Preparation of Uranium Film for Fission Ionization Chamber Electrode by Electroplating

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.