Blue pigments based on CoxZn1−xAl2O4 spinels synthesized by the polymeric precursor method

The Co_xZn_1?xAl₂O₄ system (x = 0; 0.1; 0.3; 0.5; 0.7; 0.9 and 1) was synthesized by the polymeric precursor method and characterized by the techniques XRD, TG-DTA, IR, UV–vis and colorimetry. The XRD patterns displayed the characteristic peaks of the spinel structure and a good crystallinity. The DTA curves showed an exothermic peak corresponding to the enthalpy of the transition taking place at about 700 °C. The infrared spectra displayed vibrations at about 650, 550, 540, 520, 500, 490 cm^?1, which were ascribed to the spinel structure. The UV–vis spectra presented three bands at 550, 580 and 620 nm attributed to the Co²⁺ spin transitions in tetrahedral sites. The colorimetric data point out the formation of blue pigments, corresponding to highly negative values of b¹. The lightness, coordinate L¹, increases with the heat treatment temperature. These facts reveal that Co_xZn_1?xAl₂O₄ is a promising system that can be employed to obtain ceramic blue pigments.     

航空发动机钛合金压气机组件防钛火用阻燃可磨耗涂层研究进展

本文描述了钛合金在航空发动机的应用优势及出现的钛火问题,并介绍了解决钛火的方案,如阻燃钛合金、阻燃涂层及阻燃可磨耗涂层等.着重介绍了阻燃可磨耗涂层的技术研究现状,包括其涂层阻燃可磨耗性的评价标准以及阻燃可磨耗的相关机理研究.最后指出了在600～750℃区间应用的钛合金阻燃可磨耗涂层未来研究趋势和发展方向.     

一种大口径薄壁高铬铸铁管的离心铸造工艺研究

通过对一种大口径薄壁高铬铸铁管(φ700 mm×5000 mm,壁厚为20 mm)的离心铸造试制,研究了影响此种铸管生产的关键工艺参数.得出的工艺参数为:浇注温度1430～1450℃,浇注时间＜1 min,转速750r/min.     

254SMO不锈钢铸态组织及其高温固溶处理工艺

通过显微组织观察和背散射电子扫描观察了不同时间、不同温度的固溶处理对超级奥氏体不锈钢254SMO铸态组织的影响,并采用电子探针技术观察了钢中σ相的溶解过程。结果表明,随着固溶时间和温度的增加,不锈钢中的铸态枝晶组织逐渐消融,偏析逐渐消除,σ相逐渐溶解并转化为δ相(铁素体)。其中1280 ℃×9 h固溶处理的效果最好。     

维生素K的生产及应用研究

综述了维生素K的生理功能、应用领域及生产工艺,并介绍了维生素K在国内外的生产现状及发展方向.     

小间隙下狭缝节流静压气体止推轴承静态性能的研究

减小气膜间隙可以提高气体轴承的刚度和承载,为研究小间隙下狭缝节流气体止推轴承静特性,运用FLUENT软件对小间隙下狭缝节流止推轴承进行流场仿真。采用滑移边界条件对小间隙下轴承流场进行计算,结果表明,随着气膜厚度的增加,滑移的影响逐渐减小,当膜厚大于等于4μm时滑移影响可以忽略。计算了狭缝结构对轴承静特性的影响,结果表明,在其他参数相同的条件下,轴承的承载力随狭缝的宽度的增加而增加;随着狭缝深度的增加而减小。在其它结构参数相同的条件下,随着狭缝宽度的减小,最大刚度值增加,最大刚度对应的气膜厚度逐渐减小;随着狭缝深度的增加,最大刚度值增加,最大刚度对应的气膜厚度逐渐减小。     

Axial impeller selection for anchorage dependent animal cell culture in stirred bioreactors: Methodology based on the impeller comparison at just-suspended speed of rotation

Animal cells, which are nowadays essential for the industrial production of proteinic compounds, are commonly cultivated inside stirred tank bioreactors. In case of anchorage dependent cells, they are usually fixed on microcarriers. The choice of agitation conditions (impeller type, rotational speed…) in this type of process is not an easy task as it has to fulfil three potentially conflicting goals: (1) maintaining microcarriers in complete suspension, (2) homogenizing the culture medium, and (3) limiting mechanical constraints generated by the hydrodynamics on the cells. The aim of this study is to present an original methodology to select the most appropriate axial impeller for this specific application. Seven propellers are preselected on basis of their characteristics available in the literature. Instead of comparing impellers at a given rotational speed or a given power input, they are compared at their respective minimum impeller rotational speed that leads to a complete microcarrier suspension, i.e. at their respective just-suspended speed N_js. They are then compared at higher rotational speeds N, expressed as multiples of N_js. The impeller classification is based on the intensity of mechanical constraints they produced, evaluated from: (1) the macro-shear rate quantified by the spatial derivative of time average velocity fields measured by P.I.V., (2) the micro-shear rate characterized by the ratio between the microcarrier diameter to the average Kolmogorov scale computed from power input measurements, and (3) the impact of microcarrier collisions on cells described via the turbulent collision severity index also computed from power input measurements. Results show that the 125 mm diameter TTP impeller (Mixel) and the 150 mm diameter Elephant Ear impeller (Applikon) produce the smallest mechanical constraints at their just-suspended speed (50 and 20 rpm, respectively). Moreover, the mechanical constraints they produce increase more slowly with the N/N_js ratio than the mechanical constraints produced by other impellers. These propellers are thus even more advantageous if rotational speeds higher than the just-suspended speed have to be used.     

水性工业涂料废液的处理研究

采用混凝-生物接触氧化-芬顿高级氧化组合工艺对水性涂料废液进行处理研究.重点考察了该工艺对涂料废液COD、氨氮和SS的去除效果.结果表明,pH升高对涂料废液中的SS、COD有去除效果并且能够避免混凝时发生板结,当pH为10时,COD由148 000 mg/L降至46 000 mg/L,SS质量浓度由18 500 mg/...     

Cobalt nanoparticle decorated N-doped carbons derived from a cobalt covalent organic framework for oxygen electrochemistry

The low cost and highly efficient construction of electrocatalysts has attracted significant attention owing to the use of clean and sustainable energy technologies. In this work, cobalt nanoparticle decorated N-doped carbons (Co@NC) are synthesized by the pyrolysis of a cobalt covalent organic framework under an inert atmosphere. The Co@NC demonstrates improved electrocatalytic capabilities compared to N-doped carbon without the addition of Co nanoparticles, indicating the important role of cobalt. The well-dispersed active sites (Co–N_x) and the synergistic effect between the carbon matrix and Co nanoparticles greatly enhance the electrocatalytic activity for the oxygen reduction reaction. In addition, the Co content has a significant effect on the catalytic activity. The resulting Co@NC-0.86 exhibits a superb electrocatalytic activity for the oxygen reduction reaction in an alkaline electrolyte in terms of the onset potential (0.90 V), half-wave potential (0.80 V) and the limiting current density (4.84 mA·cm^–2), and a high selectivity, as well as a strong methanol tolerance and superior durability, these results are comparable to those of the Pt/C catalyst. Furthermore, the superior bifunctional activity of Co@NC-0.86 was also confirmed in a home-built Zn-air battery, signifying the possibility for application in electrode materials and in current energy conversion and storage devices.