铁尾矿提纯纳米白炭黑的研究

以铁尾矿为原料,采用热碱反应法,经过浸酸、滤洗、酸浸渣热碱反应、稀酸法控制沉析二氧化硅工艺,并在稀酸沉析过程中进行表面处理,制备出超细纳米白炭黑。采用单因素变量法考察NaOH的浓度、混合料煅烧时间、碱溶时间、碱溶温度对白炭黑产率的影响,并采用XRD、SEM对产物的微观结构和形貌进行了表征。得最佳工艺条件为:5g煅烧铁尾矿的酸浸渣与10g NaOH混合均匀,于500℃煅烧50min后,将混合物溶于190ml水,并加入4g NaCl,混合液于70℃搅拌反应60min后过滤,滤液用HCl酸化至pH=8,陈化1h后,再经抽滤、洗涤、干燥,得到纳米白炭黑产品。通过计算,此工艺条件下制备纳米白炭黑的产率可达到97.41%,所得白炭黑为水合非晶物质,颗粒近似球状,粒径为50～100nm左右。     

碳酸氢铵-氨水-草酸共沉淀法制备微米稀土CeO2工艺的研究

以碳酸氢铵-氨水-草酸(AAO)为共沉淀剂对氯化铈进行了沉淀实验,研究了反应温度、物料浓度、搅拌速率、陈化时间等因素对草酸盐粒度的影响;探讨了较佳的条件:AAO共沉淀法,陈化时间60min,CeCl3浓度1.6mol/L,搅拌速率650r/min,反应时间3h,焙烧温度800℃,AAO的pH为5～6,制备了微米级氧化铈,为其工业化提供参考。     

用纯橄岩制备白炭黑的工艺

以纯橄岩为原料,经700℃煅烧4h,用4mol/LH2SO4于100℃处理2h,碱溶除杂后的硅酸钠中加入分散剂,控制pH=7左右,SiO2的浸取率可达91.58%.经化学分析,白炭黑中SiO2的纯度为96%;经FT-IR检测,白炭黑的化学结构为水合SiO2;经XRD分析,白炭黑为无定型结构;TEM图像显示白炭黑的形貌近似球状粒子,平均粒径50nm以下.白炭黑pH值6.0～7.0,加热减量为5.92%,1000℃灼烧减量为6.12%,产品符合中国行业标准HG/T 3061-1999的要求.     

水氯镁石制备硅钢级氧化镁

以水氯镁石为原料,采用氨法沉镁-煅烧-添加剂的方法制备硅钢级氧化镁。考察了反应温度、反应pH值、陈化时间对中间体氢氧化镁纯度及转化率的影响;研究了煅烧温度和煅烧时间对氧化镁水化率的影响及添加剂的量对氧化镁悬浮性能的影响。控制实验条件为:反应温度55℃,pH值为9.5,陈化时间2h,煅烧温度1050℃,煅烧时间2h,添加剂量为0.8%,制得氧化镁的纯度为98.99%、水化率为2.92%、悬浮性能为3mm/h,达到硅钢级氧化镁的要求。     

苏州土制备纳米白炭黑的影响因素研究

以苏州土为原料制备纳米白炭黑粉体。研究并讨论了煅烧温度、酸浸条件、PH、反应时间、凝胶煅烧等因素对苏州土分解，纳米白炭黑粉体制备的影响，采用XRD，TG—DSC，SEM，TEM等方法进行了表征，结果表明苏州土在700℃左右煅烧2h后用20wt％IICl溶液在100℃酸溶2h，控制Al／HCl摩尔此为1：7时可以使二氧化硅获得率达到97％;碱溶除杂后的硅酸钠溶液加入分散剂后，在70℃～90℃时控制pH=5～7反应0．5h获得的溶胶在400℃煅烧2h获得平均粒径35nm的球形纳米白炭黑粉体。     

镀锌钢铈盐转化膜硅酸钠封闭后的耐蚀性能

为进一步提高镀锌钢铈盐转化膜的耐蚀性能,采用硅酸钠溶液对其封闭处理,优化封闭条件,并采用扫描电镜(SEM)、能谱、中性盐雾加速腐蚀测试和电化学测试研究了封闭前后试片的形貌、成分及耐蚀性。结果表明:最优封闭条件为10 g/L硅酸钠,pH值11.5,温度35℃,时间5 min;硅酸钠溶液封闭处理后,铈盐转化膜表面裂纹消失,膜层连续完整,耐中性盐雾腐蚀时间从封闭前的24 h提高到72 h,腐蚀电流密度从4.64μA/cm2降低到1.51μA/cm2,耐蚀性大大提高。     

具有二次微粒结构的高分散型白炭黑的制备及工艺研究

制取具有二次微粒结构的高分散型白炭黑,选用两步法工艺。在反应过程中,第一步和第二步反应分别采用不同的反应条件,产生了两种不同形态的小簇团,形成具有新结构的聚集体。通过改变底液浓度、反应温度、搅拌速度、滴加速度、pH值、消化温度和处理方式等反应条件,得到生产结构度高、比表面积适中、分散性较高的沉淀白炭黑工艺。     

核-壳结构TiO_2@Al_2O_3制备工艺的优化

探究温度、p H值、包覆量、包覆时间、初始质量浓度、搅拌速率、陈化时间等7个因素对并流法制备核-壳结构TiO_2@Al_2O_3的酸溶率的影响;采用响应面实验优化制备工艺,并以高分辨透射电镜(HRTEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)、紫外-可见光谱(UV-vis)等表征产物,并测试其性能。结果表明:当TiO_2初始质量浓度为200 g/L、搅拌速率为300 r/min、包覆时间为60 min时,各因素对酸溶率的影响次序为包覆量、温度、p H值、陈化时间;优化的工艺条件为:包覆量质量分数为4.5%、温度为83℃、p H=10、陈化时间为28 h,此时产物的酸溶率为17.4%; TiO_2@Al_2O_3壳层的厚度约为6 nm,其组成为勃姆石型Al2O3,并且与Ti O2核形成Ti—O—Al化学键,核-壳结构TiO_2@Al_2O_3具有更好的水分散性、分散稳定性及紫外屏蔽能力。     

内蒙古油砂尾砂制备白炭黑的工艺研究

探索了内蒙古油砂尾砂经水玻璃制备白炭黑的工艺路线。通过单因素与正交试验考察得出4因素对白炭黑粒径的影响程度依次为:反应温度沉淀剂加入速度分散剂加入量(占水玻璃溶液的质量分数)陈化时间。并对正交试验结果进行曲线拟合及最优化求解得出:沉淀剂加入速度27.11mL/min,反应温度70℃,分散剂加入量21.06%,陈化时间2h为最优工艺条件时粒径为38.029nm。     

恩施矿区煤矸石中白炭黑的提取试验

以恩施矿区煤矸石为原料,经煅烧活化、碱熔和乙醇的作用,最后酸中和等工艺过程,制得非晶态、纳米白炭黑。考察了煤矸石煅烧活化温度、NaOH用量、碱熔时间、乙醇浓度和盐析pH值对白炭黑溶出率的影响,并利用X-射线粉末衍射仪、傅里叶红外光谱仪和扫描电子显微镜对煤矸石和白炭黑进行了表征。结果表明,当煤矸石煅烧活化温度为720℃、NaOH用量为煤矸石用量的40%、碱熔时间为2h、乙醇浓度为2mol/L和盐析pH值为9时,白炭黑的溶出率较好,达到90.1%。     

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.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

卧式金属罐容量的测量结果不确定度

本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。     

盐酸浓度不确定度的评估

通过对盐酸浓度标定的过程分析，找出影响结果的各个分量，进行不确定度的评定，按照计量技术规范给出标准的表示法。     

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.     

Numerical study of methods of linearization of the output characteristics of radio-frequency sensors of the level of dielectric media

Different constructions of the sensing elements of radio-frequency level sensors based on sections of long lines are numerically investigated by means of the Matlab program for the purpose of minimizing the measurement error caused by the nonlinearity of the output characteristic. It is shown that the nonlinearity is lowest for U-shaped designs. The nonlinearity factor KN may be regulated by varying the capacitance of a correcting capacitor connected to the input of the sensing element and (or) the length of one of the sections of the long line. In selecting an optimal capacitance of the correcting capacitor KN ≤ 0.15% for control media with dielectric permittivity in the range 2.2–30.