Evaporation rate and kinetic mechanism of noble antimony under vacuum

Abstract

Herein, a novel mathematical and statistical method is applied to the kinetic study of vacuum gasification of noble-antimony alloys. The evaporation rates of pure and noble antimony in a unit time at 823–1023 K and 5–600 Pa are determined using a vacuum differential gravimetric furnace, and their respective evaporation mechanisms under vacuum are analyzed in detail in conjunction with their triple point. Results show that the actual evaporation rates of pure and noble antimony are consistent with those obtained using a nonlinear logistic model (ω=A2+(A1-A2)/[1+P/P0a); the goodness of fit (R2) is > 0.9965 at all temperatures. The critical pressure values of pure and noble antimony at 823–1023 K are obtained, which are linearly dependent on the temperature. According to the theoretical and actual maximum evaporation rates of pure and noble antimony, the evaporation coefficient is corrected and the relation between the actual evaporation rate and temperature (lgω=AT+B) is further obtained, which can be used to calculate and predict the evaporation rates of noble antimony at different temperatures. By studying the evaporation rate of pure and noble antimony, this study provides the kinetic parameters for vacuum gasification of noble antimony and simultaneously enriches the kinetic database, which develops and improves the theory and practice of vacuum gasification of noble-metal alloys.