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排序方式: 共有159条查询结果,搜索用时 15 毫秒
1.
大型复杂高精度波导钎焊设备的研制:简介ZHS—132型真空钎焊炉 总被引:1,自引:0,他引:1
应军事电子装备,特别是军用雷达预研和生产的急需,电子工业部第二研究所近期研制的成功大型、复杂、高精度波导钎焊设备ZHS-132型真空钎焊炉。文中主要介绍了该设备的开发背景和对波导钎焊工艺的影响,该设备的设计构思、结构和技术特征,使用功能和效果,以及推广应用前景。 相似文献
2.
The electrochemical behaviour of Cu-xZn alloys, as well as their constituent metals, in a borate buffer containing chloride ions in the molar range from 0.01 to 1 M are studied. Characteristics of these materials under anodic polarization are compared and the composition and morphology of the corrosion products formed in the course of polarization experiment are analysed by SEM and EDS. X-ray photoelectron spectroscopy and electrochemical impedance measurements are used for characterization of the surface layers formed on Cu, Zn and Cu-40Zn alloy during 2-h immersion at Eoc in a borate buffer containing two different concentrations of chloride ions. New aspects of the behaviour of brass under Eoc condition are revealed. The improved corrosion resistance of brass in chloride media, if compared to zinc metal, is attributed to a Cu-rich layer formed by the selective dissolution of zinc. Based on the results, a structural model describing the improved corrosion resistance of Cu-40Zn alloy with respect to Zn metal is proposed. 相似文献
3.
在复杂黄铜等效变换的多元变化过程中,存在着第三种当量系数I。它是确保合金转化为二元形式所必不可少的导向给定值,是一个定位常数。找出了K+J=0的误解的产生原因,论证了K+J=1所在达的过程的实质。指出用二元相图理解等效变换这一三元变化过程的认识误区。 相似文献
4.
Effect of Zn and Pb as alloying elements on the electrochemical behavior of brass in NaCl solutions 总被引:4,自引:0,他引:4
The electrochemical behavior of brasses with various Zn content (5.5–38 mass%) and brass (Cu–38Zn) with different Pb contents (1–3.4 mass%) in 0.6 M NaCl was investigated. The effects of temperature, immersion time, and concentration of chloride ions on the behavior of the different alloys were studied. The pitting corrosion behavior of Cu–Zn alloys and leaded–brass alloys in 0.6 M NaCl solution was also investigated. Open-circuit potential measurements (OCP), polarization techniques and electrochemical impedance spectroscopy (EIS) were used. The results show that the increase in the Zn content increases the corrosion rate of the brass alloys in chloride solutions, while the increase of Pb content in Cu–38Zn–Pb decreases the corrosion rate of the alloy. Long immersion time of the alloys in the aqueous electrolyte improves their stability due to the formation of passive film on the alloy surface. The breakdown potential is shifted to more negative direction with increasing the Zn content, whereas it shifts towards positive values with increasing Pb content. Equivalent circuit model for the electrode/electrolyte interface under different conditions was proposed to illustrate the electrochemical processes taking place at the interface. The electrochemical behavior of the different alloys was discussed in view of the fitting results. 相似文献
5.
易切削Bi黄铜机理的研究 总被引:1,自引:0,他引:1
在保持传统黄铜易切削条件下,通过加入Bi代替Pb并添加少量RE获得了易切削黄铜。试验表明:绝大多数的Bi以单质游离态分布在卢相内,RE元素的加入一方面使黄铜组织细化,另一方面使更多的Bi颗粒存在于口相内,从而提高切削性能,最终得到易切削的且表面光洁的黄铜。 相似文献
6.
运用Procast软件对HSi80-3硅黄铜船用舵盖零件在两种浇注工艺方案下的凝固过程进行模拟计算,在此基础上分析探讨了该铸件可能产生缩孔或缩松的部位。模拟显示第一种浇注工艺会在零件主体部位产生严重缩孔,而第二种浇注工艺则能自下而上顺序凝固,避免缩孔或缩松的产生,据此确定了第二种铸造工艺方案,并采用试验进行验证。结果表明,此浇注工艺没有产生技术要求缺陷,证明了凝固模拟的可行性。 相似文献
7.
8.
Problems about the uncertainty in raw material compositions are a critical issue for the blending problems. It is feared that uncertainty in raw material compositions would often cause percent values of the actual blend to go out of specification limits. In this paper, the aleatory and epistemic uncertainties have been handled simultaneously in a blending optimization problem for brass casting. The aleatory and epistemic uncertainties are modeled by using probability and possibility theories respectively. However, the probabilistic and the possibilistic uncertainties are different from the each other. Therefore to solve the mathematical model, including these uncertainties, a transformation of any type of uncertainty to the other is needed. In this study, probabilistic uncertainties are transformed to the possibilistic uncertainties by considering Rong and Lahdelma’s (2008) and the Dubois, Prade, and Sandri (1993) and Dubois, Foulloy, Mauris, and Prade (2004) transformation approaches. This transformation process converts the former model to a possibilistic model. Then the possibilistic models, obtained from each transformation, are solved by using α cuts approach. The solutions of the two possibilistic models have shown that the model, which uses Dubois’s transformation, prepares blends with lower cost than the other model, which uses Rong and Lahdelma’s transformation. 相似文献
9.
10.
Xianlong Wang Jinchuan Jie Shichao Liu Zhuangzhuang Dong Guomao Yin Tingju Li 《材料科学技术学报》2021,61(2):138-146
In the present work, in-situ Ti5Si3 reinforced special brasses were prepared by melt reaction method. The synthesized Ti5Si3 phase shows various morphologies in brasses with different Ti5Si3 content, and the3 D morphological evolution of primary Ti5Si3and its growth mechanism were investigated. The Ti5Si3 crystal, which bears D88 hexagonal crystal structure, grows along <0001> direction and is revealed by{1010} faces during growth. With the increase of Ti5Si3 content in the brasses, the morphology of primary Ti5Si3significantly changes from fibers to hexagonal prisms to short-rods with hollow. In addition,the influence of Ti5Si3 volume fraction and morphology on the wear behavior of special brass was also revealed. It was substantiated that the wear resistance increases with the increasing volume fraction of Ti5Si3, and the corresponding wear mechanism changes from delamination to slight adhesive wear and abrasive wear. However, the friction coefficient shows an abnormal increase when most of the Ti5Si3 containing hollows appears in the brass. That is mainly due to the fact that the Ti5Si3 is easier to break and fall off resulted by the hollow as a crack source, which makes it unable to resist the plastic deformation of the contact surface during the sliding. 相似文献