Sapphire fibers

Xiao, H. Deng, J. Pickrell, G. May, R. G. Wang, A., Single crystal sapphire fiber based strain sensor for high temperature applications, J. Lightwave Technol. 2003, 21, 2276 2283... 

Mackin, T.J., Yang, J. and Warren. P.D. (1992b). Influence of fiber roughness on the sliding behavior of sapphire fibers in TiAl and glass matrices. J. Am. Ceram. Soc. 75, 3358-3362. 

In 1991, Harrington et al. [36] reported the spectrum of 20% CO2 recorded with a 1.06-mm inner diameter and 150-mm-long hollow sapphire fiber. 

Morscher and Sayir (1995) studied the effect of temperature on the bend radius that a c-axis-oriented sapphire fiber can withstand for fibers of various diameters. They did this by performing bend stress rupture tests on these fibers... 

Available forms Structural shapes of all types, plates, rods, wire foil flakes, powder (technical and USP). Aluminum can be electrolytically coated and dyed by the anodizing process (see anodic coating) it can be foamed by incorporating zirconium hydride in molten aluminum, and it is often alloyed with other metals or mechanically combined (fused or bonded) with boron and sapphire fibers or whiskers. Strengths up to 55,000 psi at 500C have been obtained in such composites. A vapor-deposition technique is used to form a tightly adherent coating from 0.2 to 1 mil thick on titanium and steel. 

Figure 8.79 Scanning electron micrographs showing failure origins in singlecrystal alumina (sapphire) fibers a) internal pore b) surface flaw. (Courtesy of Paul Heydt.)...

FIGURE 3-21 One-hour bend stress relaxation ratio for directionally solidified eutectic YAG/alumina fibers grown by edge-defined film growth (EFG), for polycrystalline alumina-based fibers, and for c-axis sapphire fibers. Source Morscher et al., 1995. 

Davis, J.B., E. Bischoff, and A.G. Evans. 1991. Zirconia coatings for sapphire fiber-reinforced composite. Pp. 631-638 in Advanced Composite Materials, M.D. Sacks (ed.) Westerville, Ohio American Ceramic Society. 

Sayir, A. 1993. Time dependent strength of sapphire fibers at high temperatures. Pp. 691-702 in Advances in Ceramic Matrix Composites. Vol. 38 in Ceramic Transactions, N. Bansal (ed). Westerville, Ohio American Ceramic Society. 

R. L. Callender and A. R. Barron, Formation and evaluation of highly uniform aluminate interfece coatings for sapphire fiber reinforced ceramic matrix composites (FRCMCs) using carboxy late-alumoxane nanoparticles, J. Mater. Sci., 36 4977-A987 (2001). 

D. Baneijee, H. Rho, H. E. Jackson and R. N. Singh, Characterisation of Residual Stresses in a Sapphire-Fiber-Reinforced Glass-Matrix Composite by Micro-Fluorescence Spectroscopy, Comp. Sci. Technol. 61, 1639-1647(2001). 

T. J. Mackin, J. Y. Yang, C. G. Levi, A. G. Evans, Envirorunentally Compatible Double Coating Concepts for Sapphire Fiber Reinforced yTiAl, Mater. Sci. Eng., A161,285-93 (1993). 

In summary, continuous sapphire fibers are commercially available, and new YAG fibers are readily achieved with the Saphikon process, or the LHPG process (see Chapter 6), or else by the new containerless laser melt process (Chapter 4). Currently however, there is only one route known, i.e., HP-LCVD, that might eventually be capable of yielding continuous, single crystal fibers such as SiC or titanium carbide fibers. A single crystal SiC fiber by LCVD has... 

This process yields commercial single crystal sapphire fibers. A liquid pool from which the continually growing filamentary crystal is withdrawn is formed on top of a planar surface of the orifice and fed by capillaries which extend down through the orifice into a liquid reservoir. The crystal shaping or edge definition is maintained by the geometry of the top surface of the orifice and the fulfillment of a contact angle of <90 between the liquid and material from which the orifice is fabricated. 

Sapphire is produced commercially throughout the world and is used in virtually every industry. The optical, electrical, chemical, mechanical, and nuclear properties of sapphire fibers, as described in the literature [13], make them an ideal material for many applications other than their use as sensor or reinforcing fibers for metal and ceramic matrix composites. Frequently, the combination of two or more of its properties make sapphire the only material available to solve complex engineering design problems. 

Continuous sapphire fibers (Chapter 4) and continuous sheath/core bicomponent silicon carbide/carbon fibers (Chapter 3) offer impressive performance as reinforcing fibers and in ceramic and metal matrix composites. Here are some noteworthy commonalties and differences. 

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