Torsional behaviour of glass-joined, laser-processed Crofer 22 APU interconnect: Unravelling the effect of surface roughness on the shear strength. Issue 22 (15th November 2022)

• Record Type: Journal Article
• Authors: Smeacetto, F.; Zanchi, E.; Meena Narayana Menon, D.; Janner, D.; Lamnini, S.; Salvo, M.; De La Pierre, S.; Javed, H.; Ferraris, M.
• Is Part Of: Ceramics international. Volume 48:Issue 22(2022)
• Page Start: 32837
• Page End: 32843
• Publication Date: 2022-11-15
• Subjects: Joining -- Torsion -- Shear strength -- Solid oxide cell -- Laser -- Surface modification; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.07.210
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Glass-to-metal interfaces play a crucial role in the robustness and the mechanical integrity of solid oxide cells, and it is well known that a sound interface improves the mechanical reliability of the whole stack. The present work focuses on the torsional behaviour of hourglass-shaped Crofer 22 APU stainless steel joined by a glass sealant specifically designed for this application. Specific focus was given to the Crofer surface modification by laser processing, namely, the laser fluence was varied to find suitable roughness parameters; a laser fluence of 14.1 J cm −2, leading to a Crofer surface roughness of about 4.6 μm, was selected as the optimal Crofer surface processing before the joining process. The torsional shear strength of glass-joined as-received Crofer was measured as 24 ± 7 MPa with mainly adhesive fracture mode, with failure jumping from one interface to the other, while the laser-processed Crofer gave 32 ± 5 MPa with cohesive failure. The approximate 30% increase of torsional shear strength is due to the mechanical interlocking effect given by glass infiltration inside the laser-induced protrusions on Crofer as evidenced by SEM/EDS on cross-sections and fracture surfaces after torsion tests.