WETTABILITY BY WATER AND OXIDATION RESIST ANCE OF ALUMINA-COATED GRAPHITE POWDER

Graphite powder was coated with a chelate compound of aluminum and hea ted at 500 degrees C in air to prepare Al2O3-coated graphite powder. T he sedimentation volume and the heat of immersion in water indicated t hat the wettability of the graphite powder by water was improved by th e Al2O3 coating. The oxidation resistance of Al2O3-coated powder was h igher than that of the uncoated one. The first and second adsorption i sotherms of water vapor indicated that H2O vapor was adsorbed not only physically but also chemically on the Al2O3-coated layer. The specifi c surface area by N-2 and the second adsorption isotherms of water vap or suggest that the layer has micro pores <0.4 nm in diameter.