Oxidation kinetics of Cr-coated zirconium alloy: Effect of coating thickness and microstructure

By E. Kashkarov, D. Sidelev, M. Syrtanov, Chongchong Tang, M. Steinbrück. Corrosion Science, 2020

169 citations recorded by the source corpus.

Abstract Cr coatings with the thickness of 4.5–9.0 μm and dense/columnar microstructure were deposited onto Zr alloy by cooled or hot target magnetron sputtering. Steam oxidation tests were performed under temperature ramp from 500 to 1200 °C and isothermal treatment at 900−1200 °C for 10−30 min. The measurements of mass gain showed different oxidation kinetics depending on microstructure and thickness of the as-deposited Cr coatings. The dense microstructure is favorable to prevent alloy oxidation as long as the Cr layer is intact. The higher activation energy of 202 kJ/mol is observed for the dense 4.5 μm-thick Cr coating while thicker columnar coatings have 177−183 kJ/mol. The time of transition from protective to non-protective behavior increases with coating thickness. It was shown that the 9 μm-thick Cr coating with columnar microstructure better protects the zirconium alloy from oxidation at 1200 °C for 10 min in comparison with thinner coatings. The fast inter-diffusion of Cr and Zr at coating/alloy interface significantly affects the oxidation kinetics of Cr-coated zirconium alloy at temperatures above 1100 °C and long oxidation time.

Subfields: Aerospace Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/eaf8a351342685cb8af6607c17dab9fc092454b2