Features of the Electrophoretic Formation of Bulk Compacts Based on Zirconium Oxide Nanopowder
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ICAL CHEMISTRY OF NANOCLUSTERS AND NANOMATERIALS
Features of the Electrophoretic Formation of Bulk Compacts Based on Zirconium Oxide Nanopowder E. G. Kalininaa,b,* a
Institute of Electrophysics, Ural Branch, Russian Academy of Sciences, Yekaterinburg, 620016 Russia bUral Federal University, Yekaterinburg, 620002 Russia *e-mail: [email protected] Received December 12, 2019; revised February 3, 2020; accepted February 11, 2020
Abstract—The possibility of forming bulk compacts via electrophoretic deposition (EPD) using a nanopowder based on yttria-stabilized zirconia (YSZ) is considered. Features of the kinetics of mass growth and changes in cell resistance and the morphology of the sediment during a long deposition time are studied using different geometries of the counter electrode of the EPD cell (flat and conical). EPD is performed with a stepwise increase in electric field strength. It is found that the shape of the counter electrode does not appreciably affect either the kinetics of changes in current or the growth of cell resistance, or the fraction of the solid phase in the wet compact in a suspension with sufficiently low conductivity (∼22.2 μS/m). Slight increases of 8– 10% in the mass of wet and dry compacts and 10.5% in the electric current are observed when a conical form of the counter electrode is used instead of a flat one. Numerical modeling is done in a two-dimensional approximation, allowing determination of the effect the counter electrode’s geometry has on the local distribution of the electric potential and current density near the electrode. Keywords: electrophoretic deposition (EPD), nanoparticle compaction, yttria-stabilized zirconia (YSZ), deposition kinetics DOI: 10.1134/S0036024420090113
INTRODUCTION One line of modern materials science is developing and improving the technology for manufacturing high-strength zirconium-dioxide-based ceramic materials [1–3]. ZrO2-based ceramics have unique properties that include resistance to aggressive environments, high melting points, and biological compatibility in addition to strength and hardness. This opens up prospects for its use in different fields of industry and medicine [4]. Other applications for the development of ceramic technology include the fabrication of highly porous ceramic foams used as heat insulating materials [5, 6]. One feature of zirconium dioxide is its polymorphism. This material exists in three crystalline modifications: monoclinic, tetragonal, and cubic, which reversibly transform into one another at certain temperatures [7]. In the last three decades, stabilizing additives (metal oxides Y2O3, CaO, MgO) that form solid solutions with zirconia have been introduced to stabilize high-temperature modifications in order to prevent polymorphic transformations [8–10]. Ceramic materials based on zirconium dioxide ZrO2 stabilized with yttrium oxide Y2O3 (YSZ) have high strength and crack resistance [11]. YSZ ceramics find application in SOFC [12, 13] and in their thin-film
versions (electrolyte thickness, 1–10 μm) [14, 15], where
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