In the present work niobium based complex cubic perovskite oxide Ba 2 AlNbO 6 ceramics were produced, characterized and their stability in crude petroleum environment was studied for inert ceramic embedding used in petroleum extraction. Ba 2 AlNbO 6 ceramic powder was prepared by means of thermo-mechanical processing. Structural characteristics of calcined material were investigated by powder X -ray diffractometry, which presented a single phase complex cubic perovskite structure with lattice parameter a = 8.3418 Å. Compacted Ba 2 AlNbO 6 ceramics were sintered at 1150ºC during 72 hours in ambient atmosphere. The microstructure of the sintered ceramics was studied by scanning electron microscopy and mechanical behavior was studied by Vicker's micro-hardness testing. The sintered ceramics were submerged in crude petroleum for 60 days. The ceramics were taken out from petroleum periodically and subjected to structural, microstructural and mechanical characterizations. The results showed that the ceramics submerged in crude petroleum did not suffer any change at any stage of submersion. These characteristics make this material suitable for inert ceramic embedding for sensors used in petroleum extraction.

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Ceramic matrix composites have attracted the interest of turbine manufacturers for use in coating hot sections because of their higher capacity to withstand high temperatures and because they have a lower requirement for air cooling. One of the most commonly used ceramic coatings is zirconia-yttria. However, its main disadvantage is the inherent fragility of ceramics, which limits the use of these materials in mechanical structures and industrial applications. Ceramics are generally reinforced with the incorporation of additives to reduce their brittleness and increase their mechanical strength and toughness. It is known that La2O3 which are potential source for stabilization of zirconia composites. In this context, ZrO2-Al2O3-La2O3 based ceramic matrix composites were developed for deposition of a thermal barrier coating on the substrate of exhaust nozzles of aerospace turbines varying the content of La2O3 by 5, 7 and 10 wt%. The composites were produced by a thermomechanical process and sintered at 1385 °C. The properties of these composites were studied by X-ray diffraction, relative density, scanning electron microscopy, and Vickers microhardness tests. The results indicate that the composite with 10% La2O3 has great potential for use as ceramic coatings of turbine exhaust nozzles in the aerospace industry.

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