In situ high-temperature 3D imaging of the damage evolution in a SiC nuclear fuel cladding material

• Published in: Materials & design Vol. 227; no. C; p. 111784
• Main Authors: Yuan, Guanjie, Forna-Kreutzer, J. Paul, Xu, Peng, Gonderman, Sean, Deck, Christian, Olson, Luke, Lahoda, Edward, Ritchie, Robert O., Liu, Dong
• Format: Journal Article
• Language: English
• Published: United Kingdom Elsevier Ltd 01.03.2023; Elsevier
• Subjects: C-ring compression; Digital volume correlation; SiC nuclear fuel cladding; Toughening mechanisms; X-ray computed micro-tomography; C-ring compression; Digital volume correlation; X-ray computed micro-tomography; Toughening mechanisms; SiC nuclear fuel cladding
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2023.111784

[Display omitted] •Fracture processes in a coated SiC composite nuclear cladding material were found different at room temperature and 1200 °C.•At both temperatures, cracking initiated in the outer monolithic SiC coating.•The stress and strain when first coating crack occurred are much higher at 1200 °C than room temperature.•Typical crack toughening mechanisms occurred simultaneously in underlying composites upon load drops at both temperatures. Silicon carbide (SiC)-based nuclear fission fuel rod cladding has been considered as one of the possible designs for accident tolerant fuels. It is in the form of a SiC fibre reinforced SiC matrix composite tube (SiCf-SiCm) with monolithic SiC outer and/or inner coating layers. This study focuses on the deformation and fracture processes in this material using in situ X-ray micro-computed tomography (XCT) at room temperature (RT) and 1200 °C in an inert gas environment in a C-ring compression loading configuration. Prior to testing, local properties and residual stresses were characterised using nanoindentation and Raman spectroscopy since they can impact the mechanical behaviour of the material. The 3D strain distribution, crack formation and propagation processes including the toughening mechanisms (e.g., crack deflection, micro-cracking, crack bridging and bifurcation) are investigated in the coating and underlying composites at RT and 1200 °C. There is no particular sequence which toughening mechanism occurs first – this is very different from the conventional toughening theory in ceramic-matrix composites under uniaxial tension loading. Indeed, no evidence of fibre pull-out or fibre fracture was observed in this SiCf-SiCm nuclear cladding material in the current C-ring compression configuration. The correlation between local measurements and bulk mechanical behaviour are discussed.