Oxide fibers

Two types of oxide fibers are known, mainly used as a reinforcing agent for high-temperature composites - single-crystal and eutectic threads and rods, as well as nanostructured threads. The first type of fiber is obtained by melt crystallization by methods based on the Stepanov concept (EFG (Edge-defined Film-fed Growth) and micropulling-down), LHPG (Laser Heated Pedestal Growth), as well as internal crystallization. The second type of fiber is produced using procedures traditional for powder metallurgy (slip, sol-gel ).

Single crystal and eutectic fibers are stable at high temperatures and are characterized by high creep resistance (creep resistance). For example, the fibers of mullite (2Al ₂ O ₃ ∙ SiO ₂ ) and yttrium-aluminum garnet (YAG, Y ₃ Al ₅ O ₁₂ ) are creep-resistant at temperatures up to 1600 ° С.

Polycrystalline fibers recrystallize at high temperatures and lose their initial nanocrystalline structure at temperatures of 1100–1300 ° С, depending on the composition and exposure time. The most creep-resistant of them, which are a mixture of mullite and alumina, can be used for a long time at temperatures up to 1300 ° C.

Oxide fibers are used in composites with nickel and oxide matrices. Inexpensive fibers that are not distinguished by high strength can be used as thermal insulation.

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