Redox state and transition metal concentration effects on microstructure of simulated simplified glasses for waste immobilization
- Catholic Univ. of America, Washington, DC (United States). Vitreous State Lab.
Chromium, iron, and nickel are present in many waste-streams from DOE sites. This study considers a simplified lime-aluminosilicate glass system, similar to one proposed for high temperature (1,250--1,450 C) vitrification of soil and wastes from DOE sites, in which concentrations of Cr, Fe, and Ni are being varied and different redox states induced for selected melting conditions. The solubilities of Cr{sub 2}O{sub 3} and NiO in the simplified system are determined at 1,350 C, 1,400 C, and 1,450 C. The enthalpies of solution calculated from the solubility data for Cr{sub 2}O{sub 3} and NiO are 12.2 and 15.2 kcal/mol, respectively. The iron redox ratio, Fe{sup 2+}/Fe{sup total}, in selected glasses is determined by Moessbauer Spectroscopy and related to changes in microstructure. The crystallization of eskolaite (Cr{sub 2}O{sub 3}) seems to be favored at intermediate states of reduction (Fe{sup 2+}/Fe{sup total} {approx} 0.8) in Cr-containing glass at near the solubility limit. Pseudoternary diagrams are plotted for melts in air at 1,450 C in which Fe{sub 2}O{sub 3} + SiO{sub 2} + X (X = NiO or Cr{sub 2}O{sub 3}) is held constant. Time-Temperature-Transformation (TTT) curves are plotted using data from heat treatment studies. Liquidus temperatures of base, 1.5 wt% Cr{sub 2}O{sub 3} glass and 8 wt% NiO, 7 wt% Fe{sub 2}O{sub 3} glass are found to be 1,150 C, 1,175 C, and 1,175 C, respectively.
- OSTI ID:
- 264418
- Report Number(s):
- CONF-951155-; ISBN 1-55899-315-0; TRN: 96:016563
- Resource Relation:
- Conference: Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 27 Nov - 1 Dec 1995; Other Information: PBD: 1996; Related Information: Is Part Of Scientific basis for nuclear waste management 19; Murphy, W.M. [ed.] [Southwest Research Inst., San Antonio, TX (United States)]; Knecht, D.A. [ed.] [Lockheed Idaho Technologies Co., Idaho Falls, ID (United States)]; PB: 957 p.; Materials Research Society symposium proceedings, Volume 412
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
GLASS
REDOX POTENTIAL
MICROSTRUCTURE
WASTE FORMS
CHROMIUM OXIDES
SOLUBILITY
IRON OXIDES
NICKEL OXIDES
SOILS
LOW-LEVEL RADIOACTIVE WASTES
VITRIFICATION
SOLVENT PROPERTIES
CHEMICAL COMPOSITION
VISCOSITY
ELECTRIC CONDUCTIVITY
SOLUTION HEAT
PHASE DIAGRAMS
EXPERIMENTAL DATA
MORPHOLOGICAL CHANGES