A HIGH-PURITY POWDER OF HEXAGONAL BORON NITRIDE AND A METHOD FOR THE PREPARATION THEREOF

The invention provides a method for the preparation of an upgraded high-purity powder of hexagonal boron nitride still having low crystallinity to retain activity for sintering. The first method comprises the steps of admixing a crude powder of hexagonal boron nitride with a carbonaceous material an...

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Hauptverfasser:	KOSHIDA, TAKAHISA RESEARCH LABORATORIES, KOITABASHI, TOSHIMITSU RESEARCH LABORATORIES, OGASAWARA, TAKESHI RESEARCH LABORATORIES, SASAKI, KIMIAKI KAWASAKI REFRACTORIES CO. LTD
Format:	Patent
Sprache:	eng
Schlagworte:	ARTIFICIAL STONE CEMENTS CERAMICS CHEMISTRY COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDINGMATERIALS COMPOUNDS THEREOF CONCRETE INORGANIC CHEMISTRY LIME, MAGNESIA METALLURGY NON-METALLIC ELEMENTS REFRACTORIES SLAG TREATMENT OF NATURAL STONE
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Beschreibung
Zusammenfassung:	The invention provides a method for the preparation of an upgraded high-purity powder of hexagonal boron nitride still having low crystallinity to retain activity for sintering. The first method comprises the steps of admixing a crude powder of hexagonal boron nitride with a carbonaceous material and heating the blend in a stream of an inert gas. The second method comprises the steps of admixing the powdery blend of boric acid or boron oxide as the boron source and a nitrogen compound as the nitrogen source with borax or anhydrous borax, heating the powdery blend to form a crude powder of hexagonal boron nitride, admixing the crude powder of hexagonal boron nitride with a carbonaceous powder, and heating the powdery blend at a temperature of 1300 DEG C or higher in a stream of an inert gas.