Crystal aluminas

Edge defined, film-fed, growth process for making a single-crystal alumina fibre (reproduced by permission of Chapman Hall)56. 

Figure 8.2 Thermal conductivity as a function of temperature for various solids [2][3]. The two traces of single-crystal alumina were from separate investigations.

Figure 6.11 Schematic of the edge-defined fihn-fed growth (EFG) method of making a single crystal alumina fiber.

In the present work, palladium catalysts supported on a well-crystallized alumina, the a-alumina, and a transition alumina were studied. The state of the catalysts was examined after a reproducible standard test procedure and the catalysts samples were characterized by different physicochemical techniques. 

Table 5 Elastic properties of single crystal alumina at room temperature [2, 15] in GPa...

H.M. Kizilyalli and P.R. Mason, DC and AC electrical conduction in single crystal alumina, Phys. Status Solidi 36, 499 (1976). 

Figure 2.2 Classification of biomaterials according to their bioactivity (a) bioinert single crystal alumina dental implant, (b) bioactive hydroxyapatite [Ca10(PO4)6(OH)2]...

It is experimentally well established that the fracture toughness of a polycrystalline ceramic is appreciably higher than that of single crystals of the same composition. For example, Ki. of single-crystal alumina is about... 

Figure 34.3 shows the thermal conductivity of single crystal alumina as a function of temperature. At very low temperatures the mean free path, /, of the phonons becomes comparable to the size of the specimen and k depends mainly on the heat capacity, which increases with T. The thermal conductivity reaches a maximum at some low temperature ( 40 K in this case). As the temperature increases k decreases because there are more phonons... 

In Figure 3-21, BSR data (one hour) for several oxide fibers are compared, including the single-crystal alumina monofilament (Morscher et al., 1995)... 

Ceramics, inorganics, and glasses Bioactive glasses, bioactive glass/ceramics, high-density alumina, hydroxylapatite, single-crystal alumina, zirconia Carbons... 

GPa for single crystal alumina fibers. The overall trend reflects the weight percent increase in alumina. Differences in each category reflect super-imposed effects of other oxides (not shown) or process-induced differences. 

The main interest of YAG fibers is their creep resistance. The BSR behavior of polycrystalline fibers prepared from diphasic gel [107] is intermediate between those of commercially available alumina based polycrystalline fibers (except coaindum/mullite Nextel 720) and that of monocrystalline sapphire (c-axis) fiber. Hence, the creep resistance of polycrystalline YAG fibers (m = 0.5 at 1300°C for a 1 h BSR test) represents a significant improvement over that of the other alumina based fibers (m = 0.5 at 950-1100°C). However, it is much lower than the creep resistance of the monocrystalline fibers. Polycrystalline YAG creeps four orders of magnitude faster than single crystal alumina and five orders of magnitude faster than single crystal YAG. 

ALUMINA (fused) ALUMINA (SINGLE crystal) alumina (sintered) ALUMINA (tabular) CORUNDUM. Alumina Cement. See high-alumina CEMENT. 

Sapphire. Single-crystal alumina sapphire boules can be made by the VERNEUiL PROCESS (q.v.) and find use as bearings and thread guides. 

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