An Experimental and Numerical Investigation of the Bridgman Growth of a Transparent Material

A combined experimental and numerical study of the horizontal Bridgman growth of pure succinonitrile (SCN) has been performed. The effect of convection on interface propagation and shape is quantified and discussed. Measurements were obtained both under conditions of no-growth and for a 40 µm/s growth rate. The quantities measured include interface shape and location, melt velocities, and temperature boundary conditions on the ampoule exterior. The melt velocities were measured using a new technique that employed digital cameras to image the locations of seed particles in the melt. The growth front was stable and non-dendritic, but was significantly distorted by the influence of convection in the melt and, for the growth case, by the moving temperature boundary conditions along the ampoule. Both two-and three-dimensional numerical simulations of the growth process were performed. Temperatures throughout the phase change material and ampoule as well as melt velocities were obtained from the simulations. The predicted interface shapes and melt velocities agree well with experimental results. Two different numerical algorithms were used; the utility of each for simulating phase-change problems is discussed. This combined experimental and numerical study provides a database for the validation of phase-change numerical models, in addition to furnishing detailed information about the influence of convection on the Bridgman growth process. In ongoing work, the computer models presented in this study are being used to simulate alloy solidification problems. NOMENCLATURE a term in energy equation (Eq. 1) A apparent heat capacity (Eq. 1); surface area of control volume c p specific heat capacity at constant pressure f volume fraction g acceleration due to gravity (9.81 m/s 2) k thermal conductivity K 0 permeability P pressure Pr Prandtl number, / t time T temperature u, v, w velocity in x, y and z directions U velocity x, y, z Cartesian coordinates  thermal diffusivity  T