Abstract
A new laser-flash apparatus for thermal diffusivity measurement from 300 to 1500K is described. In this apparatus the sample is surrounded by an isoperibol heat sink made of tantalum, which diminishes heat loss from the sample by radiation at high temperatures. The temperature of the sample is sensed by an infrared detector or alternatively by a thermocouple, whereas that of the heat sink is detected by a thermocouple. An improved method of correction for heat leak is also presented employing a parameter kt1/2, where k is the relaxation constant of the heat-loss curve and t1/2 is the half rise time to reach the maximum temperature. These values can be experimentally determined and the proposed method provides a convenient and useful way in the correction for the heat loss from the sample. As an example, the thermal diffusivity data on tantalum with the correction for the heat loss are presented and are compared with the available data.
