Density of Superheated and Undercooled Liquid Alumina by a Contactless Method

The density of liquid alumina drops maintained in levitation with an aerodynamic device and heated with CO2 lasers is determined by analysis of high-speed video digital images between 2000 and 3100 K in various gases. It is shown that consistent results can be achieved for the lighter drops (m < 100 mg) which do not depend on the nature of the gas. Experiments performed with lasers impinging the drop surface or during free cooling of the preheated drop gave similar results. The density is represeInted by the following expression: d = (2.79 ± 0.01)(l-a(T-2500)) g.cm-3, where a = (4.22 ±0.14) x 1 0 - 5K- 1 .