Development of a Novel Radial Heat Flow Apparatus for Measuring Solid-Liquid Interfacial Energy
thesisposted on 17.01.2017, 12:18 by SungWoo Son
The solid-liquid interfacial energy,σ𝑆𝐿, plays an important role in all processes that involves nucleation and growth of solids from its liquid state. In nucleation, interfacial energy affects the temperatures at which solids nucleate from its liquids during growth, the interfacial energy affects the transformation rate. Solid-liquid interfacial energy also plays important role in determining the growth morphology which may lead to solidification occurring in the preferred crystallographic directions. The solid-liquid interfacial energy is also important in the phenomena such as coarsening of dendrites, sintering and wetting. It is thus very important to have quantitative values of the interfacial energy, as this will assist in gaining fundamental knowledge into the structural nature and physics of interfaces. To measure the σ𝑆𝐿, the grain boundary groove method is used. The grain boundary grooves are obtained in a stable temperature gradient and by using direct application of the Gibbs-Thomson equation on the groove shape, the σ𝑆𝐿 can be obtained. The main aim of this study is to design and construct aradial heat flow apparatus and then to commission and test using a commercial Al alloy. The Radial heat flow apparatus provides ideal set up to obtain grain boundary groove shape, as the central heating element in the centre of the sample and the water cooling jacket around the sample provides the radial temperature gradient to produce solid-liquid interface. The equilibrated grain boundary groove shapes for an industrial alloy LM25 were obtained in experiment at above eutectic temperature for 10 days with the temperature control to within ±0.05K. From the observed grain boundary groove shapes, the σ𝑆𝐿 for LM25 has been determined to be 167.361± 8.312 mJ/m2.