Process for manufacturing boron nitride fiber mats using calender rolls
AssigneeKennecott Corporation
InventorsJohn L. Tworek, Gordon R. Rignel
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Abstract
A process is disclosed for producing a non-woven, boron nitride-bonded boron nitride fiber mat, suitable for use as an electric cell separator in a lithium-sulfide battery. A web having a combination of structural boron nitride (BN) fibers and interstitial, thermally bondable boron oxide (B.sub.2 O.sub.3) fibers is passed through the nip of a pair of cooperating calender rolls at an appropriate temperature and pressure to soften the boron oxide binder throughout the web to fuse the BN fibers together. The interstitial boron oxide then is heated in an anhydrous ammonia atmosphere to convert it into boron nitride.
Claims10
A process for producing a boron nitride-bonded vitreous fiber mat from a web having a dispersion of said vitreous fibers with interstitial thermally bondable boron oxide fibers, comprising the steps of:
- passing said web through the nip of a cooperating pair of calender rolls, at least one of which said rolls is heated to a temperature sufficient to soften said boron oxide fibers, so as to fuse together said vitreous fibers;
- and
- heating the calendered web in an anhydrous ammonia atmosphere at a sufficient temperature for a sufficient time to convert essentially all of said interstitial boron oxide into boron nitride.
Dependencies are inferred from the claim text.