乙烯-乙烯醇共聚物纳米复合材料的辐射效应

采用5万CiCo-60源进行辐照,制备了乙烯-乙烯醇共聚物TiO2纳米复合材料、SiO2纳米复合材料、ZnO纳米复合材料和有机蒙脱土纳米复合材料。分析了纳米粒子对体系力学性能的影响,研究了辐照剂量、不同基体、不同纳米填料及改性剂等实验条件对体系力学性能的影响。结果表明,以EVOH-68(乙烯醇基含量为68%)为基体的纳米复合材料经过辐照,力学性能明显下降,且下降幅度大。以EVOH-56(乙烯醇基含量为56%)为基体的纳米复合材料经过辐照,在小辐照剂量下力学性能提高,大剂量下力学性能下降,且下降幅度较小。EVOH-56/纳米ZnO体系与EVOH-56/纳米TiO2体系相比表现的更耐辐照。     

EVOH基体对EVOH纳米复合物力学性能的影响

为研究乙烯-乙烯醇共聚物(EVOH)基体对复合材料性能的影响,分别制备了EVOH-56(乙烯醇基含量为56%)/纳米TiO2复合材料、纳米ZnO复合材料、纳米蒙脱土复合材料,EVOH-68(乙烯醇基含量为68%)/纳米TiO2复合材料、纳米ZnO复合材料、纳米蒙脱土复合材料。根据TPT方程,分别计算出体系中各组分间相互作用相关的参数B,分析了基体对体系力学性能的影响。结果表明,EVOH-68/纳米TiO2,ZnO体系的参数B值小于EVOH-56/纳米TiO2,ZnO体系,并且相关力学性能数据也证明EVOH-68/纳米TiO2,ZnO体系的相间相互作用好,力学性能优于EVOH-56/纳米TiO2,ZnO体系。EVOH-56/纳米MMT体系和EVOH-68/纳米MMT体系的力学数据与TiO2,ZnO体系一起证明了复合体系的力学性能是两种机理竞争的结果。     

紫外辐照对EVOH/纳米SiO2复合材料性能的影响

用硅烷偶联剂y-氨丙基三乙氧基硅烷（KH550）对纳米SiO2进行改性,采用熔融共混法制备了合SiO2的质量分数为5％的乙烯-乙烯醇共聚物（EVOH）／纳米SiO2复合材料,并吹塑成薄膜,将复合膜进行不同时间、不同强度的紫外辐照处理。利用FTIR、TEM、SEM对纳米SiO2和复合材料进行了表征分析,测试了复合材料紫外辐照处理前后的阻隔性能和力学性能。结果表明：纳米SiO2与偶联剂KH550形成化学键合,经紫外辐照处理的EVOH／纳米SiO2复合膜的力学性能、阻隔性能得到了较大地提高。     

紫外辐照对聚丙烯／纳米TiO2／POE复合材料薄膜紫外光透过性能的影响

采用UV-Vis漫反射光谱法研究比较了表面改性前后金红石型纳米TiO2的紫外．可见光学特性，通过熔融共混法制备了金红石型纳米TiO2和受阻胺光稳定剂改性PP／POE材料，对其进行了15d的紫外辐照加速老化，对比测试了纯PP和改性PP复合材料薄膜辐照前后的紫外光透过性能，结果表明：纯PP和PP／POE薄膜经过1d的紫外光辐照后，其紫外光总透过率，分别增大了11．53％和22．09％，而添加了0．5％（质量分数）纳米TiO2的复合材料薄膜虽经过15d紫外光辐照，但是透过率，基本未发生变化。     

TiO2改性M40/EP648复合材料的抗真空紫外辐照性能

利用射流式真空紫外辐照设备模拟空间的辐照条件，在温度为150K和压力为10^-4Pa的条件下，研究了波长为1-200nm的真空紫外线对纳米TiO2／EP648、纳米TiO2 M40／EP648、M40／EP648复合材料以及环氧树脂EP648的辐照损伤效应．结果表明，纳米TiO2具有明显的抗真空紫外辐照的作用．辐照后，与EP648和M40／EP648相比，纳米复合材料TiO2 EP648和M40／TiO2 EP648的质量损失率大幅度降低；纳米复合材料M40／TiO2 EP648的层间剪切强度随着辐照时间的延长呈上升趋势，M40／EP648呈下降趋势；辐照后，纳米复合材料M40／TiO2 EP648的表面形貌无明显变化，M40／EP648表面破损严重．     

聚乙烯/无机纳米复合材料的抗紫外老化性能

研究了茂金属聚乙烯（mPE）／纳米TiO2、线形低密度聚乙烯（LLDPE）／纳米ZnO、LLDPE／纳米CaCO3复合材料经过不同时间紫外辐照后的力学性能和热学性能,用傅立叶红外光谱测定了紫外辐照后的基团变化。结果表明,纳米TiO2和ZnO对聚乙烯抗紫外老化性能有比较明显的提升,为聚乙烯纳米复合材料的制备、加工和应用提供了理论依据。     

纳米二氧化钛／绢云母复合材料紫外屏蔽及光催化性能研究

通过液相沉积法将TiCl4水解沉淀到绢云母表面，制备得到纳米TiO2／绢云母复合材料，并用XRD、SEM和分光光度计对其进行了结构和性能的研究。研究表明，纳米TiO2／绢云母复合材料的紫外屏蔽性能明显好于白云母，也优于纯绢云母粉；同时它还具有很好的光催化性能，在弱紫外光（20W）下，其对次甲基蓝（20mg／L）的降解率4h达到了96．68％。     

环氧树脂／纳米TiO2复合材料的制备与性能研究

以纳米TiO2和聚苯胺包覆纳米TiO2后的颗粒作为增强组分，通过溶液共混法制备环氧树脂基纳米复合材料。IR结果表明，纳米TiO2颗粒表面舜口聚苯胺之间存在强烈的相互作用：这种包覆后的纳米粒子作为填料，能提高其与基体环氧树脂的界面相容性，使其能均匀地分散在环氧树脂基体中，在添加量为3％（质量分数，下同）时，拉伸强度比纯的环氧树脂提高了39．3％。     

一维钛纳米材料的SEM和TEM形貌研究

在10mol／L氢氧化钠溶液中，以溶胶状纳米TiO2为钛源，分别于150℃和180℃采用水热法合成了钛纳米晶须和钛纳米线；以金红石型纳米TiO2为原料在150℃水热合成了钛纳米管。用扫描隧道显微镜（SEM）、电子透射电镜（TEM）对产物进行了表征，结果表明钛酸钠纳米晶须扫描形貌为球形颗粒状，透射形貌为直径l～3nm针尖...     

TiO2／（O′＋β′）-Sialon复相陶瓷的制备与表征

以纳米TiO2粉和（O′＋β′）-SiMon粉为原料、Yb2O3或Tb2O3为添加剂，在高纯N2气氛下采用常压烧结制备出了TiO2／（O′＋β′）-Sialon复相陶瓷。采用XRD对材料进行物相、晶粒度分析，采用SEM＆EPMA对材料进行形貌观察和元素面分布分析。结果表明，随烧结温度的升高和恒温时间的延长，TiO2逐渐由锐钛矿相向金红石相转化，同时晶粒也逐渐长大。Tb2O3和Yb2O3分别对锐钛矿相变有显著的抑制和促进作用，通过控制烧结制度、添加剂种类及含量可得到不同TiO2相组成的TiO2／（O′＋β′）-Sialon。Tb2O3和Yb2O3均对TiO2晶粒生长有抑制作用，在不高于800℃的温度下烧结可得到纳米TiO2／（O′＋β′）-Sialon复相陶瓷。     

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.     

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.     

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.     

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)。