Water absorption,biodegradation, thermal and morphological properties of Spartium junceum fiber-reinforced polyvinylchloride composites: effects of fibers content and surface modification

In this study, we want to investigate the effects of fibers content and surface modification of Spartium junceum (SJ) fibers on the water absorption characteristics, thermal degradation, and morphological properties of SJ-reinforced poly (vinyl chloride) (PVC) composites. In addition, the change in mechanical proprieties of the composites after biodegradation test was evaluated by tensile strength. In order to improve the interfacial interactions between the PVC matrix and the SJ fibers, SJ fibers were modified by sodium hydroxide (NaOH), vinyltrimethoxysilane (VTMS) and treated with sodium hydroxide solution followed by VTMS (NaOH+VTMS). The results show that the water uptake of PVC/SJ fibers composites increases with the increase in the fibers’ content. However, the surface modification reduces water uptake. Moreover, the results indicate that the kinetics of water absorption of the PVC/SJ fibers composites approaches the Fickian diffusion mechanism. Also, the results indicate that the tensile strength of the composites is affected by the biodegradation test and chemical treatments. The atomic force microscope pictures of the composites illustrate the reduction of roughness via surface treatments of fibers.     

基于多线程运行控制的高效节能型净水工艺

华北地区某净水厂以当地水库水为水源,原水受到有机物污染,水质受季节影响变化较大。为应对上述水质问题采用高密度沉淀池—V型滤池—超滤—臭氧加活性炭吸附的工艺流程,但该工艺流程较长,运行能耗较高。针对季节和水质变化,以供水安全可靠为前提,高效节能为目标,提出了水厂运行的多线程工艺流程。经节能评估,运行改进后可节能23.96%。     

某小型航空发动机排气锥裂纹焊接修复

某小型航空发动机排气锥服役中产生大量裂纹,通过观察裂纹断口宏观形貌、微观组织及能谱分析,判断裂纹为应力腐蚀裂纹。焊前采用固溶处理恢复母材为奥氏体组织,消除晶间贫铬,采用脉冲钨极氩弧焊修复裂纹,焊后对焊缝进行喷丸强化处理,成功修复排气锥裂纹。     

Cone-shaped hollow flexible reinforced concrete foundation (CHFRF) – Innovative for mountain wind turbines

This paper presents an innovative type of mountain wind turbine foundation, namely, the cone-shaped hollow flexible reinforced concrete foundation (CHFRF). It consists of a top plate, a base plate and a side wall that are made of reinforced concrete. The cavity of the CHFRF is filled with rubble and soil directly from the excavation for the CHFRF, which means that it can absorb the spoil. A rubber layer is placed beneath the CHFRF to increase the foundation flexibility to resist cyclic and dynamic loadings and to increase the bearing capacity. The great advantages of the CHFRF are the reduction in the usage of concrete and steel and the protection of the vegetation around the wind turbine, compared with conventional mountain wind turbine foundations that are solid structures. It is verified through model tests and a numerical simulation that the CHFRF can provide higher lateral bearing capacity in comparison to the regular circular gravity-based foundation under the same foundation diameter and height, and that the bearing capacity is increased by approximately 33.5% accordingly. It is also found that the rubber layer can effectively reduce the accumulated rotation of the CHFRF under cyclic loading. The accumulated rotation of the CHFRF with a rubber layer having a thickness of 4 mm is decreased by about 50% compared to that of the CHFRF with a rubber layer having a thickness of 2 mm. In addition, the volume of concrete used for the CHFRF is only one-fifth of that used for the circular gravity-based foundation. Therefore, the CHFRF outperforms regular mountain wind turbine foundations.     

镀铜钢纤维表面改性及其耐腐蚀性能和黏结性能

为了改善镀铜钢纤维与水泥基体的黏结强度,用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)和γ-巯基丙基三甲氧基硅烷(MPTS)对镀铜钢纤维进行表面处理.采用红外光谱、扫描电子显微镜(SEM)、氯化钠溶液浸泡腐蚀试验和黏结强度测试来评价处理后镀铜钢纤维的性能.结果表明:MPTS与镀铜钢纤维表面发生了化学键合,提升了钢纤维表面粗糙度;经过MPS处理和MPTS/MPS组合处理的钢纤维腐蚀溶液的吸光度积分只有未处理组的91%和45%;经过MPS处理和MPTS/MPS组合处理的钢纤维从水泥基体中拔出时所做的功相对于未改性组分别提升了43%和224%,与水泥基体的黏结强度得到了相应提高.     

Effect of thermal treatment on energy dissipation of granite under cyclic impact loading

High temperature treatment causes thermal damage to rocks in deep mining. To study the thermal effect on the energy dissipation of rocks during the dynamic cyclic loading, cyclic impact loading experiments of heat-treated rocks were carried out using the splitting Hopkinson pressure bar (SHPB) experimental system. The correlations among the energy dissipation, energy dissipation rate, impact times, accumulated absorbed energy per volume, failure mode and temperature were analyzed. The results show that the reflected energy under the first impact increases and finally exceeds the absorbed energy when the temperature increases; however, the total reflected energy decreases above 200 °C. The absorbed energy under the first impact and the total absorbed energy all decrease as the temperature increases, the rates of which decrease accordingly. And the same phenomenon appears for the transmitted energy and the rate of the transmitted energy. On the contrary, the rate of the reflected energy increases with the rising temperature. When the temperature increases, the fewer impact times are needed to destroy the sample. In addition, the failure modes are different when the rock is treated at different temperatures; that is, when the temperature is high, even though the absorbed energy is low, the sample breaks into powder after several impacts.     

稀土Ce对化学沉积Co-Fe-B合金涂层功能特性的影响

借助显微硬度计、磨损试验机和振动样品磁强计等分析稀土金属Ce对化学沉积Co Fe B合金涂层显微硬度、磨损体积、磁化强度、矫顽力和磁导率的影响。结果表明 ,稀土Ce明显地提高了涂层的显微硬度和耐磨性 ,随镀液中稀土Ce量增加 ,显微硬度和耐磨性先增后降 ,在 [Ce] =0 8g/L时达到最大值。稀土Ce还提高了涂层的饱和磁化强度和磁导率 ,降低了剩余磁化强度和矫顽力。     

深层载荷试验应用中的几个问题

本文介绍了深层载荷试验系统的设计与安装,载荷试验和动力触探、标准贯入试验结果的对比,以及有关沉降量和地基承载力问题的分析。     

堆焊敷层技术在立柱中缸上的应用

介绍利用堆焊熔敷技术生产制造立柱中缸。针对立柱中缸的结构特点,提出堆焊具体方法、方案,并从理论上分析了27SiMn管堆焊技术应用的可行性,结合生产实际过程,就焊材、焊接工艺、焊后热处理等几个方面提出一些建议,同时对应用前景进行了展望。     

竖向荷载作用下单桩侧摩阻力及剪切位移研究

提出一种利用土的基本力学指标，可以确定桩在竖向荷载作用下桩侧摩阻力与剪切位移的关系公式，对于理论分析桩的荷载沉降提供一种有益的参考。