电镀法制备裂变电离室电极铀膜

    Preparation of Uranium Film for Fission Ionization Chamber Electrode by Electroplating

    • 摘要: 裂变电离室电极镀铀(235U)的均匀性、镀膜厚度和结合力是影响中子探测器灵敏度等性能关键所在,以无水乙醇为电镀液,铂丝为阳极,通过考察阴极镀件(铝管)处理工艺、pH值、电流密度、电镀时间和镀液中U(Ⅵ)初始浓度对电镀效率及镀膜的影响,进而确定了电镀铀的最佳工艺参数。研究结果表明,当电流密度为6.50 mA/cm2、电镀时间为30 min、pH=2.6、极间距为12 mm、镀液中U(Ⅵ)初始质量浓度为1.96 mg/mL时,电镀效率约达92.4%,镀膜厚度可达2.26 mg/cm2。采用X射线光电子能谱(XPS)和扫描电镜(SEM-EDS)等对镀层进行了表征。XPS表明U以六价态的UO2+2聚合物和四价态的二氧化铀(UO2)形式存在,且纯度较高。SEM显示镀层表面平整、致密。划痕法测试结果表明,镀层结合力一般。

       

      Abstract: The uniformity, coating thickness and adhesion of uranium(235U) plating on fission ionization chamber electrode are the key factors affecting the sensitivity of neutron detector. In this paper, ethanol is used as electroplating solution and platinum wire as anode. By investigating the effects of cathode plating process(aluminum tube), pH value, current density, initial U(Ⅵ) concentration in plating solution and electroplating time on electroplating efficiency and coating, the optimum process parameters of uranium electroplating were determined. The results show that when the current density is 6.50 mA/cm2, the electroplating time is 30 min, pH=2.6, the electrode spacing is 12 mm and the initial U(Ⅵ) mass concentration in the plating solution is 196 mg/mL, the electroplating efficiency can reach about 92.4% and the coating thickness can reach 2.26 mg/cm2. The coating was characterized by X-ray photoelectron spectroscopy(XPS) and scanning electron microscopy(SEM-EDS). XPS shows that U exists in the form of hexavalent U polymer and tetravalent uranium dioxide(UO2) with high purity. SEM shows that the surface of the coating is flat, dense and firmly bonded with the substrate. The scratch test results show that the adhesion of the U coating is weak.

       

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