短切碳纤维/AZ91D镁合金复合材料高温变形动态再结晶行为

在变形温度为340~400℃、应变速率为0.001~0.1 s^-1、最大真应变为0.7的条件下,采用等温压缩实验研究了短切碳纤维（CF_s）/AZ91D复合材料和AZ91D镁合金的动态再结晶行为。结果表明：CF_s/AZ91D复合材料和AZ91D镁合金在高温压缩过程中均发生了显著的动态再结晶;CF_s极大地促进了AZ91D基体的动态再结晶过程,减小了动态再结晶临界应变并细化了再结晶晶粒组织;AZ91D镁合金动态再结晶体积分数随应变量增加表现为典型的"S"型变化曲线,而CF_s/AZ91D复合材料则呈现出快速增长-缓慢增长-趋于平稳的非线性变化规律。根据实验结果分别建立了CF_s/AZ91D复合材料和AZ91D镁合金的动态再结晶临界应变模型和动力学模型,在此基础上分析了二者高温变形动态再结晶行为的差异。     

Adsorption equilibria for oxygen and nitrogen gas mixtures on 5a molecular sieves

Equilibria data for the adsorption of oxygen, nitrogen and binary mixtures of these gases are determined on 5A molecular sieve pellets. Pure component isotherms are presented at pressures up to 9 bar and at 278.15, 293.15 and 303.15 K. The binary equilibria are presented at the same temperatures and at pressures of 1.7 and 4.4bar. The binary data have been examined against values predicted by various models using regression parameters obtained from the pure component isotherms. For these systems the ideal adsorbed solution theory, Cook and Basmadjian model and the statistical thermodynamic model gave the best representation of the experimental data.     

虹吸式屋面雨水排水系统设计软件

以科列勃洛克公式和伯努利方程为基础,采用Visual Basic语言设计虹吸式屋面雨水排放系统的水力计算软件,实现了设计及校核计算的自动化,并给出该软件的一个工程算例.     

CF4/CO2混合气体工频击穿特性的试验研究

SF₆是目前电气设备中广泛使用的气体绝缘介质,但其产生的温室效应对环境影响极大,因此,研究能替代SF₆的环保型气体绝缘介质具有重要的意义。CF₄是一种具有低温室效应指数（global warming potential, GWP）和低液化温度的强电负性气体。通过工频击穿试验,研究了CF₄/CO₂混合气体的工频击穿特性,并对其协同效应和GWP值进行分析。结果表明：CF₄混合比为50%的CF₄/CO₂混合气体的绝缘强度能达到纯CF₄的90%左右,同时GWP值低,具有用于气体绝缘的潜力;CF₄/CO₂混合气体的协同效应值在0.12~0.38,表现出明显的协同效应。     

热处理对40CrMnSiMoVA超高强度钢腐蚀疲劳裂纹扩展的影响

采用裂纹扩展微机自动测试系统，研究了热处理对４０ＣｒＭｎＳｉＭｏＶＡ（ＧＧ－４）超高强度钢腐蚀疲劳裂纹扩展行为的影响，结果表明，不同热处理时ＧＣ－４钢在３．５％ＮａＣｌ溶液中的ＣＦ裂纹扩展曲线上，都出现了类似于应力腐蚀的平台区，而且随等温温度升高，平台区裂纹扩展速度大大降低，这与材料的显微组织特性有关，研究表明，氢脆在ＧＣ－４钢的腐蚀疲劳中起重要作用。     

Effect of CNT-coated carbon fibres in HDPE composites

The mechanical properties of thermoplastic HDPE composites filled with CF and CNT were studied. Coupling agent surface-treated CF-filled HDPE composites increased their tensile strength and impact strength, which is further increased with the addition of CNT. Coupling agent was proved to play an important role in the improvement of the interfacial adhesion of the CF/HDPE composite. SEM showed that CNT coating-treated CF/HDPE composites show better dispersion of the ?ller into the matrix.     

七氟丙烷气体清洁灭火剂的灭火原理

基于哈龙（Halon）灭火剂的消防产品是一种最为有效的气体消防系统。根据《蒙特利尔议定书》的建议，一些新的清洁消防灭火剂将用来取代哈龙减火剂。其中一种候选者就是七氟丙烷（Heptafluoropropane）灭火剂以及基于七氟丙烷的全覆盖灭火系统正开始应用于电脑机房、电信交换投施等领域。然而，大泉仍未封七氟丙烷灭火剂的灭火原理有一个全面了解。该类型系统的操作是有其缺点的，比如，使用遇程会产生氟化氩（hydrogen fluorideo本文将回顾哈龙灭火剂的灭火原理及使用中的一些相关问题，然後讨论七氟丙烷的化学分解遇程、灭火原理以及在使用遇程中减少氟化氢产生的添加剂妁工作原理。本文亦将简要介绍将水雾冷却系统（waterspray coolingsystem，WSCS）与七氟丙烷灭火剂结合以减少氟化氢产生的设想，同时会论及如何定义更好的添加剂的标准。     

Effect of rare earths surface treatment on tribological properties of carbon fibers reinforced PTFE composite under oil-lubricated condition

The effect of rare earths （RE） surface treatment of carbon fibers （CF） on tribological properties of CF reinforced polytetrafluoroethylene （PTFE） composites under oil-lubricated condition was investigated. Experimental results revealed that RE treated CF reinforced PTFE （CF/PTFE） composite had the lowest friction coefficient and wear under various applied loads and sliding speeds compared with untreated and air-oxidated composites. X-ray photoelectron spectroscopy （XPS） study of carbon fiber surface showed that, after RE treatment, oxygen concentration increased obviously, and the amount of oxygen-containing groups on CF surfaces were largely increased. The increase in the amount of oxygen-containing groups enhanced interfacial adhesion between CF and PTFE matrix. With strong interfacial adhesion of the composite, stress could be effectively transmitted to carbon fibers; carbon fibers were strongly bonded with VITE matrix, and large scale rubbing-off of PTFE be prevented, therefore, tribological properties of the composite was improved.     

碳/环氧树脂复合材料吸湿水分浓度场的有限元分析

采用ABAQUS有限元软件的质量扩散模块,对碳纤维增强环氧树脂基(CFL/EP)复合材料在湿热环境下吸湿后的水分浓度场进行了分析计算。计算在环境温度T=37℃及T=80℃的条件下进行。计算结果和试验结果吻合得较好,为后续的CFL/EP复合材料湿热残余应力的分析打下了初步基础。