液相沉淀法制备镁铝水滑石及其表征

采用液相沉淀法以AlCl3·6H2O，MgCl2·6H2O，Na2CO3，NaOH为原料，制备镁铝水滑石。研究结果表明水浴70、80、90℃加热时均能制备出纯净的镁铝水滑石，从热重分析可知镁铝水滑石有两个失重阶段，第一次热分解起始点约为173℃失重约15％，释放出镁铝水滑石中间层的4个结晶水，第二次热分解起始点约为352℃失重约30％，中间层中的碳酸根离子以二氧化碳的形式放出，同时羟基分解产生水。镁铝水滑石晶粒呈不规则的六边形，晶粒大小约在为30～70nm之间。     

纳米镁铝水滑石的制备及其对聚氨酯阻燃性能的影响

采用液相沉淀法制备纳米镁铝水滑石微粉,利用XRD、TEM和TG对试样进行表征,研究了反应温度、干燥时间以及碳酸根浓度对镁铝水滑石纳米晶的影响.镁铝水滑石微粉经硅烷偶联剂KH550表面改性后填充到聚醚多元醇组合料中,采用原位聚合法制备出镁铝水滑石/软质聚氨酯纳米复合材料,研究了纳米镁铝水滑石对聚氨酯的阻燃效果及阻燃机理,并与Al(OH)_3阻燃效果进行对比.实验结果表明,晶粒尺寸随反应温度的升高而增大;干燥5h镁铝水滑石的热分解性能较好;适当提高碳酸根浓度可以改善镁铝水滑石晶体规整度;硅烷偶联剂KH550用量为5%时对镁铝水滑石表面改性效果最好;镁铝水滑石阻燃剂填充软质聚氨酯复合体系的阻燃效果要优于Al(OH)_3阻燃剂.     

氧化亚铜微米棒的制备及其机理

借助X射线衍射（XRD）和扫描电镜（SEM）表征，利用CuSO4·5H2O和NaC2H3O2·3H2O为主要原料，D-山梨醇为还原剂，水热还原制备了氧化亚铜微米棒。具体条件是：CuSO4·5H2O和NaC2H3O2·3H2O加入量为摩尔比1：4，D-山梨醇的加入与CuSO4·5H2O等摩尔量，水热180℃下反应12h。微米棒的直径小于1μm，长度在10μm以上，棒表面有晶体生长印迹。其机理是：C2H3O2-水解生成OH-，OH-与Cu^2＋生成Cu（OH）2，Cu（OH）2再被D-山梨醇还原生成Cu2O。     

卤水-氨法制备纤维状碱式氯化镁

以MgCl2·H2O和NH3·H2O为原料，采用直接沉淀法合成纤维状碱式氯化镁。考察了各种因素对产物理化性能的影响，获得了最佳的工艺条件。利用XRD、SEM及化学分析方法对产品进行了表征。     

叶腊石及其粉末基本性质和工艺性能

叶腊石为晶体结构，属层状硅酸盐矿物，其晶体结构是每一结构单位层由上下二层（Si—O）四面体层中间夹一层（Al—O，OH）八面体层组成。结构式为Al2[Si4O10]（OH）2，实验式为Al2O3·4H2O，理论化学成分为Al2O3 28．3％，SiO2 66．7％，H2O 5．0％，自然界很少见到纯叶腊石，往往有各种杂质伴生。[第一段]     

相变材料CH3COONa·3H2O的研究进展

本文介绍了CH3COONa·3H2O用作相变材料的储能特性，综述了针对CH3COONa·3H2O过冷和相分离现象的解决方法以及CH3COONa·3H2O某些共晶盐的研究，同时简要概括了各因素对CH3COONa·3H2O结晶速度的影响，指出CH3COONa·3H2O未来的发展方向。     

Bi3.15Nd0.85Ti3O12纳米棒的水热合成与Raman光谱研究

以Bi（NO3）3·5H2O，Nd（NO3）3·6H2O和Ti（OC4H9）4为原料，NaOH为矿化剂，聚乙烯醇-124（PVA-124）为模板剂，采用水热法在2OO℃经48h合成了铋层状钙钛矿结构Bi3.15Nd0.85Ti3O12（BNdT）纳米棒。利用X射线衍射（XRD）、透射电子显微镜（TEM），选区电子衍射（SAED）和扫描电子显微镜（SEM）研究产物的物相和显微结构特征．结果表明合成的BNdT纳米棒为单晶，直径约10～200nm，长度达数微米。Raman光谱分析表明，Nd离子取代了类钙钛矿层中A位的Bi。     

两种钛电极电生过氧化氢性能的比较

分别采用钛电极与IrO2·Ta2O3涂层钛电极作为阳极，与活性炭纤维布作为阴极构成两电极电解池来产生过氧化氢。比较了IrO2·Ta2O3涂层钛电极和钛电极对过氧化氢产生性能的影响；分析了电压、空气流量和pH值对过氧化氢生成的影响。实验结果表明，采用IrO2·Ta2O3涂层钛电极的阳极和活性炭纤维组成两电极电解池能够有效地产生过氧化氢，IrO2·Ta2O3涂层钛电极作为阳极的性能明显优于钛电极的性能；电压对过氧化氢的生成有重要影响，过高过低的电压均对过氧化氢的生成不利，增加空气流量以及降低pH值均能有效地提高过氧化氢的生成浓度。     

氧化吸附法合成硝酸根型铜铁铝类水滑石

采用氧化吸附法制备了硝酸根型铜铁铝类水滑石,借助XRD、FTIR、SEM等分析手段研究了样品的结构、形貌及形成机理.结果表明:存在水蒸气的条件下,以碳酸根型铜铁铝类水滑石为前驱体经过500℃焙烧得到的铜铁铝复合氧化物可以氧化吸附NO2,生成Cu(NO3)2.上述样品在干燥器中放置9 d后转化成直径约为5μm的硝酸根型类水滑石.此外,铜铁铝复合氧化物吸附NO2、H2O和O2后也可直接转化成硝酸根型铜铁铝类水滑石,不存在中间相Cu(NO3)2.本文提出的氧化吸附法为制备类水滑石提供了一种新途径.     

液相法合成针状镁铝水滑石纳米晶的研究

研究了合成条件(原料种类、加料次序、NaOH浓度和合成温度)对液相法制备镁铝水滑石试样的相组成的影响.以MgCl₂为镁源、NaAlO₂为铝源、NaCO₃和NaOH为沉淀剂,在常压下采用液相法制备了长度约100nm、直径约10nm的Mg₆Al₂(OH)₁₆CO₃-4H₂O针状纳米晶体.并且发现:可溶性原料的选取、最后加入MgC_l2的加料次序、>45℃的合成温度和保证反应溶液的pH>12,是瞬间生成镁铝水滑石纳米晶的充分必要条件.提出镁铝水滑石纳米晶核形成的过程是:均匀分布于溶液中的Al₁₃(OH)₃₂⁷⁺迅速吸附于带羟基OH-的无定型态的Mg(OH)₂表面,并进行Al³⁺扩散,为平衡电价,CO₃^2-也扩散进入Mg(OH)₂,从而在瞬间完成镁铝水滑石晶核的形成.     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

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.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

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.     

Estimation of potentialities of methods of summation of direct measurement errors

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.     

空压机轴承箱蜗壳温度探头油封改造

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。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

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.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

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.     

Analysis of the rate of propagation of the wave of change of boiling modes

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.     

水三相点复现的不确定度评定

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)。