Nanocrystalline particle coatings on alpha-alumina powders by a carbonate precipitation and thermal-assisted combustion route.
We have suggested ultrafine particle coating processes for preparing nanocrystalline particle coated alpha-alumina powders by a carbonate precipitation and thermal-assisted combustion route, which is environmentally friendly. The nanometric ammonium aluminum carbonate hydroxide (AACH) as a precursor for coating of alumina was produced from precipitation reaction of ammonium aluminum sulfate and ammonium hydrogen carbonate. The synthetic crystalline size and morphology were greatly dependent on pH and temperature. By adding ammonium aluminum sulfate solution dispersed the alpha-alumina core particle in the ammonium hydrogen carbonate aqueous solution, nanometric AACH with a size of 5 nm was tightly bonded and uniformly coated on the core powder due to formation of surface complexes by the adsorption of carbonates, hydroxyl and ammonia groups on the surface of aluminum oxide. The synthetic precursor rapidly converted to amorphous- and y-alumina phase without significant change in the morphological features through decomposition of surface complexes and thermal-assisted phase transformation. As a result, the nanocrystalline polymorphic particle coated alpha-alumina core powders with highly uniform distribution were prepared from the route of carbonate precipitation and thermal-assisted combustion.
Nano-Materials Research Center, Korea Institute of Science and Technology, 39-1 Haweoulgog-dong, Sungbuk-gu, Seoul 136-791, Korea.
Sang Woo
SW
Kim
Young Mi
YM
Jung
D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D002255:Carbonic Acid / Q000737:chemistry*; D011232:Chemical Precipitation; D003460:Crystallization / Q000379:methods*; D005740:Gases / Q000737:chemistry; D006358:Hot Temperature; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D011208:Powders; D013499:Surface Properties
D005740:Gases; D046911:Macromolecular Substances; D011208:Powders; D002255:Carbonic Acid; D000537:Aluminum Oxide