The errors when determining thermal characteristics by the laser flash method due to the thickness of the sample and the duration of the heating pulse

Evaluation of the laser-flash method and its errors for determining of materials thermal diffusivity at high temperatures

“…Simulation of heat transfer process was made for stainless steel 12H18N10T, titanium and silicone carbide at temperature band 673-1173 K under the following conditions: 7 7 3.5 10 6.6 10 q 7 6.6 10 6 6 W/m 2 , 1.0 t ' ms, 0 300 T K. Numerical values of TC were adopted in accordance with the papers [15,16]. Samples thickness was chosen 5 mm according to conditions in [9] to minimize error of TC determination method. During the simulation a time step was chosen 1 ms.…”

“…During the LFA development it was supposed, that there is not abstraction of heat form the sample surface to the outdoor environment [4,5]. As was shown in [9,10], such assumption doesn't influence the TC of the sample at low temperature. In the case under consideration, when temperature is over 1000 K, heat-gravitational convection will significantly affect the heat flow pattern of a sample during the experiment.…”

“…For equation (1) solution values T max and 05 W must be known. Conditions for TC reliable determination at low temperature band and estimation errors of it are described in a fairly large number of papers [4][5][6][7][8][9][10]. TC at medium and high temperatures (no greater than 1173 K) can be determined only in experimental way.…”

“…Results of this experiment could be used for planning of physical experiment. In this case, the determination of TC by theoretical way is based on mathematical modelling of thermal conductivity process in plane sample, under relevant conditions for LFA [9,10].…”

“…Comparison of calculated TC by mathematical modelling with TC assumed during this simulation in [9,10] is allowed to evaluate influence various factors to errors of TC determination. The approach [9,10] is used for determination of TC of highly heatconductive materials at medium and high temperatures (no greater than 1173 K).…”