Modelling the evaporation of boron species. Part 1: Alkali-free borosilicate glass melts

A laboratory test facility has been used to measure the boron evaporation rates from borosilicate glass melts. The impact of furnace atmosphere composition and glass melt composition on the temperature dependent boron evaporation rates has been investigated experimentally. In Part 1 of this paper the results for alkali-free borosilicate glass melts are discussed. From the measured boron evaporation rates, information on the chemical activity of B 2O3 in the melt (at the glass melt surface) has been derived and compared with results of thermodynamic modelling. For alkali-free borosilicate melts, a modified thermodynamic associated species model is presented. Furthermore, the transport of volatile boron compounds in these melts are discussed. In Part 2 of this paper the impact of the glass composition and glass structure on the boron evaporation rates will be discussed.