Micro/nanostructure evolution of zircaloy surface using anodization technique: Application to nuclear fuel cladding modification

Zircaloy with nano-scale and micro/nano-scale (dual-scale) surface structures was fabricated using an anodic oxidation fabrication technique. The surface structure evolved as a function of duration of anodization. The resulting nanotubes and dual-scale surface structure were characterized by scanning electron microscopy (SEM) to analyze the evolution of the structures. The current density curve during the anodization was closely related to morphology of surface structure. Thus, surface structures can be selectively fabricated by watching the current density and controlling the duration of anodization. Control of surface structure formation resulted in change of wettabilities in the range of 0°–50° contact angle. The modified surfaces significantly enhanced critical heat flux, meaning this simple yet effective surface modification method can enhance the thermodynamic performance of the surface, especially in the case of the nuclear fuel cladding application. This technique would greatly contribute to the safety of nuclear reactors.