Cu中间层SiCp/Al MMCs TLP扩散连接过程分析

采用铜箔作中间层,在连接温度为853 K、无压的条件下进行了瞬间液相连接,对TLP扩散连接过程及其动力学模型进行了分析,并对试验结果进行了的验证.结果表明TLP扩散连接理论模型和试验结果之间还存在着一些差异,对等温凝固过程还需要进一步探讨.分析认为,AlMMCs中大量的晶界、亚晶界、位错等短路扩散通道的存在,直接影响TLP连接过程及其动力学.     

FeAl/FeAlSi非对称膜材料的制备及膜基结合性能

目的制备高温腐蚀环境下应用的Fe Al/Fe Al Si非对称膜材料,研究膜与基体的结合性能。方法采用粉末反应合成法制备大孔径、高孔隙度的FeAlSi多孔体作为支撑体,通过浸渍法在支撑体表面制备小孔径的FeAl涂层作为膜层,再经烧结得到Fe Al/Fe Al Si非对称膜材料。研究Fe Al/Fe Al Si非对称膜材料的孔结构性能及膜基结合性能。采用XRD和SEM研究多孔膜材料的物相组成及微观形貌,采用孔结构测试仪及压汞法测试支撑体与膜层的孔结构参数,采用拉伸法和反吹实验研究Fe Al/Fe Al Si非对称膜材料的膜基结合性能。结果 Fe Al/Fe Al Si非对称膜材料表面膜层均匀、完整,膜层与支撑体之间具有冶金结合。支撑体的孔隙度和平均孔径分别为43.0%和22.7μm,膜层的孔隙度和平均孔径分别为36.5%和7.5μm。当膜层厚度增加时,膜材料的透气度下降,最大孔径在一定膜层厚度范围内变化不大,当膜层厚度在150～300μm范围内时,最大孔径约为7.8μm。膜层与支撑体的结合强度大于5.5 MPa。结论浸渍法制备的Fe Al/Fe Al Si非对称膜材料的孔结构性能优异,膜基结合性能满足工业应用。     

Study on interfacial structure and strength of Si_3N_4/Ti/Cu/Ti/Si_3N_4 PTLP bonding

0IntroductionRecently,the development of bonding technique ofhigh temperature structure ceramic Si3N4becomes a hottopic in the field of ceramic bonding[1].Partial transientliquid phase bonding(PTLP)has been applied in the fieldof high temperature ceramic bonding and made some pro-gress.The selection of interlayer materials is key to PTLPbonding.Since Bender discovered that Ag-based brazingmaterial including Ti could wet ceramic in1954,morestudies have shown that Ti has good wetting prope…     

Examination of superplastic forming combined with diffusion bonding for titanium: Perspective from experience

Superplastic forming (SPF) combined with diffusion bonding (DB) has been used successfully for the fabrication of titanium aerospace hardware. Many of these applications have been for military aircraft, whereby a complex built-up structure has been replaced with monolithic parts. Several methods for applying the two- and four-sheet titanium SPF/DB processes have been devised, including the welding of sheets prior to forming and the use of silk-screened stop-off (yttria) to prevent bonding where it is undesirable. Very little progress has been made in the past few years toward understanding and modeling the SPF/DB process using constitutive equations and data by laboratory testing. Concerns that engineers face in designing for fatigue life, acceptable design loads, and damage tolerance are currently being studied, but the database is very limited. This is a summary of past work found in the literature and forms the foundation for additional research. This paper was presented at the International Symposium on Superplasticity and Superplastic Forming sponsored by the Manufacturing Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium was organized by Daniel G. Sanders, The Boeing Company.     

塑性成形技术在金属复合管制备中的应用及展望

按金属界面间形成结合方式,机械结合和冶金结合,对目前国内外金属复合管的主要塑性成形制备技术进行了分类。对拉拔法、滚压法、旋压法、轧制法、抽真空法、液压胀形法和复合挤压法、爆炸成形法、多坯料挤压法、电磁成形法等各种塑性成形制备技术,进行了较详细的介绍和比较,指出各自的优缺点,并与离心技术法、消失模真空吸铸法、中频感应加热钎焊法等几种非塑性成形制备技术进行了比较,对其未来的发展趋势进行了展望。     

喷涂与激光重熔技术制备镍基纳米钴包碳化物复合涂层的研究

采用横流2．0kW CO2激光器，在45钢表面制备了表面较平整、较细密、基本消除了裂纹与孔隙并与基体呈冶金结合的镍基纳米WC／Co复合涂层。通过SEM，EDAX，XRD，AFM及Nano Indenter XP分析了熔覆层的显微组织、成分、物相及结合强度。结果表明，涂层的显微组织为涂层中镶嵌着大量与Ni基合金结合良好的WC／C。颗粒，其中在原子力显微镜下可见相当数量的粒度≤100μm的纳米颗粒。涂层的结合强度比传统热喷涂涂层提高了2．1倍。涂层中纳米WC／Co的纳米效应在激光熔覆中起着重要作用。     

Advances in fabricating superplastically formed and diffusion bonded components for aerospace structures

Superplastic forming and diffusion bonding (SPF/DB) production hardware is being fabricated today for aerospace applications. Metal tooling is being used to bring the titanium sheets into contact so diffusion bonding can occur. However, due to material sheet and tooling tolerances, good bond quality is difficult to achieve over large areas. A better method for achieving DB is to use “stop-off” inside sealed sheets of titanium, which constitutes a pack, and then the pack is bonded using external gas pressure. A good method for heating the pack for this process is to use induction heating. Components using “stop-off” that were diffusion bonded first and then superplastically formed have shown much better bond quality than components that were produced using matched metal tooling. This type of tooling has been successful at bonding small areas as long as the exerted pressure is concentrated on the area where bonding is required. Finite element modeling is providing weight effect solutions for titanium SPF/DB aerospace structures. This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium was organized by Daniel G. Sanders, The Boeing Company.     

特种覆膜砂粘结机理的研究

运用扫描电镜对特种覆膜砂试样的破坏机理进行了分析,研究了酚醛树脂粘结剂用于特种砂时的粘结机理。研究结果表明：采用偶联剂进行表面处理的特种覆膜少具有较高的强度,其关键在于偶联剂使树脂与特种砂砂粒间断裂方式由附着断裂转变为内聚断裂,表明偶联剂能改善特种砂粒表面与树脂的粘附性,使树脂更为牢固地附着在砂粒表面,充分发挥树脂的粘结效率。     

硬质合金与钢的热等静压扩散连接

研究了硬质合金ＹＧ１５Ｃ与４５~＃碳钢的热等静压扩散连接工艺，探讨厂连接温度、压力、保温保压时间、中间夹层及其厚度和连接残余热应力等对接合强度的影响．结果表明：热等静压扩散连接强度强烈依赖于连接温度，受控于连接后因ＹＧ１５Ｃ与４５~＃钢热膨胀失配而产生的残余热应力。采用镍箔作中间夹层可有效地减小残余热应力对连接的影响，显著提高接合强度．     

双金属固相结合的有限元分析

双金属是由两种不同性能的金属结合而成的，经过恰当组合的两种金属结合以后，可以获得高强度、耐腐蚀以及导电、导热等综合性能，使材料在某些特殊的环境下发挥良好的作用。固相结合法是制造双金属的有效方法。本文基于刚粘塑性有限元理论，在两组元金属相互接触的表面之间引入摩擦单元，对Ｃｕ／Ａｌ双金属挤压固相结合的非稳态过程进行了有限元分析，得到了两组元金属之间的相对滑动量以及成形过程中的载荷－行程曲线，计算结果与试验结果比较接近。同时获得了变形体内的应力、应变分布，揭示了组元金属在成形过程中的流动规律。