超音速电弧喷射成形技术及其在贵金属领域中应用的展望

简述了国内外喷射成形技术的发展历程、特点和现状，着重讨论了超音速电弧喷射成形技术的原理、特点及应用，对比阐述了超音速电弧喷射成形技术的独特优点。针对目前国内外贵金属材料的应用领域、使用特点及制备方法，讨论了超音速电弧喷射成形技术在贵金属材料领域内应用的可行性。提出利用超音速电弧喷射成形技术制备贵金属基快冷材料是一种切实可行的途径，具有广阔的发展前景。     

超音速电弧喷射成形工艺参数对AgNiCu15-5沉积坯致密性的影响

采用正交设计方法和通过极差分析研究了超音速电弧喷射成形工艺参数对AgNiCu15-5沉积坯致密性的影响,同时采用SEM对沉积坯的组织形貌进行观察。研究结果表明,当沉积距离L为250 mm时,影响沉积坯致密性的工艺参数的主次顺序为:电弧电压U、雾化气压P、电弧电流I、沉积盘转速Z;综合分析表明,优化的沉积工艺参数为U2P2I3Z2,即U为32 V、P为0.9 MPa、I为220 A、Z为800 r/min。SEM分析表明,优化工艺参数制备的沉积坯内部组织致密,孔隙极少。     

电弧喷涂工艺参数对涂层组织和性能的影响

为研究电弧喷涂中工艺参数对涂层的组织和性能的影响,以低碳钢为基材,选用1Cr13、3Cr13两种丝材为电弧喷涂材料制备了不同工艺参数下的涂层,对比了不同材料、不同工艺参数下制备的电弧喷涂涂层的组织和性能,通过实验分析了工艺参数对涂层组织和性能的影响,说明了喷涂工艺参数对涂层组织影响的基本规律.     

金属喷涂、堆焊与修复：金属喷涂工艺与设备

电弧喷涂工艺参数对Zn-Al伪合金制模涂层性能的影响；工艺参数对超音速电弧喷涂钛-铝涂层表面粗糙度的影响；铁基含TiC陶瓷粉电弧喷涂粉芯丝材的研究；电弧喷涂Fe基非晶硬质涂层的组织及性能研究；高速电弧喷涂FeCrNi／CBN粉芯丝材的研制与性能研究.     

超音速电弧喷射雾化制备AgNiCu15-5粉末工艺参数的优化

通过正交设计和极差分析研究了超音速电弧喷射雾化制取AgNiCu15-5粉末工艺参数的优化,并运用SEM、XRD对制备的粉末进行了表征.结果表明,影响粉末粒度在25～38 μm范围的质量分数的工艺参数的主次顺序为:雾化距离L＞电弧电流I＞电弧电压U＞雾化气压P;优化的制粉工艺参数为L1I1U2P1,即雾化距离L为250 mm、电弧电流I为100 A、电弧电压U为32V、雾化气压P为0.8 MPa.在优化的实验条件下,制备出了粒度分布均匀的球形AgNiCu15-5粉末,其中94％以上的粉末粒度小于38 μm.     

喷射成形Al-Fe-V-Si系耐热铝合金的制备工艺和性能

采用喷射成形方法制备了不同成分的Al-Fe-V-Si耐热铝合金，对喷射成形工艺参数进行了优化，对沉积坯件的热挤压工艺进行了探索，对材料的组织进行了分析，并对不同成分材料的性能进行了比较。结果表明：当喷射成形工艺参数选择合理时，沉积坯件具有良好的成形性与致密度，在随后的热挤压过程中，通过较低的挤压比即可使材料达到全致密；沉积坯件热挤压温度的降低有利于使材料获得更高的力学性能；同时，通过对合金成分的优化，可以获得加工和使用性能更加优良的Al-Fe-V-Si耐热铝合金。     

异质金属丝电弧喷涂工艺的试验研究

本文主要介绍利用电弧做热源,通过电弧喷涂的工艺方法,使不锈钢丝和铝丝瞬间同时熔化后喷射粘附在基体金属表面上,得到一种复合材质涂层。试验中通过改变送丝速度和电弧电压等参数,制备一些涂层试样,并对涂层进行了宏观和微观组织结构检测、X射线衍射分析和显微硬度测量。由试验分析结果可以得到以下结论: (1)通过调节送丝速度和电弧电压等参数,铝和钢的异丝喷涂是可以实现的;(2)涂层的颗粒大小可以通过改变工艺参数来控制;(3)铝和钢异丝喷涂层中有Fe-Al化合物生成,其硬度高于铁、铝纯金属;(4)利用电弧喷涂装置有望使异质金属丝同时熔化并发生冶金反应,从而制备具有特殊性能的金属化合物涂层。     

CuCr25触头材料的喷射成形制备及其组织分析

研究了CuCr25合金的快速凝固喷射成形制备工艺，考察了喷射成形过程中各工艺参数对沉积坯件成形性的影响，观察和对比了喷射成形、真空熔铸和真空浸渗3种不同工艺制备的触头材料的显微组织。结果表明：喷射成形制备的材料具有典型的快速凝固组织，合金化状况良好，微观组织均匀，Cr析出相细小并弥散地分布在Cu基体中，Cr颗粒尺寸大约为3～10μm。这将大幅度提高材料的耐电压、抗电击穿等电学性能。     

双丝电弧增材制备Al-Mg-Zn-Cu-Sc铝合金工艺与组织性能

为改善Al-Zn-Mg-Cu铝合金电弧增材过程中出现的工艺和缺陷问题,利用双丝电弧增材技术,制备了Al-Mg-Zn-Cu-Sc合金. 根据电弧增材过程中的工艺以及成形情况,对该工艺中的送丝位置,送丝速度以及变极性频率等工艺参数进行分析. 通过工艺试验得到气孔含量较少和成型情况较好的参数并进行双丝电弧增材制造. 分析了不同扫描速度下的制备的Al-Mg-Zn-Cu-Sc合金组织以及力学性能,对微观组织和试样失效区域进行观察,确认了断裂类型和组织特点. 最终得到双丝电弧增材技术制备Al-Mg-Zn-Cu-Sc铝合金的工艺区间,明确了沉积态Al-Mg-Zn-Cu-Sc铝合金的基本组织特点.     

热等静压对电子封装60wt%Si-Al合金组织与性能的影响

采用喷射成形技术制备了新型电子封装材料60wt%Si-Al合金,选用两种热等静压工艺对其进行致密化处理,研究热等静压对材料组织和性能的影响。观察、分析了热等静压致密化后合金组织,测试了热等静压后合金的致密度、导热及热膨胀性能。结果表明,热等静压可有效减少或消除喷射成形60wt%Si-Al合金坯件内部的缩松缩孔,使合金接近理论密度。固态(520℃)热等静压后的合金相比半固态(600℃)热等静压合金,表现出更高的致密度、热导率和更低的热膨胀系数。     

智能材料的发展

智能材料的研制是一个迅速发展的新领域，它吸引着诸如医学，生物材料，航空航天，材料科学以及计算机工程等众多学科研究者的关注。智能材料也是一种由传感器、信息处理器和驱动器构成的新型复合材料，它能够感知外界的刺激并改变自身的特性来适应环境的变化。从概念上智能材料的基础是材料科学和计算机工程先进成就的结合，它使人们去探索利用材料复合的非线性效应来创造新型材料，本文讨论了几类智能材料的构成模式及其工程应用前     

医用贵金属材料的研究与发展

由于贵金属材料具有独特的抗腐蚀性、生理上的无毒性、良好的延展性以及生物相容性，它在医学领域的应用日益拓展。作者在本文着重介绍贵金属材料在牙科(包括牙科汞齐合金和铸造合金)、针灸、体内植入的电子器件及医用生物传感器等方面的研究与发展，分析了牙科用贵金属材料的演变过程等。     

Corrosion behavior of composite brake materials

It is very important to study the corrosion behavior of composite brake materials for their design, manufacture, and application. In the study, one kind of composite brake material used in engineering machinery, two kinds used in automobiles, and gray cast iron HT200 were selected as tested materials. Their corrosion behavior in typical acid solution, alkali solution, salt solution, running water, and air were investigated. The results showed that some components of composite brake materials, such as iron matrix, steel fiber, and iron powder, were easily subject to corrosion in acid solution. Corrosive pitting, net‐like cracking, and breakage appeared at their corrosion surfaces, and in the solution of 3.5% NaCl, corrosive pitting took place and corrosion holes of 2–8 µm diameter formed at the corrosion surface of these components. But when brake materials were exposed to the solution of 5% NaOH, the organic binder was corroded seriously, nearly parallel cracks formed at the corrosion surface and some samples even became loose powders because the corrosion makes the binder lose its adhering function. In running water and air, the tested samples have an excellent corrosion resistance, and the composite brake material containing organic binder has a better corrosion resistance compared with other tested materials. The investigation has also indicated that the interface between ingredients easily corrodes.     

Syntheses of metal nitrides, metal carbides and rare-earth metal dioxymonocarbodiimides from metal oxides and dicyandiamide

We design a facile and efficient solid-state reaction method by selecting an organic reagent dicyandiamide and metal oxides as precursors to prepare metal nitrides, carbides and rare-earth metal dioxymonocarbodiimides in sealed ampoules. Some fine divided nitride and carbide nanoparticles with small and uniform size can be easily obtained at the relatively low temperatures. It is interesting to find that dicyandiamide is not only a highly efficient nitridation reagent but also a highly efficient carburization reagent, and can be used as a precursor to directly synthesize rare-earth metal dioxymonocarbodiimides. A possible mechanism is proposed to explain the results of the reactions between the organic reagent and metal oxides.     

Dynamic magnetic properties of ZnO nanocrystals incorporating Fe

The aim of the present work is to study the magnetic properties of ZnO(Fe) nanocrystalline samples prepared by two methods of synthesis. We have used the microwave assisted hydrothermal synthesis and traditional wet chemistry method followed by calcination. The detailed structural characterization was performed by means of X-ray diffraction and micro-Raman spectroscopy measurements. The dynamic magnetic properties were studied by means of AC susceptibility χ. The measurements were performed at small AC magnetic field with amplitude not exceeding 5 Oe and different frequency values (from 7 Hz to 9970 Hz). The AC susceptibility maxima have been found for in-phase susceptibility Re(χ) and for out of phase susceptibility Im(χ). We analyzed the observed frequency dependence of the peak temperature in the AC susceptibility curve using the empirical parameter Φ that is a quantitative measure of the frequency shift and is given by the relative shift of the peak temperature per decade shift in frequency, as well as Vogel-Fulcher law.     

Oxidation of etched Zn foil for the formation of ZnO nanostructure

Oxidation of Zn foil at temperatures of 100-400 °C was carried out in air to produce ZnO with various nanostructures. The final morphology of the oxidised Zn foil is largely dependent on the oxidation temperatures. At less than 300 °C, spherical oxide grains are seen. At 400 °C, 50 nm thick, porous nanosheets were formed after 30 min of oxidation. In portions of the samples, nanorods can be seen with diameters <10 nm and lengths reaching 1 μm. The nanosheets were formed in accordance to a vapour-solid mechanism whereas the nanorods were formed by diffusion of Zn through a certain path leading to the rod structure. At 450 °C, the nanorods became much more uniform. Oxidation at 500 °C resulted in ZnO nanorods. The rods are also blunt with smaller rods seen to branch out from the main rod. The luminescence properties of the ZnO were investigated as a function of the morphology of the oxide. Both green and blue emissions are seen for the samples with nanosheets whereas the nanorods ZnO has mostly green emission.     

Advanced synthesis of nanostructured materials for environmental applications

The present study deals with Aerosol Spray Pyrolysis (ASP) synthesis of two families of nanostructured redox materials targeted to two different environmental applications: transition-metal-doped ferrites and base metal-doped cerium oxide, used for hydrogen production through solar-assisted water splitting and for catalytic soot oxidation, respectively. The synthesized powders were characterized with respect to their phase composition, morphology and particle size distribution by XRD, SEM and TEM analysis, which have shown their nanostructured character. Doped ferrites were evaluated, with respect to their hydrogen production activity from water dissociation, in an in-house built water-splitting testing rig. ASP materials proved to be very active water splitters demonstrating higher water conversion and hydrogen yields than materials of the same composition synthesized through Solid State Synthesis (SSS), with material performance depending on the dopants’ kind and stoichiometry. Base metal-doped cerium oxides were evaluated with respect to their direct soot oxidation activity, via Thermogravimetric Analysis (TGA), as well as on a diesel engine bench under realistic conditions. It was found that doping improves their activity and that they enhance soot oxidation at lower temperatures compared to materials synthesized through Liquid Phase Self-propagating High temperature Synthesis (LPSHS).     

常用银基电工触头材料及无镉新材料的开发

本文介绍了当前国内外银基电工触头材料的研究应用情况,阐述了电工触头材料的种类、性能及用途,以及在实际应用中的选用原则,指出无镉新材料的研究及新技术开发将成为电工触头材料领域的发展目标.     

生物基材料产业化进展

在全球石油资源供给日趋紧张,环保问题日益突出,对低碳经济发展需求日益迫切的情势下,以可再生资源为基础的生物基材料迅速发展成为必然趋势。综述了目前国内外生物基材料产业化的最新进展,系统介绍和总结了乳酸、1,3-丙二醇、聚乳酸、聚丁二酸丁二醇酯、聚羟基脂肪酸酯、透明质酸、大豆蛋白、聚天冬氨酸、木塑复合材料等几种生物基材料产业化最新结果。对比了美国、日本和欧洲等国家生物基材料产业状况,分析了生物基材料产业化的发展趋势及前景。     

新型隐身材料吸收剂的研究进展

综述了国内外目前用于隐身技术的几种隐身材料,介绍了几种新型隐身材料的吸收剂.对纳米隐身材料进行了较为详细的描述,简述了其吸收机理.比较了各种吸收剂的特点,提出了雷达波吸收剂的发展趋势.