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Abstract: To mitigate magnetohydrodynamic (MHD) pressure drop in liquid Li blanket system, Er2O3 coating is under development. Er can oxide in Li and form Er2O3 layer which may have electrical insulating capacity. To investigate formation of Er2O3 layer on Er, immersion tests of Er plate into high temperature Li at 773K and 973K are carried out. Li2O was introduced into Li as O agent. Formation of Er2O3 layer was observed by SEM observation and XRD analysis. Formation rate became lower for long-term immersion. Formation of LiErO2 was negligible even for high O concentration condition. From these results, there is possibility that Er can form Er2O3 insulating layer on the surface. [Copyright &y& Elsevier]

Abstract: Corrosion of Er2O3 coatings in liquid Li is crucial issue for Li blanket system development. Recent researches revealed that the Er2O3 forms LiErO2 in Li and the reaction rate depends on the O concentration in Li. In this paper, the detailed chemical behavior of Er2O3 and LiErO2 in Li is investigated to develop a methods to prevent the corrosion of Er2O3. Test of Er2O3 bulk ceramics were carried out with several impurity and Li flow condition. From these corrosion tests, it became clear that LiErO2 is not stable in low O concentration Li, but corrosion can be prevented by O concentration control. Corrosion prevention was tested in flowing Li and it suggests Er2O3 can be stable in Li with O control, even with flow, or thermal gradient condition. [Copyright &y& Elsevier]

Abstract: Y2O3 insulating coating is under development to mitigate the MHD pressure drop in Li blanket system. The problem in the development is that Y2O3 coating forms LiYO2 in high temperature Li and properties of LiYO2 are not investigated. In this study LiYO2 was synthesized by two methods to research its characteristics. XRD analysis shows pure LiYO2 can be obtained from Li2O and Y2O3 by reaction in liquid Li. Then, primary tests for chemical stability and electrical conductivity were carried out. These experiments suggested LiYO2 is stable in Li and its electrical resistivity is lower than Y2O3. [ABSTRACT FROM AUTHOR]

Abstract: Er2O3 is candidate material for insulating coating to prevent the magnetohydrodynamic (MHD) pressure drop in the self-cooled liquid Li blanket system. Although Er2O3 is stable material, detailed chemical behavior in liquid Li is not clear. Corrosion behavior of bulk Er2O3 in Li is investigated in static and flowing condition in the present study. After these tests, good compatibility of Er2O3 was confirmed and slight formation of LiErO2 was detected by XRD analysis. This chemical behavior did not change in a static and flowing tests, however some of the corrosion product of LiErO2 was removed easily by the Li flow. Intensity of LiErO2 peaks in XRD spectrum suggests that the temperature gradient may affect the reaction rate in the natural convection loop. Since corrosion rate of Er2O3 is very small, slight change in state will be important information to evaluate lifetime of coating. [Copyright &y& Elsevier]

Abstract: Static corrosion tests for SS304 and SS316L austenitic steels in high purity LiF–BeF2 (Flibe) were carried out at 500 and 600°C for 1000h. After the exposure, the steel surfaces were corroded due to the fluoridation by HF dissolved in Flibe. The grain boundary of the steel surfaces was preferentially attacked. The mechanism of corrosion including selective intergranular attack was discussed. The corrosion rate of SS304 and SS316L in Flibe at 600°C was estimated as 10.6 and 5.4μm/year, respectively. [Copyright &y& Elsevier]