几何因素与摩擦耦合对高纯铝箔剪切织构的影响

采用取向分布函数 (ODF)研究了轧制几何因素、轧制摩擦条件对高纯铝箔轧制织构的影响。结果显示 ,如果轧制摩擦因数大 ,当处于均匀变形几何条件 1相似文献   

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.     

滚切剪剪切力的实验研究

对直导向滚切剪的剪切力进行了实验研究，得到了计算最大剪切力的经验公式。     

高层住宅结构设计

主要介绍长沙梦泽园高层住宅从基础到上部楼层各部位的结构设计,以及在设计、施工过程中所考虑的一些问题及处理方法。     

Adhesion Mechanisms of Polyurethanes to Glass Surfaces I. Structure-Property Relationships in Polyurethanes and Their Effects on Adhesion to Glass

Polyurethanes were prepared from toluene diisocyanate (TDI), 1-4-butane diol (BDO) and polycaprolactone-based triols with varying molecular weights. Among each molecular weight triol-based urethane, hard segment content was varied from 20% to 70%. Differential scanning calorimetry, tensile testing, and Iosipescu shear testing were done on all the various urethanes prepared. Thermal characterization data revealed the dependence of phase separation on hard segment content as well as on the triol molecular weight. Tensile data and Iosipescu shear data further confirmed the observations made from the DSC data. The data further indicated that phase separation can greatly improve the modulus of cross-linked segmented urethanes. Adhesion of these urethanes to glass surface was evaluated using soda-lime float glass plate. Urethane samples were cast on the air side of the glass plates and adhesion was measured in shear mode. Adhesion data indicated that in addition to hard segment content, modulus, cross-link density, and molecular weight of the triols, phase separation seems to be a major factor in controlling adhesion. Surfaces of the failed adhesion samples were also analyzed and the failure mode was found to be cohesive, in varying degree, with the different urethane systems.     

一种耐超高温、耐酸聚合物的制备及性能测试

摘要：为解决常规聚合物无法满足超高温深井酸化压裂的技术要求，本文分别以丙烯酰胺（AM） 甲基丙烯酰氧乙基三甲基氯化铵（DMC）、AM DMC SMA（十八烷基甲基丙烯酸酯）为原料，通过自由基聚合制备出两种耐酸聚合物SY-1和SY-2，并对其结构进行表征及性能测试。结果表明：SY-2红外谱图中720 cm-1为—(CH2)n—的弯曲振动吸收峰，单体成功接枝到聚丙烯酰胺分子链上；热重分析表明，SY-1升温至600℃失重比为98%，SY-2失重比86%，热稳定性得到改善；质量分数为20%盐酸中，SY-2质量分数0.8%：180℃，170s-1流变性能测试，SY-2剪切终点黏度56mPa?s，90℃、120℃、150℃剪切1h，黏度为83.6mPa?s、43.5mPa?s、27.8mPa?s，剪切稳定性分别为85.66%、74.45%、52.01%； 180℃、3MPa条件下，静态酸岩反应速率为8.94?10-5(g/cm2?s)，较常规SY-1反应速率1.69?10-4(g/cm2?s)减小一个量级。且与缓蚀剂、铁离子稳定剂配伍性良好，克服高温酸化压裂技术的应用瓶颈。     

Electrodiffusion diagnostics of the flow and mass transfer inside a network of crossing minichannels

The global mass transfer and the local flow structure inside a set of crossing minichannels were characterized using the electrodiffusion method. The individual square-cross channel sections (a = 1.5 mm in sides) intersect at right-angles in order to form the flow cell. An array of 39 circular platinum electrodes (0.25 mm in diameter) was flush-mounted into the wall of the flow cell to investigate the wall shear rate at different locations. This array of small sensors allowed characterization of longitudinal and lateral variations in wall shear rate across the flow cell, flow distribution at the inlet and outlet sections, transition between laminar and turbulent flow regimes, and flow behaviour at the channel crossings. The results of global wall mass transfer measurements demonstrated that, from a mass transfer point of view, the flow cell exhibits similar behaviour to a porous medium.     

Preadhesion Laser Treatment of Aluminum Surfaces

An excimer laser may be used for preadhesion treatment of aluminum alloys. This method presents an alternative to the use of ecologically unfriendly chemicals involved in conventional anodizing pretreatments.

Experimental results indicate that preadhesion laser surface treatment significantly improved the shear strength of modified-epoxy bonded aluminum specimens compared with untreated and anodized substrates. The best results were obtained with laser energy of about 0.2 J/Pulse/cm² where single lap shear strength was improved by 600-700% compared with that of untreated Al alloy, and by 40% compared with chromic acid anodizing pretreatment.

The mode of failure changed from adhesive to cohesive as the number of laser pulses increased during treatment. The latter phenomenon has been correlated with morphology changes as revealed by electron microscopy, and chemical modification as indicated by Auger and infrared spectroscopy.

It can be concluded that the excimer laser has potential as a precise, clean and simple preadhesion treatment of Al alloys.     

环氧-聚酰胺体系中增韧剂的研究

在环氧-聚酰胺体系中分别加入“海岛结构”QS-1、聚硫橡胶、液体丁腈橡胶增韧改性,通过对固化物剪切强度、弯曲弹性模量及断裂强度的对比,“海岛结构”QS-1增韧综合性能较好.     

垂直管内弹状气泡上升中壁面传递的实验研究

垂直管内弹状流壁面传递是诸多工业应用中需研究的重要问题之一。今用极限扩散电流技术,对弹状气泡上升时瞬时壁面剪应力和传质系数进行了测定,结果显示:当基于表观气速的Froude数FrG < 0.74时,壁面剪应力随弹状气泡和液塞的到来呈现方向相反的交替变化,壁面传质系数亦相应变化;而当FrG > 0.74时,剪应力方向一直向下,说明液膜向下流动,且弹状气泡和液塞的到来对壁面传质系数的影响很小。这说明下落液膜射流穿透了液塞段,控制了整个壁面传递过程。研究还对下落液膜区、尾迹区及液塞段的不同传递特征及机理进行了分析, 并结合气泡塔熔融结晶器中弹状气泡上升时的传热,对结晶操作条件的合理选择进行了讨论。