sensor area is 1.36 mmx 0.55 mm and the active area is only 0.63 mmx 0.55 ram. Excellent NH3 sensing properties are obtained based on the sensors at room temperature. The sensitivity is at most 28 when the sensors are exposed to NH3 of 10 ppm. The response time is 8 s or so and the recovery time is nearly 2 s. Not only fine selectivity, but also long- time stability is obtained. The results not only demonstrate the obtained micro-sensors are very promising devices for NH3 detection, but also show a possible route for large-scale NH3 sensor fabrication at the industrial level.     

110kV单芯电缆金属护套感应电压计算及分段

电缆线路较长时将引起过高的金属护套感应电压,从而降低电缆的使用寿命,并危及人身安全。建立三相线芯对屏蔽层感应电压计算模型,推导出单芯电缆金属护套的感应电压表达式,得到了正常运行条件下不同长度的单芯电缆线路感应电压。     

渗硼对钢材机械性能的影响

本文研究了固体渗硼对钢材(20CrMo,45,T8及 GCr15)机械性能的影响。渗硼后得到Fe_2B或 FeB Fe_2B渗硼层。本研究进行了渗硼试样的拉伸、多次冲击以及旋转弯曲疲劳试验,并与未渗硼试样进行比较。其结果为:(1)对于低碳合金钢(20CrNiMo、20CrMo),渗碳对拉伸强度及多次冲击抗力的影响很小,韧性有所下降;渗硼后进行淬火及低温回火处理,使强度及韧性均下降。(2)对中碳结构钢(45),渗硼对拉伸强度及多冲抗力影响也很小,韧性也有所下降。渗硼后经淬火高温回火,刚拉伸强度有所增加,塑性稍有下降。若渗硼后再经淬火及低温回火,拉伸强度及塑性均有显著降低。45钢渗硼后,疲劳强度提高,单相时提高更多。(3)对于高碳工具钢T8及滚动轴承钢GCr15,渗硼后拉伸强度及塑性均下降,后者下降幅度更大;多冲抗力也有所下降。     

浅谈我国金属矿山采矿技术现状及发展方向

首先,文章对我国金属矿山采矿技术的现状及金属矿山开采中存在的问题进行了分析。为了实现国民经济的可持续发展,国家提出要建设绿色矿山。我们必须提高采矿技术水平,我国才能由矿业大国真正成为矿业强国。最后,对我国金属矿山采矿技术发展方向进行了阐述。     

金属基复合材料的研究现状与应用

金属基复合材料是一类新型的复合材料，它因具有高比强度、高比模量、高耐磨性高优异性能而引起人们的关注。本文综述了金属基复合材料的研究现状，制造工艺和性能。同时介绍了这种材料在航天、航空、先进武器系统、汽车工业等领域中的广泛应用。     

运用形象思维法讲解"金属材料与热处理"

采用形象思维法进行教学 ,能充分发挥教师的想象能力 ,培养学生的灵感、创造力和抽象思维能力 ,激发学生学习兴趣 ,加深课后印象。“金属材料与热处理”教学中 ,很多理论、概念均可以用形象的、具有个性的语言进行描述 ,进而取得较好的教学效果。     

Effect of nanoparticle (Pd, Pd/Pt, Ni) deposition on high temperature hydrogenation of Ti-V alloys in gaseous flow containing CO

The hydrogenation properties of Ti-V hydrides coated with nanoparticles have been studied in gaseous mixtures of argon and hydrogen with and without additions of 1% CO. Nanoparticles of Pd, Ni, and co-deposited Pd/Pt with particle sizes of ~30–60 nm were formed by electroless deposition on the hydride surfaces. The alloy resistance to CO could be significantly improved by particle deposition. Large amounts of hydrogen were absorbed in a CO-containing gas when Ni and Pd/Pt deposition had been applied, while pure Pd deposition had no positive effect. Ni was found to have a stronger effect than those of Pd/Pt and Pd, possibly because of the size effect of Ni nanoparticles.