Abstract No.:
3962

 Scheduled at:
Thursday, May 22, 2014, Hall A 1:40 PM
Plasma Spraying 2


 Title:
Process effect on chemistry, microstructure and functional properties of plasma sprayed lanthanum strontium manganites for oxide scale protection in SOFCs

 Authors:
Su Jung Han / Center for Thermal Spray Research/Stony Brook University, NY
Yikai Chen / Center for Thermal Spray Research / Stony Brook University, USA
Richard Gambino/ Center for Thermal Spray Research / Stony Brook University, USA
Sanjay Sampath*/ Center for Thermal Spray Research / Stony Brook University, USA

 Abstract:
LSM perovskite coatings are produced via air plasma spray technique to protect Cr-poisoning into the cathode side from the metallic interconnect of SOFC. Various spray conditions have been manipulated such as fuel ratio, current and mass flow rate in order to understand process effect on the coating properties as well as performances. Particle temperature and velocity are investigated to visualize thermal and kinetic energies of LSM particles in the plasma plume by particle diagnostics. Coating density increases with increasing thermal and kinetic energies of the LSM particles. However, phase decomposition also occurs when the material is exposed to high temperatures for longer periods because of preferential loss of oxygen and manganese. Particularly, the amount of Mn loss is primarily governed by the process temperature not by dwell time. La2O3 secondary phase is also formed in high temperature processed LSM coatings with residual La cations after breaking stoichiometry by Mn loss. Due to hygroscopic property of La2O3, the Cr-oxide scale grows toward the LSM coating faster rate than without LSM layer, but lower temperature processed LSM coatings show oxide scale blocking effect with lowering rate about 70 % at 800 oC for 600 hours. Furthermore, Electrical conductivity of lower temperature processed coatings show up to 60 S/cm at 800 oC and higher than those of high temperature processed about 1 order of magnitude despite porous microstructure. Both oxidation test and electrical conductivity results indicate that keeping LSM stoichiometry plays significant role in protection performance without impeding electron flow. Thus, plasma spray can be a possible solution process of Cr-poisoning protection layer with its fast and economic benefits.

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