Enhancing the long-term stability of Ag based seals for solid oxide fuel/electrolysis applications by simple interconnect aluminization. (28th January 2019)

• Record Type: Journal Article
• Authors: Si, Xiaoqing; Cao, Jian; Ritucci, Ilaria; Talic, Belma; Feng, Jicai; Kiebach, Ragnar
• Is Part Of: International journal of hydrogen energy. Volume 44:Number 5(2019)
• Page Start: 3063
• Page End: 3074
• Publication Date: 2019-01-28
• Subjects: Reactive air brazing -- Aluminization -- AgCuO braze -- Solid oxide fuel cell -- Solid oxide electrolysis cell -- High temperature corrosion; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2018.11.071
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Ag-(0–8 mol%) CuO is used to successfully join aluminized ferritic stainless steel interconnect to the ceria-gadolinia (CGO) barrier layer of a solid oxide fuel/electrolysis cell by reactive air brazing at 1000 °C in air. The wetting of AgCuO on CGO is tailored by varying the CuO content. The effects of the CuO content on the joint microstructure are discussed. The long-term stability of brazed joints is evaluated by aging in oxidizing (air) and reducing (4% H2 –50% H2 ON2 ) atmospheres at 800 °C for 250 h. An Ag-2mol% CuO braze results in the best joint stability during aging. Aluminization of the steel to create an alumina surface layer provides excellent protection of the steel both during the joining process and aging in the 2 atm. No degradation related to steel corrosion and outward diffusion of elements from the steel can be observed. Graphical abstract: Highlights: A dense Al2 O3 layer (∼2 μm) is formed on Crofer 22 H by reactive air aluminization. Al2 O3 layer blocks the reaction between AgCuO braze and Crofer 22 H substrate. Al2 O3 layer hinders outward diffusion of Fe, Cr and Mn from Crofer 22 H during aging. Ag-2 mol% CuO provides good balance between sufficient wetting and minimal reaction.