Sol-gel composite coatings as anti-corrosion barrier for structural materials of lead-bismuth eutectic cooled fast reactor

In order to protect the structural components of lead-bismuth eutectic (LBE) cooled fast breeder reactors (FBRs) from liquid metal corrosion, advanced aluminum-yttrium nano- and micro-composite coatings were developed using an improved sol-gel process, which includes dipping specimens in a Y-added sol-gel solution dispersed with ultrafine α-Al2O3 powders prepared by mechanical milling. Scanning electron microscopy (SEM) and field emission electron probe microprobe analyzer (FE-EPMA) analyses revealed that the coatings are composed of alumina with high density. Accelerated corrosion tests were conducted on coated specimens in liquid LBE at 650 °C under dynamic conditions. After the corrosion tests, no cracking, spallation, erosion and liquid metal (e.g., lead) penetration occurred to the coatings, indicating that the coatings possess an enhanced dynamic LBE corrosion resistance. The superior LBE corrosion resistance is due to the presence of the nano-structured composite particles integrated into the coatings and the addition of trace amount of yttrium.