中间相沥青基碳纤维的生产及其性能表征

中间相沥青基碳纤维具备高模量、高导热性等特性,在航天、电子等领域具备广阔的应用前景.山东瑞城实现了中间相沥青基碳纤维的产业化生产,本文对其所生产的中间相沥青基碳纤维的结构和性能进行了表征研究.研究结果表明,1.5K连续纤维的平均直径为11μm;强度为2400 MPa;模量为811 GPa;导热率达到600 W/(m·k...     

复合挤压对Mg-4Sn-2Al-1Zn合金组织及力学性能的影响

针对镁合金室温强度低、塑性差的问题,采用复合挤压工艺在250℃对Mg-4Sn-2Al-1Zn合金进行了挤压,研究了复合挤压对合金的组织演变、织构及力学性能的影响。结果表明,复合挤压能将Mg-4Sn-2Al-1Zn合金的晶粒尺寸由45.2μm细化至3.1μm,组织均匀。挤压后的合金硬度提升,均匀性改善,屈服强度、抗拉强度和断后伸长率分别为204 MPa、287 MPa和21.0%,较匀质态分别提高了140.0%、91.3%和156.1%。动态再结晶是晶粒细化的主要机制,晶粒细化以及挤压后基面织构增强、织构向挤压方向均匀扩展使合金强度、塑性提高,挤压过程中Mg2Sn相破碎进一步提高了合金的力学性能。上述研究表明复合挤压是一种能有效提高镁合金综合性能的工艺。     

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.     

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。     

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.     

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.     

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/...     

粗纱机吸尘管道的改进设计及分析

探讨粗纱机吸尘管道系统各吸尘孔口吸力不均匀的问题.通过测试粗纱机吸尘管沿程各孔口静压,发现各吸尘孔口静压差异过大,造成了各吸尘孔口吸尘效果难以满足吸尘的需要.针对该问题对吸尘管道重新进行了设计,采用了扩大吸尘管道横截面、改进吸口形状及减小管道转角处的局部阻力等措施.经过测试与验证,在配用原风机的条件下,较好地解决了粗纱机吸尘管沿程孔口吸力分配不均匀的问题,并在一定程度上可减少纱疵,提高纱线质量.     

CO2 emissions,energy consumption,and output in France

This paper examines the dynamic causal relationships between pollutant emissions, energy consumption, and output for France using cointegration and vector error-correction modelling techniques. We argue that these variables are strongly inter-related and therefore their relationship must be examined using an integrated framework. The results provide evidence for the existence of a fairly robust long-run relationship between these variables for the period 1960–2000. The causality results support the argument that economic growth exerts a causal influence on growth of energy use and growth of pollution in the long run. The results also point to a uni-directional causality running from growth of energy use to output growth in the short run.     

河流连通性综合评价方法研究

保障河流连通性是生态系统保护与修复的一项重要举措,为推进我国江河湖库水系连通工作,亟需加强河流连通性评价的理论方法研究。基于河流生态系统四维结构和功能整体模型,构建了河流连通性综合评价方法;通过梳理国内外河流连通性评价的研究和实践,从4个维度凝练了构建河流连通性指数的5个评价指标,包括破碎度指数、库容调节系数、水资源利用消耗率、路网密度和城市夜间灯光指数;通过综合分析各个指标的阈值和权重,建立了河流连通性指数计算方法、综合评价方法及评价依据。研究成果进一步完善了河流连通性评价的理论方法,为河流连通性评价提供了一种新的思路,可为河流生态系统保护与修复提供参考。