Comparative analysis of solidification curves obtained by thermal analysis system and multi-channel digital recorder

The aim of the study was to determine the possibilities and conditions for the use of a multi-channel digital recorder to control cast iron quality by rapid thermal analysis. A computer program cooperating with a digital recorder was developed. It supports processing of the acquired data "live" or stored in the recorder memory. The program establishes parameters of the characteristic points on the cooling curve responsible for the properties of the iron melt. A series of melts of cast iron with pearlitic matrix and a varied form of graphite was made. Using professional system of thermal analysis and digital recorder, the waveforms of the cast iron solidification process were plotted for samples of standard and reduced wall thickness. The obtained solidification curves were subjected to detailed analysis to determine the critical temperatures, like TL, TElow, TEhigh, R, TS. The chemical composition and structure of the cast iron from experimental melts were examined. The results of measurements were compared using both sets of equipment. It was found that the use of the recorder and high sampling frequency allow carrying out the thermal analysis of cast iron at a high cooling rate and create favourable conditions for control of the production process of thin-wall iron castings.

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