PREPARATION METHOD OF α-ALUMINA POWDER WITH HIGH α-RATIO AND LARGE SURFACE AREA

• Main Authors: MAKI, HAJIME, KAJIHARA, KAZUHISA, TAKEUCHI, YOSHIAKI
• Format: Patent
• Language: English; Korean
• Published: 02.12.2004
• Edition: 7
• Subjects: CHEMISTRY; COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM,CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THERARE-EARTH METALS; INORGANIC CHEMISTRY; METALLURGY

PURPOSE: Provided is a preparation method of α-Al2O3 powder with high α-ratio and large surface area by removing water from compounds containing α-Al2O3 precursor, seed crystal, water and nitrate(NO3-) ion, and sintering. The resultant α-Al2O3 powder is used for the production of sintered α-Al2O3 with high strength. CONSTITUTION: The α-Al2O3 powder is prepared by removing water from compounds containing α-Al2O3 precursor, seed crystal, water, and 2.8-3.3M of nitrate(NO3-) ion per 1M of Al contained in α-Al2O3 precursor and seed crystal, and sintering compound powders at 600-1000deg.C for 10min-24hrs at air or inert gas(N2, Ar) atmosphere. The α-Al2O3 precursor is at least one compound selected from aluminum salt, aluminum alkoxide, transition alumina, aluminum hydroxide and hydrolysate of aluminum compound, and preferably, aluminum nitrate. The seed crystal is at least one metal oxide, having the crystal structure of corundum, selected from α-Al2O3, α-Fe2O3 and α-Cr2O3, wherein the size of seed crystal is 0.01-0.5micrometer and the amount of seed crystal is 5-50pts.wt in terms of metal oxide, based on 100pts.wt. of α-Al2O3 precursor and seed crystal. The amount of water is 50-1000pts.wt., based on 100pts.wt. of α-Al2O3 precursor and seed crystal. The resultant α-Al2O3 powder has 0.01-0.1micrometer of size, more than 90% of α-ratio and more than 15m2/g of specific surface area.