Density of superheated and undercooled liquid alumina by a contactless method

The density of liquid alumina drops maintained in levitation with an aerody namic device and heated with CO2 lasers is determined by analysis of high-s peed video digital images between 2000 and 3100 K in various gases. It is s hown 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 wi th lasers impinging the drop surface or during free cooling of the preheate d drop gave similar results. The density is represented by the Following ex pression: d = (2.79 +/- 0.01)( 1 - alpha(T - 2500)) g . cm(-3), where alpha = (4.72 +/- 0.14) x 10(-5) K-1.