Caracterização termo-mecânica de interconectores metálicos recobertos com filmes de LaCrO3

The cells unitaria of the solid oxide fuel cell are separated by means of interconnects, which serve as electrical contact between the cells. Lanthanum Chromite (LaCrO3) has been the most common material used as interconnect in solid oxide fuel cells. Reducing the operating temperature around 800 º C of cells to solid oxide fuel make possibilite the use of metallic interconnects as an alternative to ceramic LaCrO3. Metallic interconnects have advantages over ceramic interconnects such as high thermal conductivity, electricity, good ductility, low cost, good physical and mechanical properties. In this work evaluate the thermo-mechanical properties of the metallic substrate and coated metallic substrate with the ceramic LaCrO3 film via spray-pyrolysis, in order to demonstrate the feasibility of using this material as a component of a fuel cell solid oxide. The materials were characterized by X-ray diffraction, oxidation behavior, mechanical strength, optical microscopy (OM) and scanning electron microscopy (SEM). The X-ray diffraction proved the formation phase of the LaCrO3 on the metallic substrate and the identification of the phases formed after the oxidative test and mechanical strength at high temperature. The oxidation behavior showed the increased oxidation resistance of the coated metallic substrate. It was noted that the mechanical resistance to bending of the coated metallic substrate only increases at room temperature. The optical microscopy (OM) has provided an assessment of both the metallic substrate and the LaCrO3 film deposited on the metal substrate that, in comparison with the micrographs obtained from SEM. The SEM one proved the formation of Cr2O3 layer on the metallic substrate and stability of LaCrO3 film after oxidative test, it can also observe the displacement of the ceramic LaCrO3 film after of mechanical testing and mapping of the main elements as chromium, manganese, oxygen, lanthanum in samples after the thermo-mechanical tests.

Síntese e caracterização de espinélios a base de Cu, Fe e Cr para pigmentos cerâmicos

Inorganic pigment comprises a host lattice, which is part of the chromophore component (usually a transition metal cation) and possible components modifiers, which stabilize, add or restate the properties pigments. Among the materials with spinel, ferrites, and the chromite stand out, because they have broad technological importance in the area of materials, applicability, pigments, catalytic hydrogenation, thin film, ceramic tiles, among others. The present work, pigments containing CuFe2O4, CuCr2O4,e CuFeCrO4, were synthesized by a method that makes use of gelatin as organic precursor using their application to ceramic pigments. The pigments were characterized by X-ray diffraction (XRD), Infrared spectroscopy, scanning electron microscopy (SEM) spectroscopy in the UV-visible and Colorimetry. The results confirmed the feasibility of the synthetic route used, with respect to powders synthesized, there is the formation of spinel phase from 500°C, with an increase in crystallinity and the formation of other phases. The pigments were shown to be crystalline and the desired phases were obtained. The copper chromite have hues ranging from green to black according to the calcination temperature, while the copper chromite doped with iron had brownish. The ferrites showed copper color and darker brown to black, which may indicate an interesting factor because of the importance of black pigment

Estudo termo-mecânico de interconector metálico recoberto com filme de La0,8Ca0,2CrO3 e de interconector cerâmico de La0,8Sr0,2Cr0,92Co0,08O3 para PaCOS

Doped lanthanum chromite ( LaCrO3 ) has been the most common material used as interconnect in solid oxide fuel cells for high temperature ( SOFC-HT ) that enabling the stack of SOFCs. The reduction of the operating temperature, to around 800 º C, of solid oxide fuel cells enabled the use of metallic interconnects as an alternative to ceramic LaCrO3, From the practical point of view, to be a strong candidate for interconnect the material must have good physical and mechanical properties such as resistance to oxidizing and reducing environments, easy manufacture and appropriate thermo-mechanical properties. Thus, a study on the physic-mechanical interconnects La0,8Sr0,2Cr0,92Co0,08O3 ceramics for SOFC -AT obtained by the method of combustion , as well as thermo-mechanical properties of metallic interconnects (AISI 444) covered with La0,8Ca0,2CrO3 by deposition technique by spray-pyrolysis fuel cells for intermediate temperature (IT-SOFCs). The La0,8Sr0,2Cr0,92Co0,08O3 was characterized by X -ray diffraction(XRD) , density and porosity , Vickers hardness (HV) , the flexural strength at room temperature and 900 °C and scanning electron microscopy (SEM). The X -ray diffraction confirmed the phase formation and LaCrO3 and CoCr2O4, in order 6 GPa hardness and mechanical strength at room temperature was 62 MPa ceramic Interconnector. The coated metal interconnects La0,8Ca0,2CrO3 passed the identification by XRD after deposition of the film after the oxidation test. The oxidative behavior showed increased resistance to oxidation of the metal substrate covered by La0,8Ca0,2CrO3 In flexural strength of the coated metal substrate, it was noticed only in the increased room temperature. The a SEM analysis proved the formation of Cr2O3 and (Cr,Mn)3O4 layers on metal substrate and confirmed the stability of the ceramic La0,8 Ca0,2CrO3 film after oxidative test