Process for manufacturing boron nitride fiber batts using a spinner
AssigneeKennecott Corporation
InventorsJohn L. Tworek, Gordon R. Rignel
Life of this patent
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Abstract
A process is disclosed for producing non-woven, yet internally cohesive, boron nitride fiber batts, suitable for use as an electric cell separator in a lithium-sulfide battery. Molten boron oxide is centrifugally spun into strands and attenuated by an annular gas stream into fibers at a controlled relative humidity. The fibers are funnelled into a chamber and subjected to a turbulent air flow, which causes random orientation and intertwining of the fibers, resulting in multiple mechanical bonds thereamong. The compacted boron oxide fiber bundle thus produced is heated in an anhydrous ammonia atmosphere to convert boron oxide in the fibers into boron nitride (BN).
Claims8
A process for producing non-woven, internally cohesive, boron nitride fiber batts, comprising the steps of:
- melting solid boron oxide;
- extruding the molten boron oxide from a rapidly spinning drum having a plurality of circumferentially arranged perforations, whereby said molten boron oxide is extruded through said perforations into a plurality of strands;
- directing an annular gas stream at a temperature in excess of 700.degree. C. obliquely against each of said strands to attenuate said strands into fibers said temperature being of an intensity and duration to cause the fibers to become sticky and bond together;
- subjecting said fibers to a turbulent air flow sufficient to cause random orientations and intertwining of the fibers;
- collecting said fibers into a bundle;
- and
- heating said bundle in an anhydrous ammonia atmosphere to a sufficient temperature and for a sufficient time to convert essentially all boron oxide in the fibers into boron nitride.
Dependencies are inferred from the claim text.