The corrosion behavior of AlOx coatings exposed to lead-bismuth eutectic at 350 °C–650 °C

Abstract

The service life of heat-resistant materials is crucial for safe operation in the nuclear industry. Usually, it is necessary to coat the surface of the materials with a heat-resistant coating. In this paper, XPS, EDS, XRD, SEM, and TEM characterization techniques were used to study the corrosion behavior of continuous high-power magnetron sputtered (C-HPMS) AlOx coatings with different oxygen contents exposed to lead-bismuth eutectic (LBE) at 350 °C–650 °C for 2000 h was investigated. Stable oxide γ-Al2O3 and Al2PbO4 were formed at 350 °C–550 °C, which will increase the hardness and Young's modulus of the coating, and the dense layer Al2PbO4 and AlOx layer inhibited the outward diffusion of iron and the inward diffusion of O. At 650 °C, the internal Fe will be oxidized to Fe3O4, resulting in corrosion resistance failure. Therefore, the AlOx coating at the oxygen injection rate of 120 sccm (O/Al = 1.5) is best, which can resist corrosion at T < 550 °C. Finally, the corrosion mechanism of the AlOx coating in liquid LBE is discussed, providing a research idea for developing high-performance anti-corrosion coatings.

Keywords

• Microstructural evolution
• Ceramic coatings
• Corrosion behavior
• Phase transformation