铝/铜异种金属电阻热辅助超声波缝焊工艺特性

1060纯铝箔作为中间层,通过电阻热辅助超声波缝焊的方式实现1 mm厚度6061铝合金和T2紫铜异种金属焊接,分析了焊接过程中电阻热对铝/铜焊接接头焊缝成形、界面形貌、温度场以及力学性能的影响. 结果表明,采用单独超声波缝焊焊接铝/铜异种金属时,因产生的焊接能量较小,接头连接界面处仅局部区域位置形成连接,接头拉剪强度为45 MPa. 但在电阻热辅助超声波缝焊过程中,电阻热的加入能够有效预热工件,令待焊材料表面发生软化,在高频振动作用下,接头连接界面处形成有效连接. 同时,引入电阻热提高了铝/铜界面处温度,由单独超声波缝焊的140 ℃增加至190 ℃,界面处原子扩散距离增加,获得焊接接头的拉剪强度增加至75 MPa,相对前者接头拉剪强度提高67%.     

焊接时间及焊接温度对Sn35Bi0.3Ag/Cu焊接接头性能的影响

分别在不同焊接时间和不同焊接温度下制备了Sn35Bi0.3Ag/Cu焊接接头,采用扫描电子显微镜(SEM)、万能拉伸试验机、超声波成像无损探伤检测仪等测试手段,研究了焊接时间(1～9 min)和焊接温度(210～290℃)对Sn35Bi0.3Ag/Cu焊接接头微观结构和力学性能的影响.结果表明,在焊接过程中,Cu元素扩散到焊接界面处,形成了(Cu₆Sn₅,Cu₃Sn)界面层,同时发现生成的Ag3Sn相能够抑制界面层的生长.随着焊接时间的延长或焊接温度的升高,反应层变厚,抗剪强度先增大后减小.对焊接接头断口形貌分析发现,焊接接头的断裂由Bi相颗粒及Cu₆Sn₅颗粒共同作用.焊接接头的断裂发生在IMC/焊料一侧,Bi相颗粒及Cu6Sn5颗粒共同影响着接头的抗剪强度.此外,当焊接时间为3 min、焊接温度为230℃时,接头的钎着率最大,为99.14%,抗剪强度达到最大值,为51.8 MPa.     

C/C复合材料与TC4钎焊接头的组织与断裂形式分析

在钎焊时间10 min,钎焊温度820～900℃的条件下,采用AgCu钎料对C/C复合材料和TC4进行了钎焊试验.利用扫描电镜、X射线衍射分析仪、EDS能谱分析仪对接头的界面组织及断口形貌进行了研究.结果表明,C/C复合材料与TC4连接接头的界面结构为C/C复合材料/TiC C/TiCu/Ag(s.s) Cu(s.s) Ti3Cu4/Ti3Cu4/TiCu/Ti2Cu/Ti2Cu Ti(s.s)/TC4.由压剪试验测得的接头抗剪强度可知,在钎焊温度850 ℃,保温时间10 min的钎焊条件下,接头获得的最高抗剪强度达到38 MPa.接头的断口分析表明,接头的断裂位置与被连接处碳纤维方向和钎焊温度有关.当碳纤维轴平行于连接面时,断裂发生在复合材料中.当碳纤维轴垂直于连接面时,若钎焊温度较低,断裂发生在C/C复合材料/钎料界面处;若钎焊温度较高,断裂主要发生在C/C复合材料/钎料界面和钎料/TC4界面处.     

镀银铜箔平行微隙电阻焊接头组织与性能

研究了0.1 mm厚镀银铜箔与纯铜箔平行微隙电阻焊接头的微观组织和力学性能,分析了不同参数对接头力学性能的影响,利用扫描电子显微镜对典型接头界面处的微观组织特征进行了分析. 结果表明,焊点连接面处组织致密;连接面由富银相和富铜相组成的两相区和只有富铜相的单相区组成,焊接温度达到了银的熔点,其连接机理与钎焊类似;试验所用参数范围内,焊点的最大剪切抗力达到了59 N,焊接功率和焊接时间对焊点性能的影响较大,而电极压力的影响较小.     

Cf/PPS复合材料辐射预热超声焊接工艺及其接头断裂分析

研究了辐射预热超声波焊接方法对碳纤维增强聚苯硫醚复合材料（C_f/PPS）的适用性,重点考察了预热温度和焊接压力对连接界面成形及接头力学性能的影响.结果表明,升高预热温度可促进接头界面树脂的熔合,当预热温度大于110℃时,熔合率可达百分之百;当焊接压力增大时,接头的连接面积逐渐增加,但其拉剪强度呈现先上升后减少的趋势.当预热温度为110℃,焊接压力为0.3 MPa时,接头成形最佳,强度达到最高的20 MPa.     

工艺参数对Cu/Al大功率超声波焊接微观组织和力学性能的影响

尽管大功率超声波焊接可以更好的焊接较高的导电、导热性的材料,但是对焊接机理的认识还很少. 为了深入明晰焊接过程以及得到高质量的Cu/Al焊接接头,研究了不同夹紧力、焊接时间、焊接振幅以及焊头形状对Cu/Al大功率超声波焊接的界面温度、中间相生长和接头力学性能的影响. 结果表明,随着夹紧力的增大,界面中间相厚度先增大后减小. 随着焊接振幅的下降,界面温度的降幅增大且中间相厚度呈现近似线性下降. 最优的焊头齿数为9个,焊头齿数的增多和减少均会导致界面温度降低和焊接裂纹产生. 为获得较高的Cu/Al大功率超声波焊接质量,焊接振幅应设置为最高. 对焊接接头的拉伸断口进行扫描电镜测试表明,Cu/Al超声波焊接接头的断裂模式是韧性-脆性复合断裂. 研究结果为优化超声波焊接工艺参数提供了指导.     

焊接温度对铜合金T型接头断裂失效影响分析

铜合金作为导电用材料,在焊接过程中由于产品结构特点,不可避免地采用T型搭接接头形式,该接头形式在动载作用下,接头拐角热影响区容易发生疲劳断裂。采用电阻钎焊方法,从焊接接头断口显微分析、组织形貌、硬度测量等方面,分析焊接接头断裂原因,发现焊接温度过高、高温停留时间过长会使得接头受热区组织粗大,粗大的热影响区组织会使焊接接头软化,降低屈服强度等机械性能,焊接接头在动载及交变温度场的反复作用下,会造成焊接接头疲劳断裂失效,因此控制焊接温度和高温处焊接时间是保证焊接接头质量的重要手段。     

钉头管电阻点焊工艺研究

钉头管是一种通过在光管上焊接钉头来达到增加换热面积的传热元件,是石油化工企业管式加热炉中的重要组件.本文通过金相显微镜和扫面电镜对钉头管的电阻点焊工艺进行研究,测量了不同焊接电压(电流)下焊接接头接触面积,对各参数的焊接接头进行显微组织分析,并对最佳参数的焊接接头进行断口分析.结果表明,在焊接电压为4.64V,通电时间为0.44s时,焊接接头的接触面积最大(达106.18 mm~2,占整个焊接接头的93.9%)且未形成焊瘤,接头的显微组织最为均匀,断口为韧窝断口.     

40Cr与QCr0.5的固态焊接接头显微组织分析

对40Cr待焊接面的表层实施激光淬火的组织超细化预处理后,将其与QCr0.5在焊接温度750~800℃、初始应变速率(2.5~5)×10-4s-1、预压应力56.6~84.9 MPa、焊接时间120~180 s的条件下,可实现二者异材的固态焊接,接头强度能够达到QCr0.5母材的强度。焊后对接头区的显微组织观测表明,焊接接头区的界面两侧显微组织连续,已经实现了良好的冶金结合;界面两侧近界面处的组织因C、Cr、Cu原子的扩散而发生了明显变化。     

CuMnNiSi钎料钎焊不锈钢接头组织性能研究

采用新型的Cu-Mn-Ni-Si钎料真空钎焊2Cr13不锈钢,研究了钎焊温度和保温时间对接头组织和室温力学性能的影响.结果表明:钎焊接头组织由钎缝中心区Cu-Mn基固溶体和钎缝界面反应区的(Fe,Ni,Mn)- Si化合物组成.随着钎焊温度的增加,钎缝界面处化合物层厚度减小,Cu-Mn基固溶体相应增多,接头室温剪切强度随之增加,在钎焊时间15min、钎焊温度1050℃时达到321 MPa.在钎焊温度1000℃时,接头室温剪切强度随着钎焊保温时间的延长先增加后降低,在钎焊保温时间30min时取得最大值305 MPa.     

From conductive polymer composites with controlled morphology to smart materials

Conductive polymer composites (CPC) based on insulating matrix with conductive dispersed fillers are extensively studied since many years. A specific feature of such materials is a value of the filler content corresponding to the percolation threshold where a sharp transition insulating/conductive state occurs. The objective of this work is first the study of percolation phenomena in composites based on polypropylene (PP), on copolymers of polyamides (CPA) and polymer blends PP/CPA filled with dispersed iron (Fe) related to their structure but also to pay attention to their specific behaviour in temperature so-called PTC effect which can be controlled according the composition and the structure in the heterogeneous polymer matrix of the composites to elaborate intelligent/smart materials.     

预涂导电密封胶的轨道车辆不锈钢车体电阻点焊工艺试验

根据某不锈钢车辆上下侧墙板搭接结构形式,采用涂导电密封胶的电阻点焊技术,实现结构连接的同时保证了车辆密封.为验证该工艺的可靠性,采用预涂导电密封胶的电阻点焊技术分别对三种搭接结构试件进行焊接试验.焊后根据相关标准分别对三种搭接结构进行电阻点焊接头试验,包括外观检验、剥离试验、剪切拉伸试验和金相检验,并对点焊接头的表面凹...     

Dissimilar materials joining of metal/carbon fibre reinforced plastic by resistance spot welding

ABSTRACT

Dissimilar materials joining of metal to carbon fibre reinforced plastic (CFRP), which consisted of PA6, modified polypropylene (PP) or polyphenylene sulphide (PPS) as matrix polymer with short carbon fibre, was performed using series resistance spot welding (series-RSW). The metal plate was placed on CFRP plate as the lap joint, and electrodes of series-RSW were pressed only on the metal plate side. The metal around the electrode was heated by electrical resistance heating, and the thermoplastic near the interface was slightly melted by the heat conduction from heated metal. The objectives of this research are to confirm the possibility of direct joining of CFRP and metal, and to investigate the effects of the heat input during series-RSW, silane-coupling treatment and chemical structure of matrix plastics on the joint properties.

The direct joint formations of SUS304 to CFRP (PA6) and CFRP (PP) were accomplished, and CFRP (PPS) was not. The joining area, which corresponding to the melted area of CFRP, enlarged with increasing the welding current and welding time, therefore, the tensile shear fracture load also increased. The silane-coupling treatment for metal surface was highly effective to increase the joining strength. The maximum tensile shear strength of about 13 MPa was obtained for SUS304/CFRP (PA6) joint.     

Influence of polarity on mechanical properties of dissimilar resistance spot welds of DP 600/AISI 304 steels

The influence of polarity during resistance spot weld (RSW) of dissimilar lap joints on mechanical properties and failure mode is assessed in this work. A dissimilar lap joint was set using DP 600 dual phase steel with AISI 304 stainless steel. The experiments were performed on a medium-frequency direct current spot welding machine with proper data acquisition of voltage and welding current. Temperature evolution was also acquired by using IR camera. The mechanical properties of spot welds were evaluated by using a coach peel testing. The effect of welding current and welding time on mechanical properties was also evaluated. Correlations between polarity with the welding nugget size, failure mode, tensile strength, temperature evolution and dynamic resistance were analysed. The analysis confirmed that the polarity on dissimilar lap joints affects the behaviour of dissimilar RSWs.     

铝基复合材料扩散焊接接合区微连接行为

以铝基合材料Al2O3p/6061Al为对象,对该种材料扩散焊接接合区微连接行为进行了探索性的研究,分析了接头微观组织及力学性能。研究表明,扩散焊接温度对接合区的微连接行为有显著影响,当焊接温度低于铝基复合材料固相线温度时,增强相-基体、增强相-增强相之间微连接属弱连接;当焊接温度介于该种材料液、固两相温度区间时,接头区域出现液态基体金属,增强相-基体之间可以实现较好结合,同时液态金属对增强相-增强相接触部位进行渗透,使增强相-增强相接触转化为增强相-基体-增强相结合,在此基础上发现在铝基复合材料液、固两相温度区有“临界温度”存在,为成功实现该种材料扩散连接奠定理论基础。     

Al2O3纤维增强铝基复合材料储能焊接头微观组织分析

应用自制微型储能电阻焊机对Al2O3纤维增强铝基复合材料进行了点焊连接，分析了接头的组织形貌。在储能焊接头中形成了规则的扁平熔核，复合材料基体与熔核金属过渡良好。极短的焊接时间和大的冷却速率使共晶Si显著细化。细小的共晶Si颗粒均匀分布于铝基体中，形成与MMCs不同的基体组织。少量Al2O3纤维发生了一定程度的破碎，大部分纤维仍保持其原有的形貌特征，随机分布于熔核金属基体中。适当增大电极压力，焊前对复合材料做除氢处理并保持干燥是减小和消除气孔、提高和改善MMCs储能焊接头质量的有效途径。     

Predicting effects of diffusion welding parameters on welded joint properties by artificial neural network

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采用非夹层液相扩散焊连接铝基复合材料

采用真空扩散焊焊接铝基复合材料ＳｉＣｗ／６０６１Ａｌ通过系列试验研究了焊接工艺参数对接头强度的影响。结果表明：该材料扩散焊时,焊接温度是影响接头强度的主要工艺参数,当焊接温度介于基体铝合金液－固两相温度区间时,接合面上出现了液态基体金属,可获得较高的接头强度。     

钎焊工艺对Ni-14Cr-10P-x Ti钎料连接C/C复合材料组织和性能的影响

用真空熔炼、惰性气体雾化的方法制备Ni-14Cr-10P金属粉末,再加入Ti粉和高分子聚合物高速搅拌分散制备了Ni-14Cr-10P-x Ti膏状活性钎料。用制备的焊膏在真空钎焊炉中钎焊C/C复合材料,然后测试了钎焊接头的抗剪切强度,采用SEM、EDS、XRD等方法对接头微观组织进行了分析。结果表明,在钎焊温度1000℃,保温时间30min时,接头获得了最高的抗剪切强度,然后随着钎焊温度的上升、保温时间延长,钎焊接头强度下降;添加Ti元素加快了钎焊强度随温度和保温时间的增加而下降的速度,结合微观组织结构,对Ti元素加入后钎焊强度随温度和保温时间增加而下降更为迅速的原因进行了分析。     

Resistance welding of carbon fibre reinforced polyetheretherketone composites using metal mesh and PEI film

Weldability of polyetheretherketone( PEEK) with polyetherimide( PEI) is tested. And carbon fiber reinforced PEEK laminates are resistance welded using stainless steel mesh heating element. The effects of the welding time and welding pressure on the lap shear strength of joints are investigated. Results show that PEEK can heal with PEI well in welding condition and the lap shear strength of PEEK/CF(carbon fibre) joint increases linearly with welding time, but reaches a maximum value when welding pressure ranging from 0.3 MPa to 0.5 MPa with constant welding time. The fracture characteristics of surface are analyzed by SEM techniques, and four types of fracture modes of lap shear joints are suggested.