Communication—Reactive Sintering of a CoFe₂O₄Coating on Ferritic Stainless Steels for SOFC Interconnect Application

Abstract

A mixed Fe+CoO precursor was successfully utilized to synthesize a dense CoFe 2 O 4 spinel coating on the Crofer 22 APU interconnect via reactive sintering at 900 • C for 2 h in air without the use of any reduction treatment. Both the uncoated and coated samples were subject to thermal oxidation at 850 • C for 500 h in air. Phase constituents, microstructure, and area specific resistance (ASR) of the uncoated and coated samples before and after the oxidation testing were evaluated. The CoFe 2 O 4 layer effectively reduced the Cr 2 O 3 scale growth and lowered the scale ASR.

Effect of Off-Stoichiometry on Electrical Conductivity in Ni-Fe and Mn-Co Spinel Systems

“…Furthermore, while the sinterability of the spinels is normally poor, an innovative approach has been identified to dramatically lower their sintering temperature to close to the stack firing/operating temperatures, making the utilization of spinel-based contact materials an appealing alternative to the conductive perovskites. 14,58…”

Investigation of high‐entropy alloy derived spinel‐based layer for SOFC cathode‐side contact application

“…Different systems of binary spinels, including Mn-Co, Ni-Co, Ni-Fe, and Cu-Mn, have been evaluated and investigated as contact materials in previous reports [12][13][14][15]. The spinels typically possess reasonable conductivity and excellent Cr-blocking ability [16][17][18][19][20][21]. Furthermore, it has been demonstrated that the modification of the spinel by adding different dopants can contribute to better performance, such as electrical conductivity and CTE [22][23][24][25][26].…”

Highly-Conductive and Durable SOFC Cathode-Side Contact Based on Reactively-Sintered Mn-Co Spinel

“…1,7,8 One of the key concerns for spinelbased contact is their poor sinterability, which could be addressed via the utilization of an environmentally-assisted reactive sintering mechanism with at least one metal-containing powder in the contact precursor layer. 1,[7][8][9][10] Despite having excellent static long-term stability, the performance of SOFC decays rapidly in thermal shock due to its multilayered feature, thus restricting its application as auxiliary power supplies where frequent, rapid thermal cycling is expected. Even in stationary application, SOFC experiences cooling and restarting for hot standby, emergencies such as unexpected interruption of gas supply and partial maintenance, which could lead to thermal stress generation and subsequent stack durability concerns.…”