OBTENÇÃO E CARACTERIZAÇÃO DE CERÂMICAS À BASE DE CROMITAS DE LANTÂNIO

Lanthanum chromite-based ceramics are the main materials used as solid oxide fuel cell interconnects. The objective of this work is to investigate and to characterize the relationships between powder preparation methods and microstructural development process of metals doped lanthanum chromites-based ceramic systems. Calcium, strontium and magnesium-doped lanthanum chromites-based ceramic powders were produced by auto-ignition combustion process from respective metallic nitrates (with urea as fuel) and by the traditional (solid state, mixture of oxides) ceramic method. The microstructural characterization was made by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and thermal analysis techniques. The obtained results corroborate the literature comments concerning the difficulty of production of lanthanum chromite-based ceramics with high densification level and evidence the great influence of the nature of the dopants on the sintering mechanism and the microstructural and electric characteristics of the produced ceramics. Additionally, the results show that the chemical synthesized powders, showing well crystallized and sub-micrometric size particle powder, provided the production of lanthanum chromites-based ceramics with more dense and more homogeneous grain size distribution than that produced by traditional ceramic method.