ALUMINA ALUMINUM COMPOSITES FORMED BY THE DIRECTED OXIDATION OF ALUMINUM USING SODIUM-HYDROXIDE AS A SURFACE DOPANT

Al2O3/Al composites have been formed by the directed oxidation of Al u sing NaOH as a surface dopant. Oxidation kinetics were monitored by th ermogravimetric analysis. Product microstructures were examined using optical microscopy and scanning electron microscopy coupled with micro analysis using energy and wavelength dispersive spectroscopy. NaOH-dri ven directed oxidation of Al occurs in the temperature range of 850-de grees-1200-degrees-C, and the resulting microstructure varies with dif ferent doping levels. The growth product is seen to nucleate and grow not only on the top surface of the parent Al but also along the crucib le wall and even on the external surface of the crucible. The A channe l size in the product is determined by the initial surface dopant leve l.