Impact of Glass Composition on the Production of Borosilicate HGMs

1. R2O B/R +0.5 Alkali-Borosilicate Immiscibility Region -3 wt% SiO2 +6 wt% SiO2 B +3 wt% SiO2 -6 wt% SiO2 B/R -0.5 • Eliminate minor components (one at a time) from the baseline composition • CaO • ZnO HGM Forming Region Immiscibility • P2O5 • Fluorine B2O3 SiO2 Impact of Glass Composition on the Production of Borosilicate HGMs Fabienne C. Raszewski, Erich K. Hansen, David K. Peeler and Ray F. Schumacher Savannah River National Laboratory, Aiken, SC 29808 This work was sponsored by Washington Savannah River Company (WSRC) for the United States Department of Energy under Contract No. DE-AC09-96SR18500. The Savannah River National Laboratory is operated for the U.S. Department of Energy by Washington Savannah River Company. Hollow Glass Microspheres (HGMs) Glass Selection • HGMs are produced by a flame forming (FF) process using an experimental apparatus designed at SRNL • Sized glass frit containing a blowing agent is passed through a flame at elevated temperatures (~1300°C) • HGMs are quenched with water and collected • Average diameters are within the range of 45 – 75 μm • Yield is determined by: LDRD Glasses (R=alkali metals) • Baseline composition is derived from the Na2O-B2O3-SiO2 system • Two components were modified • SiO2 content (wt%) • Constant B2O3/R2O molar ratio • B2O3/R2O molar ratio • Constant SiO2 content Zero Glasses Solid beads, defects, etc. LDRD Glasses Zero Glasses Yield Yield Viscosity of the glass is provided for reference. Viscosity of the glass is provided for reference. Density Density No data for “0 wt% CaO” – yield was too low • Elimination of ZnO, P2O5 or F from baseline composition has no influence on yield • Yield is considerably reduced when CaO is removed from the baseline composition • Density is relative unaffected by the removal of ZnO, P2O5 or F from the baseline composition • Baseline composition has the highest yield • Yield is maximized in the region of ~60 – 62 wt% SiO2 and ~21.5 – 22 wt% B2O3 • Density increases linearly with increasing SiO2 and B2O3 content • Density of baseline composition is low – no explanation at the present time