空心玻璃微球低温绝热性能研究进展

空心玻璃微球作为一种新型高性能粉末材料,特殊的球形空心结构使其在低温绝热领域有很好的应用前景。文章综述了空心玻璃微球与珠光砂、气凝胶等粉末绝热材料和真空多层材料以及单纯高真空的低温绝热性能对比研究,并进一步综述了空心玻璃微球本身性能变化和金属包覆对其低温绝热性能的影响研究。另外,还介绍了微球绝热系统在1 000 L、22 700 L和218 000 L储罐中的实际应用情况。     

Co-Fe还原机理及其晶体结构对吸波性能影响的研究

采用化学镀工艺,在空心陶瓷微球表面复合钴-铁合金.首先,利用场发射扫描电子显微镜(FE-SEM)、X射线能谱仪( EDS)分别对化学镀前后的空心陶瓷微球进行表征;其次,利用X射线衍射仪(XRD)表征镀钴-铁空心陶瓷微球的结晶状态;最后,用网络矢量分析仪和振动样品磁强计(VSM)分别测试镀钻-铁空心陶瓷微球的电磁损耗和磁性能,并通过计算分析微球的微波吸收性能.结果表明:经过化学镀,空心陶瓷微球表面沉积了均匀、致密的钴-铁合金.镀钴-铁空心微球(2.5g/cm3)在2～18GHz的频率范围内有良好的吸波性能,并且强于单种金属镀层的空心陶瓷微球,具有宽频的吸收特性.另外,热处理还能改善镀层钴-铁合金的软磁性能.     

中空纳米微球制备及应用的研究进展

近年来，中空纳米微球的制备极大地吸引了国内外学者的目光。空心微球具有比表面大、质轻、高的流动性、高的堆积密度、不易团聚、可包容客体分子，填充到复合材料中不易引起应力集中等多种优异特性，在生产和生活中受到越来越多的重视。就目前国内外微球制备的研究状况，综述了近年来空心微球的制备原理、方法及应用，并对其制备技术的发展作了介绍。     

水热法制备空心微球的研究进展

空心微球是一种兼具一般空心球和超细功能材料优势的新型结构,在生物医学、化工、功能材料等领域具有应用前景。介绍了模板辅助水热法、无模板水热法制备空心微球技术的原理和特点,并概括了其涉及的反应机理,最后提出了水热法合成空心微球存在的问题并预测了其发展趋势。     

电火花-超声复合技术制备镍微米空心球的研究

采用电火花-超声复合技术,以电火花放电过程裂解及超声空化效应所产生的气泡为模板制备微米金属空心镍球,通过扫描电子显微镜、真密度比重仪、振实密度仪、豪斯纳比等对镍微粒在气泡球面的生长过程、镍空心球的成型机理和不同镍空心球的成型原因进行分析和研究,阐述了基于液相基底表面金属薄膜理论的空心球成型过程,并且着重研究超声对颗粒的空心率、微球形貌及微球流动性的影响。结果表明超声的加入使镍空心球的空心率提高10%~20%,改善了颗粒的流动性。     

低密度碳空心微球的制备及酚醛树脂空心微球复合材料的性能

以BJO-0930酚醛树脂空心微球为原料,通过酸洗、预氧化、碳化三步工艺,成功制备球形度好、强度高的碳空心微球,并与热固性酚醛树脂复合,热压成型得到轻质酚醛树脂/空心微球复合材料。系统考察了碳化温度、循环酸洗、预氧化等对碳空心微球强度的影响。复合材料的力学性能和隔热性能分别通过压缩性能以及热导率测试进行表征。结果表明:直接碳化得到的碳空心微球破球率高、强度低;通过循环酸洗可以有效去除树脂球的灰分,破球率由28.07%降低至18.03%;进一步预氧化处理可以显著提高碳空心微球的强度,其破球率和等静压破球率分别为10.03%和17.34%;制备得到的酚醛树脂/碳空心微球复合材料具有优异的隔热性能和力学性能,热导率降低至0.115 W·m~(-1)·K~(-1),压缩强度为46.02MPa。     

铁氧化物纳米晶自组装空心微球的制备、表征及其应用

铁氧化物纳米材料和纳米结构空心微球分别代表了材料研究中组分和结构的研究热点. 而由铁氧化物纳米晶自组装形成的空心微球的研究则是二者相结合, 具有重要的科学意义和良好的应用前景. 虽然已发展了多种方法制备各种单质及化合物的空心微球, 但铁氧化物纳米晶自组装空心微球的制备方法报道较少. 本文简要介绍了近几年发展起来的多种铁氧化物纳米晶自组装空心微球的一些制备方法, 利用上述方法, 制备出了多种不同组成单元、不同尺寸、不同空心程度的铁氧化物纳米晶自组装空心微球, 对所制备的铁氧化物纳米晶自组装空心微球进行了表征, 并初步介绍了所制备的铁氧化物纳米晶自组装空心微球在药物缓释和环境领域中的应用.     

空心玻璃微球表面功能化及其应用研究进展

空心玻璃微球是一种新型无机非金属材料,具有质轻、高强、隔热、耐腐蚀、流动性好等特性,具有广阔的应用前景.对空心玻璃微球进行表面功能化可进一步扩展其应用领域.综述了空心玻璃微球表面包覆、表面接枝、表面镀膜、表面沸石化等改性方法,并就其在隐身、环境等领域的应用进行了探讨.     

空心玻璃微球制备的研究进展

由于空心玻璃微球（HGM）具有呈完全球形的空心体、密度小、热导率小以及极好的流动性等特点，从而使得以空心玻璃微球为核心的一系列新型材料得到广泛运用。结合国内外研究情况概述了液滴法、干凝胶法、降解芯轴技术和喷雾干燥法等HGM的制备方法以及HGM粒度、壁厚、耐压强度等的测试方法。     

具有开口结构SnO2空心微球的水热合成及表征

以锡酸钠和尿素为原料,采用水热法制备出具有开口结构的SnO2空心微球。主要考察了尿素浓度和水热时间对空心微球形貌 的影响;利 用XRD、SEM、TEM等分析手段对空心结构进行了表征,并对空心微球的形成机制进行了讨论。结果表明,SnO2空心微球直径约为2μm,球壳由SnO2纳米片或纳米晶粒堆积而成,壁厚约250nm。尿素不仅有助于纳米粒子自组装成微球,其分解产生的气泡还可以作为软模板形成空心结构;同时因气泡逸出形成的特殊开口结构可以为引入功能性粒子提供快速通道,具有很好的应用前景。     

复合中空球的研究进展

在简要介绍单一中空球的基础上,对复合中空球的分类、制备方法、性能特点等进行了详细的阐述,并分析归纳了复合中空球较单一中空球在抗压强度、光学、磁学、催化等性能方面的优势.最后,提出了复合中空球的应用前景和发展方向.     

Production of hollow spheres (HS) and hollow sphere structures (HSS)

In our paper we focus on component materials, production and prospective applications of metallic hollow spheres. We give an insight into technology, production, and the hollow spheres' diversity. It is our aim to provide an overview of the technology and enable the reader to evaluate whether the hollow spheres technology meets their specific needs.     

Novel Metallic Hollow Sphere Structures

The obvious advantages of metallic hollow sphere materials have lead to several attempts to produce such structures. None of these approaches has gained practical significance owing to the very high cost of the methods. A new powder metallurgical process using styrofoam spheres allows for the production of hollow spheres from arbitrary metals and alloys. The IFAM Department of Powder Metallurgy and Composite Materials, Dresden, has developed this process and added a method that produces random hollow sphere structures (RHS) directly from the green spheres.     

HA/Fe~(3+)层层自组装后碳化的副产物-碳纳米空心球研究

将腐植酸和Fe3+在氧化铝纤维上进行层层自组装,自组装40双层以后,在N2气氛下于1000℃下碳化,碳化后在装纤维的坩埚上沉积了一层黑色具金属光泽的物质,应用FESEM、EDX、Ra-man、XRD对这一物质进行了分析。结果表明,这层黑色物质是尺寸在几十到几百纳米的空心球,这些纳米空心球主要由C构成,还含有少量Fe、O,Fe元素以FeO和FeC3的形式存在,碳空心球的石墨化和有序程度较低,且与相同条件下纤维上所得碳材料的拉曼光谱存在较明显区别。     

Numerical investigations on the mechanical properties of metallic hollow spheres structure with perforations under compression

This paper numerically investigates the compressive mechanical properties of the perforated hollow spheres structures with different geometrical and physical properties. In these structures, the metallic hollow spheres are perforated regularly with several holes, which open the inner sphere volume and surface and are bonded in simple cubic, body-centered cubic and face-centred cubic patterns. The 5×5 cells finite element models under uniaxial compression are established by ABAQUS 6.14 software for simulation. The influence of the spheres’ spatial pattern, as well as base materials for the spheres and bonding necks on the structural mechanical properties are evaluated. By changing the wall thickness, hole diameter and bonding radius in the body-centered cubic packing finite element model, the elastic modulus, Poisson's ratio and initial yield stress are calculated and discussed as functions of these geometrical parameters and their average densities.     

TiO2空心球制备及在染料敏化太阳能电池和锂离子电池中应用的研究进展

空心球结构的半导体氧化物具有密度低、比表面积大、机械和热稳定性好等优点。空心球结构对TiO_2纳米材料的电化学性能有着显著的优化作用,TiO_2空心球作为一种重要的半导体氧化物具有良好的物理和化学性质,在多种领域均表现出潜在的应用价值,制备大小和壳层数均可控的半导体TiO_2空心球已引起了研究者的广泛关注。主要综述了在硬模板、软模板和无模板条件下TiO_2空心球的制备方法;同时还介绍了其在染料敏化太阳能电池和锂离子电池方面的最新研究进展;最后,对TiO_2空心球的可控合成前景进行了展望。     

中空氧化锌微球的制备及应用研究进展

中空ZnO微球具有密度低、比表面积大、渗透性好、光电性能优异等特点,受到科研工作者的广泛关注。综述了中空ZnO微球的制备方法及其应用领域,首先,主要阐述了硬模板法、软模板法、自模板法和无模板法4大类制备方法的研究进展,其次,介绍了中空ZnO微球在光催化、太阳能电池、气体传感器及生物医药等领域的应用进展,最后,对中空ZnO结构材料的发展前景进行了展望。     

Finite element modelling of the mechanism of deformation and failure in metallic thin-walled hollow spheres under dynamic compression

Recent interest in lightweight metallic hollow sphere foams for aerospace applications requires a better physical understanding of dynamic properties of single spheres. Finite element modelling supported by high rate experiments was developed to investigate the underlying deformation and failure mechanisms of electrodeposited nickel thin-walled hollow spheres. Parametric simulation was performed to further explore the effect of sphere geometry (wall thickness to diameter ratio) and loading rate. It was found that decreasing the ratio of wall thickness to diameter tends to transit the side wall failure mode from bending to buckling. For a thin-walled sphere (the thickness to diameter ratio less than a critical value), the macroscopic dynamic behaviour is primarily dominated by the two deformation and failure mechanisms: (1) buckling failures of wall materials and (2) self-contacts of wall surfaces and wall-anvil contacts. At higher impact velocity (greater than a critical velocity), inertia effect due to dynamic localisation of wall crushing arises and significantly influences the deformation/failure mode of the sphere, resulting in an increased initial crushing strength and asymmetric deformation. Finally, the behaviour of hollow spheres was correlated to explore the power law behaviour of bulk foams with respect to the relative density; it was found that metallic thin-walled hollow sphere foams can be better approximated as open-cell rather than closed-cell foams.     

冲击作用下薄壁金属空心球压缩变形研究

金属空心球结构是一种新型的多孔金属材料,对单个金属空心球在冲击作用下的压缩力学性能研究是对整体结构压缩力学性能研究的基础。该文研究了单个球壳冲击压缩特性,得到了单个金属空心球在冲击作用下的名义应力-应变曲线并与实验结果进行了对比验证,同时研究了径厚比和冲击速度对变形过程的影响。结果表明:名义应力-应变曲线和变形模态图显示其变形失效过程可分成六个阶段:局部压平、轴对称凹陷、多边形形成、内表面相互作用、侧壁失效以及密实阶段;径厚比越大,金属空心球越容易形成非对称的多边形形式,且在内表面相互作用阶段,上部壳体发生逆向翻转,侧壁发生了屈曲失效;径厚比较小时,在内表面相互作用阶段,下部壳体发生逆向翻转,侧壁发生了弯曲失效;冲击速度越大,底端壳开始发生凹陷的时间越早,空心球产生的不对称度越大。     

Fabrication of photonic crystal heterostructures by a simple vertical deposition technique

This paper describes a facile method for the fabrication of photonic crystal heterostructures (PCHSs) composed of photonic crystals (PCs) of core–shell spheres with different diameters and effective refractive indexes. The PCs are fabricated by a simple vertical deposition technique. The PCs of monodisperse polystyrene/silica core–shell (PS@SiO₂) spheres or hollow silica spheres are used as substrates to fabricate PCHSs, respectively. The results indicate that the resultant PCHSs formed from PS@SiO₂ spheres or hollow silica spheres have a very high quality and a good adsorbing interface between the PCs. Transmission spectra show that there are two optical stop bands of the PCHSs, and the positions of optical stop bands are controlled by tuning the size and the effective refractive index of spheres. The PCHSs formed from hollow silica spheres may facilitate the development of the potential applications due to the novel properties of hollow silica spheres, such as, low density, low refractive index, and high specific surface area.