Specific heat of volcanic rock
Natural materials such as rocks aredifficult to analyze with regard totheir chemical composition. Volcanic rocks are generally solidified frommolten magma and their maincontents are different oxides. Thisexample shows a DSC measurementresult for such a material. It canclearly be seen that it solidifiedalmost completely amorphous. The glass transition was determinedbetween 623°C and 655°C. Coldcrystallization and melting weredetected at 884°C and 1111°C (peak temperature). The heat re- leased during crystallization wascomparable to the heat of fusion, indicating the highly amorphousnature of this mixture. Phase transitions in an SAE107steel material
Presented here are the transforma- tion energetics of a steel (SAE 107).At 751°C, two phase transitionsoverlap each other. The increase inthe heat flow rate up to 735°C is due to the Curie transition (changein the magnetic properties). Achange in the crystal structure (bccto fcc structure) is causing the majorpeak. The structural change is connected with an enthalpy changeof 63 J/g. Melting was seen at1367°C and occurred in two steps(peaks at 1395°C and 1471°C). Theheat of fusion was 268 J/g. 9