Single crystal fibers

Fibers produced in this manner have some shortcomings. For example, these fibers are of very short length, no more than 5-10 cm long, and are produced rather slowly. One should also add that the only single crystal fiber produced is based on solid state polymerization of certain substituted diacetylenes and the technique does not seem to be applicable to other systrans. 

Most non-aerospace CMC applications require long service lives. For these applications CMC components must avoid creep rupture and must exhibit creep strains lower than 1 percent after 10,000 hours of service (e.g., at 1,200°C [2,192°F] and 100 MPa [14.5 ksi]) components must also be chemically and microstructurally stable. These stringent demands present major challenges to researchers and engineers, particularly for material development and accelerated testing. The performance objectives limit the material choices to polycrystalline oxides, SiC, or amorphous Si-C-N-B compositions (single-crystal fibers are not affordable). 

Fig. 9.52 Micro-pulling down setup and view of the growth of a single-crystal fiber. Reproduced with permission from [326]. Copyright 2009, Elsevier...

Figure 9.56 shows photographs of representative samples of both the undoped and Yb-doped LuAG single-crystal fibers, while laser efficiency is shown in Fig. 9.57 [329]. The laser beam could be remained unguided inside the singlecrystal fiber, with an estimated waist size of 120 pm in diameter, which was much...

Fig. 9.57 Laser efficiency of the Yb LuAG single-crystal fiber (0.8 mm diameter,...

Sangla D, Aubry N, Didieijean J, Perrodin D, Balembois F, Lebbou K et al (2009) Diode-pumped laser with Yb YAG single-crystal fiber grown by the micro-pulling down technique. Appl Phys B Lasers Opt 94 203-207... 

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