Liquidus-solidus phase relations in the system CaO-CrO-Cr sub 2 O sub 3 -SiO sub 2

Journal Article · Mon Jun 01 00:00:00 EDT 1992 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1992.tb04191.x· OSTI ID:7279877

de Villiers, J P.R. ^[1]; Muan, A ^[2]

---

1. Council for Mineral Technology, Randburg, 2125 (ZA)
2. College of Earth and Mineral Sciences, Pennsylvania State Univ., University Park, PA (US)

This paper reports on phase relations in the system CaO-chromium oxide-SiO{sub 2} were determined in equilibrium with metallic chromium and at various oxygen pressures in the range of {approximately}10{sup {minus}10} to 10{sup {minus}13} atm. Two ternary phases occur on the liquidus surface in equilibrium with metallic chromium, viz, the garnet Ca{sub 3}Cr{sub 2}Si{sub 3}O{sub 12} (uvarovite), and CaCrSi{sub 4}O{sub 10} of the gillespite-type structure and in which essentially all the chromium is present in the divalent state (Cr{sup 2+}). Furthermore, a previously reported binary calcium chromite phase X of approximate composition (Ca{sup 0.4}Cr{sub 0.6})Cr{sub 2}O{sub 4} is stable also on the liquidus surface of the present system. The lowest liquidus and solidus temperatures in the system under these conditions (contact with metallic chromium) are significantly lower (by 100{degree} to 200{degree}C, depending on Cao/SiO{sub 2} ratios of the melts) than those for the same system in air. Furthermore, there is considerable solid solution of chromium oxide in lime (CaO) and the various crystalline calcium silicates (pseudowollastonite, CaSiO{sub 3}; Rankinite, Ca{sub 3}Si{sub 2}O{sub 7}; dicalcium silicate, Ca{sub 2}SiO{sub 4}; tricalcium silicate, Ca{sub 3}SiO{sub 5}), presumably by partial substitution of Cr{sup 2+} for Ca{sup 2+} toward hypothetical chromium analogs of each CaO-containing phase, particularly in lime and Ca{sub 2}SiO{sub 4}.

• OSTI ID: 7279877
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 75:6; ISSN JACTA; ISSN 0002-7820
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
DISPERSIONS
ELEMENTS
EQUILIBRIUM
MIXTURES
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHASE STUDIES
PHYSICAL PROPERTIES
PRESSURE GRADIENTS
SILICON COMPOUNDS
SILICON OXIDES
SOLID SOLUTIONS
SOLUTIONS
STOICHIOMETRY
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS