耐高温陶瓷接头的合金化——用Al／Ti／Al复合层连接Si3N4陶瓷

用Ａｌ／Ｔｉ／Ａｌ复合层真空连接Ｓｉ３Ｎ４陶瓷,研究了Ａｌ与Ｔｉ的匹配和工艺参数对接头显微组织及强度的影响。结果表明,当Ａｌ与Ｔｉ的匹配合理且采用适当的连接工艺时,Ａｌ与Ｓｉ３Ｎ４和Ａｌ与Ｔｉ的相互扩散和反应可分别获得牢固的结合界面和以Ａｌ３Ｔｉ耐高温相为主的焊缝金属,获得性能良好的陶瓷接头;Ｔｉ的厚度,连接温度和保温时间直接影响接头强度,当这些参数组合适当时,接头剪切强度在室温及６００℃可分别达     

急冷Al基活性钎料钎焊Si3N4陶瓷高温性能研究

用急冷Ａｌ基活性钎料钎焊Ｓｉ３Ｎ４陶瓷接头高温剪切强度的研究表明，对用不同成分钎料钎焊的接头均存在一较合适的钎焊工艺，５００℃时的高温剪切强度最高可达１１０ＭＰａ，经Ｎｉ粉复合的接头强度最高为１７０ＭＰａ。加Ｎｉ粉复合的接头在一定的钎焊。艺条件下能明显提高接头的高温剪切强度。高温断裂多发生于陶瓷界面处。界面处所富集的富Ｉｎ相是接头高温断裂的薄弱环节。随着富Ｉｎ相尺寸的增大，接头强度明显下降。     

陶瓷与灰铸铁在水润滑条件下滑动摩擦学特性的研究

在Ｍ－２００环一块磨损试验机上研究了蒸馏水润滑条件下Ｓｉ３Ｎ４、Ａｌ２Ｏ３陶瓷与灰铸铁（ＨＴ）配副时的滑动摩擦磨损特性，并与这两种陶瓷和０．８％Ｃ钢（Ｔ８）配副相对比；在扫描电镜（ＳＥＭ）下对磨损后的试样表面进行了形貌观察和能谱分析。结果表明：Ｓｉ３Ｎ４／ＨＴ的摩擦系数最小，而且Ｓｉ３Ｎ４与ＨＴ的磨损率均比Ｓｉ３Ｎ４与Ｔ８配副时低得多，其原因是由于在灰铸铁表面形成了一层含石墨的氧化膜；Ａｌ２Ｏ３／ＨＴ与Ａｌ２Ｏ３／Ｔ８的摩擦系数差别不大，但灰铸铁的磨损体积小于Ｔ８。这是由于当Ａｌ２Ｏ３与ＨＴ配副时，很难在ＨＴ表面形成含石墨的表面膜，但ＨＴ中的石墨膜减轻了Ｆｅ向Ａｌ２Ｏ３表面的转移从而降低了磨损。     

刀具材料的回顾与展望（下）

３．陶瓷陶瓷刀具材料分为３类：１）氧化铝基陶瓷　一般在Ａｌ２Ｏ３基体中加入ＴｉＣ、ＷＣ、ＳｉＣ、ＴａＣ、ＺｒＯ２等成分,经热压制成复合陶瓷。硬度达ＨＲＡ９３～９５,抗弯强度达０．７～０．９ＧＰａ。为提高韧性,常添加少量的Ｃｏ、Ｎｉ等金属。２）氮化硅基陶瓷　常用的是Ｓｉ３Ｎ４＋ＴｉＣ＋Ｃｏ的氮化硅基复合陶瓷,其韧性常高于Ａｌ２Ｏ３基陶瓷,硬度相当。３）复合氮化硅—氧化铝陶瓷　其化学成分为Ｓｉ３Ｎ４７７％,Ａｌ２Ｏ３１３％,Ｙ２Ｏ３１０％,硬度可达ＨＶ１８００,抗弯强度可达１．２０ＧＰａ。这种陶瓷…     

化学镀镍Si3N4与金属钎焊接头的强度研究

对化学镀镍Ｓｉ３Ｎ４－Ｑ２３５钎焊接头的微观结构和界面反应进行分析,并对有关工艺因素对接头强度的影响规律进行了探讨,为化学镀镍陶瓷－金属钎焊规范的优化选择提供了必要的试验及理论依据。     

Al2O3/(Ag72Cu28)97Ti3/Ti-6Al-4V界面反应

在１．８　ｋｓ、１　０７３～１　１７３　Ｋ条件下对Ａｌ２Ｏ３／（Ａｇ７２Ｃｕ２８）９７Ｔｉ３／Ｔｉ－６Ａｌ－４Ｖ进行了钎焊试验。通过扫描电镜、波谱、能谱和Ｘ射线衍射对界面反应产物进行了测试，确定了界面结构，并讨论了这些反应产物形成的可能性。结果表明，温度小于１　１２３　Ｋ的界面结构为Ａｌ２Ｏ３／Ｃｕ２Ｔｉ４Ｏ／Ｃｕ４Ｔｉ３＋Ｃｕ固溶体／Ａｇ－Ｃｕ共晶　＋　富Ａｇ相；温度１　１７３　Ｋ的界面结构为Ａｌ２Ｏ３／Ｃｕ３ＴｉＯ５　＋　ＣｕＡｌ２Ｏ４／Ｃｕ４Ｔｉ３／富Ａｇ相＋　Ｃｕ４Ｔｉ３。     

Ti6Al4V／Al_2O_3的扩散连接及界面问题的初步研究

成功地用真空扩散焊法获得了Ｔｉ６Ａ１４Ｖ／Ａｌ２Ｏ３的连接界面。分析了不同温度下的界面结构、界面反应情况，同时用压痕法初步偿派了界面残余应力分析。结果表明，在８００℃时扩散焊界面上没有显著的化学反应，随着温度的提高，界面上Ｔｉ６Ａ１４Ｖ和Ａｌ２Ｏ３反应生成ＴＩＡｌ、Ｔｉ２Ａｌ、Ｔｉ３Ａｌ与Ｔｉ组成的脆性混合过渡层。该过渡层，并通过氧的固溶使基体金属脆化；压痕裂纹扩展方式可以在一定程度上反映残余应力的局部分布特征。     

SiC晶须增韧Al_2O_3－（Ti，W）C陶瓷材料增韧机理的研究

改善陶瓷材料的脆性是陶瓷研究领域里急待解决的关键性课题。本文在Ａｌ２Ｏ３－（Ｔｉ，Ｗ）Ｃ复相陶瓷中加入不同含量的ＳｉＣ晶须以提高基体材料的断裂韧性。研究表明，ＳｉＣ晶须增韧Ａｌ２Ｏ３－（Ｔｉ，Ｗ）Ｃ复相陶瓷的断裂韧性与烧结密度、晶须含量等因素有关，增韧效果与晶须和基体的复合密切相关，增韧机制主要是裂纹偏转和裂纹桥接机制，同时，Ａｌ２Ｏ３与（Ｔｉ，Ｗ）Ｃ形成的双骨架结构亦使断裂韧性得到提高。     

SiC晶须增韧Al2O3—（Ti,W）C陶瓷材料增韧机理的研究

改善陶瓷材料的脆性是陶瓷研究领域里急待解决的关键性课题。本文在Ａｌ２Ｏ３－（Ｔｉ，Ｗ）Ｃ复相陶瓷中加入不同含量的ＳｉＣ晶须以提高基体材料的断裂韧性。研究表明，ＳｉＣ晶须增韧Ａｌ２Ｏ３－（Ｔｉ，Ｗ）Ｃ复相陶瓷的断裂韧性与烧结密度、晶须含量等因素有关，增韧效果与晶须和基体的复合密切相关，增韧机制主要是裂纹偏转和裂纹桥接机制，同时，Ａｌ２Ｏ３与（Ｔｉ，Ｗ）Ｃ形成的双骨架结构亦使断裂韧性得到提高。     

陶瓷─铸铁摩擦面上形成的表面膜对其摩擦学特性的影响

在Ｍ─２００环─块磨损试验机上研究了陶瓷─铸铁配副在蒸馏水和空气润滑下的摩擦学特性，并以陶瓷─碳钢配副作为对比，对磨损后的试样磨面进行了扫描电镜和光镜观察，采用俄歇电子能谱（ＡＥＳ），Ｘ射线能谱（ＥＤＡＸ）以及图象分析等方法对表面膜进行了分析。结果表明：Ｓｉ３Ｎ４陶瓷与铸铁在蒸馏水润滑下配副获得了非常优异的摩擦学特性，其摩擦系数仅为０．０２，系统的磨损率几乎接近于零，其原因是由于在磨面上形成了具有一定厚度和面积的化学反应膜；当Ｓｉ３Ｎ４与碳钢在蒸馏水润滑下配副时，由于在磨面上不能形成有效的化学反应膜，所以摩擦系数仍然崐较高；当Ａｌ２Ｏ３与金属配副时，在陶瓷磨面上形成了材料转移膜，转移膜的形成大幅度减轻了陶瓷磨损，但却加剧了金属的磨损，并使摩擦系数升高     

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。     

Al_2O_3陶瓷与Q235钢的活性钎焊

采用二元Cu-Ti活性钎料连接氧化铝陶瓷与Q235钢,研究了反应温度、保温时间等钎焊工艺对接头组织与接头强度的影响,分析了接头的微观组织和界面产物。试验结果表明,界面分为3层结构,即液态钎料填充陶瓷微孔形成的反应层、合金钎料层、钢侧扩散层。XRD分析结果表明,界面产物为Cu3Ti3O、TiFe、TiFe2和Cu基固溶体。钎焊温度1050℃,保温时间30min时,接头抗剪强度达到99.3MPa。     

Influence of high temperature diffusion bonding process parameters on mechanical and metallurgical characteristics of nickel superalloy to martensitic stainless steel

Welding of dissimilar metals is challenging because of the formation of microfissuring, strain age cracking and brittle intermetallic compounds. The above‐said problems can be avoided by controlled heating and cooling rates and the formation of beneficial intermetallic layers in the joint interface using solid‐state welding techniques such as diffusion bonding. This study investigates, the effect of diffusion bonding process parameters of dissimilar metals (AISI 410 martensitic stainless steel and nickel [Su 718] based superalloy). Fifteen joints were fabricated using different levels of bonding temperature (920–1,000°C), bonding pressure (10–18 MPa) and holding time (30–90 min). From this investigation, it is identified that joints fabricated at bonding temperature 980°C, bonding pressure 16 MPa and holding time 75 min yielded an extreme tensile strength (263 MPa) and hardness (450 HV) compared to the other joints. The tensile properties of the welded joints were assessed and associated with the microstructures. Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and X‐Ray Diffraction (XRD) analysis were used to estimate the metallurgical characteristics of the weldment. The EDS examination was supported out to analyses the interface composition and to decide the composition at the interface. Furthermore, a lot of δ phase precipitates were likewise found in the bonded region.     

面向即时检测芯片超声波精密键合的熔接结构及工艺参数

针对芯片即时检测(POCT)芯片对键合精度、键合强度、生产效率和生物兼容性的要求,基于超声波键合技术设计了结构化的导能筋布置形式和阻熔导能接头结构。研究了超声波键合时间和键合压力对微通道高度保持性能的影响,确定了精密超声波键合工艺参数。利用高精度显微镜、拉伸试验机和羊全血分别对键合后芯片的微通道高度、键合强度、微通道密闭性以及液体自驱动性能进行了测试。结果表明:所设计的导能筋布置形式合理可靠;利于芯片各功能的集成,阻熔导能接头结构能够较精确地控制键合后微通道的高度,键合精度达到2μm;全血驱动时间的极差在20s以内;所确定的键合工艺参数能够实现高强度的键合,键合强度不小于2.5 MPa。该熔接结构及工艺参数具有键合精度高、键合强度高、生物兼容性好和熔接均匀等优点,可应用于医用POCT芯片产品中。     

Optimization of brazing conditions for OFHC Cu and ASTM A501 low carbon steel by taguchi method

This paper concerns the optimization of brazing conditions for joining the two dissimilar materials Oxygen-free high conductivity (OFHC) copper and ASTM A501 low carbon steel usually used for an Oil-Separator of an air-conditioner using Ag-based (BAg) alloy as a brazing filler metal (BFM). A mixture of 70% N₂ and 30% H₂ gases was used to prevent oxidation of the joints during furnace brazing process. Brazing joint clearance, length, temperature, and time were selected as design parameters that have significant effect on the bonding strength of a brazed joint. Taguchi method was used as a statistical technique for design of experiment (DOE) in an attempt to optimize brazing conditions in terms of shear strength. L₉ (3⁴) orthogonal array was designed for conducting the experiments. The relative influence of design parameters and their interaction on the response were also discussed. The experimental results verified that the brazing conditions predicted in this study by Taguchi method could produce the brazed joint between OFHC copper and ASTM A501 low carbon steel with maximum shear strength.     

Evaluation of interface bonding strength of aluminum/silicon carbide

The quality of interface bonding between matrix and reinforcement is important in composite strengthening. Interface bonding strength of particulate reinforced metal matrix composites were investigated by joining process. The aluminum/silicon carbide specimens were prepared by different processing temperature with constant holding time. The structural morphologies have been evaluated by using scanning electron microscope and interfacial products were identified by using energy dispersive spectroscopy. The interface strength has been evaluated by tensile test and microhardness test.     

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.     

TP304H/12Cr2MoWVTiB异种钢管的双温瞬时液相扩散焊工艺

采用传统的和双温瞬时液相扩散(TLP)焊接工艺对TP304H/12Cr2MoWVTiB异种钢管进行了焊接,研究了不同焊接工艺对接头组织与性能的影响。结果表明:采用双温TLP焊接工艺所获得的焊接接头的组织和性能优于传统TLP焊接工艺的;采用1 240℃加热30 s1、200℃加热3 min的双温焊接工艺所获得的接头抗拉强度为570 MPa,弯曲角达180°时不断裂。     

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。     

超声波键合熔接结构及压力自平衡夹具

聚合物微流控芯片对键合精度、键合强度及键合效率要求高。为了避免超声波键合中微通道被堵塞,解决键合过程中由调平精度和高频振动引起的键合强度低、键合压力分布不均的问题,设计了一种基于超声波键合的熔接结构和压力自平衡夹具。首先,利用感压胶片对压力自平衡夹具和不带自平衡功能的夹具的压力分布进行测量,并定义了压力分布系数进行量化。其次,利用两种夹具分别对设计芯片进行超声键合,并利用工具显微镜对焊线和微通道截面进行观测。最后,对两组芯片进行键合强度测试和密封性测试。实验结果表明:所设计的熔接接头结构对微通道的控制精度可达2.0μm。压力自平衡夹具结构简单可靠,可提高压力均匀性35.20%~43.18%,并使得焊线均匀一致,同时可提高键合强度15.3%~45.1%,并保证密封性。该熔接结构和压力自平衡夹具可满足聚合物微流控芯片的控制精度、键合强度、压力均匀性及其密封性的要求。