Compatibility of AlN with liquid lithium

Development of ceramic coatings is one of the most important subjects in liquid blanket research and development. Compatibility of sintered AlN and AlN coatings with liquid lithium, a candidate breeding material, was investigated. Sintered AlN with or without the sintering aid of Y2O3 examined in lithium at 773 K for 1390 h showed a slight decrease in electrical resistivity because of a reduction in Al2O3 impurity, though AlN and Y2O3 components themselves were subject to no severe corrosion. On the other hand, AlN ceramic coatings on SUS430 with high resistivity (>1011 Ω m) fabricated by the RF sputtering method disappeared in liquid lithium at 773 K in 56 h. This may be because cracks were formed due to the difference in thermal expansion between the coatings and the substrate or because the oxide formed between the two was removed by liquid lithium.