Effect of Sr and Ca dopants on oxidation and electrical properties of lanthanum chromite-coated AISI 430 stainless steel for solid oxide fuel cell interconnect application

摘要

Lanthanum chromite coating occupies a noticeable position as a ceramic coating on metallic interconnects in solid oxide fuel cells because of its excellent electrical conductivity, high oxidation resistance and desirable chemical stability in both oxidizing and reducing atmospheres. In the present work, a sol-gel process based on the dip-coating technique was used to prepare dense and uniform coatings on metallic alloy for interconnect application (AISI 430 type). The effect of strontium and calcium doping into lanthanum chroinitc structure on electrical conductivity and oxidation behavior of the coated sample has been investigated. The oxidation behavior was evaluated by cyclic oxidation test at 800 ℃ in lab air. In addition, the area specific resistance (ASR) of the coated and uncoated samples after long-term oxidation was measured through a two-point, four-wire probe method. It was found that, for the coated sample, when compared to the bare metallic one, the addition of Ca into lanthanum chromite coating drastically lowered the oxidation rate and electrical resistance by approximately 2 and 6 times, respectively.