Plasma Spraying of Lanthanum Chromite Films for Solid Oxide Fuel Cell Interconnection Application

This paper discusses a novel plasma-spraying process for depositing dense LaCrO{sub 3}-based interconnection for solid oxide fuel cells (SOFCs). Calcium aluminate was mixed with LaCrO{sub 3} in a slurry containing PVA binder and spray dried to form free-flowing agglomerates. These free-flowing agglomerates were plasma sprayed onto a porous substrate of doped LaMnO{sub 3} and then heat-treated to form a gas-tight and electrically conducting interconnection. Samples of the plasma-sprayed interconnection were characterized for morphology, phase constituents, and coefficient of thermal expansion, as well as electrical resistivity and oxygen nonstoichiometry at 1,000 C in the P{sub O{sub 2}} range from 1 to {approximately}1 {times} 10{sup {minus}16} atm. The calcium aluminate additive was found to facilitate densification of the interconnection, most likely through the formation of low-temperature melting phase(s) in the system Ca-Cr-Al-O. A SOFC with such a plasma-sprayed interconnection was fabricated and electrically tested. This cell exhibited good electrical performance, and the interconnection was stable under fuel cell operation conditions.