玻璃微珠/固体润滑剂改性PA6的力学和摩擦学性能

采用玻璃微珠(GB)增强聚酰胺6(PA6),固体润滑剂聚四氟乙烯(PTFE)、石墨(Gr)降低PA6的摩擦系数。重点研究GB含量、PTFE、Gr含量及配比对PA6复合材料的拉伸强度、冲击强度和摩擦系数的影响。结果表明,GB可提高PA6的力学性能,随着GB含量增大,PA6复合材料的拉伸强度和冲击强度先增大后减小,GB含量为15%时,其综合力学性能较好,但GB不能降低PA6的摩擦系数。固体润滑剂不能进一步提高PA6/GB(85/15,质量比)的力学性能,但是能大大降低其摩擦系数,且PTFE和Gr对降低摩擦系数有协同效应,PTFE/Gr为10/5时,PA6复合材料的摩擦系数仅为0.131 9。     

轻骨料吸水和返水特性研究进展

近年来,高性能混凝土在各类建筑结构中得到了越来越多的应用,但是自收缩和自重成为了高性能混凝土应用过程中的主要问题,轻骨料(LWA)自身的多孔结构使其具有较普通骨料相比特有的属性—吸返水能力.因此,将预湿轻骨料掺入到混凝土能够对起到内养护的作用,从而改善高性能混凝土自收缩.基于国内外已有的研究成果,本文综述了轻骨料内养护的作用机理和吸返水性能的试验方法.然而,轻骨料的吸水和返水特性研究较少,轻骨料的吸水和返水性能对混凝土的内养护作用仍处于探索阶段.     

MT轮胎专用胎面配方开发技术研究

介绍泥地专用轮胎胎面配方开发技术的研究。研究结果显示通过对在用越野专用胎面配方的生胶并用体系及不同比表面积的填料综合设计,新升级的MT轮胎专用胎面胶料配方的拉伸强度、抗撕裂性能均比在用配方改善明显。新设计的MT专用配方的生热更低;使用新专用配方试制的成品轮胎台架性能得到进一步优化。     

40000m~3/h空分装置内外压缩流程热力计算

通过对40000m3/h空分装置内外压缩流程热力计算,分析外压式、半内压式、全内压式流程所需功耗的高低和影响产品的能耗指标的因素,并结合用户实际情况,对压缩流程作出最佳选择,即:流程最实用,能耗较低。通过计算和实际情况证明,内压缩流程通过合理的组织,能耗已越来越低。     

开环聚合酚醛树脂基复合摩阻材料的研究及应用

以开环聚合酚醛树脂为基体,以碳纤维、钢纤维为增强材料制备新型复合摩阻材料,通过摩擦性能测试、差示扫描量热分析等方法研究了树脂基体对材料各项性能的影响。结果表明,该摩阻材料具有适宜的摩擦系数、极低的磨损率和优异的抗热衰退性能;树脂含量显著影响材料的摩阻性能,当树脂质量分数为18%~19%时,磨损率达到最小,摩擦系数也较高而稳定。而模压成型工艺参数研究表明,采用200℃模压成型,可以获得固化良好的制品;所制备的摩阻材料的各项性能指标达到准高速列车用摩阻材料技术要求,可以用作准高速列车闸瓦材料。     

A Study on the Friction and Wear Behavior of PTFE Filled with Acid Treated Nano‐Attapulgite

Summary: A solid lubricant composite material was prepared by compression molding PTFE and acid treated nano‐attapulgite. The friction and wear tests were performed on a block‐on‐ring wear tester. Scanning electron microscopy (SEM), energy‐dispersive X‐ray spectrometer (EDS) and DSC were utilized to investigate material microstructures and examine modes of failure. Experimental results showed that there was no significant change in coefficient of friction, but the wear rate of the PTFE composite was orders of magnitude less than that of pure PTFE. Acid treated nano‐attapulgite was superior to untreated nano‐attapulgite in enhancing the wear resistance of PTFE. Moreover, the wear resistance of the composite increased monotonically with increasing treated attapulgite concentration. Investigation of transfer film and analysis of debris for PTFE and its composite showed that acid treated nano‐attapulgite filled to PTFE could facilitate formation of transfer film on the steel ring surface and inhibit breakage of PTFE molecular chain. The PTFE composite with higher heat absorption capacity exhibited improved wear resistance. Furthermore, the steel ring counterface abrasion was not found.

Effect of load on the wear rate of PTFE and its composites.     

沸石对海水拌合超高性能混凝土性能的影响

利用沸石部分或完全(体积分数为0%、50%、100%)取代海水拌合超高性能混凝土(UHPC)中的河砂,对比研究了沸石对海水拌合UHPC宏观和微观性能的影响。结果表明,海水拌合促进UHPC的水化,从而缩短UHPC的凝结时间,提高UHPC的抗压强度和自收缩,而沸石吸收氯离子会抑制氯离子的加速水化作用,使海水拌合UHPC的凝结时间延长,抗压强度降低。此外,沸石的内养护作用可以有效改善海水拌合UHPC的自收缩,且效果比在淡水拌合UHPC中更好,这主要是因为沸石在海水拌合UHPC中释水的时间更早且更长。由于多孔沸石的强度低于河砂,所以UHPC的早期抗压强度随着沸石含量的增多而逐渐降低,养护至28 d后,沸石的内养护作用优化了界面过渡区,从而促使后期硬化浆体进一步密实。     

重整甲醇高温聚合物电解质膜燃料电池研究进展与展望

甲醇作为一种安全便捷的液态储氢燃料,具有高含氢量以及高体积能量密度,可经重整为富氢气后与燃料电池系统集成为重整甲醇高温聚合物电解质膜燃料电池,从而高效地将甲醇和氧气的化学能转变为电能。本文针对重整甲醇高温聚合物电解质膜燃料电池的不同类型（外置重整型和内置重整型）,分别对其系统集成的实现与发展进行了总结,并介绍了其现阶段在军用和民用方面的应用情况,同时指出了技术研究与应用存在的瓶颈,并对未来的研究方向进行了展望。未来提升重整甲醇高温聚合物电解质膜燃料电池性能的努力在于开发低温工作的高效甲醇重整催化剂,以及高温稳定运行的聚合物电解质膜和非贵金属材料等燃料电池关键材料。     

Multiscale simulation on dynamic friction behavior of cylinder sealing rings under hydrothermal aging

The friction behavior of cylinder seal greatly affects the dynamic position accuracy of the cylinder execution terminal under hydrothermal aging. So, the hydrothermal aging test, friction test, tensile and compression test, topography analysis and infrared spectroscopy analysis, and multiscale simulation were carried out for studying the effect of the hydrothermal aging on the friction performance of cylinder seal. It was found that when the aging temperature increases from 40 to 80°C, the dynamic friction forces of the cylinder seals increase by more than 15%; the friction force increases with the increasement of the initial mechanical stress. Aging makes rubber to be brittle and more cavities on the fracture surface and reduces the fractured activation energy of the nitrile rubber molecular chain.     

内置洁能芯换热管强化换热实验研究

针对于在化工换热设备中期强化传热与自清洁作用的"洁能芯"内插件强化换热装置进行了实验研究,实验的雷诺数范围2300到9000,对比了插入"洁能芯"内插件换热管与光管的努塞尔数与摩擦因素,分析了"洁能芯"内插件对于强化传热的效果与增加的阻力损失。结果表明:"洁能芯"内插件能够有效的扰动流体,使管内流体的流动状态有利于强化传热,提高的幅度在30%到60%,并且随着雷诺数的增大而减小。同时,"洁能芯"内插件也会对增大换热管的摩擦因素,造成一定的阻力损失。