Infrared heat treatment of Ti-6Al-4V with electroplated Cu

The objective of this study is to investigate an innovative infrared (IR) technique to enhance adhesion of electroplated copper (Cu) on Ti-6Al-4V without dichromate dipping. The ultimate goal is to develop a Cu coating process on Ti-6Al-4V without hazardous hexavalent chromium (Cr) solution treatments. Cu coatings of around 50 μm were electroplated on Ti-6Al-4V specimens at a current density of 0.03 A/cm² in an acidic Cu solution. To improve adhesion of coatings, IR heat treatments were performed on the Cu-coated samples at different temperatures and durations: 860 °C for 600 s and 875 °C for 20–120 s. This process was accomplished in an attempt to replace the use of dichromate dipping before electroplating. For samples heat treated at 860 °C, no bonding existed, even after 600 s. It is believed that solid-state diffusion prevailed at 860 °C and that 600 s was not enough for sufficient diffusion to occur. Adhesion was poor when samples were heat treated at 875 °C for 20 s. Excellent adhesion was observed when the heat treatment holding time was increased to 40 s. For 90 s, the surface appearance of coatings partially changed from Cu-colored to a grayish color. There was no Cu left on the surface after a 120 s heat treatment. From optical microscopic observations on sample cross sections, an interlayer between the Cu and Ti-6Al-4V formed when heat treated at 875 °C for 40 s and longer. The interlayer thickness increased as the holding time increased, until depletion of Cu. The sheet resistivity of coated specimens was on the order of pure Cu for samples heat treated at 875 °C and less than 90 s. During the 875 °C heat treatment, the following occurred: solid-state diffusion of Cu in Ti-6Al-4V, formation of eutectic solutions, dissolution of Cu and Ti-6Al-4V into the liquid phase, and the formation of intermetallic compounds. The lowest eutectic temperature of 875 °C played a key role in this innovative process of Cu coating on Ti-6Al-4V. This paper was presented at the 2nd International Surface Engineering Congress sponsored by ASM International, on September 15–17, 2003, in Indianapolis, Indiana and appears on pp. 403–10 of the Proceedings.     

DEPENDENCE OF PREDICTION MODEL OF FORMING LIMIT STRAINS ON FORMING METHOD AND MECHANICAL PROPERTIES OF SHEET METALS

ＤＥＰＥＮＤＥＮＣＥＯＦＰＲＥＤＩＣＴＩＯＮＭＯＤＥＬＯＦＦＯＲＭＩＮＧＬＩＭＩＴＳＴＲＡＩＮＳＯＮＦＯＲＭＩＮＧＭＥＴＨＯＤＡＮＤＭＥＣＨＡＮＩＣＡＬＰＲＯＰＥＲＴＩＥＳＯＦＳＨＥＥＴＭＥＴＡＬＳ①ＺｈｏｕＷｅｉｘｉａｎＤｅｐａｒｔｍｅｎｔｏｆＡｅ...     

电镀塑料制品对结构设计及成形工艺的要求

为保证电镀塑料制品的质量,提出了符合电镀要求的塑料制品设计原则,并且指出在注塑成形时,对塑料经过充分干燥,采用较高的注塑温度,较低的注射压力和较慢的注射速度,是使镀层获得良好结合强度的先决条件。     

Stresses in bent copper tubing: Application to fatigue and stress-corrosion cracking failure mechanisms

The residual and applied stresses in u-bent copper tubing are addressed in the context of both cyclic fatigue and stress-corrosion cracking. Failures as a result of fatigue and stress corrosion cracking in u-bent copper tubing have been observed to initiate at nonintuitive locations when only the applied stresses on the component are considered. This paper presents both qualitative classical and quantitative finite-element stress analysis results for the forming of u-bends. The resulting residual stress distributions are compared to fracture patterns generated by both fatigue and stress-corrosion cracking mechanisms.     

表单提交对象化-Struts

在b／s结构中可以完全实现逻辑和界面的分离，而它们之问的数据交流只有一个途径：表单提交。实现表单提交的对象化一直是很多程序员的愿甲，水文将通过对struts的介绍末展示其恭本工作原理，阐述如何用struts实现表单提交对象化：     

TC4合金锥体模锻过程的数值模拟

采用刚塑性有限元法对钛合金锥体的模锻成形进行有限元数值模拟,分析了锥形件模锻过程中的金属流动规律,应力场、应变场、变形区的压力分布,压力的变化规律等。模拟结果表明,锥体模锻成形分为3个阶段:初期变形过程是圆柱体变形为一个小曲率壳体的阶段,应力主要集中在上模的正下方,应变主要发生在此变形区;变形中期是与下模相接触的部分参与变形的体积逐渐增大,直至最后形成所需要的锥体形状;变形后期由于摩擦作用产生严重的不均匀壁厚减薄现象。     

铁素体区轧制技术及应用于攀钢生产的可行性

讨论了铁素体区轧制技术的优势,特点及其在国内外生产厂家的应用现状,分析限铁素体区轧制工艺在攀钢实施的可行性。     

金属拱型屋面板的开发与应用

简要介绍了武钢Ｗ６６６金属拱型层面板的开发、设计、试验研究及应用情况,探讨了理论分析的方法和应用前景。     

材料力学性能对液力胀接过程的影响分析

为寻求装配式空心凸轮轴结构设计和材料选择的理论依据,应用弹塑性力学分析了弹性模量和流动应力对液力胀接的影响.将内外管的变形过程简化为平面应变问题,根据典型点应力-应变曲线分析了液力胀接过程,并给出了不同材质套管的连接条件.研究结果表明:影响液力胀接的主要因素是内外管弹性模量和流动应力,这两个材料参数决定胀后内外管弹性回复量的大小;实现液力胀接内外管应满足的条件是:内外管弹性模量的比值大于内外管流动应力的比值.