Desenvolvimento de eletrodo FGM a base de Ni-zircônia para célula a combustível de sólido óxido
Abstract
The search for alternatives sources to fossil fuel has stimulated the
technological development of solid oxide fuel cell. Hydrogen is the ideal fuel for
this application. However, due to technical reasons, alternatives fuels to
hydrogen such as methanol and natural gas has been tested. Therefore, the
use of these fuels makes necessary the substitution of the anode materials that
are normally used with hydrogen. The anode materials substitution must be
based on the knowledge about the relationship between anode microstructure
and its performance during cell operation. This knowledge makes possible
introduce new materials besides new fabrication process for solid oxide fuel cell
anodes. The main characteristics of anode are: high chemical activity and
durability. The durability of the anode can be attained using FGM material that
makes possible to match the thermal expansion of the interfaces. Ni-8YSZ
cermet is normally used as anode material. In this work it was studied the
cermets Ni-8YSZ as electrodes on the YSZ electrolyte. Two types of electrodes
were prepared: with and without compositional gradient along the electrode
thickness. This work was developed in two steps. The first one was the
development of the powder 8YSZ-NiO suspension with the appropriated
rheological characteristics. The second one was the electrodes characterization
by impedance spectroscopy and scanning electron microscopy. It was found
that electrodes containing layers with ≤30 vol% Ni are inefficient to promote the
reactions because de Ni particles are not percolated.