目的:建立一种简便、高效、灵敏的硝酸-盐酸混合酸-石墨消解仪消解-氢化物发生原子荧光光谱法测定猪肝样品中(干粉)全硒含量。方法:使用HCl和HNO+3对猪肝样品(干粉)进行消解,采用原子荧光光度计测定猪肝中全硒含量。结果:硒工作曲线的线性范围是2~20μg·L^(-1),相关系数为0.999 7;检出限和定量限分别是0.029μg·L^(-1)和0.098μg·L^(-1),不同浓度下的加标回收率在91.2%~111.4%,日内精密度为1.2%,日间精密度2.1%。同时对石墨消解仪消解样品条件进行了单因素条件优化,最优化条件为消解还原溶剂4 mL HCl和1 mL HNO+3,最佳料液比1/25(0.200 g/5 mL),消解温度采用离心管最大耐受温度120℃,消解时间3 h。结论:本研究为猪肝中全硒含量的测定提供了一种简单、快捷、高效、环保的方法。
A Zr-Gd alloy with neutron poisoning properties and resistance to boiling concentrated HNO3 corrosion was developed based on a corrosion-resistant Zr-702 alloy to meet the demand for neutron shielding in the closed-loop treatment of spent fuel and the nuclear chemical industry.In this study,1 wt.%,3 wt.%,5 wt.%,7 wt.%,and 9 wt.%Zr-Gd alloys were designed and fabricated with Zr-702 as the control element.The electrochemical behavior of the Zr-Gd alloys in boiling concentrated HNO3 was investigated,and the neutron shielding effect on plate thickness and Gd content was simulated.The experimental results demonstrate that the corrosion resistance of the alloy decreased slightly before~7-9 wt.%with increasing Gd content;this is the inflection point of its corrosion resistance.The alloy uniformly dissolved the Gd content that could not be dissolved in the Zr lattice,resulting in numerous micropores on the passivation coating,which deteriorated and accelerated the corrosion rate.The MCNP simulation demonstrated that when the Gd content was increased to 5 wt.%,a 2-mm-thick plate can shield 99.9%neutrons;an alloy with a Gd content≥7 wt.%required only a 1-mm-thick plate,thereby showing that the addition of Gd provides an excellent neutron poisoning effect.Thus,the corrosion resistance and neutron shielding performance of the Zr-Gd alloy can meet the harsh service requirements of the nuclear industry.
This paper experimentally studied the stress corrosion behavior of 2195-T8 Al-Li alloys with prefabricated pits in 30vol%HNO3.The microstructure was observed and determined by the scanning electron microscopy and the transmission electron microscopy.The typical corrosion features,i.e.,regular or irregular corrosion pits and sub/intergranular corrosion,were investigated,and the role of stress were analyzed.The statistical results of the number and area of corrosion pits in various sizes were studied using an improved image processing method.Experimental results demonstrate that stress affects the intergranular corrosion or sub-intergranular corrosion of the alloy most,and promotes them to evolve into cracks under stress corrosion.Stress also plays a role in accelerating corrosion severity of certain corrosion feature.The number of corrosion pits with an area of 0–50μm~2 can be seen as an index to reflect the degree of corrosion.Besides,a corrosion phenomenon,i.e.,the pit bottom in the site with the maximum stress locally suffering from no severe corrosion,was observed and discussed.