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Phase Equilibria in the Na 2 O–CaO–SiO 2 System
Author(s) -
Zhang Zhan,
Xiao Yanping,
Voncken Jack,
Yang Yongxiang,
Boom Rob,
Wang Nan,
Zou Zongshu
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2011.04442.x
Subject(s) - liquidus , eutectic system , analytical chemistry (journal) , phase diagram , ternary numeral system , mineralogy , phase (matter) , differential scanning calorimetry , materials science , ternary operation , crystallography , chemistry , microstructure , thermodynamics , physics , organic chemistry , chromatography , computer science , programming language
Equilibrium phase relations in the Na 2 O–CaO–SiO 2 system at <50 wt% SiO 2 concentrations have been experimentally investigated at temperatures between 1200° and 1400°C. The liquidus temperature was determined with differential scanning calorimetry. The equilibrated samples were quenched with high‐pressure nitrogen, and examined with electron probe X‐ray microanalysis and X‐ray diffraction. Based on the experimental results, the liquidus surface projection has been constructed for this temperature range. Six primary phase fields, Ca 2 SiO 4 , Ca 3 Si 2 O 7 , CaSiO 3 , Na 2 Ca 2 Si 3 O 9 , Na 2 Ca 2 Si 2 O 7 , and Na 2 CaSiO 4 were identified. The ternary eutectic point of Na 2 Ca 2 Si 3 O 9 , Na 2 Ca 2 Si 2 O 7 , and Na 2 CaSiO 4 was determined to be at 1258°C with the composition of 22.5 wt% Na 2 O, 34.5 wt% CaO, and 43.0 wt% SiO 2 . The ternary invariant point of the Na 2 Ca 2 Si 3 O 9 , Na 2 Ca 2 Si 2 O 7 , and CaSiO 3 was established at 1245°C with the composition of 11.8 wt% Na 2 O, 41.6 wt% CaO, and 46.6 wt% SiO 2 . The crystalline phase Na 2 Ca 3 Si 2 O 8 was also identified in the system.