Thermophysical properties of containerless liquid iron up to 2500 K

Thermophysical properties of high temperature liquid iron heated with a CO2 laser have been determined in an aerodynamic levitation device equipped with a high-speed camera and a three-wavelength pyrometer. Characteristic curves of the free cooling and heating of the drop can be used to determine the same apparent emissivity of solid and liquid iron and to calibrate pyrometers based on the known value of the melting point of iron, i.e., 1808 K. Examination of the recalescence of undercooled liquid iron and further solidification are used to obtain the ratio of the melting enthalpy versus the heat capacity of liquid iron as DeltaH(m)/c(p)(l) = 306+/-2.5 K. The surface tension sigma was determined from an analysis of the vibrations of liquid drops. Results are accurately described by sigma (mJ.m(-2))=(1888+/-31)-(0.285+/-0.015) (T-T-m) between 1750 K (undercooled liquid) and 2500 K. The density of liquid iron has been deduced from the image size and the mass of the liquid iron drops.