Investigations on 1200 °C steam oxidation behavior of Cr coatings with distinct crystallographic orientation on Zircaloy-4 alloys

Abstract

Cr-coatings with distinct crystallographic orientation were deposited on Zircaloy-4 alloy by high-power pulsed magnetron sputtering ion plating technology. The crystallographic orientation transformed from Cr (110) to Cr (200) because of high probability of ion collision with the pressure increase. Cr coatings with (200) crystallographic orientation shows superior 1200 °C steam anti-oxidation behavior than Cr coatings with (110) crystallographic orientation due to the formation of compact Cr2O3 oxide layer and equiaxial Cr2O3 oxide particle at initial stage and later stage, respectively. In the case of Cr coatings with (200) crystallographic orientation, compact Cr2O3 oxide with short rod-like structures formed during the initial stage of steam oxidation. The thickness of the Cr2O3 oxide layer decreases and short rod-like structures transform into equiaxial Cr2O3 particles in the interim stage. Due to the occurrence of redox reaction, the thickness of the residual chromium layer increases in the later stage of steam oxidation. The study illustrates the steam anti-oxidation behavior of Cr coatings with Cr (200) crystallographic orientation, which is anticipated to provide a potential way for optimized design of Cr-coated nuclear fuel cladding.