Influence of the Working Media of Fuel Cells on the Structure and Physicomechanical Characteristics of Ceramics of the Z
- PDF / 4,937,443 Bytes
- 7 Pages / 594 x 792 pts Page_size
- 27 Downloads / 227 Views
INFLUENCE OF THE WORKING MEDIA OF FUEL CELLS ON THE STRUCTURE AND PHYSICOMECHANICAL CHARACTERISTICS OF CERAMICS OF THE ZrO 2 – Y2O 3 –NiO SYSTEM B. D. Vasyliv,1 V. Ya. Podhurska,1 O. P. Ostash,1,2 I. O. Polishko,3 E. M. Brodnikovs’kyi,3 S. E. Ivanchenko,3 and O. D. Vasyl’ev3
UDC 539.4.015: 666.3
We study the properties of ZrO 2 – Y2O 3 –NiO ceramics obtained by using the technologies of sintering of powders and tape casting in the intact state and after one-time reduction both in pure hydrogen and in Ar–5% H 2 and N 2 –10% H 2 –5% CO 2 mixtures. It is demonstrated that, by using the technology of tape casting, it is possible to obtain materials for anodes-substrates of solid-oxide fuel cells with smaller grains and a more uniform structure, which improves their strength characteristics. It is shown that, in the hydrogen-containing medium containing carbon dioxide ( N 2 –10% H 2 –5% CO 2 ), the strength of 8YSZ–Ni cermet decreases as its electric conductivity increases as compared with the material reduced in the Ar–5% H 2 mixture. Keywords: solid-oxide fuel cells, 8YSZ–NiO ceramic system, hydrogen, carbon dioxide, structure, strength, electric conductivity.
Introduction A fuel cell (FC) is an electrochemical device that transforms chemical energy into electrical energy. At present, there are various types of available FC but the so-called solid-oxide fuel cells (SOFC) prove to be most efficient. As an additional advantage of SOFC, we can mention the possibility of application, not only of hydrogen but also of some other types of fuel. Thus, they may also operate on carbon monoxide and hydrocarbons (methane, etc.) [1, 2]. The ceramics of the ZrO 2 – Y2O 3 –NiO system is the material most often applied material for the production of the anode-supported SOFC. After reduction in working hydrogen-containing media, the ZrO 2 – Y2O 3 –Ni cermet must have a high electric conductivity, satisfactory strength (≥ 100 MPa), a coefficient of thermal expansion comparable with the corresponding coefficient of the electrolyte, and porosity of 25–35% [3]. Various admixtures ( H 2O , H 2S , CO 2 , etc.) present in the working media of FC may lead to the in-service degradation of the anode material, which manifests itself in the loss of catalytic ability of nickel caused by the deposition of carbon on its surface, changes in the morphology and properties (e.g., in the strength and conductivity of the material) as a result of the diffusion of carbon, and the formation of nickel compounds, in particular, with sulfur [1, 4–6]. Supporting anodes are traditionally made of ceramic materials obtained by the method of powder sintering [7]. However, the procedure of tape casting is now regarded as the most promising among the technologies 1 2 3
Karpenko Physicomechanical Institute, Ukrainian National Academy of Sciences, Lviv, Ukraine. Corresponding author; e-mail: [email protected].
Frantsevych Institute for Problems in Materials Science, Ukrainian National Academy, Kyiv, Ukraine.
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vo
Data Loading...
