No abstract

One challenge for advancing solid oxide fuel cell (SOFC) technology is to develop interconnect materials with adequate conductivity and stability for efficient long-term use. Proposed here is a technology for effectively modifying the surface of SOFC current collectors and significantly reducing the oxidation rate of ferritic stainless steel at elevated temperatures and high current densities. The formation of "Kirkendall voids" at the Crofer 22 APU ferritic stainless steel-intermetallic compound interface was observed and investigated. The Kirkendall voids play the role of a barrier layer blocking Cr diffusion to the surface and suppressing the formation of the resistive Cr2O3 surface layer. Long-term test measurements showed that the ASR value of the current collector-LSM junction decreases two times during the first 3000 hours and subsequently remains constant.

The modified method of electrostatic spray pyrolysis was designed to apply protective coatings based on Mn-Co spinel to ferritic stainless steels (Crofer22APU and 08X18T1). The comparative thermogravimetric (TG) studies of ferrite stainless steels with and without protective coatings were carried out. The electrochemical characteristics of protective coatings exposed to long current loading were studied. The formation of the Mn-Cr spinel observed and studied at the contact between the ferrite stainless steel and the Mn-Co spinel. The coatings of Mn-Co spinel were shown preventing formation of continuous Cr2O3 oxide film on the stainless steel surface.