Solution Precursor Plasma Spray of Porous $La1−xSrxMnO3$ Perovskite Coatings for SOFC Cathode Application

The deposition of porous $La1−xSrxMnO3$ (LSM) perovskite cathode materials by conventional plasma spray has been a challenge because of the decomposition of perovskite materials to their suboxides at high temperature. In this paper, the solution precursor plasma spraying (SPPS) process, in which solution precursors of the desired resultant materials are fed into a direct current plasma jet by atomizing gas, was used to simultaneously synthesize LSM perovskite and deposit porous cathode coatings. The experimental results show that process parameters have a significant effect on the fabricated coatings. The perovskite coatings consist of porous agglomerates of small particles with rounded features and local denser regions referred to as thick flakes. The small particles and thick flakes were held together by the previously molten material. There are two kinds of pores in the fabricated coatings: large pores located between the agglomerates and fine pores inside the agglomerates. The porous LSM cathode coatings have $20–40area%$ of desirable homogeneous pores determined by several processing parameters. X-ray diffraction of sintered coatings shows that no suboxides of $La1−xSrxMnO3$ perovskite appear. The results of this project indicate that the SPPS is a potential process to produce high quality cathodes for solid oxide fuel cell application.