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布儒斯特角显微镜及其在气液界面膜研究中的应用 总被引:2,自引:0,他引:2
布儒斯特角显微镜出现于1991年,是一种新型的能在原位测定气/液界面单分子膜形态与缺陷的仪器,本文介绍了法国、德国和本实验室安装的布儒斯特角显微镜的结构。利用布儒斯特角显微镜可以研究气-液界面上单分子膜的均匀性与缺陷,多组份混合膜中的相分离,膜中畴的取向、尺寸与形貌,来自亚相的吸附过程、松弛与压缩过程的动力学、光化学和光物理过程等。 相似文献
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建筑垃圾的高效、高值再生利用是目前工程上面临的严峻挑战。为进一步提高建筑垃圾红砖高值、高效再生利用率,在分析建筑垃圾红砖粉(以下简称砖粉)掺量、细度与砖粉-硅灰复掺对砂浆强度影响规律的基础上,基于灰熵分析方法评价砖粉颗粒分布特征对砂浆强度影响的显著性。结果表明,砖粉替代部分水泥后降低了砂浆早期强度,当替代量≤10%时,早期强度降低幅度不大,28 d强度有所提升;砖粉的颗粒参数及分布对砂浆强度有一定的影响,其中比表面积与<10μm粉体颗粒含量是影响砂浆强度的显著因素。为了进一步提高砖粉活性,进而提高其高值利用率,应尽量增加<40μm尤其是<10μm的颗粒含量,减少>60μm的颗粒含量。 相似文献
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本文采用美国产 MTS试验机 ,分别研究了掺聚醋酸乙烯水泥砂浆的轴拉和轴压应力 -应变关系及抗弯性能。试验结果表明 ,随着聚醋酸乙烯的掺入 ,砂浆的轴压强度和弹性模量显著下降 ,但极限应变却明显增大 ;砂浆的轴拉强度和抗弯强度均略有提高 ,而极限应变、拉压强度比和弯压强度比则显著增加。因此 ,掺入聚醋酸乙烯能有效改善砂浆的变形力学性能。根据 12年龄期的粘结抗弯强度试验结果 ,聚醋酸乙烯砂浆不但具有优良的粘结性能 ,还具有良好的耐久性 ,可广泛用于新老混凝土的粘结、修补及结构加固中的钢板粘贴和表面粉刷等。 相似文献
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孔结构是影响砂浆或混凝土性能的重要参数。通过压汞法研究了橡胶颗粒对砂浆孔隙率及孔径分布的影响规律,分析了橡胶颗粒对砂浆孔结构的影响机理。结果表明,随橡胶颗粒含量增加,橡胶砂浆最可几孔径增加,总孔隙率增加,其中大孔(D>1000nm)含量增加最为明显,而凝胶孔(D<10nm)含量变化不大。橡胶表面与水的接触角为99.5°,说明其具有憎水性,同时由于橡胶颗粒表面存在着大量凹坑,水在毛细管作用下无法充满橡胶颗粒表面凹坑,导致橡胶颗粒与水泥基体界面处存在大量孔径较大的孔隙。 相似文献
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微波照射回收废弃混凝土中的粗骨料是一种高效、节能、环保的混凝土再资源化技术。粗骨料表面附着砂浆耗散的微波能量对于回收粗骨料的质量有显著影响。本实验选取了两种常见的粗骨料,花岗岩和玄武岩,制成表面包裹均匀厚度砂浆的试样进行微波加热试验,研究了不同的砂浆厚度和含水率下试样表面的温度变化,并对微波照射后砂浆失水特性、裂纹扩展及破坏特征进行了分析。微波加热结束后剔除粗骨料表面剩余的附着砂浆,选取形状完整未发生熔融的粗骨料进行单轴抗压强度测试,研究包裹砂浆对微波照射粗骨料强度折减的影响。结果表明:微波照射后花岗岩和玄武岩骨料的强度随粘结砂浆含水量的增加而增加;微波照射后花岗岩骨料强度随黏附砂浆厚度增加而增加,玄武岩骨料强度随黏附砂浆厚度增加呈下降趋势。与厚度相比,砂浆的含水率对微波加热后粗骨料的强度影响更大。 相似文献
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《工程爆破》2022,(5)
分析乳化炸药内相粒子大小和分布、界面膜、油膜、第三相物质(敏化剂)对其爆炸性能、稳定性、流变性或黏度等宏观性能的影响,建立了微观结构与宏观性能的关联关系,对一些常见现象进行了解释。分析认为,乳化炸药内相粒子的大小与分布,主要取决于机械作用强度和乳化剂的种类和用量两个方面。在相同的配方和工艺条件下,乳化炸药的内相粒子越小,粒径分布越窄,其稳定性和爆炸性能就越好,黏度较大。内相粒子间界面膜和油膜既与内相粒子密切相关,也对乳化炸药的黏度、流动性和稳定性有重要作用。依据热点理论,当气泡或者气泡载体的尺寸在有效范围之内,且分布均匀时,则形成热点的时间接近,有利于爆炸反应的快速激发和传递,宏观上表现为乳化炸药爆轰感度、爆速和猛度等较大。 相似文献
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分析乳化炸药内相粒子大小和分布、界面膜、油膜、第三相物质(敏化剂)对其爆炸性能、稳定性、流变性或黏度等宏观性能的影响,建立了微观结构与宏观性能的关联关系,对一些常见现象进行了解释。分析认为,乳化炸药内相粒子的大小与分布,主要取决于机械作用强度和乳化剂的种类和用量两个方面。在相同的配方和工艺条件下,乳化炸药的内相粒子越小,粒径分布越窄,其稳定性和爆炸性能就越好,黏度较大。内相粒子间界面膜和油膜既与内相粒子密切相关,也对乳化炸药的黏度、流动性和稳定性有重要作用。依据热点理论,当气泡或者气泡载体的尺寸在有效范围之内,且分布均匀时,则形成热点的时间接近,有利于爆炸反应的快速激发和传递,宏观上表现为乳化炸药爆轰感度、爆速和猛度等较大。 相似文献
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通过比对试验,分析采用JG158-2004《胶粉聚苯颗粒外墙外保温系统》和DB33/T1054-2008《无机轻集料保温砂浆及系统技术规程》中界面砂浆黏结强度性能试验方法的差异,JG158-2004中的方法不能客观反映界面砂浆黏结强度的主要原因,并指出浙江地方标准DB33/T1054-2008的试验方法能较真实反映界面砂浆的黏结强度。 相似文献
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This is a research report about the effects of polypropylene fiber and wood fiber on mechanical properties of cement mortar. First, using advanced Hopkinson pressure bar (HPB) tests, it investigates the wave propagation in cement mortar comprised polypropylene fiber and wood fiber. Second, according to the experiment, the spallation position is recorded by high-speed camera. Thirdly, it analyzes the test data of ultra-fiber reinforced and common cement mortar by numerical method. Finally, it deduces the spalling strength of all kinds of cement mortar by integrating all experimental data above. The results indicate that, compared with the strength of common cement mortar, the dynamic spalling strength of ultra-fiber especially that of the polypropylene fiber reinforced cement mortar increases evidently. However, adding too much fibers will deteriorate the dynamic spalling strength of cement mortar specimen. So the results will provide a test basis for further optimizing performance of cement mortar. 相似文献
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There is a compelling economic incentive to develop concrete materials that can repair its own damage, increase durability and prevent structural failure. This research investigated the potential of adding two different mineral producing bacteria into two types of cementitious mortar matrix to enhance self-healing ability for autonomous crack repair. In this study, zeolite was used as a carrier material to protect bacteria in high pH environment normally exists in concrete. The spore forming ability and ureolytic activity of zeolite-immobilized bacteria were investigated in order to examine potential for producing healing compounds. The self-healing ability of bacteria incorporated normal and fiber reinforced mortars was judged based on the development of compressive strength and permeation properties of cracked specimens with age as well as micro-structural characterization of crack healing compounds using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction. 相似文献
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为了进一步揭示低温硫酸盐侵蚀条件下水泥砂浆抗折强度的发展规律,本文以不同配合比砂浆试件为研究对象,进行了20℃、10℃、5℃条件下的硫酸盐侵蚀试验,并对不同龄期的抗折强度进行了测试。试验结果表明:侵蚀过程中砂浆试件抗折强度呈现出先上升后下降的变化趋势,且明显受到温度影响,温度越低,侵蚀情况越严重,主要表现为整体强度下降,上升段可达到的最大值减小,劣化开始的时间提前。为考虑温度的影响,在Irassar模型的基础上,引入温度修正系数,提出了低温硫酸盐侵蚀过程中抗折强度的预测模型。模型的计算值与实测值吻合度更高,最大误差为9%,平均误差为2.3%,故该模型可较为准确的预测水泥砂浆在5~20℃硫酸盐腐蚀环境下抗折强度的发展规律。 相似文献
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采用双铜带压接法制备铜包钢线,研究了铜包钢线的退火热处理工艺,探讨了退火温度和时间对铜-钢复合界面扩散和结合强度的影响。结果表明,随着铜包钢线退火温度的升高和时间的延长,扩散层厚度增加,界面结合强度提高。与保温时间相比,退火温度对其影响较大。退火温度为750℃,保温2h后界面结合效果最佳,继续升高温度和延长时间,界面扩散层厚度和结合强度几乎不变。利用扩散方程计算Fe和Cu原子的扩散激活能和扩散常数,确定了扩散常数与退火温度的关系。综合考虑铜包钢线扩散层厚度与结合强度的关系及生产实际要求,得到铜包钢线的最佳退火工艺为750℃保温2h。 相似文献
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The use of waste glass incorporated into construction materials has been the focus of several studies. Its utilization in cementitious matrices as a cement surrogate has been the most suitable application because of its potential pozzolanic properties. In this study, the influence of varying the amount of cement replaced by waste glass on several mechanical properties considered essential to ensuring the performance of mortars in structural repair, such as compressive strength, modulus of elasticity, linear shrinkage and tensile bond strength, was analyzed. Additionally, the influence of waste glass on water absorption by capillarity and the microstructure of these mortars were also assessed. The results indicate the potential use of this waste material for cement mortars. The 5% replacement rate showed the best results. 相似文献
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Xiangyu Li Chenyang Li Yanming Liu Shu Jian Chen C. M. Wang Jay G. Sanjayan 《先进材料力学与结构力学》2018,25(15-16):1313-1322
ABSTRACTAs a two-dimensional nanomaterial, graphene oxide has attracted much attention for its use in reinforcing cementitious materials. However, the dispersion of graphene oxide in cementitious materials has been found unsatisfactory due to crosslinking of divalent calcium ions. In this study, we propose a modified mixing procedure to improve graphene oxide dispersion in cement mortar by utilizing silica sand to mechanically separate graphene oxide nanosheets. Apart from the improved graphene oxide dispersion, adhesion between sand and cement matrix is also believed to be enhanced due to the improved roughness of the sand surface. According to our mechanical properties study, with the introduction of 0.02% by weight graphene oxide in cement mortar, compressive strength was significantly improved by more than 25% and tensile splitting and flexural strength were improved by around 15%. In a microstructural investigation, the interfacial transition zone in cement mortar was found to be denser due to the addition of graphene oxide. Moreover, graphene oxide incorporated cement mortar also showed pore structure refinement and porosity reduction. Therefore, improvement in mechanical properties may result from an improved interfacial transition zone and a more refined pore structure with the introduction of a small quantity of well-dispersed graphene oxide nanosheets. 相似文献
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采用扩散焊技术对Fe3Al金属间化合物与Q235碳钢进行焊接,研究了Fe3Al/Q235扩散焊界面的剪切强度,并利用扫描电镜分析了界面断裂特征.结果表明,Fe3Al/Q235扩散焊界面断裂位置靠近Fe3Al一侧,剪切断口为解理断裂,伴随少量的韧性断裂特征,微裂纹多数沿靠近Fe3Al一侧的界面交界线扩展,有时偏向界面中心;控制加热温度1060℃,保温45~60min,压力12~15 MPa时,可以获得界面结合紧密、剪切强度112.3 MPa的Fe3Al/Q235接头. 相似文献