POLYCRYSTALLINE, SINTERED ABRASIVE GRANULE BASED ON ALPHA-ALUMINUM TRIOXIDE, ABRASIVE COMPOSED OF ABRASIVE GRANULE, PRODUCTION OF ABRASIVE GRANULE, AND PRODUCTION OF REFRACTORY CERAMIC PRODUCT

摘要

PURPOSE: To obtain tight and hard abrasive granules by an economical SG- method without expensive special treatment technique by holding the pH of a mixture of a boehmite dispersion and -Al₂O₃ crystal nuclei to a specific pH value range by the addition of an acid by heating the same under reflux. ;CONSTITUTION: -Al₂O₃ crystal seeds are added to a hoehmite dispersion and this mixture is acidified to be gelled and the obtained gel is dried, ground and sintered to produce polycrystalline sintered abrasive granules based on -Al₂O₃. In this method, the mixture of -Al₂O₃ crystal nuclei to the sintered abrasive granules is heated under reflux and, in this case, the pH value of the mixture is held to 2.5-3.5 by the addition of an acid. By this method, polycrystalline sintered abrasive granules based on -Al₂O₃ having a density of 98% with respect to a theoretical value of corundum, a Vickers hardness of 21 GPa or more and a microcrystalline size of 0.05-1.3 m are obtained.;COPYRIGHT: (C)1993,JPO