DETERMINATION OF THERMAL CONDUCTIVITY OF SELECTED TYPES OF DUCTILE IRON (SPHEROIDAL GRAPHITE/CAST IRON) BY MEANS OF THERMAL DIFFUSIVITY MEASUREMENTS WITH LASER-FLASH METHOD

This paper presents the results of measurements of thermal conductivity coefficient as a function of temperature for two species of spheroidal cast iron by using one of the most modern experimental sets LFA 427 (Laser Flash Apparatus) produced by Netzsch Company. In order to measure the specific heat c_p(T) and density р(T), two methods of dynamic thermal analysis were used - differential scanning calorimetric DSC and dilatometric technique. Based on results of these measurements the coefficients of thermal conductivity were calculated with the use of Netzsch LFA Analysis software. Changes of slope of thermal diffusivity coefficient curvilinear dependence on temperature were observed, as well as rapid change on thermal conductivity λ(T) caused by thermal effect registered on c_p(T) dependence. These observations allowed to identify decomposition process of ausferrite, caused from the disintegration of high-carbon retained austenite in ADI cast iron at approximately 400°C.

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