Synthesis of nanoscale zirconium dioxide powders and composites on their basis in thermal DC Plasma

ZrO2, ZrO2–MgO, and ZrO2–Al2O3 nanopowders are obtained via oxidation of disperse ZrCl4 and its blends with (Mg, Al) metals by oxygen in a plasma reactor with confined plasma jet flow on the basis of an dc arc plasma generator. The change in the ZrCl4 rate and plasma jet enthalpy allows one to synthesize nanopowders with the specific surface area of 18–32 m2/g (Dav = 33–58 nm). The obtained nanopowders are polydisperse, consist of uniaxial spherical particles, and contain 0.25–0.75 wt % of chlorine. The dependence of the chlorine content in powders on the zirconium chloride output exhibits an extreme behavior. The ZrO2 nanopowders represent a mixture of monoclinic and tetragonal zirconium dioxide modifications with approximately equal contents. The ZrO2–MgO nanopowders (10 mol %) with the cubic structure identified as Zr0.875Mg0.125O1.875 are obtained in oxidation of the ZrCl4–Mg mixture in an oxygen–argon plasma stream. The ZrO2–Al2O3 nanopowders (30 wt %) are synthesized by oxidation of the ZrCl4–Al blend, whose phase composition is represented by tetragonal ZrO2 structure with monoclinic phase impurity in the absence of any Al2O3 phases, which can be explained by the formation of nonequilibrium Zr–Al–O solid solution with tetragonal structure as a result of the size effect. © 2015, Pleiades Publishing, Ltd.