镁基复合材料微区力学状态的有限元分析

弹性变形范围内,在采用三维有限元模型分析了颗粒增强Mg基复合材料(PRMMCs)中,颗粒的分布形态对材料微区力学状态的影响。结果表明,在保持颗粒长径比(2:1)和颗粒间距(d)不变的情况下,随着θ的变化,不存在颗粒断裂的危险,材料的主要失效方式为界面脱离和基体开裂。增强体相对夹角θ=15o时的结果优于其它情况,这更有利于充分发挥材料的性能。     

钛制容器产品试板压弯角度的探讨

针对钛制容器产品试板弯曲角度按现行标准执行中出现的问题，从力学角度进行探讨，导了了试板压弯对所采用的压头直径与试板厚度和延伸率的关系，即Ｄ〉（１／δ－１）ｔ，并提出了设定试板弯曲压头直径的新思路。     

含Li的Al-Zn-Mg-Cu合金沉淀析出过程的定量分析

应用小角度X射线散射技术结合TEM分析定量的描述Al-Zn-Mg-Cu-Li合金时效过程中析出相尺寸分布和形貌等信息。通过分析确定合金在几种时效状态下析出相为轴比在0．2～0．4之间的扁回转椭球形。确定了析出相特征尺寸的对数正态分布和质量依回转半径的Maxwell分布。并分析分布曲线随动力强度Ks的变化特征，可以看出，析出相尺寸和质量分布曲线基本满足随动力强度增加，几何平均值增加，分布范围变宽。     

摆动滚子从动件盘形凸轮的CAD动画设计与加工

在AutoCAD基础上利用速度瞬心进行摆动滚子从动件凸轮机构轮廓曲线的CAD动画设计,同时可以生成刀具中心的加工轨迹、计算出压力角,能够实现CAD/CAM一体化,是一种简捷实用的新方法,可以直接应用于生产实际和教学.     

剪切变形方向特征对高纯铝箔轧制织构的影响

运用取向分布函数(ODF)研究了每个轧制道次的剪切变形特征对高纯铝箔轧制织构的影响.提出用中性角的相对大小来量化轧制剪切变形作用方向改变的位置,运用Taylor晶体塑性变形理论模拟计算了中性角的相对大小对轧制织构演变的影响.实测与模拟的轧制织构特征表明:中性角靠近轧制变形区的中心位置有利于形成{001}<110>剪切织构,从而证实了除剪切变形的程度外,剪切变形方向改变的位置也是影响高纯铝箔轧制织构的重要因素.     

The role of the surface free energy in the selection of a suitable excipient in the course of a wet-granulation method

Pellets containing metronidazole were produced in a centrifugal granulator, with hydroxypropylcellulose (Klucel LF®) as binding agent, and corn starch, microcrystalline cellulose (Vivapur 101®) and lactose as excipients. The wettability of the pharmaceutical powders was assessed by means of contact angle measurements, and the dispersive and polar surface energies were determined. The spreading coefficients, the work of adhesion and the work of cohesion were calculated and correlated with the pellet properties (friability, bulk and tapped density, and porosity). The aim was to investigate the role of the surface free energy of one- and two-component powder compositions in pellet production. The interactions between the particles were found to be connected with the measured pellet parameters. It was concluded that, in the course of the growth of the pellets, the particle sizes of the pharmaceutical powders and the interactions between them are important. If the work of cohesion of the binder is lower than the work of cohesion of the substrate and the work of adhesion, then the optimal amount of the binding agent is that which coats the particles uniformly in minimal quantity and in continuous layer.     

薄板坯连铸浸入式水口结构数值模拟

使用有限元计算方法开展薄板坯连铸浸入式水口流场的研究 ,分别对水口不同浸入深度的流场分布、水口出口不同角度的流场分布进行计算。结果发现 :水口的浸入深度在 30 0mm时较为合理 ;水口的出口角度以R1 5、60°、45°为宜     

Surface modification of tetrafluoroethylene–perfluoroalkyl vinylether copolymer (PFA) by plasmas for copper metallization

Tetrafluoroethylene–perfluoroalkyl vinylether copolymer (PFA) sheet surfaces were modified with argon, helium, oxygen, and hydrogen plasmas. How the four plasmas modified the PFA sheet surfaces was investigated. All plasmas modified the PFA surfaces and at the same time initiated degradation of the PFA polymer chains. The balance between modification and degradation was strongly influenced by the magnitude of the discharge current in the plasmas. Efficiency of the plasmas in modification was hydrogen plasma > oxygen plasma > argon plasma > helium plasma. The modification involved defluorination of CF₂ carbons into CHF and CH₂ carbons and oxidation into O? CH₂, O? CHF, and O? CF₂ groups. The surface‐modification technique (a combination of hydrogen plasma treatment and silane coupling treatment) proposed in this study was applied for copper metallization of the PFA surface. The utility of the technique was confirmed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1087–1097, 2002     

臭氧氧化处理法对聚丙烯表面涂装性的改良 Ⅳ.聚丙烯表面亲水性和涂膜剥离强度的关系

讨论了用臭氧氧化法对聚丙烯表面进行涂装性改良时,丙烯均聚物、乙烯-丙烯嵌段共聚物及无规共聚物表面以接触角表示的亲水性和涂膜剥离强度之间的关系。结果表明,当聚丙烯表面对水的接触角在84°附近时,可反应型涂料的涂膜剥离强度将出现最大值。在此也证明了涂膜的剥离破坏存在着接着破坏和凝集破坏两种机理,当接触角减小到84°及84°以上时,剥离发生在聚丙烯和涂层的界面上产生接着破坏;当接触角减小到84°以下时,剥离发生在聚丙烯的表面氧化层相中,产生凝集破坏。     

High resolution solid state 13C n.m.r. of butadiene grafted polypropylene

¹H dipolar decoupled ¹³C n.m.r. experiments with the aid of the magic angle spinning technique have been used to determine the graft content and the isomer content of the polybutadiene grafts in a graft copolymer with isotactic polypropylene.