Research and development on ceramic coatings for fusion reactor liquid blankets

Fabrication and properties of three kinds of ceramic coatings for fusion reactor liquid blankets such as Cr2O3-SiO2, Al2O3 and Y2O3 are reviewed, focusing on the activities in the University of Tokyo. A composite coating of SiO2 particles in a Cr2O3 matrix was prepared on the surface of SUS316 by the chemically densified method. It has a very low tritium permeability and is quite effective as a tritium permeation barrier without the presence of the molten Li17-Pb83 alloy. An alumina (Al2O3) coating was prepared on the surface of SUS316 by the hot-dipping and oxidation method. It showed a very high corrosion-resistance to Li17-Pb83 and a very low tritium permeability. An yttria (Y2O3) coating was formed on the surface of SUS316 by the plasma-spraying method. The product has a poor compatibility with liquid lithium. However, since sintered Y2O3 is more resistant to degradation than plasma sprayed Y2O3, it may be possible to use Y2O3 as a ceramic coating for liquid blankets if crackfree coating is made on the surface of piping materials. (C) 1997 Elsevier Science B.V.