Corrosion performance of Ti3SiC2, Ti3AlC2, Ti2AlC and Cr2AlC MAX phases in simulated primary water conditions. (15th July 2018)

• Record Type: Journal Article
• Authors: Ward, Joseph; Bowden, David; Prestat, Eric; Holdsworth, Sam; Stewart, David; Barsoum, Michel W.; Preuss, Michael; Frankel, Philipp
• Is Part Of: Corrosion science. Volume 139(2018)
• Page Start: 444
• Page End: 453
• Publication Date: 2018-07-15
• Subjects: Accident tolerant fuel coatings -- Nuclear -- MAX phases -- Corrosion; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2018.04.034
• Languages: English
• ISSNs: 0010-938X

Abstract

Graphical abstract: (A) SEM image of Ti3SiC2 after autoclave testing in simulated primary water at 300 °C. (B–E) EDS maps of (A) for O, Fe, Ti and Si, respectively. (F) HAADF STEM micrograph of Ti3SiC2 post autoclave (left) and a schematic of the 4-stage corrosion process occurring during autoclave testing. 1 is the starting bulk material. 2 is the diffusion of Si out and the diffusion of O into the A-layers. 3 is the ingress of Fe into the TiO regions within the delaminated areas. 4 is growth of TiFeO3 out of the MAX surface, forming facetted features observed on the surface. Highlights: Al and Si will not form a protective oxide during normal PWR operation. Cr2 AlC showed the best resistance to oxidation due to the high Cr content. Delamination of the MAX phase layered structure is observed by selective oxidation. Abstract: The response of Ti3 SiC2, Ti3 AlC2, Ti2 AlC and Cr2 AlC MAX phases under simulated primary water has been explored for the first time. Samples were tested for 28 days in 300 °C water with the addition of 2 ppm LiOH. The Ti-based MAX phases formed oxides of TiO and TiFeO3 . X-ray diffraction and scanning electron microscopy showed no evidence of a passive Al or Si-based layer forming during testing. A-layer dissolution was observed to cause delamination of the layered structure. In contrast, Cr2 AlC showed little change during autoclave testing, suggesting that a thin passivating chromia layer was formed.