Temperature and Time-Dependent Ion Diffusion Across Stainless Steel-Zirconium Film Interface Studied by Scanning Surface Potential.

Abstract

ABSTRACTZirconium is of interest in the development of high-density diffusion barriers in nuclear reactor applications because of its low thermal neutron absorption cross section and good thermal and mechanical properties. It is used in these applications to protect the low enriched fuel from interacting directly with the cladding material to prevent swelling and cracking of the fuel. In this work, we investigated the use of plasma spraying as a method to produce high quality, dense Zr barrier coatings over large surface areas. A thin sheet of 21Cr-6Ni-9Mn stainless steel (SS) was used as the substrate material. Both sides of the SS sheet were coated, one side at a time. A transfer arc (TA) current between a torch and the substrate was used to vary the substrate temperature to explore the effect of temperature and time on the film grain size, interface quality, and film porosity. The films were characterized using light optical microscopy (LOM), scanning probe microscopy (SPM) and Kelvin probe force microscopy (KPFM) and EDS-SEM Although the film quality did improved with temperature, at the elevated substrate temperatures used in this study, metal atoms from the substrate diffused into and, at the highest temperature and longest time, through the Zr coatings.