STUDY OF HEAT TRANSFER IN A GRAPHITE THERMAL UNIT OF THE FACILITY FOR GROWING SINGLE CRYSTALS BY THE HDC METHOD

Abstract

We report the development of a high-temperature installation for the synthesis of halide compounds to improve the capabilities of the method of horizontal directed crystallization (HDC) that makes it possible to expand the chemical classes of crystals grown. The main element of the facility is a graphite thermal unit, developed for growing fluorine-containing single crystals for the first time by the HDC method. To assess the installation operability and to identify the temperature features of the crystallization process, the research complex included mathematical modeling of the processes of hydrodynamics, heat and mass transfer inside the graphite thermal unit, as well as between it and the crystallization apparatus. Numerical calculations relied on Reynolds-averaged Navier-Stokes equations and a modified Stefan-Boltzmann law used for a not absolutely black body. The temperature ranges of thermal inertia, as well as the establishment of the thermodynamic equilibrium in the thermal unit of the growth facility up to temperatures above 1500 °C, were experimentally determined. Knowledge of the values of these temperature parameters is necessary to prevent spontaneous overheating of the melt during the growth of fluoride crystals.

Keywords

• graphite thermal unit
• heat transfer
• thermal inertia
• thermodynamic equilibrium
• heat insulation coating
• finite element method