Pulse Electroplating of Ni-P-Nano TiO<sub>2</sub> and ZrO<sub>2</sub> for Steam Generator Tube Repair

Abstract

Steam generator tubes provide the pressure boundary between the primary and secondary regions of a nuclear power plant. Alloy 600 is a tube material with good corrosion resistance; however, tubes of this material have experienced damage, particularly as Stress Corrosion Cracking, under the elevated temperature and pressure environment of a nuclear power plant. These damaged tubes must be repaired to prevent leakage of radioactive material from the primary to the second regions in the nuclear steam generator. In this study, Ni-P-Nano TiO2 and ZrO2 layers were produced by pulse electroplating for steam generator tube repair. These electroplate layers were obtained from Ni sulfamate bath with an added small quantity of H3PO3 and Nano TiO2 and ZrO2 particles with an average size of 20-80nm. Results of TEM analysis in these layers show that Nano TiO2 and ZrO2 particles were uniformly distributed into the electroplated Ni matrix and the tensile strength of these layers at 800-1000MPa was higher than that of alloy 600 with a conventional pure Ni electroplate layer.