High-temperature oxidation behaviors of ZrSi2 and its coating on the surface of Zircaloy-4 tube by laser 3D printing

Abstract

The high-temperature oxidation behavior of ZrSi2 used as a coating material for nuclear fuel cladding was investigated for developing accident-tolerant fuel cladding of light water reactors. Bulk ZrSi2 samples were prepared by spark plasma sintering. In situ X-ray diffraction was conducted in air at 900, 1000, and 1100 degrees C for 20 h. The microstructures of the samples before and after oxidation were examined by scanning electron microscopy and transmission electron microscopy. The results showed that the oxide layer of zirconium silicide exhibited a layer-by-layer structure of crystalline ZrO2 and amorphous SiO2, and the high-temperature oxidation resistance was superior to that of Zircaloy-4 owing to the SiO2 layer formed. ZrSi2 was coated on the Zircaloy-4 tube surface using laser 3D printing, and the coated tube was oxidized for 2000 s at 1200 degrees C under a vapor/argon mixture atmosphere. The outer surface of the coated tube was hardly oxidized (10-30 m), while the inner surface of the uncoated tube was significantly oxidized to approximately 300 m.