Viscous sintering with crystallization

The principal processing parameters that control reaction sintering and viscous sintering with crystallization were considered. For such systems, successful fabrication generally depends on the ability to achieve a processing path in which full densification occurs prior to the reaction (reaction sintering) or in which full densification occurs prior to crystallization (viscous sintering). 

Commercial polycrystalline oxide fibers are produced by spinning and hydrolyzing precursors. First a fiber precursor solution is filtered and concentrated to remove excess solvent, forming a viscous spin dope. Then, continuous filaments are extruded by spinning. The filaments are pyrolyzed to remove volatile components and then heat treated above 800X (1,472°F) to crystallize and sinter the fiber. Polycrystalline oxide fibers are produced in tows of200 to 1,000 fibers with diameters of 10 to 16 pm (0.39 to 0.63 mils). Typical ranges of properties are listed in Table ES-1. 

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