Refractories zirconia-fibers

These materials offer outstanding properties, including thermal stabiUty to 2600 °C and corrosion resistance to hot aUcahs and many aggressive chemicals and melts neither are they wetted by a range of molten metals. The appUcations of zirconia refractory fibers range from highly efficient thermal insulation to separators in aerospace batteries, hot gas filters and electrolysis diaphragms (see below). 

The Chemical Abstract Service has defined these materials under the CAS number 142844-00-6 as Refractories, fibers, aluminosilicates. Amorphous man-made fibers produced from melting, blowing or spinning of calcinated kaolin clay or a combination of alumina (AI2O3) and silica (SiOa). Oxides such as zirconia, ferric oxide, magnesium oxide, calcium oxide and alkalines may also be added. 

Refractory Fibers Recently, zirconia-based insulating material with a low density and a low thermal conductivity has been developed in the form of fibers, paper, felt, board and shaped articles. The material is a cubic zirconia soHd solution stabilized with yttria, and has a maximum usable temperature of >2100 C. The innovative fabrication technique involves the use of an organic precursor fiber as a structural template, impregnated with an aqueous solution of zirconium chloride and yttrium chloride. The metallic salts are deposited within the organic fiber, which can subsequently be burned off by a controlled oxidation. The hollow remainder is then fired at a sufficiently high temperature (800-1300 °C) so as to induce crystallization, after which the oxide particles are sintered to develop a ceramic bond. Other techniques to produce refractory fibers involve phase inver-... 

Fig. 2. Thermal conductivity of refractories where ASF = aluminosilicate fiber and ZF = zirconia fiber. See Table 13 for group classifications (5,25).

Fig. 6 A schematic drawing of microwave casket (refractory specimen enclosure) composed of a hollow zirconia fiber-board material with disk-shaped aluminosilicate end caps.

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