Mechanical behavior of SOFC electrolytes based on zirconium dioxide

DOI: 10.62564/M4-MB1129

Mykola Brychevskyi

Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine


The materials based on zirconium dioxide are popular to using for high-temperature SOFCs[1]. In particular, there are occurs due to flexibility of phase and structural changes and opportunity of symmetry raising by replacing the four-valent zirconium ion with a three- or five-valent ion. This leads to the formation of an additional sublattice of oxygen vacancies [2]. But mechanical behavior is of critical importance too for a carrier-electrolyte technological scheme. Since increased mechanical properties allow to manufacturing of thinner electrolyte, which will proportionally reduce the total resistance as of the component and the device as a whole [3]. Three different starting powders of zirconium dioxide stabilized with 10 mol. % scandium oxide and 1 mol. % cerium oxide were used. One-sided pressing with follow by isothermal sintering in air in the temperature range of 1200-1550 ℃ during 1,5 hours was used to produce of ceramic specimens. The base research methods were biaxial strength studying and SEM of fracture surface. It was shown that using of initial powders to allow producing the various type ceramics with significant structure changes: porosity and sizes of effective structure components, and implement all possible fracture micromechanisms: interparticle, intergrain and cleavage fracture. The produced materials can be classified by changes of structural features with increasing of thermal influence, which are manifested with fracture surface studying. Type I material is porous, has a low recrystallization rate and was fractured exclusively by cleavage. Type II is a dense material, with has a high rerycstallization rate and has fractured by cleavage. Type III material has a high rapid recrystallization rate and intergranular fracture. It was found that the shift of activation energy of densification and grain size grow was taking place in the temperature range of 1300-1400 ℃ and was coincided with the dominant fracture micromechanism changes.

Keywords
fracture micromechanism, biaxial strength, zirconium dioxide.

Acknowledgments
Not provided

References
[1] K. C. Wincewicz, J. S. Cooper, Taxonomies of SOFC material and manufacturing alternatives, J. Power Sources, (2005). 140, pp. 280–296. [2] S. Fabris, A.T. Paxton, M.W. Finnis, A Stabilization Mechanism of Zirconia Based on Oxygen Vacancies Only, Acta Materialia, (2002), 50(20), pp. 5171-5178. [3] O Vasylyev, M Brychevskyi, Y Brodnikovskyi, The structural optimization of ceramic fuel cells, Universal J. of Chem, (2016),4 (2), pp. 31-54.