奈非西坦的合成研究

奈非西坦是新研制的一种对阿尔茨海默氏病和脑血管后遗症有良好的临床治疗价值的药物。对奈非西坦的各种合成方法进行了总结,分析了各路线的优缺点,并对奈非西坦的药理学内容做了概述。     

整体式无痕注塑模芯的快速成型工艺

详细阐述了以SRW金属粉末快速成型毛坯,然后经过热处理及精加工制作整体式无痕注塑模具模芯的过程,并以实例对制作过程进行了研究。结果表明,利用该工艺制造的模芯,其致密度接近理想密度,机械性能达到模具的设计要求。     

芦丁提取与纸色谱检测条件的优化

多年来,从槐花米中提取芦丁及纸色谱检验一直是华南农业大学一年级本科生必做的基础化学实验,但根据教材中提供的实验条件,学生实验过程中总出现产品量少、纸色谱效果差的问题。文章从提取与纸色谱检验两个方面对原始实验条件进行了改进,使芦丁的提取率提高了74%、纸色谱的实验效果得到显著改善。文章得到的最佳提取条件为:冷水投料、加入1%亚硫酸钠、液固比为10、碱溶pH为9.0～10.0、浸煮温度为90～95℃、浸煮时间为30min;展开剂最佳组成为乙酸乙酯︰甲醇︰水=2︰1︰1。     

碳酸盐岩处理煤矿酸性废水的试验研究

以碳酸盐岩颗粒为反应介质,采用动态模拟试验来处理煤矿酸性废水.结果表明,pH平均由进水2.5左右上升到出水的7.0左右;出水Fe3+的质量浓度均低于0.5 mg·L-1,Fe3+的去除率都达到99.5%以上;出水锰的质量浓度在6.5～8.5 mg·L-1,去除率在40%～50%,部分高于50%,并有逐渐提高的趋势;对SO2-4的去除效果较差.因此,碳酸盐岩颗粒作为可渗透反应墙介质去除酸性煤矿废水中的铁以及提高pH具有很好的效果.     

Effect of Substrate Temperature on CaHPO4 Coating on HT-C/C Composites Prepared by Ultrasonic Induction Heating Method

采用超声感应加热法在H2O2水热处理C/C复合材料表面沉积了CaHPO4涂层,借助SEM、XRD、FTIR、EDS等手段,研究了衬底温度对涂层的微观结构的影响,并通过划痕测试评价涂层与C/C基体之间的结合强度,同时运用分析天平测量质量以研究涂层的沉积动力学。结果显示,所制得的CaHPO4涂层钙磷比为1.2左右,晶格中出现碳离子。涂层形貌无明显变化,但是伴随温度的升高,涂层致密度降低。涂层与基体之间的结合强度随温度升高而增强,但内聚强度随温度升高而减弱。CaHPO4涂层的感应加热沉积过程受表面化学反应控制,沉积活化能为46.7 kJ/mol。     

真空热压烧结对高纯W-Si合金靶材性能影响

以高纯W-Si合金粉(>99.995%)为原料,采用真空热压烧结工艺制备高纯W-Si合金靶材。研究烧结温度、热压压力、保温时间等工艺条件对靶材密度、微观组织性能的影响。结果表明,烧结温度在1350~1380℃,热压压力25~30 MPa,保温时间1.5~2 h,可制备出相对密度99%以上、平均晶粒尺寸100μm以内的高性能W-Si合金靶材。     

Infiltration mechanism and factors influencing carbon/carbon–Zr–Ti–C composites prepared by liquid metal infiltration

The effects of fibre architecture, reaction temperature and holding time on the infiltration performance of carbon/carbon (C/C)–Zr–Ti–C composites prepared by liquid metal infiltration were investigated. The results indicated that samples with a chopped-web needled preform and low initial density had a high final density. Increasing the reaction temperatures resulted in a decrease of the final density of samples. Additionally, increasing the initial holding time appeared to obviously result in a high final density, but its effectiveness was not obvious in later observations. An analysis of the infiltration kinetics and mechanisms indicated that the diffusivity of carbon in the carbide, the open-pore sizes and their distribution in C/C composites were the essential characteristics that controlled the height of infiltrating melts.     

Characterisation of periodic variation in torque occurred in friction stir welding process

Friction stir welding was physically simulated to study torque variation by a rotational friction process under constant axial pressing speed. The results indicated that the torque accurately reproduce the same periodic characteristics as the friction stir welding torque, i.e. the torque cycle is equal to the time of one tool rotation. The periodic variation intensity of torque, which was obtained at a constant rotational speed ω and a constant axial pressing speed v, was characterised by non-dimensional amplitude of the torque Γ*. Moreover, a semianalytical model, which describes Γ* as a function of ω²/v in Arrhenius form, was established. In this model, Γ* exponentially increases with ω²/v, and low ω²/v suppresses the variation intensity of torque.     

微波-超声波协同制备微细仲钨酸铵

在不使用外力搅拌和不添加任何表面活性剂的条件下,采用微波-超声波协同蒸发结晶制备微细仲钨酸铵。考察了结晶温度,钨酸铵浓度,微波与超声波的协同功率、协同时间对仲钨酸铵粒度及形貌影响。在较佳条件下,微波-超声波协同可制得平均粒度为7.6μm、粒径分布均匀、晶型完整的微细单晶五水仲钨酸铵。     

时效处理对高频感应熔覆TiC/Ni复合涂层的组织及性能影响

为了改善抽油杆材料的表面性能,采用高频感应熔覆技术在其表面制备了TiC/Ni复合涂层。采用光学显微镜、扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)等研究了涂层经固溶及不同时间时效处理后的显微组织及物相组成,并利用显微硬度计及摩擦磨损实验测试了时效后涂层的性能变化。结果表明:经固溶时效后的涂层并未出现明显缺陷,涂层主要以γ-Ni固溶体、Ni的化合物、CrB、碳化物以及δ相等硬质颗粒组成;时效后涂层的最大硬度达到928.2 HV0.2,相比时效前提高了4%,最低磨损量为48.9 mg,比基材减少了62%,在时效4 h后,涂层的综合性能最好。