29th Symposium on Fusion Technology (SOFT 2016)

P3.147 Al2O3 coatings as barrier against corrosion in Pb-Li

7 Sep 2016, 11:00

1h 20m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 147

Poster H. Fuel Cycle and Breeding Blankets P3 Poster session

Speaker

Maribel C Gazquez (Fusion National Laboratory)

Description

Al-based coatings are proposed as anti-permeation and anti-corrosion barrier in Pb-Li breeding blankets -Water Cooled Lithium-Lead (WCLL), Helium Cooled Lithium-Lead (HCLL) and Dual Coolant Lithium-Lead (DCLL). In this work, Al2O3 coatings have been prepared by Pulsed Laser Deposition (PLD) at Istituto Italiano di Tecnologia (IIT) and they have been qualified in Pb-Li to evaluate its suitability from the point of view of corrosion. Some samples of EUROFER, as-received and coated with Al2O3, have been exposed in Pb-17Li, at ENEA, in stagnant conditions for 1000 hours at 550 ºC, which is the maximum operating temperature expected in the three models of Pb-Li blanket. Full characterization of the samples, before and after the corrosion tests, has been carried out using different techniques such as attenuated total reflectance spectroscopy (IR-ATR), scanning electron microscopy (SEM), energy dispersive x-ray fluorescence (EDX), confocal microscopy and secondary ion mass spectrometry (SIMS) to evaluate the migration of Li into the EUROFER. The surfaces of the uncoated samples are damaged irregularly due to the dissolution of the steel into the liquid metal. The corrosion process, observed only in the uncoated specimens, produces chromium desegregation. Thus, the EUROFER steel becomes poor in chromium in the region which has been in contact with the liquid metal. Furthermore, Li penetration into EUROFER has been observed by SIMS. By contrast, the corrosion process is negligible for Al2O3 coated samples. On these surfaces, it is observed that Li and Pb go through the alumina coating forming a thick interface between the coating and the steel. These results suggest a good performance of the alumina coatings under the test conditions.