硬脂酸用量对表面改性水菱镁石粉体特性的影响

为了提高水菱镁石(4MgCO_3·Mg(OH)_2·4H_2O)与高分子材料的相容性,采用硬脂酸对水菱镁石粉体进行表面改性;研究硬脂酸用量对水菱镁石BET比表面积、吸油值、粒度、在有机相中分散与沉降速度等特性的影响,并用红外光谱对表面改性水镁石粉体进行表征。结果表明:硬脂酸用量质量分数为2.5%时,水菱镁石粉体的BET比表面积为9.049 m~2/g、吸油值为0.2425 m L/g,d50=4.58μm、d97=7.96μm,且水菱镁石在有机相中的分散性显著提高,红外光谱表明硬脂酸成功吸附于水菱镁石表面。     

纳米碳酸钙湿式复合改性工艺探索

本文采用硬脂酸钠与水溶性磷铝酸脂对纳米碳酸钙进行湿式复合包覆，以改善纳米碳酸钙的表面性能。实验结果表明：采用固含率为18%(w/v)的纳米碳酸钙悬浮液为原料，当硬脂酸钠与水溶性磷铝酸脂的加入量均为3.0g/100gCaCO3，在70℃处理20min后，纳米碳酸钙的吸油值可降至67ml/100g，而活化度增至98%。复合改性后碳酸钙在四氯化碳介质中的分散性得到明显改善，其团聚粒径由350-550цm降至150цm以下。     

纳米碳酸钙湿式复合改性工艺探索

本文采用硬脂酸钠与水溶性磷铝酸脂对纳米碳酸钙进行湿式复合包覆 ,以改善纳米碳酸钙的表面性能。实验结果表明 :采用固含率为 18% (w v)的纳米碳酸钙悬浮液为原料 ,当硬脂酸钠与水溶性磷铝酸脂的加入量均为 3 0g 10 0gCaCO3 ,在 70℃处理 2 0min后 ,纳米碳酸钙的吸油值可降至 67ml 10 0g ,而活化度增至 98%。复合改性后碳酸钙在四氯化碳介质中的分散性得到明显改善 ,其团聚粒径由 3 5 0～ 5 5 0 μm降至 15 0 μm以下     

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。     

利用硬脂酸改性中铬黄颜料的效果和机理

选用硬脂酸对中铬黄颜料进行表面改性,对硬脂酸改性中铬黄的工艺优化和机理进行研究。结果表明:随着硬脂酸用量的增加,中铬黄的吸油量从0.22 g/g逐渐减小至0.15 g/g,减小了约30%,沉降时间由原来的1 h逐渐增加到28 h,流动性没有得到改善,硬脂酸质量分数为2.5%~3.5%时改性效果最优;改性中铬黄在干燥状态下分散性得到明显提高;硬脂酸通过—COO-键吸附Pb Cr O4中的Pb2+实现对中铬黄的表面改性。     

二甲基硅油对中铬黄颜料的表面改性

为了提高中铬黄颜料在漆料中的分散性,采用包覆改性法,以二甲基硅油为改性剂对中铬黄颜料进行表面改性,通过研究表面改性对颜料的吸油量、流动性、沉降时间、傅里叶红外光谱、扫描电镜图像的影响规律,对改性机理进行探讨。结果表明,使用二甲基硅油对中铬黄颜料进行表面改性可改善其在干燥状态下和有机聚合物基体中的分散性,随着改性剂用量的增大,中铬黄颜料的每百克吸油量由原来的30 g减小为16 g;经过二甲基硅油表面改性处理后,中铬黄粉体在煤油中的沉降时间由1 h延长到16 h左右;最佳工艺条件是二甲基硅油的质量为中铬黄质量的2.5%;二甲基硅油与中铬黄颗粒的表面吸附方式为物理涂覆;经过表面改性处理后,颗粒在干燥状态下的分散性明显提高。     

碳酸钙表面改性及在水介质中的聚团行为

为了实现碳酸钙颗粒在水中聚团,实现碳酸钙固液分离及与其他物质的分离,通过测量颗粒的沉降指数和观察颗粒的显微图像,对硬脂酸钠改性碳酸钙颗粒在水介质中的聚团行为及其机理进行研究。结果表明,碳酸钙表面诱导疏水性是导致其颗粒聚团的主要因素,与未改性碳酸钙相比,改性碳酸钙颗粒在水介质中形成大尺度聚团,并具有一定强度;推测改性碳酸钙颗粒间的聚团应为颗粒表面改性剂碳链间的缔合所形成。     

硅烷偶联剂对聚乳酸／硅灰石复合材料力学性能的影响

硅烷偶联剂KH550和KH570在乙醇溶剂中以酸水溶液为．催化剂进行水解后时硅灰石粉末进行湿法表面修饰改性。用称重法测定了粉体表面偶联包覆率,以此为指标确定了适宜的水解条件以及反应时间,对偶联效果进行了评价。用溶剂共沉淀法及热压工艺制备了聚乳酸／硅灰石（PDLLA／wollastonite）复合材料。经红外光谱（IR）分析,硅烷偶联剂与硅灰石表面发生化学键合,从而实现表面修饰改性。通过透射电镜（TEM）以及扫描电子显微镜（SEM）分析发现改性硅灰石粒子在有机相中的分散性和稳定性均得到了改善。对改性前后的复合物材料的力学性能进行了测试,结果表明,对硅灰石进行表面改性后,力学性能均得到一定提高,拉伸强度大约提高了5％,弯曲强度大约提高了10％。     

改性纳米氢氧化镁的制备与表征

采用易于工业化的液相沉淀法,在石油磺酸盐的作用下,合成改性纳米氢氧化镁。通过沉降体积实验确定改性剂的最佳用量为0.2%(质量分数)。通过X射线衍射(XRD)、透射电镜(TEM)、N2吸附、堆密度分析等手段对改性前后样品进行表征分析。结果表明:改性后样品分散性好,结晶度高。红外光谱(FT-IR)和沉降实验结果表明:该方法可以使改性剂吸附在氢氧化镁颗粒表面,使氢氧化镁表面由亲水性变成亲油性,可提高氢氧化镁在有机介质中的分散稳定性。     

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。     

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)。