Thermal Spray Deposition of Fuel Cell Interconnect Material

In this work two different thermal spray techniques were used to deposit La_0.9Sr_0.1CrO₃ interconnect material: high velocity oxy-fuel (HVOF) using a modified nozzle and atmospheric plasma spray (APS). Two different APS torches were employed: A commercial torch that uses Ar/H₂ as plasma forming gases and a new torch design that uses CO₂ gas mixtures. A substitute powder with similar physical properties to La_0.9Sr_0.1CrO₃ was employed for the development and optimization of the process parameters to achieve the highest density before the deposition of the La_0.9Sr_0.1CrO₃ on zirconium oxide substrates. The microstructures observed by scanning electron microscopy (SEM) and the phase composition of the coatings obtained from X-ray diffraction analysis are correlated to the spraying characteristics of the different techniques employed. The electrical resistivity of the as-sprayed coatings is discussed in terms of microstructure features and the phase composition. Post-deposition heat treatments were studied in order to reduce the electrical resistivity.