硬质合金与钢异种金属焊接工艺的研究现状

从焊接接头显微组织和力学性能两个方面概述了硬质合金与钢异种金属焊接的基本工艺。总结出:采用Ni基、Fe基及Co基等合金作为填充金属能够获得良好的焊接接头,在其焊缝界面处会生成高强度的Fe-Co-Ni固溶体,而焊缝内部会出现硬脆的缺碳M_6C型金属间化合物η相;增加Co、Ni元素的含量有利于Fe-Co-Ni固溶体的生成,同时也会抑制η相;用钎焊和扩散焊焊接的接头力学性能较好,钎焊接头的抗弯强度可以达到665MPa,扩散焊接头的抗弯强度可以达到1 192MPa。     

扩散焊接异种金属及陶瓷/金属的研究进展

扩散焊接作为一种新颖的焊接技术之一,在异种材料的连接领域得到了广泛应用.本文在综述扩散焊接原理和特点的基础上,着重介绍了扩散焊接在异种金属、陶瓷/金属异种材料连接中的应用及研究现状.     

异种钢的焊接及其应用

本文主要介绍了异种钢的焊接,并阐述了异种钢焊接接头的主要问题及其预防措施。     

应用电刷镀技术进行铝与异种金属焊接的研究

铝与异种金属因性质不同而很难焊接在一起。通过多次试验研究，采用电刷镀技术在异种金属上刷镀改性材料并用氧－乙炔焰焊接解决了这一技术难题。介绍了试验研究经过及试验结果。     

钢/铝异种金属焊接分析

钢/铝异种焊接因钢和铝物理和化学性能存在的差异,一直困扰着钢/铝焊接的进步和推广,但是随着科学技术的发展,单一构造的材料已经满足不了当下社会对于材料强度高、质量轻等优良性能的要求,所以对于钢/铝异种焊接的研究迫在眉睫.如何攻克钢/铝焊接出现的问题,目前钢/铝异种焊接需要研究的主要对象为充分利用铝合金质量轻、强度高的优良...     

SAF2507与321管板异种金属焊接接头组织形态和相组织分布

为了解SAF2507和321异种金属管板焊接接头的相比例分布情况,按照ASTM标准对其焊缝截面各重要部位进行了铁素体含量检测。通过金相分析,发现两道焊缝组织形态区别很大,第1道焊缝基本为针片状或羽毛状奥氏体,第2道焊缝却成团块状奥氏体。     

Size Effect of the Adhesive Bonding Strengths of Metal/Polymer Similar and Dissimilar Material Joints

The relationship between the adhesive bonding strengths and the bonding areas (sizes) is important for material and structural designs, because adhesive bonding is widely used not only in small scale electronic devices, but also in large-scale composite–metal joints of modern aircraft/ship structures. Therefore, a systematic experimental investigation on adhesive bonding strengths of polymer/polymer, metal/metal, and polymer/metal joints was conducted. Results show that the size effect of the bonding strengths is small for the current bonding areas (from 30 to 300 mm²), which are widely employed in most of the test standards for engineering designs.     

活性炭负载金属催化剂的研究进展

活性炭作为一种优良的催化剂载体被广泛应用于催化领域,其经酸碱预处理或氧化预处理后表面可负载一种或多种金属催化剂,是优化各种金属催化剂性能的有效方法之一。为给今后活性炭载体催化剂的研发提供一些参考和方向,从单一金属催化剂负载和复合金属催化剂负载的制备、催化活性及应用着手,对近年来新制备的活性炭负载金属催化剂进行综述。     

碳纳米管负载纳米金属氧化物的研究进展

综述了碳纳米管负载纳米金属氧化物的制备方法以及当前研究的热点和存在的问题,重点论述了纳米金属氧化物沉积在碳纳米管表面上的方法及其相互作用机理,并展望了这类复合材料的应用前景.     

土壤中重金属元素运移规律研究进展

在全球气候变化及空气污染严重加剧的前提下,酸雨会加速土壤中的重金属离子以溶解态的形式存在于土壤溶液中,从而使土壤肥力下降,造成土壤环境的污染。因此,土壤中的重金属元素的运移成为其污染土壤的主要原因之一,对土壤中重金属的运移特征及其影响因子进行了综述,得出重金属在土壤中的运移特征除了与重金属污染物本身的活性有关外,更取决于它所进入的土壤的性质。     

金属络合物在超临界CO_2中的溶解度研究

在温度为308.15～328.15 K、压力为10～30 MPa的条件下,用超临界萃取装置测定了8-羟基喹啉铅、8-羟基喹啉汞、二乙基二硫代氨基甲酸铅、二乙基二硫代氨基甲酸汞4种络合物在超临界CO2(SC-CO2)中的溶解度,分析了压力和温度对溶解度的影响.     

金属纳米粒子修饰的碳纳米管研究进展

多壁和单壁碳纳米管（CNT）是被广泛研究的纳米材料之一,可以用作良好的金属或其它纳米粒子的载体。金属纳米粒子-碳纳米管复合材料在催化、传感、贮氢、及各种光学电学方面有广泛的应用前景,文章就近期各种碳纳米管负载的金属纳米材料（主要集中在贵金属）的合成做一小结。     

Residual Stresses in Ceramic–Interlayer–Metal Joints

Thermal residual stresses due to the thermal expansion mismatch in a ceramic–interlayer–metal joint are calculated analytically. A qualitative estimate of the stress distribution is obtained by assuming the joint consists of one or two elastic slabs sandwiched between two semi-infinite isotropic elastic solids. These elastic solids and the interlayer(s) are perfectly bonded to each other at the planar interfaces. The region where temperature change takes place is assumed to be a cylinder with its axis normal to the interface. A simple equation is obtained for the stress value at the center of the ceramic-interlayer interface as a function of the thermal expansion coefficients, elastic constants of the constituent materials, and the thickness of the interlayer(s). The results obtained by this simple model agree well, qualitatively, with those obtained experimentally and numerically (finite element calculations). An appropriate interlayer material to reduce the residual stress in ceramic-metal joints is suggested.     

A Stress Analysis of Adhesive Butt Joints of Dissimilar Materials Subjected to Cleavage Loads

Stress distributions are examined when an adhesive butt joint, in which two thin plates made of dissimilar materials are joined, is subjected to cleavage loads. General representations of the stress and displacement fields are given using the two-dimensional theory of elasticity. The effects of the ratios of young's modulus among two adherends and an adhesive and the thickness of the adhesive on the stress distributions of the joints are clarified by numerical calculations. In addition, the stress singularity near the edge of the interface in the load application side is evaluated. For verification, the strain distributions near the interface of each adherend were measured. The analytical results are closely consistent with the experimental ones.