High-speed visualization of unsteady-state thermophysical experiment as a means of making it more informative and accurate

The determination of the properties of a sample, such as enthalpy, heat capacity, and resistivity, in unsteady-state thermophysical experiment is based on measurements of electric energy input to an extended zone of sample identified by contact probes. If this zone is nonisothermal, the determination of temperature to which the obtained values of the above-listed characteristics are to be related becomes a hard-to-resolve problem. An experiment with subsecond heating of titanium sample in an air atmosphere using a Sprint high-speed digital camera (manufactured by ZAO Videoskan, Moscow) and procedure for transforming the pattern of luminosity of object to temperature fields produces distributions of brightness temperature on the sample surface, which are indicative of the strong nonuniformity of the heating of sample throughout the experiment. It is demonstrated that the use of means of monitoring the space-time variation of temperature fields on the surface of the object under investigation enables one to make definite the estimation of reliability of measurement of the thermal properties of substances, which is based on mathematical models of ideal thermal processes.