超细铁粉和氧化铁颗粒的研究

用透射电镜和图像分析仪等研究了超细铁粉和γ-Fe_2O_3粉末的结构、形貌、粒子的平均尺寸以及粒度分布。研究结果表明,多数超细铁粉粒子近似呈球形,并且,铁粉粒子由两相组成,粒子的核心部分是金屑a-Fe,表面的包裹层为氧化物层,它由Fe_3O_4和7-Fe_O_3的混合物组成。氧化层的平均厚度大约占整个粒子直径的20％左右。羰基铁粉粒子(含氧化层)的平均直径为16nm。直径在4～24nm范围的粒子数占总粒子数的91％,而7-Fe_2O_3粉末既有雪茄状粒子,也有小球状粒子。分析表明,球状粒子的平均直径为113nm,雪茄状粒子的平均直径(按<长 宽>/2计算)为148nm。由于超细铁粉粒子很细,且有磁性,制备电镜试样时分散比较困难。本文比较了几种分散方法后,使用了一种较好的分散方法——超声喷管分散法。     

Nitrogen addition to iron powder by mechanical alloying

Nitrogen was alloyed into iron (a) by mechanical processing in a nitrogen gas environment, and (b) by mechanically alloying with iron-nitride powders to characterize resulting nano-structure and nitrogen distribution. Although the infused nitrogen concentration was significantly greater than the thermodynamic equilibrium solubility of iron, no nitrides formed, even for nitrogen concentrations as high as 4.1 wt.% However, a bctFe phase did form. Lattice expansion calculations indicate that the sum of the interstitial bcc-Fe and bctFe nitrogen concentrations was significantly less than the total measured nitrogen concentration. A considerable portion of the mechanically infused nitrogen was determined to be associated with nanograin boundaries.     

Iron pyrite films prepared by sulfur vapor transport

Iron films deposited via thermal evaporation, with a thickness between 100 and 250 nm, were converted into FeS₂ by open sulfur transport using nitrogen as a gas vector. The films thus obtained constituted a single pyrite phase and were optically highly absorbing. The sulfurization process was optimized. As a result, sample temperature and conversion time were found to be the major determining parameters. The films were characterized using several methods. The crystallinity and phase identification were determined by X-ray diffractometry. Scanning electron microscopy showed a homogeneous surface of both iron and pyrite layers. Optical transmission measurements confirmed the highly absorbing character of FeS₂ and allowed the determination of direct (1.35 eV) and indirect (0.82 eV) transitions.     

一种悬臂式钢管喷印装置及其控制系统

本文介绍了一种用于成品钢管生产线上的悬臂式钢管喷印装置，它是一台结构和功能都较复杂的大型机电一体化设备。文中简介了它的性能、特点和工作原理，对其各部分机械装置的构成及动作以及喷印控制系统的组成和功能进行了较为深入的描述。     

凸非球面补偿检验的工艺球面分析解

本文从三级像差理论出发,推导了几种工艺球面检验凸二次曲面的计算公式。根据这些公式计算结果,进行了光路追迹,给出了这些公式对凸二次曲面的补偿范围;并讨论了几种特殊情况下的平面解。     

热收缩套管及其成型方法

本文介绍了热收缩套管的收缩机理及成型方法，如气压吹胀法、机械扩张法和缠绕法等。并对管材结构、原料及主要工艺技术简要地进行了比较和评价。     

Synthesis of Nearly Monodisperse Iron Oxide and Oxyhydroxide Nanocrystals

Uniform magnetite, hematite, and goethite nanocrystals were prepared through an attractive method based on an oleic acid/alcohol/water system. By adjusting the synthetic parameters (base concentration, alcohol content, categories of alcohols, etc.), the controlled synthesis of uniform magnetite, hematite, and goethite nanocrystals can be easily achieved. Detailed investigations on the effect of the experimental parameters on the morphology of the final products and the phase transitions among the magnetite, hematite, and goethite phases were carried out. Finally, a method of doping other metal ions into magnetite was developed and the magnetic properties of magnetite doped with different metal elements were studied.     

Dynamic responses and damages of water-filled pre-pressurized metal tube impacted by mass

An account is given of some principal observations made from a series of experiments in which three-span pipe beams were subjected to central impact by indenters with different nose shapes. These pipes were filled and pre-pressurized with water in order to identify the main effects produced by the fluid–structure interaction. In comparison, the impact experiments of the pipes with no water were also carried out. The perforation failure modes and corresponding critical impact energies were obtained in different test conditions. The experimental results indicated that the critical perforation energy and the deformation of the wall of the pipe were significantly influenced by the presence of the water and the pressure.     

圆筒形铸件缩松缩孔的产生原因及解决方法

针对圆筒形铸铁辊体冒口端面产生的缩松、缩孔缺陷，进行了举例说明、系统分析，找到了缺陷产生的原因及影响因素。通过解决措施的应用与实施，有效地克服了圆筒形辊体铸件冒口端面产生的缩松、缩孔缺陷，同时应用到其它大型圆筒形铸件中，都得到了良好效果。     

Biomimetic synthesis of spherical nano-hydroxyapatite in the presence of polyethylene glycol

Spherical nano-hydroxyapatite (nano-HA) was synthesized successfully by a biomimetic method using Ca(NO₃)₂·4H₂O and (NH₄)₃PO₄·3H₂O as reagents in the presence of polyethylene glycol (PEG). The crystalline phase, microstructure, chemical composition, and morphology of the obtained samples were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The results show that spherical nano-HA with diameter of 30–50 nm can be synthesized in the presence of a certain concentration (2–6%) of PEG. The crystallinity of HA powder synthesized in the presence of PEG was higher than that synthesized in the absence of PEG, but the crystallinity of HA reduced with increasing the concentration of PEG. The electrical conductivity (EC) of the solution revealed that PEG reduced the transfer rate of Ca²⁺ in the process of HA crystallization, indicating the interaction between PEG and HA. The possible mechanism of formation spherical nano-HA was discussed.