Mechanical activation-assisted electro-thermal explosion synthesis of the Ti2AlC phase

This study deals with the synthesis of the Ti₂AlC phase using the Electro-Thermal Explosion under Pressure with Confinement (ETEPC) technique. The effects of the ETEPC technique and the milling process parameters on the TiC_x phase content and the formation mechanism of the Ti₂AlC phase were investigated. The latter is mainly affected by the morphology of the powder mixture and aluminum melted amount. The optimization of the above parameters allowed the achievement of the desired reaction, leading to the formation of the Ti₂AlC phase with a purity of about 97?wt%. The results clearly demonstrate that the ETEPC process enables one to control both time and material synthesis temperature.     

高能球磨制备TiB_2/TiC纳米复合粉体

研究了通过高能球磨制备ＴｉＢ２／ＴｉＣ纳米复合粉体的反应过程和机理,对粉体的显微结构进行了表征．实验结果表明,采用金属 Ｔｉ和 Ｂ４Ｃ为原料,在球磨过程中, ＴｉＣ先于 ＴｉＢ２形成．球磨５ｈ后Ｔｉ与Ｂ４Ｃ反应生成ＴｉＢ２和ＴｉＣ,在随后的长时间高能球磨过程中ＴｉＢ２和ＴｉＣ两相保持稳定．球磨 ３０ｈ后,直径约 ８ｎｍ的 ＴｉＣ纳米粒子分布在 １００～２００ ｎｍ的 ＴｉＢ２粒子中,形成均匀分布的纳米ＴｉＢ２／ＴｉＣ复合粉体．     

含能催化复合纳米材料的制备研究

亚铬酸铜是促进复合固体推进剂中高氯酸铵分解的一种很好的催化剂,但由于以往制备的亚铬酸铜及高氯酸铵超细微粒易发生团聚,不能有效地对高氯酸铵的分解起催化作用。本文使用高能球磨法,使纳米级亚铬酸铜嵌入或粘附于高氯酸铵晶体表面而形成复合粒子,因而大大地提高了对高氯酸铵的催化效果,使高氯酸铵的热分解反应温度区间明显前移,热分解反应的激烈程度大大提高     

用MasterCAM加工双金属材料链轮硬齿表面

运用MasterCAM软件对双金属材料链轮硬齿表面进行曲面三维造型,编程,并对链轮双金属材料硬齿表面进行曲面合理工艺设计,加工出了符合图纸要求的产品零件。阐述了MasterCAM软件在加工实例产品时编程的基本步骤,重点突出了其加工工艺和加工参数等关键问题。     

Preparation of PbCO3–CuO nanoparticles and catalytic performance on NC/NG and NC/NG/NQ propellants

This study demonstrates a direct, high-yield, and inexpensive route for preparation of nearly spherical PbCO₃–CuO nanoparticles (NPs) through mechanical ball milling method. The NPs were characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, EDS, and dynamic light scattering techniques. Catalytic decomposition effects of PbCO₃–CuO NPs and PbCO₃/CuO raw material mixture on nitrocotton (NC)/nitroglycerin (NG) propellant were studied by DSC analysis. Then, the combustion properties of NC/NG and nitroguanidine (NQ)/NC/NG propellants with above catalysts were researched. The results showed that the NPs exhibited good catalytic effect on both propellants. By adding 1.5% NPs in mass, decomposition temperature of NC/NG decreased by 29.35°C, and the heat of decomposition increased by 606 J g^?1. PbCO₃–CuO NPs used as burning catalyst of above propellants can increase the burning rate, decrease the pressure exponent and form good “plateau” effect at 4–12 MPa. And the NPs showed better comprehensive catalytic performance than the PbCO₃/CuO mixture. Thus, PbCO₃–CuO NPs could be a promising addictive in modifying burning behaviors of solid propellants with double base component.     

硬质合金激光铣削加工试验研究

采用不同的激光铣削工艺对硬质合金进行激光铣削试验研究。分析了工艺参数对铣削量和铣削质量的影响,并利用优化或复合的工艺对硬质合金试样进行多样激光铣削。     

塑炼1,2-聚丁二烯的无扰尺寸

利用测得(?)和[η]数据,由Stockmayer-Fixman-Burchard、Stockmayer-Kurata-Roig和Inagaki-Suzuki-Kurata方程外推,估算了塑炼过程中不同1,2-链节含量的1,2-聚丁二烯(1,2-PB)的无扰尺寸变化规律。1,2-链节含量分别为40％和87.2％时,随薄通次数的增加,无扰尺寸降低;但前者薄通50次后变化很小,后者薄通100次后仍有波动。1,2-链节含量为87.2％的1,2-PB,薄通后放置30d,其无扰尺寸随薄通次数的增加而降低的程度,均大于当日测定的结果。     

Studies on the nutritive characteristics and fracture resistance to compressive loading of selected bambara groundnut lines

Extensive laboratory experiments were conducted to determine the nutritive characteristics and fracture resistance to compressive loading of some bambara groundnut lines. Data obtained showed percentage carbohydrate, protein and oil contents of 52.60, 17.52 and 6.66 respectively for dehulled bambara groundnut seeds as against lower percentage values of 48.60, 16.99 and 6.20 obtained from the analysis of whole seeds of BgB-Br. Investigations on the mechanical properties revealed that the force needed to rupture the seeds was influenced by moisture content and loading position of the seeds. The force was found to decrease from 262 to 100 N with increase in moisture content, while the deformation increased from 1.9 to 4.5 mm with increase in moisture content. Maximum toughness occurred at different moistures which represent the moisture levels for absorbing compressive energy which are important for resisting mechanical damage during handling of the bambara groundnut lines. © 1999 Society of Chemical Industry     

单板接长工艺研究进展及其发展前景

概述单板接长工艺研究进程,着重介绍国内外单板接长机组发展概况、技术性能比较,特点。还对单板接长机组在我国推广应用前景进行了评述。