新的多孔泡沫镍制备工艺

针对目前泡沫金属制备方法的缺点,提出了一种泡沫金属制备的新方法——电解液喷射沉积法。研究了喷射沉积制备泡沫镍的工艺,自行研制了试验装置,制备了具有不同孔隙率的泡沫镍试样,分析了相关工艺参数(电解液成分、电流密度、电解液喷射速度等)对泡沫镍微观结构的影响。结果表明:采用相对较低的镍离子浓度配方Bath A对制备均匀致密的枝晶多孔结构有利。随着电流密度的提高,泡沫镍的孔隙率逐渐降低;随着电解液喷射速度的提高,泡沫镍的孔隙率逐渐增加。总体上采用电解液喷射沉积法制备的泡沫镍的孔隙率在30~70%之间。     

溶胶-凝胶法合成纳米TiO2粉体的研究进展

概述了利用溶胶-凝胶法合成纯纳米TiO2粉体时不同合成条件对制备结果的影响;综述了利用溶胶-凝胶法合成金属及非金属离子掺杂TiO2粉体、半导体复合纳米TiO2、贵金属沉积以及固体超强酸化纳米TiO2的研究现状,并指出不同方法提高光催化活性的机理在于促进电子-空穴的分离或改变能带及表面结构.针对制备纳米TiO2粉体中存在的问题,指出未来的研究方向应是提高TiO2催化活性的机理研究、可见光化纳米TiO2的制备以及工业化生产条件探索等.     

不同沉积气体对多孤法制备TiC膜的影响

采用两种不同的沉积气体CH4 和C2 H2 分别在SUS3 0 4不锈钢基片上用多弧离子法沉积TiC硬质膜。XPS结果表明 ,用C2 H2 作为沉积气体制备TiC膜中的sp2 杂化的碳多于用CH4 作为沉积气体制备的TiC膜。XRD表明 ,用CH4 气体沉积TiC膜的 ( 111)峰为择优取向 ,但用C2 H2 气体沉积的TiC膜却朝着 ( 111)和 ( 2 2 0 )取向竞争生长。TiC薄膜的高硬度某种程度上取决于TiC( 2 2 0 )峰的丰度。     

ZnS的不同制备方法及性能的对比

综述了多晶ＺｎＳ块材料的两种制备方法－热压法和化学气相沉积法的优劣，对两种方法所获材料的光学性能、热学性能、力学性能、热冲击抗力、雨蚀抗力、固体颗粒冲击抗力及化学性能进行了比较。     

泡沫金属的制备工艺及应用

根据泡沫金属制备过程中金属的状态,将泡沫金属的制备方法归类为:熔体凝固法、固态烧结法、金属沉积法,并按此分类对泡沫金属常用制备工艺进行了介绍.泡沫金属具有轻质、高孔隙率、电磁屏蔽等性能,按照功能用途和结构用途2方面对其应用领域进行了介绍.     

中科院化学所在石墨烯可控制备和性能研究方面取得系列进展

在中国科学院、科技部、国家自然科学基金委和化学所的大力支持下,中科院化学所有机固体院重点实验室相关研究人员在石墨烯的可控制备和性能研究方面取得系列进展,相关结果发表在PNAS、JACS(2篇)、Adv.Mater.(3篇),并应邀在Acc.Chem.Res.杂志上发表了述评。液态铜上生长石墨烯。在众多的石墨烯制备方法中,化学气相沉积法(CVD)由于成本低、可控性好、可大规模制备等优点近年来掀起了对其的研究热潮。2009年,美国奥斯汀大学Ruoff组利用固体铜箔作为金属催化剂制备出了连续     

垂直沉积自组装法与复杂结构光子晶体的研究进展

作为一种折光指数呈周期性分布的材料,光子晶体在功能器件、光学纤维和光学伪装材料等方面有潜在重要的应用。总结了以垂直沉积自组装法为基础,通过不同方法来制备光子晶体的研究进展,以及利用这些方法进一步制备各种具有不同复杂结构光子晶体的进展,总结了这些方法制备光子晶体的优缺点,并展望了垂直沉积自组装法制备光子晶体的发展趋势。     

金属有机化学气相沉积制备铁电薄膜材料研究进展

铁电薄膜是一类重要的功能材料,是近年来高新技术研究的前沿和热点之一.金属有机化学气相沉积(MOCVD)是制备铁电薄膜的一种重要方法.综述了金属有机化学气相沉积法制备铁电薄膜的历史、原理、工艺参数、特点和采用此方法制备出的某些材料的铁电性能.     

几种特气在半导体工艺中的应用

在半导体工艺中，如低压化学气相沉积法（LCVD）制备多晶硅和氮化硅薄膜，以及等离子刻蚀等工艺，都要使用特种气体。有些特种气体我国已有生产，如氨气、氯化氢。有些特种气体在半导体工艺中很有用途，但到目前为止，还没有生产单位，或质量没有过关。现介绍我所在半导体工艺中需用的几种特种气体。     

轻合金泡沫材料制备技术研究进展

轻合金泡沫在汽车及建筑等领域应用前景广阔,制备方法也较多.目前,轻合金泡沫的主要制备方法有粉体发泡法、熔体发泡法、渗流铸造法及气体发泡连续法等.在简要分析了这些轻合金泡沫制备方法中存在的问题后,提出了以后轻合金泡沫方面的研究重点.今后的重点应放在进一步研究金属泡沫材料性能与基体合金成分及发泡工艺之间的内在联系、发泡工艺对泡沫密度和气孔均匀性的影响规律等方面;轻合金泡沫的低成本生产工艺与相关设备的设计等方面的研究也应该作为重点.     

Process Control in Aluminum Foam Production Using Real‐Time X‐ray Radioscopy

Aluminum alloy foams were created by expanding foamable precursors containing a gas‐releasing blowing agent in a dense metallic matrix. The precursors were prepared in two different ways: either by hot‐compaction of powder mixtures or by thixocasting of billets obtained by cold compaction of powder blends. Foam evolution was visualized by means of real‐time X‐ray radioscopy with image frequencies ranging up to 18 Hz and spatial resolutions down to 10 μm. The difference in pore formation between the two processing routes could be studied. Rupture of cell walls during foam expansion could be visualized, critical rupture thickness measured, and the time‐scale of the rupture process estimated. By manufacturing foam precursors in which defects were incorporated deliberately, the question of the origin of very large pores in solid metal foams could be examined. By forced cooling of liquid metal foams while recording their structure, the importance of solidification‐induced changes of foam morphology was illustrated.     

Production of metallic foam under low gravity conditions during parabolic flights

Metallic foams are a recently developed light weight material. They are porous structures consistent of metals like aluminum, tin, zinc, lead etc. or their alloys. The pore sizes are in the range of millimeters and relative densities down to 10% of the original material can be achieved. Since metallic foams combine relative low weight with high stiffness, their applications are mainly for means of light weight structures as used for example in cars. Also other applications like sandwich structures and metallic filters are of interest. To make metallic foams applicable for an industrial use, still some technical and principle problems have to be solved. These concern mostly the structure of the resulting foam, which is very inhomogeneous and not well understood. Our aim is to contribute to the understanding of the physical processes that take place during the foaming process. In this paper we will introduce the powder metallurgical production method we used for producing metallic foams. Then we will describe the two main physical processes during the foam genesis and present our experimental idea and setup used to obtain information on these processes. Finally we will discuss the first results we got from parabolic flights and terrestrial experiments.     

多孔金属材料的制备及应用

根据制备过程中金属的状态，从液相法、固相法、金属沉积法三方面介绍了多孔金属材料的制备工艺。液态金属的发泡可以通过直接吹气法发泡法、金属氢化物分解发泡法来实现；固态金属可以通过粉末冶金法、粉末发泡法、金属空心球法和金属粉末纤维烧结法来实现；与前两种不同的是，金属沉积法是采用化学或物理的方法来实现的。最后，讨论了多孔金属材料在结构材料和功能材料两方面的应用。     

Ultrasonic Torsion Welding of Sheet Metals to Cellular Metallic Materials

One of the most important requirements for finding new applications for cellular metals is to integrate them in complex technical structures. The metal foams have to be joined to each other, or to sheet materials, by suitable joining techniques. The main topics of this paper are the ultrasonic torsion welding of cellular metallic materials to sheet metals and the investigation of the mechanical properties of the joints. The basic materials of foams and sheet metals were different aluminum and iron alloys. Depending on the materials used, weldings with tensile shear strengths of up to 25 MPa were realized. Using aluminum foam sandwich (AFS) and sheet metals, successful weldings were performed before and after the foaming process. Furthermore, it was possible to perform a successful foaming process with the unfoamed AFS/sheet metal joints. Microscopic investigations showed that the ultrasonic welding technique allows the joining of the metal foams with sheet metals without significant deformation of the joining partners. The temperatures during the welding process in the interface were below the melting point of the foams and the sheet metals.     

Editorial

In this study the Taguchi method is used to find the optimal process parameters for aluminium foam manufacturing. Porous metals are the unique materials used for light weight structural components, for filters and electrodes and for shock or sound absorbing products. Recently, interesting foaming technology developments have proposed metallic foams as a valid commercial chance. Metallic foam manufacturing techniques include solid state powder methods, gas blowing processes, metal deposition onto a polymer precursor and liquid state processing. The aluminium foams presented in this study are produced by the powder metallurgy route starting from aluminium powders with titanium hydride as the foaming agent. During the experimental work, many samples are made by utilizing the combination of process parameters based on Taguchi orthogonal design. Three manufacturing parameters are studied: the silicon carbide content in powder mixture, the compaction pressure and the foaming temperature. The Taguchi method is applied to design an orthogonal experimental array and a multi-objective optimization approach is then proposed by simultaneously minimizing the relative density and maximizing the absorbed energy. Verification test is also performed to prove the effectiveness of the presented technique.     

新型泡沫铝的制备及其孔结构的控制

发展了一种高压渗流铸造法制备孔结构可控的新型泡沫铝，推导出孔结构参数计算公式，并据此提出孔结构参数控制和测量方法。制得的泡沫铝具有较理想的孔结构。     

On the Mechanical Properties of Aluminum Matrix Syntactic Foams

Metal matrix syntactic foams (MMSFs, often referred as composite metal foams (CMFs)) are lightweight materials with high specific strength. MMSFs are on the borderline between metal matrix composites and metal foams. On one hand MMSFs are composites, because they are filled by hollow particles and the particles may add strength to the material. On the other hand, they are foams, because the hollow particles ensure porosity to the material. Among metallic foams, MMSFs exhibit outstanding specific mechanical properties due to the hollow inclusions that are typically made from ceramics or high strength alloys, therefore they can be applied as structural materials. The goal of this paper is to summarize the available data on the mechanical properties of MMSFs with aluminum matrix in order to give a strong support to the design engineers. Since the foams are most frequently loaded in compression, the main part of this paper is organized around the available standard related to the compressive properties of porous materials and metallic foams. The quasi‐static results are complemented by properties measured at higher strain rates. Besides this, some insight into the basic fatigue properties as well as into the toughness of MMSFs is also provided.

     

Influence of alumina bubble particles on microstructure and mechanical strength in porous Cu–Sn–Ti metals

In order to obtain high porosity and satisfactory strength simultaneously for the porous metallic layer of the grinding tools, alumina bubble particles were added into Cu–Sn–Ti alloy powders to fabricate porous metals using a vacuum sintering method. The influence of the alumina bubble particles on the microstructure and the mechanical strength of the porous Cu–Sn–Ti metal blocks were investigated. Results show that adding alumina bubble particles into Cu–Sn–Ti alloy powder generate closed pore structures for the metal blocks. Good bonding interface between alumina bubble particles and Cu–Sn–Ti alloy is formed mainly dependent on the chemical resultants of TiAl and TiO. A relationship between the bending strength of the porous Cu–Sn–Ti metal blocks and the size and volume fraction of the alumina bubble particles is established.     

Production of metallic foam under low gravity conditions during parabolic flights

Metallic foams are a recently developed light weight material. They are porous structures consistent of metals like aluminum, tin, zinc, lead etc. or their alloys. The pore sizes are in the range of millimeters and relative densities down to 10% of the original material can be achieved. Since metallic foams combine relative low weight with high stiffness, their applications are mainly for means of light weight structures as used for example in cars. Also other applications like sandwich structures and metallic filters are of interest.     

Optimization of the Performance of Porous Low-Carbon Steels by Means of an Evolution Strategy

Possibilities for manufacturing cellular metallic materials are reviewed. However, this study primarily concerns the role of a cell-wall structure in influencing the mechanical behavior of metallic foams. A porous low-carbon steel with a controlled porous structure is processed from spark plasma sintering of ferromagnetic metal segments with a special, elongated shape. The ferromagnetic metal segments are filled into a die-block and their orientation is settled by a static magnetic field. The cell-wall structures of the porous low-carbon steel can be modified in order to improve its performance because differences in the cell-wall structure substantially affect the mechanisms of deformation and failure under different types of loading. The optimal shape of the structure following the required macroscopic mechanical response is established by means of the search scheme of an evolution strategy.