Method for evaluating the change in specific volume of refratory substances during crystallization

Abstract

A method is proposed for quantitative evaluation of the change in specific volume of refractory substance during a liquid -solid phase transition according to the surface shape of a flat ingot crystallized under conditions of central symmetrical heating. The accuracy of the estimate is up to 5 -8%. With certain limitations the method is applied to a quantitative estimate of the volumetric effect of crystallization and in a number of cases melt density of the refractory materials themselves, for which obtaining information about melt density by any other method is impossible. Using the proposed method an estimate is provided for the density of molten yttrium and erbium oxides close to the melting temperature (for Y 2 O 3 T m = 2440°C, for Er 2 O 3 T m = 2430°C respectively).

Anomalous increase in specific volume upon crystallization of some alloys in the zirconia–yttria–erbia system

“…5c, d. The method of solid-to-liquid specific volumes ratio rough estimation via analysis of ingot surface shape has been developed. 23,24 But, the mentioned method uses an "assumed" shape of the melt pool surface. In this paper, we propose to esti- mate changing of true specific volume (( V/V ) true ) with the use of the melt pool and ingot side views at axial symmetry approximation.…”

Peculiarities of crystallization of alumina, yttria and rare-earth element oxides of yttria subgroup in an optical furnace

“…10,15 The method for the estimation of volume change upon crystallization under the conditions of a center-symmetrical temperature field in the focal zone of an optical furnace has been proposed. [32][33][34] It has significant limitations and cannot be used for substances with high melt viscosity, disposed to the formation of internal hollow spaces, to which Al 2 O 3 is related. Nevertheless, the second task was to thoroughly research the solidification process of alumina in the focal zone of an optical furnace, and comparing the peculiarities of the alumina crystallization with the crystallization processes in REE oxides under the same conditions, and to estimate the influence of their peculiarities on the reliability of the reported results.…”