超细硅微粉在塑料、橡胶及涂料中的应用

简述了硅微粉在塑料、橡胶、涂料中的应用 ,介绍了硅微粉超细粉碎、提纯、改性方面的研究状况     

中国硅微粉的应用及市场现状

本文主要介绍当前硅微粉行业市场现状以及主要应用领域,并对不同规格硅微粉市场做了简述。     

球形硅微粉粒径复配模型的构建与应用

为了获得兼具无机粉体填充量大与流动性好的有机-无机复合材料体系,基于Dinger-Funk经典颗粒堆积理论,利用MATLAB优化工具箱构建复配比例计算模型,得到满足最密堆积的无机填料体积配比;将不同粒径分布的球形硅微粉按照一定的构成比例复配后填充于环氧树脂中,结合热压-流胶、振实密度、流变性能测试,考察不同体系粉体的填充紧密度及胶体流动情况。结果表明,经模型计算得到的复配体系具有最小的熔融剪切黏度、最大的流动直径及较大的振实密度,验证了构建的比例计算模型的准确性。     

复合硅微粉及其超疏水表面的制备与表征

以球形硅微粉为主要原料,在Ca(OH)2-H2O体系中通过表面包覆使其具有微纳米阶层结构,经疏水改性处理后用来制备超疏水表面.应用扫描电子显微镜等手段对样品进行了表征,并进行对比分析,探讨了酸洗浓度、包覆温度、加热时间对复合硅微粉表面性能的影响.     

三元共聚聚酰亚胺结构胶的合成及性能研究

以2,2-双[4-(4-氨基苯氧基)苯基]丙烷(BAPP)和4,4′-二氨基二苯甲烷(MDA)作为二胺单体,3,3′,4,4′-二苯酮四酸二酐(BTDA)作为二酐单体,N-甲基砒咯烷酮(NMP)为溶剂,通过常规的两步法经热亚胺化合成了三元共聚型聚酰亚胺结构胶。采用傅里叶变换红外光谱表征了聚合物的结构;热重-差热分析(TG-DTA)表明,所合成的聚酰亚胺具有良好的热稳定性,在N2气氛中起始降解温度接近500℃,800℃质量保持率大于50%。单搭接拉伸剪切测试结果表明,所得聚酰亚胺结构胶对不锈钢片的室温粘接强度(LSS)高达14.13MPa,350℃下的拉伸剪切强度达1.91MPa。     

智能材料及其在建筑技术中的应用

<正>近些年,能在传感、处理和响应功能上模仿生命系统的智能材料引起了人们的广泛关注,与机敏材料相比较,智能材料更近于生命体系。智能材料能按照环境条件的转变,从而实现最佳适应效果。在建筑领域中,可以通过应用智能材料增强工程结构体系的安全、减轻构件质量,并降低了能量的消耗,提高系统的整体性能。图1为智能材料与普通材料的对比。一、智能材料概述智能材料的设计构思来源于模仿生物体的特征,目的是创造出类似     

浅谈低碳建筑在建筑中的应用

根据目前实际情况，主要分析了环境问题的重要性，论述了绿色建筑即低碳建筑在建筑行业的发展趋势，及其在我国的进一步发展进行了有益的探讨。     

太阳能在建筑技术中的应用

随着经济社会的发展，资源的消耗量不断增大，资源短缺成为制约经济发展的重要因素。太阳能是一种清洁能源，将太阳能技术应用于建筑设计，可以产生巨大的经济效益、生态效益和社会效益，可以在一定程度上解决我国的能源短缺问题。目前，我国大力建设资源节约型社会，提倡绿色环保，这就为太阳能技术在建筑行业的应用提供了便利，本文介绍了太阳能应用于建筑的优势以及太阳能技术在建筑中的应用，并经过分析，分析了太阳能技术应用于建筑的发展趋势。     

计算机辅助设计在建筑中的应用

随着计算机的不断发展与普及,计算机应用变得越来越广泛,同时计算机辅助设计技术也在不断发展和变化。以计算机辅助设计与建筑设计的结合为研究对象,对计算机辅助建筑设计进行分析研究。希望可以为相关领域的研究起到抛砖引玉的作用。     

Crack growth in structural adhesive joints in aqueous environments

The adhesive fracture energy, G _c , of metallic joints, bonded with a rubber-toughened epoxy adhesive, has been measured using monotonically-loaded tests. Such tests have been conducted in various relative humidities and in water, at 21 °C. Two surface pretreatments have been employed for the substrates prior to bonding: a simple grit-blast and degrease (‘GBD’) pretreatment or a grit-blast, degrease and silane primer (‘GBS’) pretreatment. The joints were formed using metallic substrates which were either (a) aluminium-alloy substrates, (b) steel substrates, or (c) ‘dissimilar’ substrates (i.e. one substrate being aluminium-alloy with the other one being steel). For both test environments, when G _c was plotted against the crack velocity, three regions of fracture behaviour could be distinguished. At low rates of displacement the crack grew in a stable manner, visually along the interface, and relatively low crack velocities could be readily measured. This was termed ‘Region I’ and here the value of G _c measured in the aqueous environment was relatively low compared to that measured in a relatively dry environment of 55% relative humidity. On the other hand, at relatively high rates of displacement the crack always grew in a stick-slip manner mainly cohesively in the adhesive layer at approximately 20 km/min. This was termed ‘Region III’, and here the value of G _c was relatively high and independent of the environmental test conditions employed. In this region the crack was considered to grow faster than the water molecules were able to reach the crack tip, which explains the independence of G _c upon the test environment. In between ‘Region I’ and ‘Region III’, a transition region was observed which was designated as ‘Region II’. The major effect of the ‘GBS’ pretreatment, compared to the ‘GBD’ pretreatment, was to increase the value of G _c both in ‘Regions I and III’, although the presence of the silane primer had the far greater effect in ‘Region I’.     

Approach to structural anisotropy in compacted cohesive powder

We investigate the mesoscopic regime between microscopic particle properties and macroscopic bulk behavior and present a complementary approach of physical experiments and discrete element method simulations to explore the development of the microstructure of cohesive powders during compaction. On the experimental side, a precise micro shear tester \((\mu \hbox {ST})\) for very small powder samples has been developed and integrated into a high resolution X-ray microtomography (XMT) system. The combination of \(\mu \hbox {ST}\) and XMT provides the unique possibility to access the 3D microstructure and the particle network inside manipulated powder samples experimentally. In simulations we explore the structural changes resulting from compaction: a Hertzian contact model is utilized for compaction of an isotropic initial configuration created by a geometrical algorithm. As a first result of this approach we present the analysis of the compaction of slightly cohesive \(\hbox {SiO}_2\) particles with special regard to bulk density, heterogeneity, compaction law and structural anisotropy.     

Epoxy polymer adhesive properties in the presence of fine powder silicas with modified surfaces

The introduction of fine powder silicas with modified surfaces into epoxy polymers was investigated. An increase in adhesive and cohesive properties was obtained. The greatest efficiency (up to 110% relative growth of adhesive strength) can be achieved by the introduction of butosil, a filler with a hydrophobic surface, and by the introduction of titanoaerosils obtained by the combined high-temperature hydrolysis of titanium and silicon chloride vapours. The mechanisms of these observed effects are discussed. The most probable causes are the decreasing inner concentration and increasing cohesive interaction as a result of macromolecular chain packing stimulated by the filler surface.     

离子液体与杉木粉对酚醛胶粘剂性能的影响

制备了离子液体/杉木粉/酚醛树脂的复合胶粘剂,用DSC、FTIR和TGA分别对其固化温度、化学结构及热稳定性进行测试分析,研究了木粉和离子液体对复合胶粘剂性能的影响.结果表明,木粉能有效降低胶粘剂的游离醛含量,离子液体可以大幅度提高胶粘剂的胶合性能.与普通酚醛胶相比,当离子液体与木粉质量比为10:1时,复合胶粘剂游离醛从1.76%降低到0.24%,拉伸剪切强度从2.16 MPa提高到5.39 MPa,且固化后不龟裂,透明度较高.TGA结果表明复合胶的热分解温度提高,但残碳率降低.分析了被离子液体溶解的木粉对游离醛的捕捉作用及离子液体对胶合性能的贡献.     

Considerations for the industrial application of structural adhesive joints in the aluminium–composite material bonding

The composite materials of the polymeric matrix reinforced with carbon fibre have an extensive industrial application as they provide light and resistant structures. However, in many products (automobiles, aircraft, etc.) the structural adhesive parts must be joined to other components manufactured with aluminium alloys. The use of structural adhesive to carry out these bonds may be a good alternative if a specific design of the adhesive joint is carried out maximising its performance and reducing its limitations. In this respect, one of the most relevant aspects of the design of the joint consists of the selection of the structural adhesive and the most appropriate surface treatment for the substratum. The present paper describes a procedure to optimise this decision by means of the combination of experimental techniques with multi-criteria decision tools. This methodology allows selecting, amongst the various alternatives, the adhesive and surface treatment better combining mechanical performance and adaptation to the manufacturing process. Thus, it has been concluded that polyurethane adhesive with a peel ply surface treatment for carbon fibre, and sandpapered for aluminium, are the best alternatives.     

The role of talc particles in a structural adhesive submitted to fatigue loadings

The ability of structural adhesive to withstand combination of cyclic loading and service environment makes them suitable for a wide range of applications. It is nevertheless true that their mechanical and micromechanical behaviour is still little understood. The purpose of the work reported here is to study the fracture process and the role of talc fillers of an epoxy adhesive subjected to oligocyclic fatigue. Tests were conducted by using a set-up based on the Arcan fixture and experimental results have been reported for both tensile and shear cyclic loadings. The cohesive failure of the adhesive seems to set off at a specific amplitude level, whatever the loading value. By an incursion at the microstructural scale using scanning electron microscopy, we suggest an explanation of these phenomena. The foliated form of talc fillers are of major importance and seem to provide a deterministic evolution of damage.     

Short- and long-term structural properties of pultruded beam assemblies fabricated using adhesive bonding

Two beam assemblies fabricated using simple pultruded sections and adhesive bonding have been tested to determine their structural properties. The test configuration was three-point bending to simulate the most severe loading in a proposed application. Short-term stiffnesses are compared with those predicted using known section properties and linear elastic beam theory. Accelerated creep test data are used to determine long-term behaviour using Findley's linear viscoelastic theory. For the purpose of structural design, Findley's model is used to estimate the increase in maximum deflection due to a constant design loading of 1 week, 1 year and 10 years.     

Effect of Ag addition on the structural and electrical properties of ITO powder compact

Nanocrystalline ITO-Ag powders were prepared using a coprecipitation method. Surface modified silver nanoparticles were mixed with the indium tin hydroxide precursor before the sintering process. The ITO-Ag nanocomposite powder was formed into pellets by uniaxial pressing process. The effect of addition of silver to the electrical and structural properties of ITO powder compact was studied. The relative density of the metal filled composite ITO-Ag powder compact is higher than the pure ITO powder compact. The result may be attributed to the melted silver eventually fills the void space between agglomerate pores and hence enhances the interconnection between nanocrystalline ITO powders. The crystal phase and particle size of ITO powder and ITO-Ag powder were measured by powder X-ray diffraction and the surface morphology of powder compact was investigated using a scanning electron microscope.