A Novel Method for Evaluation of Chromium Evaporation from Solid Oxide Fuel Cells Interconnects: A Feasibility Study

The evaporation of volatile chromium species from ferritic stainless steels (FSSs) used as interconnect is well-known as degradation source for planar solid oxide fuel cell (SOFC) stacks. This work presents a feasibility study to quantify chromium evaporation from FSSs. It is based on measuring carbon dioxide produced by an intermediate reaction. Cr evaporated is collected by sodium carbonate forming sodium chromate and carbon dioxide. Measuring the resulting carbon dioxide allowed to quantify online the amount of reacted chromium with the carbonates. The post-experiment quantification of sodium chromate confirmed the applicability of the proposed method.

Chromia Evaporation of Ferritic Stainless Steel AISI430 Coated by (La,Sr)CrO3 Perovskite and Mn-Co Oxide Spinel

A ferritic stainless steel has been intensively studied for its potential in application as an interconnect for a solid oxide fuel cell (SOFC). However, at such a high operating temperature chromia in the gaseous phase can contaminate the cathode of the SOFC, and consequently the performance of the device degrades rapidly. To overcome this problem, two kind of ceramics, (La,Sr)CrO3 perovskite and Mn-Co oxide spinel were prepared as coatings on the stainless steel AISI 430 to investigate on chromia evaporation at 800°C. In this present work, the (La,Sr)CrO3 and Co-Mn layers were formed by a sol-gel dip coating and an electrodeposition technique, respectively. The coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), rates of oxidation and rates of chromia evaporation. The coated specimens exhibited the protective behavior with a lower rate of oxidation, as well as a lower rate of chromium evaporation than the uncoated specimen both in the atmosphere of dry and humidified oxygen. But the reduction of the chromia evaporation rates of (La,Sr)CrO3 coatings was insignificant due to the presence of Cr2O3 phase in the coatings.