A rapid heating and high magnetic field thermal analysis technique

A new thermal analysis technique is described that allows measurements to be performed on bulk samples at extreme heating and cooling rates and in high magnetic fields. High heating rates, up to 1000 °C min−1, are achieved through electromagnetic induction heating of a custom-built apparatus fitted with commercial thermal analysis heads and sensor. Rapid cooling rates, up to 100 °C min−1, are enabled by gas quenching and the small thermal mass of the induction furnace. The custom apparatus is designed to fit inside a superconducting magnet capable of fields up to 9 Tesla. This study demonstrates that the instrument is capable of collecting accurate thermal analysis data in high magnetic fields and rapidly acquiring data for dynamic processes. While the full potential of the technique is still unrealized, currently, it can provide insight into phenomena at time scales relevant to heat treatment in many industrial processes and into little understood effects of high magnetic field processing.

Effect of Titanium on Microstructure and Solidification Behavior of Gray Irons

This study investigates the microstructure and the solidification behavior of titanium-alloyed gray irons. Thermal analysis technique was used to identify the Temperature of Liquidus Arrest (TLA), the Temperature of Eutectic Undercooling (TEU) and the Temperature of the Eutectic Recalescence (TER). It was found that the titanium addition promoted the formation of the primary austenite causing the larger difference in TLA and TEU. In addition, titanium encouraged the refining of eutectic mixture. The SEM showed the graphite particles were refined with increasing titanium. Fine particles of titanium-containing compound were readily observed throughout the microstructure. The hardness as high as 176 HB was achieved at 0.495%Ti addition.

Kinetic study of hydromagnesite thermolysis by constant rate thermal analysis

The present work is focused on the kinetic study of hydromagnesite thermal decomposition carried out by constant rate thermal analysis technique at 5 hPa partial pressure. The apparent activation energies were measured experimentally all along the decomposition without any assumption about the rate law of the determining step. Under these conditions the decomposition of hydromagnesite occurs in two steps. The first step is a dehydration which occurs with apparent activation energy of 60 kJ.mol-1 and D4 kinetic model. The second step is essentially decarbonatation, which occurs according to an F1 kinetic model and activation energy equal to 95 kJ.mol-1.