Construction of chromium coatings with (200) preferred orientation and exploration the high-temperature steam oxidation properties

Abstract

In order to improve the high-temperature steam oxidation resistance of Zircaloy-4 for accident tolerant fuel claddings (ATF), Cr coatings with (200) preferred orientation were deposited by changing argon flow using closed field unbalanced magnetron sputtering. The influences of the argon flow on the microstructure and high-temperature steam oxidation properties of Cr coatings were studied systematically. The results indicate that Cr coatings exhibit obvious preferred orientation of Cr (200) especially for 30sccm argon flow due to more adatom easy aggregation on Cr (200) plane under more ion collisions. With the argon flow increases, the grains of Cr coatings gradually becomes compact and homogeneous, which causes the formation of thicker Cr2O3 oxide layer and residual Cr layer on Cr coatings surface after 1200 °C high-temperature steam oxidation test at 8h. Above all, Cr coatings prepared by 30sccm argon flow still possess excellent steam oxidation resistance properties even after 12h exposure time. In addition, the high-temperature steam oxidation mechanism of 30sccm argon flow Cr coatings under different exposure time also was discussed in detail. The study about Cr (200) preferred orientation is expected to provide a new research idea for prolonging steam oxidation resistance and accident tolerant time.