阳极氧化对TB8钛合金粘接性能的影响

分别以铬酸阳极氧化（CAA）和氢氧化钠阳极氧化（SHA）两种方法,处理用于钛合金/钛合金胶接试样的TB8钛合金表面,通过拉伸剪切试验测量了钛合金/钛合金胶接试样的剪切强度,分析了氧化时间和电压对钛合金粘接强度的影响。结果表明：电压10V时,CAA方法处理10~15min、SHA方法处理15~20min的钛合金均能获得很高粘接强度;氧化膜层太薄与太厚均不利于提高钛合金/钛合金胶接剪切强度。     

激光烧蚀铝合金表面对其胶接接头耐腐蚀性能的影响

采用激光对5052铝合金进行表面烧蚀处理,对其表面物化特性进行观察分析,并测试了其胶接接头在盐雾环境腐蚀后的剪切强度与失效模式。实验结果发现,经激光表面处理后,接头的剩余强度在盐雾环境腐蚀后强度增大了40%,并且失效模式由几乎完全界面失效变成内聚失效。经分析测量,处理后的铝合金表面粗糙度从0.09μm增大到1.77μm,并且在其表面形成了凹凸不平的多孔结构,胶接时发现胶粘剂渗入其中增强了胶接界面的粘接;同时,经过表面元素能谱分析,发现氧元素含量增加,铝合金表面生成氧化铝,也有利于增强铝合金基体的抗腐蚀性能,证明激光表面处理可以提高胶接接头的耐腐蚀性能。      

不同胶接参数对CFRP层合板单搭胶接结构强度的影响及优化设计

对于碳纤维增强基复合材料(Carbon fibre-reinforced polymer,CFRP)层合板单搭胶接结构的优化问题,首先利用连续损伤力学模型、三维Hashin准则和内聚力模型研究不同胶接参数对CFRP层压板单搭胶接结构力学性能的影响,其次采用拉丁超立方试验设计方法和响应面法构建了拉伸强度代理模型,最后基于遗传算法和代理模型进行联合优化.结果 表明,仿真与试验吻合较好,数值结果与试验结果的误差均低于10％,验证了有限元模型的精确性.随着搭接长度的增大,拉伸强度和层合板层间分层损伤程度逐渐增大,剪切强度和胶层自身剪切失效程度逐渐减小;胶接结构的力学性能及失效形式随着铺层方式的不同而改变.最佳铺层顺序、胶接长度、胶层厚度和搭接宽度分别为[03/903]2s、20 mm、0.0607 mm和10 mm.与常规单搭胶接结构相比,拉伸强度和剪切强度分别提高了25.92％和25.88％.采用遗传算法对CFRP层合板单搭胶接结构进行优化,对提高单搭接接头的力学性能具有重要意义.     

CFRP/钢复合结构的Ⅱ型断裂性能研究

为了研究CFRP/钢复合结构的Ⅱ型断裂性能,采用端部切口弯曲试验(ENF),基于短纤维对树脂粘接层的桥联增韧作用,利用均匀分布的kevlar纤维薄膜、多壁碳纳米管(MWCNT)和刻槽钢板,制备两种粘接界面(刻槽/kvlar、刻槽/kvlar/CNT)的ENF试件,通过ENF试验的载荷-位移曲线、试样裂纹断裂面形貌特征,研究分析短纤维的桥联增韧机理。实验结果表明刻槽/kvlar/CNT试样相对于刻槽/kevlar试样厚度基本不变,极限载荷提高了13.5%,断裂能提高了16%。     

T700和T300碳纤维增强环氧树脂基复合材料耐湿热老化性能的对比

在温度为70℃、相对湿度为85%的湿热环境下,分别对T700碳纤维/环氧树脂基复合材料、T300碳纤维/环氧树脂基复合材料以及两种复合材料/金属胶接结构进行了70 d的加速老化试验,并对老化前后的试样进行了力学性能试验和无损检测.结果表明:湿热环境没有改变两种复合材料的破坏模式,但使复合材料的纵、横向压缩强度和剪切强度略有降低;对复合材料/金属胶接结构,湿热老化环境不会导致胶接界面产生损伤,但会使胶接强度下降;老化前两种复合材料的力学性能基本相当,老化70 d后T700碳纤维/环氧树脂基复合材料的性能保持率略优.     

胶接技术在机械制造上的应用 第二讲 胶接工艺

胶接工艺直接影响胶接强度,故胶粘剂(Adhes-lve)和胶接工艺(Adhesion)二者在国外统称为胶接学(Adhesilogy).胶接工艺包括胶粘剂的正确选用和胶接方案,接头设计,被粘物表面处理及涂胶,固化与质量检验等步骤. 一、胶粘剂的正确选用胶粘剂的种类繁多,性能各不相同,应根据不同胶接对象、施工条件及使用要求等,正确选用合适的     

考虑汽车车身涂装工艺影响的非平衡胶接接头强度

汽车轻量化的发展要求汽车采用更多的轻型材料取代传统的金属材料,而异种材料的连接就为结构胶接技术的应用提供平台。通过模拟汽车车身涂装工艺中环境温度和相对湿度的变化,采用韧性和脆性两种结构胶粘剂,分别对钢/铝和钢/碳纤维增强复合材料非平衡胶接接头的剪切强度进行环境影响研究。试验结果表明,汽车涂装环境对结构胶接接头的性能有着显著的影响,并且与胶粘剂自身性质有关。通过对不同工况接头的失效模式分析和对胶层的内聚力单元数值二维建模仿真,得到两种胶粘剂在涂装工况影响下胶层宏观力学属性和内部应力分布情况的变化趋势,并对碳纤维增强复合材料与相应胶粘剂材料表面参数的匹配问题进行研究。采用扫描电镜法对胶层失效表面进行样貌分析,探究相应宏观试验结果产生的微观原因。     

碳纳米管/石墨烯增强聚酰亚胺树脂性能研究

分别采用碳纳米管和石墨烯对聚酰亚胺树脂进行增强,并制备了模塑拉伸试样和拉剪试样。测试试样在不同温度下的拉伸、剪切性能,并通过SEM观察断口形貌,对材料微观结构进行分析。结果表明,添加增强材料后树脂的拉伸性能和界面结合能力均有所提高。与纯净树脂试样相比,添加石墨烯的试样室温下拉伸强度和300℃下剪切强度分别提升10.42%和41.03%。     

几种胶粘剂在设备修理中的应用

近年来,随着高分子合成材料的发展,国内已研制出众多系列品种的胶粘剂。我厂在应用胶粘剂修复设备的磨损擦伤,粘接损坏部件及堵漏方面,取得较好效果。简单介绍如下: 一、DG-3胶粘剂化工部某化工研究院一分院研制,四川富顺某信箱销售组供货。 1.性能该胶为双组份改性环氧胶,可粘接金属、玻璃、陶瓷、塑料等。耐温范围-55～150℃;耐油、水、酸、碱等介质;剪切强度>26MPa;钠萘处理的聚四氟乙烯与钢粘接剥离强度≥125N/2×5cm(12.5kgf/2×     

精密仪表用铝合金瓷质阳极氧化表面粘接性能研究

铝合金瓷质阳极氧化工艺是精密仪表制造中的一种特殊且关键的技术应用，但该氧化表面的胶粘连接常常出现脱粘、泄漏等失效问题。为此，通过探究瓷质阳极氧化表面的微纳形貌与润湿性特征以及高低温下的胶接强度与失效模式，并与自然氧化表面及磷酸阳极氧化表面进行对比分析，阐明瓷质阳极氧化表面胶接失效的影响机理。结果表明，磷酸阳极氧化虽未在微米尺度上显著改变表面粗糙度，但其纳米级多孔氧化膜结构，可显著提高表面润湿性与界面粘接作用力；而瓷质阳极氧化膜在50 000×的SEM形貌下较为致密、平滑，显示出不利于胶粘剂润湿与吸附的物理特征；在-30～80℃下，温度与氧化方法均对胶接强度影响显著，胶接强度随着温度的升高而降低；磷酸阳极氧化表面的强度最高(36.75～20.54 MPa)，其次为自然氧化，最差为瓷质阳极氧化(24.79～17.10 MPa)。热红外与能谱分析表明，瓷质阳极氧化表面的粘附强度低于胶粘剂的内聚强度，失效模式为粘附失效，而磷酸阳极氧化表面的失效模式为胶粘剂的内聚失效。因此，瓷质阳极氧化表面由于氧化膜的致密性，缺少类似磷酸阳极氧化膜的纳米级多孔结构，不利于表面润湿吸附，降低了胶粘剂与基底表面的机...     

Investigation on overlap joining of AZ61 magnesium alloy: laser welding, adhesive bonding, and laser weld bonding

This paper presents the research on weldability of magnesium alloy AZ61 sheets by overlap laser welding, adhesive bonding, and laser seam weld bonding processes. Microstructures and mechanical properties of the joints are investigated. In overlap laser welding, the joint fractures at the interface between the sheets and maximum shear strength can reach 85% of that of the base metal. Off-center moment during tensile shear test can lead to the strength loss, while the weld edge can also influence the strength as a cracking source. Adhesive bonded joint can offer high tensile shear failure force but low peel strength. Laser weld bonded joint offers higher tensile shear failure force than either laser welded joint or adhesive bonded joint does, and the improved failure load is due to combined contribution of the weld seam and the adhesive. The weld seam can block the adhesive crack propagation, and the adhesive improves the stress distribution, so they can offer a synergistic effect.     

陶瓷刀具材料磨损的研究现状

本文重点综述了陶瓷刀具材料显微结构和力学性能对其磨损特性的影响。阐述了陶瓷刀具材料的硬度、强度、断裂韧性和弹性模量等力学性能与其磨损特性的关系,分析了晶粒尺寸、孔隙度和晶间强度对陶瓷刀具材料磨损特性的影响。指出陶瓷刀具材料切削磨损时的基本机理仍然是磨料磨损、粘结磨损、化学反应与扩散磨损。     

Shear behaviour of brick-mortar interface in CFRP retrofitted or repaired masonry

There are many unreinforced masonry buildings all over the world. Many of them are located in seismic zones and are, therefore, susceptible to lateral forces caused by earthquakes. The transmission of these forces to the foundations is made through load bearing walls and depends on the shear strength and stiffness of masonry.In plane shear strength of load bearing masonry walls depends on many factors like the bricks and mortar strength and the way the wall is constructed. It is mainly due to shear strength of the brick-mortar interface given by the adhesion and by the friction caused by normal compression loads. Under severe seismic loads the ultimate strength capacity of the interface is achieved and the structure collapses.The results of an experimental program performed to study the shear behaviour of CFRP retrofitted and repaired masonry are presented in this paper. Increase of strength, ductility and stiffness due to the addition of CFRP laminas is specially analyzed. Specimens formed by three bricks and two mortar joints without reinforcement, retrofitted and repaired with CFRP laminas were tested under quasi-static and cyclic load.Additionally, the numerical study of the same specimens is presented. The specimens were modelled with 2D and 3D finite elements programs. Orthotropic plasticity models were used for bricks and mortar, including brick-mortar interfaces and CFRP laminas. Experimental results were used to calibrate the parameters of the material models and a numerical tool for the mechanical analysis of retrofitted or repaired masonry panels was developed. A parametric numerical study was also carried out with these numerical models in order to obtain the optimal dimensions and orientation of the reinforcing bands.     

工艺参数对6061-T6铝合金真空扩散焊接接头形貌和性能的影响

在不同工艺参数下对化学清洗去除表面氧化膜的6061-T6铝合金进行真空扩散焊接,研究了焊接温度(500~560℃)、焊接压力(1.0~5.0MPa)和保温时间(0.5~3h)对焊接接头界面形貌和剪切强度的影响,得到了优化工艺参数。结果表明:随着焊接温度的升高、焊接压力的增大和保温时间的延长,接头焊缝变窄并最终消失,剪切强度和焊合率增大;但当保温时间延长到3h时,焊缝附近晶粒发生粗化,导致剪切强度降低,且接头发生较大变形;不同工艺参数下接头的剪切断裂形式均为脆性断裂;较优的真空扩散焊接工艺参数为焊接温度540℃、保温时间2h、焊接压力4.0MPa。     

Inhibition of intermetallic formation during diffusion bonding of high-carbon steel

Diffusion bonding of high-carbon steel was carried out in vacuum brazing furnace at temperature 900–1,050 °C for 0.5 h under uniaxial load using Ni foil interlayer. Microstructure of assemblies was studied along with effect of diffusion of chemical species in reaction zone and mechanical properties. Microstructure of substrate was changed from martensite to austenite at bonding temperature and subsequently to ferrite–pearlite during cooling to ambient temperature. Diffusion zone did not exhibit formation of any intermetallic compounds. Bond strength was governed by degree of solid solution hardening and contact area of mating surfaces depending on joining parameters. In this respect, maximum ultimate strength of ~532 MPa was obtained along with shear strength of ~792 MPa for the joint processed at 1,050 °C, which was higher than literature reports on martensitic steel.     

钎焊工艺对Au-Sn/Ni焊点组织及力学性能的影响*

通过回流焊技术制备Au-Sn/Ni焊点,通过扫描电子显微镜和能谱检测分析钎焊接头的微观组织及其相组成,利用疲劳试验机对焊点的剪切强度进行检测,研究不同钎焊工艺对Au-Sn/Ni焊点组织和力学性能的影响。结果表明,在310 ℃钎焊1 min的Au-Sn/Ni焊点经过水冷或空冷后,焊料内部均形成镶嵌有离散分布的(Ni,Au)₃Sn₂相的(Au₅Sn+AuSn)共晶组织,焊料/Ni界面处形成(Ni,Au)₃Sn₂金属间化合物(intermetallic compound,IMC)层;钎焊后炉冷的焊点,由于冷却速度过慢,导致焊料中Ni质量分数增大,(Ni,Au)₃Sn₂相异常长大消耗共晶组织中的(Au,Ni)Sn相,焊料共晶组织消失。随着钎焊时间的延长,基板中的Ni原子不断往焊料扩散,界面处的IMC层厚度均有不同程度的增加。随钎焊时间延长焊点的剪切强度逐渐下降,而剪切断裂模式为脆性断裂,发生在焊料与金属间化合物层的界面处。Au-Sn/Ni焊点在310 ℃下钎焊1 min,并采用水冷方式时得到的力学性能最佳。     

Molecular dynamics simulation of tensile behavior of diffusion bonded Ni/Al nanowires

Interfaces play key roles in determining mechanical properties of materials. In current work we perform molecular dynamics simulations of diffusion bonding to evaluate the effect of temperature on the morphology of the Ni/Al interface and the strength of the diffusion bonded Ni/Al nanowires. The centro-symmetry parameter is adopted to identify defect atoms generated. Simulation results show that the thickness of the Ni/Al interface has strong dependence on the temperature of diffusion bonding. Following uniaxial tension tests indicate that the yield strength of Ni/Al nanowires is smaller than both the single crystalline Ni and Al nanowires, because of the Ni/Al interface acting as dislocation source and the mobilization of pre-existing dislocations at high temperature. It is shown that the mechanical properties of diffusion bonded Ni/Al nanowires strongly depend on the temperature.     

A Facile Surface Treatment to Improve the Abrasion Resistance of Photosensitive Film for Screen Printing

In this study, a facile surface treatment method was proposed to improve the abrasion resistance of photosensitive film for screen printing. Of the three silane coupling agents used in this study, 3-aminopropyltriethoxysilane (KH550) shows the best surface modification effect. The orthogonal experiments show that the concentration of KH550 solution is the most significant factor affecting the wear resistance of photosensitive films. Therefore, the surface characteristics and abrasion resistance of photosensitive films treated with various concentrations of KH550 solution were further investigated. The investigation shows that the abrasion resistance of photosensitive films treated with KH550 is improved greatly due to the existence of a coating on the surface, and it increases with the increase of KH550 concentration until a plateau is reached at a concentration of 15?wt%. The wear resistance of photosensitive films treated with 15?wt% of KH550 is increased by 34% compared with that of pure film. Moreover, surface treatment with KH550 leads to a decrease in surface roughness of photosensitive films and an increase in their hydrophobicity. Also, the hydrophobicity increases slightly with the increase of KH550 concentration, probably because KH550 concentration can only affect the thickness of surface coating, but has no effect on the surface property. This simple method is used for the first time to improve the abrasion resistance of photosensitive film, and it has the potential to be applied for large-scale production of durable screen plates.     

Eutectic bonding of austenitic stainless steel 316L to magnesium alloy AZ31 using copper interlayer

The eutectic bonding of magnesium alloy (AZ31) to austenitic stainless steel alloy (316L) was performed using pure Cu interlayers. The effect of hold time on the microstructural developments across the joint region and the related effect on bond shear strength were studied at a bonding temperature of 530°C. The bonding process took place through a sequential occurrence of solid-state diffusion of Cu into the magnesium alloy, eutectic phase formation, interlayer dissolution, and isothermal solidification. A (Mg–Cu–Al) ternary intermetallic phase formed within the joint and concentrated into the center of the bond during the solidification stage increasing the hardness value to a maximum average of VHN313 while the maximum recorded bond shear strength was 57 MPa achieving 69% of the AZ31 shear strength and about three to four times of the adhesive joints.     

铜铋合金与ZrO2陶瓷扩散焊接头的组织与剪切强度

在1.3Pa的真空环境下,用扩散焊接法进行了Cu-x%Bi合金(x=0,0.5,1.0,2.0)与ZrO2陶瓷的连接,并采用扫描电镜、电子探针及剪切试验机等研究了铜铋合金与ZrO2陶瓷扩散焊接头的组织及剪切强度。结果表明:在焊接压力作用下挤入接合界面的铋,在焊接后部分残留在界面上,对焊接热应力有缓释作用,可提高接头的剪切强度;当接头的使用温度高于373K后,由于界面上铋的软化,接头的剪切强度急剧下降,难以在高温环境中使用。