Fiber zirconia

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

Figure 6.5 (a) Microstructure of an alumina fiber. TEM. (b) Microstructure of an (alumina+zirconia) fiber. SEM. The white particles are zirconia. 

A sol-gel method is used to produce silica-stabilized alumina (Saffil) and calda-stabilized zirconia fibers. The flow diagram for Saffil fiber is shown in Fig. 

FIGURE 12.7 (a) Scanning electron micrograph (SEM) of a mullite matrix CMC reinforced with submicronic zirconia (fiber diameter 12 pm), (b) TEM of a cobalt dispersion in an aluminosilicate matrix synthesized by the infiltration-H2 firing route. ... 

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.

Since the initial introduction of laser diffraction instrumentation in the 1970s, many different applications to panicle si/e aniilysis have been reported. Ihese have included measurements of si/e distributions of radioactive tracer particles, ink particles used in photocopy machines, zirconia fibers, alumina particles, droplets from electronic fuel injectors, crystal growth particles, coal powders, cosmetics, soils, resins, pharmaceuticals, metal catalysts, electronic materials, phoiugraphic emulsions, organic pigments, and ceramics. About a dozen instrument companies now produce LALLS instruments. Some I.AI.LS instruments have become popular as detectors for size-exclusion chromatography. 

The oldest process known to yield zirconia fibers is the relic process [12] [83] [84]. The simplest process is a dry spinning process using a concentrated, aqueous solution of a zirconium salt [85-86]. Neither yields technically advanced fibers. The latter are best prepared by dry spinning and heat treatment of sol-gel derived or polyzirconoxane derived precursor fibers. 

M. E. Khavari, F. F. Lange, P. Smith and D. B. Marshall, Continuous spinning of zirconia fibers, relations between processing and strength, in Better Ceramics through Chemistry III, C.J. Brinker, D.E. Clark, D.R. Ulrich, eds.. Mater. Res. Soc. Symp. Proc., 21,617 (1988). 

B. Clauss, A. Grub and W. Oppermann, Continuous yttria-stabilized zirconia fibers, Adv. Mater., 8 [2], 142-146(1996). 

C. Sakurai, T. Fukui and M. Okuyama, Hydrolysis method for preparing zirconia fibers, Ceram. Bull., 7 [4], 673-674(1991). 

Zirconia fiber cloths, such as those made by the relic process (see Chapter 8), are used as separators in aerospace nickel-hydrogen and nickel-cadmium batteries [9j. These fibers display a high resistance to many corrosive media, including hot potassium hydroxide. Zirconia fiber felts are also present in aerospace solid oxide fuel cells. 

Oxide fibers include glass fibers, mullite fibers, zirconia fibers and alumina fibers. Of these, a-alumina-based fibers have been used intensively for ceramic matrix composites. Fiber FP, manufactured by Du Pont in 1979, was the first wholly a-alumina fiber produced [34]. At present, Almax (Mitsui Mining Material Co. Ltd., Japan) and Nextel 610 (3M Co., USA) are commercially available a-alumina fibers. Almax contains 99.5% alumina and has an elastic modulus of 330 GPa, and Nextel 610 has a tensile strength of 2.4 GPa and an elastic modulus of 380 GPa [35]. 

In addition to the single fiber formation, the alumina and/or zirconia fiber mats having web-like microstructure were produced by using the centrifugal spinning technique (Venkatesh et al., 1999 Chatleijee et al., 2002a). 

Katagiri Y., Nasu H., Matsuoka J., Kamiya K. Sol-gel preparation and optical nonlinearity of lead(II) oxide-titaninm(IV) oxide amorphous monoliths. J. Am. Ceram. Soc. 1994 77 673-677 Khavari M.E., Lange F.F., Smith P., Marshall D.B. Continuous spinning of zirconia fibers relation between processing and strength. Mater. Res. Soc. Symp. Proc. 1988 121 617-621 Kim C.E., Park Y.I., Lee H.W. Preparation of PbTiOs fibres using triethanolamine-complexed alkox-ide. J. Mater. Sci. Lett. 1997 16 96-100... 

Abe Y., Kudo T., Tomioka H., Gunji T., Nagao Y., Misono T. Preparation of continuous zirconia fibers from polyzirconoxane synthesized by the facile one-pot reaction. J. Mater. Sci. 1998 33 1863-1870... 

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