Abstract
Solid oxide fuel cell (SOFC) convert chemical energy directly into electrical energy with high energy conversion efficiency. The cathode material properties, such as chemical composition, grain size, microstructure, concentration of porosity, electric and ion conductivity are of great influence of the output performance. La1-XSrXMnO3 (LSM) is common application materials in the cathode. A number of fabrication approaches have been investigated to make thin-file SOFC to minimize ohmic and polarization losses in the fuel cells. Plasma spray coating was used to fabricate LSM in present work. To compare with other processes such as sintering process, it has some advantages including the strong mechanical bonding, lower cost and high deposition rate taking relatively short production time. The structure of sample was characterized by X-ray powder diffraction (XRD), X-ray absorption near edge structure (XANES), scanning electron microscope (SEM), X-ray fluorescence spectroscopy (XRF), inductively coupled plasma-atomic emission spectrometer (ICP-AES), electron probe microanalyzer (EPMA) and the method of four point probe. Different kinds of analysis help us to understand the suitable parameters used in the process. From the analysis of the XRD, the perovskite structure was observed in all samples and the XANES showed the atoms pile with body centered lattice. The grain size of LSM was about 4 ~10 μm from the measure of SEM. XRF, ICP-AES and EPMA were used to find out the ratio of composition for each element. Finally, the method of four point probe tested the resistivity. It is successful to fabricate the perovskite structure of LSM by 8.8 kW plasma spray gun. The liquid precursor is the essential point to decrease the required power. The rate of coating thickness is about 1 μm/min, it is faster than the other traditional manufacture. However, plasma spray coating may fabricate impure crystal because of unstable flame and various ratio of input solution. Also, the coating yield on the substrate is small if the distance to the flame is not close enough. To combine all of the experimental results above, it is feasible to produce La1-XSrXMnO3 thin film by plasma spray coating with low power gun.