不同改性方式对沉淀白炭黑性能的影响

以水玻璃为硅源、硫酸为沉淀剂传统化学沉淀法制备白炭黑,探索原位改性和后处理改性的效果;采用扫描电子显微镜、激光粒度分析仪、X射线衍射仪、热分析仪、傅里叶变换红外吸收光谱分析改性前后样品的形貌、团聚体粒径、结构及改性效果;采用N2吸附测试、DBP值测试对改性前后空间结构度进行表征。结果表明:原位改性比后处理改性工艺效果更好,干燥后聚集体粒子平均粒径15.59μm;改性后白炭黑表面Si—OH的强度减小,疏水性增强,BET值为112.7 m2/g,吸油值为3.44 m L/g,具有较大的比表面积和空间结构度。     

含氮长链硼酸酯偶联剂改性阻燃水镁石

用自制的含氮长链硼酸酯偶联剂对水镁石粉体进行表面改性,利用红外光谱、X射线衍射和扫描电镜对改性前后的水镁石粉体进行表征。结果表明,经过改性的水镁石粉体的活化指数可达96.7%,吸油值从未改性前的1.190 40 mL/g减小为0.392 90 mL/g;经硼酸酯偶联剂改性后,水镁石粒子表面极性降低,分散性提高,同时偶联剂吸附在水镁石颗粒表面。     

纳米铁黄的表面改性及表征

研究了纳米铁黄有机表面改性的影响因素，确定了最优改性剂和改性条件。采用红外光谱（IR）、热分析（TG）、透射电镜（TEM）和分散性实验对表面改性前后的纳米铁黄进行了表征。实验结果表明，以硬脂酸为改性剂、用量为5％、pH值为4、改性时间为1．5h时，改性后的纳米铁黄的亲油化度达到92．6％。红外光谱和热分析显示，硬脂酸以化学键合的方式结合在纳米铁黄的表面，其质量分数约为4％。透射电镜（TEM）和分散性实验表明，经硬脂酸有机表面改性的纳米铁黄具有亲油疏水性能，能较好地分散于有机溶剂二甲苯中。     

载银纳米TiO2有机表面改性的研究

采用硬脂酸对以硫酸氧钛为原料制备的栽银纳米TiO2粉体进行有机表面改性,研究了改性剂用量、改性剂浓度、改性时间、改性温度以及改性pH值的影响,利用红外谱图(FT-IR)、扫描电子显微镜(SEM)等对粒子进行了表征,并检测了其抗菌性能.结果表明,最佳的改性条件下粉体的亲油化度值可达到66.3%,硬脂酸化学键合在粉体的表面,虽抗菌率略有下降,但仍能达到99.77%.     

干燥方式对白炭黑性能的影响

利用冷冻、喷雾、真空、烘箱干燥等4种干燥方式对对湿法研磨后的白炭黑浆料进行处理,研究干燥方式对白炭黑粒径、吸油值、比表面积和微观形貌等理化性能的影响。结果表明:研磨干燥后的白炭黑,中位径d_(50)由9.6μm减小到110 nm以下,吸油值(DBP)与比表面积(BET)均小于研磨前;冷冻干燥样品的中位径d_(50)减小为73 nm,吸油值(2.15 mL/g)以及比表面积(144 m~2/g)与原样最为接近。     

氟硅酸废水制备白炭黑的改性研究

以氟硅酸废水和氢氧化铝为原料通过化学沉淀法制得沉淀白炭黑;以月桂酸钠为改性剂对所制得的白炭黑进行了表面改性,考察了月桂酸钠添加量和改性时间对白炭黑疏水性和分散性的影响。采用场发射扫描电子显微镜(FE-SEM)、傅里叶变换红外光谱仪(FT-IR)、激光粒度分析仪、X射线衍射分析仪(XRD)等对改性前后的白炭黑样品的表面形貌、结构性能及分散性等进行了表征和分析。结果表明:当改性剂月桂酸钠添加量为2%,改性时间为40min时,可制得接触角为132.5°的疏水性白炭黑。改性后白炭黑样品的平均粒径(D50)从32.4μm减小至790nm,比表面积(BET值)从75m~2/g增加到165m~2/g,吸油值(DBP值)从2.25mL/g增加到3.12mL/g。改性后白炭黑样品的分散性和稳定性明显增加,团聚现象减少。     

改性剂对二氧化硅气凝胶性能的影响

本文以正硅酸乙酯(TEOS)为前驱体,通过酸碱两步溶胶-凝胶法,常压干燥制备疏水性SiO2气凝胶。研究了两种改性剂(三甲基氯硅烷、六甲基二硅氮烷)对二氧化硅气凝胶结构和性能的影响。对制备的气凝胶样品进行表面微观形态分析、热重差热分析、傅里叶红外分析以及比表面积分析。结果表明,通过改性制备的样品具有较好的性能,使用六甲基二硅氮烷改性得到的SiO2气凝胶密度为0.204g/cm3,接触角为128°,BET比表面积为973m2/g,平均孔径7.57nm;使用三甲基氯硅烷改性得到的SiO2气凝胶密度为0.115g/cm3,疏水性优良,接触角为158°,BET比表面积为1067m2/g,平均孔径13.40nm。综合考虑各种因素,采用TMCS进行改性制备得到的SiO2气凝胶综合性能更加优异。     

无定形纳米ZrO2表面改性研究

采用溶胶-凝胶法制得粒径为57nm的无定形纳米ZrO2粒子.用硅烷偶联剂KH560、KH570、A151、钛酸酯、硬脂酸等表面活性剂对其表面进行修饰.修饰后对改性效果进行激光粒度,红外光谱,扫描电镜,透射电镜,X射线衍射分析.实验证明:A151改性效果较好,改性后无机纳米粒子表面的羟基和有机集团发生化学键结合,无机纳米粒子表面性质由亲水憎油向亲油憎水转变.     

常压干燥制备疏水性SiO_2气凝胶

以正硅酸四乙酯(TEOS)为前驱体,盐酸和氨水作为催化剂,通过溶胶-凝胶法制备了SiO2醇凝胶,再利用三甲基氯硅烷(TMCS)和正己烷(Hexane)对醇凝胶进行表面改性,最后在常压条件下干燥后制备了疏水性SiO2气凝胶。采用X射线衍射、扫描电镜(SEM)、比表面积测试(BET)、傅里叶转换红外光谱(FT-IR)等测试方法对所得样品的形貌、结构及化学组成等进行了分析。结果表明,所得SiO2气凝胶比表面积可达900m2/g以上,密度200kg/m3,并且具有优异的疏水性。     

表面活化沸石外比表面积的试验研究

利用阳离子表面活化剂(HDTMA Cl)对天然沸石进行了表面活化改性,并使用BET法测定了表面活化沸石颗粒(SMZ)和天然沸石颗粒的外比表面积,试验结果表明,粒径为4～100目时,天然沸石的比表面积为13.44～14.32m2/g,活化沸石的比表面积为4.18～6.79m2/g,与天然沸石相比较,其值要小1～2倍。通过轻拍式原子力显微镜镜像分析(TMAFM),探讨了SMZ外比表面积发生变化的原因。     

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)。