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利用硅烷偶联剂、醇、油酸钠及自制高分子表面活性剂对锑掺杂二氧化锡纳米粉体(ATO)进行表面处理,研究了不同改性剂对粉体分散性的影响.以改性纳米ATO分散浆料和水性聚氨酯为原料,采用共混法制备了纳米复合涂料,并对其隔热性及基本性能进行测试.TEM及离心实验表明,ATO粉体经自制高分子表面活性剂或硅烷偶联剂改性后,分散性明显提高.性能测试表明:ATO粉体的加入能显著提高涂膜硬度及隔热性. 相似文献
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聚乙二醇在MgAl_2O_4前驱体表面的吸附及改性作用 总被引:6,自引:0,他引:6
借助IR光谱、SEM及粒度分析、Zeta电位等测试手段,研究了非离子型表面活性剂聚乙二醇(PEG)大分子对MgAl2O4前驱体表面上的吸附状态和表面性能的影响。结果表明,在沉淀过程中引入PEG1000,并用含有少量PEG1000的溶液洗涤前驱体,可以改变前驱体表面特性,增强空间位阻效应,避免干燥和焙烧过程中形成硬团聚体以及改善粉体的分散性。 相似文献
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采用悬浮液体系吸光度法,研究不同结构表面活性剂对纳米CeO2粉体在水中分散性影响。考察了影响分散稳定性的物理分散方式、表面活性剂的结构和浓度等因素。结果表明,超声波分散效率远优于机械搅拌。表面活性剂作为纳米CeO2在水介质中的分散剂,其分散性与表面活性剂结构有重要关系。非离子型表面活性剂效果优于离子型表面活性剂。非离子型表面活性剂以亲油基团朝向CeO2粒子,且亲油基团链长较长的效果更好;而离子型表面活性剂以亲水基团朝向CeO2粒子,亲水基团小的表面活性剂效果好,亲油基团的链长度影响不太明显。 相似文献
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以SnCl4·5H2O和SbCl3为原料,采用水热法制备出了纳米级锑掺杂二氧化锡(ATO)导电微粉,运用XRD和TEM等测试手段对粉体进行了表征,比较系统地研究了掺杂量,共沉淀温度,溶液pH值,水热时间、温度和表面活性剂对粉体粒度、形貌和电性能的影响规律.研究表明,合成的ATO粉体分散性较好、导电性能优异,粒径在10nm左右,具有金红石型结构.在ATO纳米导电粉的制备过程中,前驱体制备温度对其性能有很大影响,当共沉淀温度在40-50℃时制得的粉体导电性能最佳.水热条件对粉体的形貌、粒度和导电性也有较大的影响,在200℃,4h,pH=2~4条件下可以制得导电性能良好的ATO粉体,所添加的表面活性剂可以改善粉体的粒径和分散性能,但对粉体的导电性影响极小.掺入Sb3 的量对载流子的迁移率有很大的影响,在掺杂浓度为4~5%左右可制得导电性极佳的纳米ATO粉体. 相似文献
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为了提高热还原法制备的还原氧化石墨烯(RGO)在水溶液中的分散性,采用超声波处理结合非离子表面活性剂分散的方法,选择聚乙烯吡咯烷酮(PVP)、吐温80(TW-80)和聚乙烯醇(PVA)三种非离子表面活性剂,研究RGO的分散性能。通过静置法分析了不同非离子表面活性剂对RGO水溶液的分散稳定性,结果表明添加非离子表面活性剂能有效提高RGO的分散性,其中1.5%PVP K30和3%TW-80处理后的RGO分散稳定性最好。通过拉曼光谱、X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等对分散后的RGO进行了表征,结果表明,分散后RGO的层间距增大,PVP K30-RGO的表面褶皱较少,较为光滑,且层间距最大,为0.42nm。 相似文献
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A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling. 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue. 相似文献
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An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a
rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate
agreement is demonstrated between the derived relations and experimental data. 相似文献
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Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995. 相似文献
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由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。 相似文献
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M. M. Gadenin 《Inorganic Materials》2013,49(15):1352-1356
It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle. 相似文献
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V. T. Kornienko 《Strength of Materials》1991,23(7):760-765
The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991. 相似文献
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水三相点是开尔文热力学温度的唯一基准点,也是ITS-90国际温标重要的定义固定点。因此,水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来,中国计量科学研究院研制出一系列高质量的水三相点容器,加强了水三相点的研究,为不确定度的分析提供了更为可靠的实验依据。同时,不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此,根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明,其扩展不确定度为0.16mK(k=2.69,P=0.99)。 相似文献