Influence of Al content on the oxidation behavior of CrAl coating on Zry-4 alloys in 1200 °C steam

The oxidation behavior of CrAl coatings with three representative compositions deposited on Zircaloy-4 in 1200 °C steam environment has been studied. The Cr 0.90 Al 0.10 coating shows bettter performance than the other CrAl coatings due to the protectiveness of both the outer Cr 2 O 3 oxide layer and the internal Al 2 O 3 oxide layer. The Cr 0.95 Al 0.05 coating shows partial-protective performance, exhibiting a continuous Cr 2 O 3 oxide layer and Al 2 O 3 oxide islands. However, the oxidation resistance of the Cr 0.68 Al 0.32 coating is poor, exhibiting a discontinuous Al 2 O 3 layer on the surface and cracks in the coating. The effect of Al concentration on the oxidation resistance of CrAl coatings is discussed in detail. • The effect of Al concentration on the oxidation behavior of CrAl coatings is systematically studied. • An outer Cr 2 O 3 layer and internal Al 2 O 3 oxide are formed after oxidation. • Continuous Al 2 O 3 oxide layers cannot be formed when Al concentration is greater than 10 at%.