Corrosion of candidate materials of insulating coating was investigated innatural convection lithium (Li) loop. The loop was constructed for present study and bulk specimens of Er2O3,Y2O3and AlN were placed at
several positions in the loop. The operation temperature was 400 qC in the low temperature region and 500 qC in
the high temperature region. After the exposure, specimens were cleaned and the corrosion characteristics
were investigated. The results indicated that the corrosion
characteristics of the bulk specimens were similar to those obtained by the static test in the previous study.