钛基梯度功能材料电场激活原位合成

本文采用电场激活压力辅助燃烧合成工艺(FAPAS),以Ti-Al和Ni-Ti-C体系的放热反应,实现了TiC陶瓷颗粒增强的Ni基复合材料的原位合成以及Ti-TiAl-(TiC)pNi功能梯度材料的同步连接制备。借助SEM和XRD等手段分析了各层界面的相组成和微观结构以及界面元素扩散特征,探讨了电场对功能梯度材料制备过程中各层间界面的冶金特征及连接结构的影响,揭示了电场作用下,利用放热体系进行原位合成和扩散连接的机制。研究结果表明,外加电场条件下,钛粉和铝粉反应形成TiAl相产生的化学热促进了钛基板与TiAl层界面原子的扩散溶解,是两者形成连接的关键;钛-碳反应热促进TiC/Ni细晶复合结构形成,提高了TiC颗粒与基体之间的润湿性和复合材料层的致密度。     

电场辅助原位合成TiB2-TiC-Ni/TiAl/Ti功能梯度材料及界面结构

采用电场激活压力辅助合成技术（FAPAS）并结合原位反应的方法制备TiB2-TiC-Ni/TiAl/Ti功能梯度材料,研究了TiB2-TiC-Ni/TiAl/Ti功能梯度材料的界面微结构特征及其结合强度,分析了梯度材料界面的微观组织和元素分布,并分析了试样的抗剪切强度和显微硬度。研究表明：制备的TiB2-TiC-Ni/...     

梯度材料电场辅助自蔓延燃烧合成机理研究

采用电场辅助自蔓延高温合成技术制备了SiC-TiC-xNi梯度功能材料.利用电场的焦耳加热效应,使那些通过单一自蔓延高温合成(SHS)技术难以进行或不能进行的反应物的制备得以实现;电场加快离子的扩散与迁移速度,减少晶体缺陷,使反应更加充分.实验发现,随着电场强度的增大,反应体系的温度升高、电流值变大.     

电场激活压力辅助SHS法合成TiC-Ni-Fe复合材料

采用电场激活压力辅助SHS法制备了TiC 15%Ni 20?物相体系金属间化合物基复合材料.分析表明TiC 15%Ni 20?物相体系生成物中主要相为TiC,基体成分为NiTi2与FeNi金属间化合物;随着压力增加,生成物成分更均匀,密度增大,表面硬度和显微硬度值也显著提高.     

钎焊方法制备Ti/TiAl/Al系变密度功能梯度材料

采用两步钎焊方法来完成梯度材料的制备:第一步,选用Ti-Zr-Cu-Ni-Co急冷态箔带钎料钎焊TC4/TiAl接头,钎焊规范选为960℃/10min;第二步,采用高纯度的Al,Cu和Si粉末混合配制Al-25Cu-5Si钎料,用于钎焊TiAl/LF21接头,钎焊规范选为590℃/10min.结果表明,两步钎焊法成功实...     

自蔓延高温合成法合成金属陶瓷功能梯度材料研究进展

阐述了自蔓延高温合成法(SHS)制备的功能梯度材料的种类、特性及其应用前景,探讨了自蔓延高温反应合成金属陶瓷功能梯度材料的影响因素(合成原料、点火工艺、反应环境和辅助措施),并分三个阶段(准备阶段、合成阶段和后处理阶段)讨论了SHS法制备功能梯度材料应注意的技术问题,同时介绍了自蔓延法辅助其他工艺(SHS反应喷涂)制备梯度陶瓷材料技术,并提出了自蔓延高温合成法制备金属陶瓷功能梯度材料今后的发展方向。     

ZrO2-Ni功能梯度材料的热冲击与热疲劳行为

通过抗热震参数分析和热循环试验研究了ZrO2-Ni功能梯度材料（FGM）的热冲击与热疲劳行为及其影响因素。结果表明,ZrO2-Ni FGM热热震参数呈梯度分布,ZrO2侧抗热冲击断裂能力强而富Ni区热疲劳抗力高。其热震破坏符合热疲劳损伤机理,裂纹的准静态扩展为其控制因素。热疲劳裂纹在梯度层内以微孔聚集、连接方式萌生和扩展,而在梯度层间无横向贯穿裂纹,克服了传统陶瓷／金属结合体的界面热应力剥离问题。     

TiAl/Al_2O_3复合材料的原位合成与表征

采取铝热原位合成的方法,以钛白粉和铝粉为原料原位合成制备TiAl/Al2O3复合材料。通过XRD分析了不同温度下反应过程及烧结样品的物相形成规律。分析结果表明:在750℃条件下反应时,原料中心部分变成了黑色,反应生成了钛的低价氧化物。随着温度的升高逐渐形成了部分TiAl金属间化合物和Al2O3。当温度达到1250℃时,反应比较充分,主要生成了TiAl金属间化合物和Al2O3,原位合成了TiAl/Al2O3复合材料。     

Ti基功能梯度材料的研究进展

综述了Ti基功能梯度材料的各种制备方法、性能评价以及在航空机械和生物医药等方面的应用,展望了Ti基功能梯度材料的未来发展及前景。     

先驱体转化法原位制备功能梯度陶瓷

探索性地采用一种陶瓷制备方法－－先驱体转化法原位制备功能梯度陶瓷，样品测试结果表明，材料具有电阻梯度特性以及微波段吸收电磁波特性。     

电场激活燃烧合成( TiB2)PNi/Ni3Al/ Ni功能梯度材料

采用电场激活压力辅助合成技术(FAPAS)制备了(TiB₂)_PNi/(TiB₂)_PNi₃Al/Ni₃Al/Ni梯度材料,主要研究电场激活燃烧合成过程中电场对材料合成及层界面扩散连接的作用。分析了梯度材料各层的界面微观组织及相组成和材料的硬度分布。结果表明,采用FAPAS 技术结合机械合金化工艺制备的(TiB₂)_PNi/(TiB₂)_PNi₃Al/Ni₃Al/Ni 功能梯度材料具有快速、简便和组织均匀密实的特点。梯度材料的陶瓷复合层、Ni₃Al层和Ni板的界面区产生成分的互扩散,形成了良好的冶金结合。从Ni板到陶瓷复合层的硬度呈梯度分布。     

Electric field-activated combustion synthesis of Ti5Si3-Nb and Ti5Si3-ZrO2 composites

The field-activated combustion synthesis of the composites Ti5Si3−x Nb (0≤x≤0.35) and Ti5Si3−y ZrO2 (0≤y≤0.3) has been investigated. Composites with x≥0.35 and y≥0.2 can only be synthesized in the presence of an electric field. Although in the absence of a field the systems with x=0.35, y=0.2 and y=0.3 can sustain a non-steady combustion wave, the reaction is not complete. An unstable wave propagates to the middle of the sample and then becomes extinguished. The wave velocity of the Ti5Si3-Nb and Ti5Si3-ZrO2 composites increased slightly with the application of a field. This revised version was published online in November 2006 with corrections to the Cover Date.     

Influence of stirring speed on the synthesis of Al/SiC based functionally gradient materials

In the present study, thick aluminum–silicon carbide based functionally gradient materials, with starting weight of 18% SiC were successfully synthesized, using different stirring speeds and an innovative gradient slurry disintegration and deposition technique. The results revealed, in common, an increase in: (a) the weight percentage of SiC particulates, (b) the clustering tendency of SiC, (c) porosity and (d) microhardness, and a reduction in grain size with increasing distance from the base of the functionally gradient material ingots. The results of X-ray diffraction studies indicated no evidence of interfacial reaction products. Furthermore, results revealed an increase in stirring speed increases the homogeneity of SiC particulates' distribution, thus resulting in a decrease in the average gradient of reinforcement along the deposition direction. An attempt is made in this study to establish the trend between processing parameter such as stirring speed with the gradient of SiC particulates realized in the ingots.     

Cu/ABS复合导电梯度功能材料的制备和性能

借助HAAKE转矩流变仪,采用熔融共混法制备了一系列Cu粉含量不同的Cu/丙烯腈-丁二烯-苯乙烯共聚物(ABS)复合材料,采用多层叠压法制备了内部Cu粉含量逐渐变化的板状Cu/ABS复合导电梯度功能材料,并对其结构和性能进行了表征。结果表明,所制备导电梯度功能材料的性能与均质复合材料存在很大差异。电性能测试结果显示,随着Cu粉含量沿板材厚度方向的梯度增加,其导电性能发生逾渗转变,体积电阻率从一侧的1016Ω.cm降低到另一侧的105Ω.cm。弯曲性能测试表明,富含ABS树脂的一侧表现出较高的弯曲强度,仅比纯ABS的弯曲强度低6%;而富含填料的另一侧则表现出较高的模量,比纯ABS高约20%。实验证明,将导电复合材料做成梯度结构可以兼顾材料的导电性能和力学性能。     

碳/碳/Al2O3陶瓷功能梯度材料的制备与研究

从功能梯度材料的原材料的筛选、制备工艺路线的确定出发,对碳/碳/Al2O3陶瓷功能梯度材料的组分分布、微观结构、烧蚀性能及热学性能进行了研究.从试样内表面向外表面,基体碳含量从88%变化到近乎为15%,而Al2O3陶瓷含量从12%变化到85%左右.材料内表面氧-乙炔烧蚀率为0.012nn/s,这表现为碳/碳材料的特性.材料外表面的导热系数达到0.86W/m·K(25℃),表现为良好的隔热效果.     

Fabrication and microstructure of ZrO2-Ni functional gradient material by powder metallurgy

Functional gradient material (FGM) of the ZrO₂-Ni system was developed by a powder metallurgical process, and investigated for its microstructure by means of X-ray diffractometry (XRD), electron probe microanalysis (EPMA), transmission electron microscopy (TEM) and optical microscopy. It was shown that the sintered body of ZrO₂-Ni FGM is almost fully densified, and its chemical composition and microstructure have the expected gradient distribution. With composition variation, the microstructure changes gradually from zirconia particles dispersed in a nickel matrix to the converse with nickel particles dispersed in a zirconia matrix, with network structures in the intermediate composition range. Therefore, no distinct interfaces appear in the FGM due to the gradient change of components, that is, both zirconia and nickel are present everywhere in the microstructure. In phase composition, the sintered ZrO₂-Ni FGM consists of nickel, tetragonal zirconia and a little monoclinic zirconia. No reaction between nickel and zirconia has been detected. The substructure of nickel and monoclinic zirconia are twins, and strain fringes can also be found in zirconia.     

Microstructure and mechanical property of laser melting deposition (LMD) Ti/TiAl structural gradient material

This article presents fabrication, microstructure and mechanical properties study of Ti/TiAl functional gradient material. Ti–47Al–2.5V–Cr/Ti–6Al–2Zr–Mo–V gradient material was successfully fabricated by the laser melting deposition (LMD) manufacturing process. Microstructure and chemical composition was characterized by OM, SEM, TEM and EPMA. The Vickers hardness and room-temperature tensile property was evaluated on longitudinal direction. Results showed that fully lamellar (FL) microstructure consisted of γ-TiAl and α₂-Ti₃Al was formed on the Ti–47Al–2.5V–Cr side, while coarse basket weave microstructure was formed on the Ti–6Al–2Zr–1Mo–1V side. No cracking was found in the gradient zone after aging at 800 °C for 48 h. The room-temperature tensile strength of the as-deposited specimen is up to approximately 1198.8 MPa in the longitudinal direction, while the tensile elongation is approximately 0.4%, indicating a typical brittle fracture.     

磁化学合成Al2O3/7055Al复合材料的微观结构

脉冲磁场下,以7055Al-Ce2(CO3)3为反应体系制备了内生Al2O3颗粒增强铝基复合材料。X射线衍射仪(XRD)、扫描电镜(SEM)、电子探针(EPMA)分析表明,在脉冲磁场作用下,原位合成的颗粒细小,呈球形或橄榄形的Al2O3颗粒尺寸为200～400nm,且弥散分布于基体中。从反应动力学角度进行考虑,与常规反应相比,磁场下反应更快更完全,并缩短了反应时间。随着脉冲磁场强度的增大,反应生成的增强颗粒变得更加细小,分布更均匀。当磁场作用的时间增加时,内生颗粒数目逐渐增多,尺寸逐渐细化,圆钝化,分布也变得均匀,颗粒达到纳米尺寸。