Electrospinning of Zirconia Fibers
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ELECTROSPINNING OF ZIRCONIA FIBERS Yu. A. Balinova,1, 2 N. M. Varrik,1 A. V. Istomin,1 and G. Yu. Lyulyukina1 Translated from Steklo i Keramika, No. 8, pp. 30 – 35, August, 2020.
The possibility of obtaining zirconia ceramic fibers by electrospinning was examined. The factors affecting the fiber diameter and the presence of tape inclusions were determined. It was shown that under the action of an electric field the forming solutions make it possible to obtain fibers in a wide range of viscosities. For forming solution viscosity 0.45 – 0.69 Pa × sec the fiber production process stabilizes and the fiber diameter is comparable to that of conventionally produced fibers (0.9 – 1.5 mm). Key words: fiber, zirconia, electrospinning.
Functional ceramic composites based on oxide fibers are used to afford performance efficiency of machines in aviation, space, metallurgical, energy, and other industries [1 – 4]. Progress in the development of new designs of high-energy machines requires enhanced operational properties of materials, including the working temperature of thermal protection. Thermal protection materials based on oxide fibers, such as fibers of silica, mullite, and zirconia have a number of advantages owing to the extremely low values of the thermal conductivity and volumetric density as well as high operating temperatures [5 – 7]. The heat protection products in highest demand are flexible mats, felted cloth and batts, sealing cord, slabs, and shaped objects. Zirconia are the most refractory of the enumerated oxides; its melting temperature exceeds 2700°C. The methods for obtaining high temperature oxide fibers include: a method of permeating organic polymer cloth with a mixture of compounds of zirconium and yttrium followed by heating of the permeated cloth in an oxygen environment in order to remove organic matter and convert the metal compounds into oxides; the sol-gel method of forming short or continuous fiber from a precursor solution followed by firing; and, the method of electrospinning [8]. In recent years developers have used the electrospinning method to obtain oxide fiber. This method is based on drawing thin fibers from solutions or melts in an electric field and it is used mainly for polymer solutions. A high voltage is applied to the spinning solution with the aid of a metallic electrode; under the action of electric forces the solution drops
form an accelerating and thinning jet. Under the action of the oscillations of the electric field strength the jet changes direction and assumes a twisting form, and the jet can split into daughter jets, after which it settles on the electrode and solidifies at the same time. It should be noted that surface tension and electrostatic forces acting together can change the surface morphology of jets, and a jet can have a variable diameter, bulges, and twists. The obtained fibers are characterized by a nanosize diameter; outwardly, the product resembles a very thin, fibrous, pliant, fleecy fabric. Aside from raw materials for heat protective materials ul
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