[en] Development of ceramic coatings at inner wall of duct tubing is strongly required for self-cooled Li/V-alloy blanket concept to reduce magneto-hydrodynamics (MHD) pressure drop. In our previous study, Er₂O₃ coatings fabricated by PVD method shows high electrical resistance and high compatibility with liquid lithium. In-situ formation of Er₂O₃ coatings was also explored to show oxygen in the V alloy substrate and Er dissolved in lithium could react to form thin Er₂O₃ layer at the interface. In this study, feasibility of self-healing of Er₂O₃ coating is explored by observing its in-situ formation at cracks on the coatings fabricated by PVD method. V-4Cr-4Ti substrates were oxidized and annealed to introduce proper amount of oxygen into the substrate. Er₂O₃ coatings were deposited on these substrates at room temperature (R.T.) and 873 K. The coatings deposited at 873 K had peeled off at most area. On the contrary, the coatings deposited at R.T. were uniformly flat. After introducing cracks on Er₂O₃ coatings by heating, the samples were exposed in lithium doped with Er at 873-973 K for 100-200 h to heal the cracks. At the large peeled-off area, no in-situ formation was observed, while small cracks were healed. To ascertain mechanism of peel-off and healing, depth profiles of elements in Er₂O₃ coatings were analyzed by X-ray photoelectron spectroscopy (XPS) with Ar sputtering. The heating during or after deposition contributed to form Er-V-O intermediate layer between the coating and the substrate. It was suggested that Er-V-O layer were formed by taking oxygen from substrate in case of oxidized substrates as well. It is considered Er-V-O layer itself has been peeled off and substrate without oxygen was remained on the surface, and therefore in-situ formation had not been observed at peeled-off area. At the small cracks which have healed, it is considered the oxygen was supplied from Er-V-O layer from the remained coatings at surroundings. Thus, oxygen supply in the system is a key investigation point to control the healing of cracks on Er₂O₃ coating at Li/V alloy blanket. (author)