Experimentální měření a vyhodnocení tepelných kapacit slitin na bázi Fe-C-Cr s využitím vysokoteplotního kalorimetru

Abstract

The main topic of this bachelor thesis was experimental and theoretical study of heat capacity. Experimental data can be found in a literature, but data for a particular alloy is hardly searchable. The studied materials were three model alloys based on Fe-C-Cr with almost the same carbon content (0,34 wt. % C) and different content in particular chromuim (0,92 – 4,76 wt.% Cr). The theoretical part of the thesis explains the possibilities of theoretical calculations and experimental determination of heat capacities and defines the term heat capacity. In the experimental part is presented a method of experimental determination of the heat capacity using the Setaram MHTC 96 (Multi High-Temperature Calorimeter) Line with a 3D DSC sensor using the DSC (Differential Scanning Calorimetry) method with a heating rate of 5 °C/min. Measurements were carried out in a temperature range of 150 – 1580 °C. Except heat capacities, phase transformation temperatures were also determined. In the low temperature region (150 – 1300 °C), the temperature of the start of phase transformation α → γ (Tα → γ, S) and the temperature of the end transition α → γ (Tα → γ, E) and the Curie point (TC) temperature were obtained. In high temperature region (1150 – 1580 °C), solidus (TS), liquidus (TL) and peritectic (TP) transition temperatures were obtained. Experimental heat capacity values were compared and discussed with theoretical values calculated using Thermo-Calc software and the standard deviation and variance coefficients for the experimental values were calculated. The thesis presents the results, their comparison, discussion and corresponding conclusions regarding the chemical composition of model alloys, theoretical and experimentally obtained data.