小龙潭褐煤中砷,铅,铬等元素的结合状态

本文用浮沉法及酸、碱和有机溶剂抽提方法探讨了小龙潭褐煤中As,Pb,Cr等元素的存在状态。结果说明,As主要是以有机结合状态存在,Cr有部分是与煤中腐植酸络合,Pb则主要为无机结合状态。     

回旋加速器辐照制备无载体~(203)Pb的研究

采用氧化铊靶和15MeV的氘束,通过~(203)Tl(d,2n)~(203)Pb核反应,产生出放射性同位素~(203)Pb。将辐照过的氧化铊靶经过一系列的放化分离程序,可以获得高纯的~(203)Pb示踪剂,铊的含量为～1μg/ml(最终产品为10ml)。~(203)Pb的化学回收率为71±5％。在本实验辐照条件下,辐照停止时~(203)Pb的核反应产额为180±36μCi/μA·h。     

Reactivity of no-clean pastes and fluxes for the surface mount technology process—part II: Corrosion risk measurements for printed circuit boards and solder joints

The introduction of no-clean pastes and fluxes for the surface mount technology process needs testing methods of high sensitivity and reliability to evaluate the activity of the residues after the reflow process. An electrochemical method is proposed, suitable to ascertain the reactivity and the corrosion risk of these residues. Products of normal use are tested, and their behavior described and compared. Surface morphologies and compositions are examined after reflow and after testing. Local surface oxides are investigated with x-ray photoelectron spectroscopy. Surface analytical results are interpreted and related to the electrochemical behavior of solder joints. Tin is shown to have the most important role toward the onset of possible localized corrosion.     

Growth of large crystals of (Pb,Ge)Te and (Pb,Sn)Te

Large single crystals of Pb1-xGexTe (0 < × < 0.105) up to 10 g and Pb1-ySnyTe (0 < y < 0.26) up to 125 g were grown in sealed tubes by self-transport onto oriented single crystal seeds. The crystals were free of voids and inclusions, had dislocation densities as low as 103 cm-2, and were uniform in composition. Pertinent details of the growth technique, including thermal conditions, stoichiometry of the source, and seed orientation, are described. Results of evaluation of the crystals by metallography, Laue X-ray topography, and electron microprobe analysis are presented.     

由骨骼中~(210)Pb含量估算~(222)Rn子体摄入量的方法

铀矿和某些非铀矿山的矿工往往受到较高浓度的~(222)Rn 及其子体的照射。本文介绍一种由骨骼中~(210)Pb 含量估算~(222)Rn 子体α潜能摄入量的方法。对加拿大28名铀矿工,用本方法估算的结果与国外文献给出的值基本相符合。     

红外探测用陶瓷材料研究的最新进展

本文根据热释电红外探测器对材料性能的要求,综述了国外热释电陶瓷材料研究的现状和发展。并介绍了作者用溶胶-凝胶法制备(Pb,Lb)TiO_3陶瓷薄膜近期的研究结果。     

用铅离子选择性电极测定高放废液中的硫酸根

研究了铅离子选择性电极测定高放废液中SO_4~2的可能性,对消除干扰离子的分离条件和滴定体系的选择进行了试验并建立了分析方法。采用0.3g活性氧化铝柱将样品中的微量SO_4~2从大量的干扰离子中分离出来。再于80%((?)/1)丙酮-水体系中用硝酸铅标准溶液进行电位滴定,分析测定了高放废液中的SO_4~2。方法的相对标准偏差优于5.0%,回收率为95% 101%。     

双层卷焊钢管热浸镀铅锡合金工艺与设备

详细叙述了双层卷焊钢管热浸镀铅锡合金的工艺过程及其主要设备。该工艺应用在实际生产中过程中表明是可靠的，合理的。     

Linear Coefficient of Thermal Expansion and Mechanical Property of Pb/B4C/BPR Composite

Lead/boron carbide/boron phenolic resin (Pb/B₄C/BPR) is a new kind of shielding composite with high temperature resistance and high shielding performance for radiations. In this paper, the effects of lead powder content, particle size and surface treatment (SiO₂ coating) on the linear coefficient of thermal expansion (CTE) and mechanical properties of the composites were systematically studied. The results show that the composites have the smallest linear CTE and excellent comprehensive mechanical properties when the lead powder content is 36% (volume fraction) and the particle size is 38 μm. Proper coating of SiO₂ on the surface of lead powder effectively reduces the density difference between lead powder and B₄C powder, which not only significantly reduces the linear CTE of the composites, but also improves the tensile, flexural strength and impact toughness. However, too much SiO₂ coating content will result in the linear CTE of the composites increasing and the tensile, flexural strength and impact toughness reducing.     

介质辅助微波消解和原子荧光法测定蔬菜中的铅

利用介质辅助微波消解仪对样品进行前处理,原子荧光法测定蔬菜中铅的含量,加标回收率在87.9%～101.2%之间,RSD在2.5%～4.0%。整个方法快速、高效、安全。