Solide state thermal conversion of polycrystalline alumina to sapphire

A solid state process for the bulk conversion of a dense polycrystalline ceramic body to a single crystal body has been accomplished by heating the polycrystalline material to a temperature above one-half of the melting temperature of the material but below the melting point of the material. As the...

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Bibliographic Details
Main Authors LIONEL MONTY LEVINSON,RANDOLPH E. MAXWELL, CURTIS E. SCOTT
Format Patent
LanguageEnglish
Published 15.12.1999
Edition6
Subjects
AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUSPOLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE
APPARATUS THEREFOR
ARTIFICIAL STONE
CEMENTS
CERAMICS
CHEMISTRY
COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDINGMATERIALS
CONCRETE
CRYSTAL GROWTH
LIME, MAGNESIA
METALLURGY
PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE
REFINING BY ZONE-MELTING OF MATERIAL
REFRACTORIES
SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE
SINGLE-CRYSTAL-GROWTH
SLAG
TREATMENT OF NATURAL STONE
UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL ORUNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL
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Summary:A solid state process for the bulk conversion of a dense polycrystalline ceramic body to a single crystal body has been accomplished by heating the polycrystalline material to a temperature above one-half of the melting temperature of the material but below the melting point of the material. As the process is a solid state process, no melting of the ceramic body is necessary to convert it to a single crystal. The process has been used to convert a dense polycrystalline alumina body (PCA) containing less than 100 wppm of magnesia to sapphire (single crystal alumina) by heating the PCA to temperatures above 1100 DEG C but below 2050 DEG C, the melting point of alumina.
Bibliography:Application Number: CN19941015321