Physical stabilization of the. beta. yields. gamma. transformation in dicalcium silicate

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.tb04234.x· OSTI ID:7088854

Chan, C J; Kriven, W M; Young, J F ^[1]

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1. Dept. of Materials Science and Engineering, Univ. of Illinois at Urbana-Champaign, Urbana, IL (US)

This paper reports that it has been shown that the monoclinic {beta}-phase of dicalcium silicate (Ca{sub 2}SiO{sub 4}) can be stabilized against transformation to the orthorhombic {gamma}-phase by physical rather than chemical factors. Stabilization was studied in different types of microstructures of fabricated under various processing conditions such as different powder or grain sizes, chemical additives, cooling kinetics, or high-temperature annealing treatments. The observations can be explained in terms of a critical particle size effect controlling nucleation of the transformation. Rapid quenching through the high-temperature hexagonal ({alpha}) to orthorhombic a ({sub H}{prime}) transformation at 1425{degrees}C, which is accompanied by a {minus}4.7% volume decrease, causes periodic fracture of {beta}-twins due to accumulated strains. Chemical doping with K{sub 2}O or Al{sub 2}O{sub 3} promotes the formation of amorphous phases which mold themselves around {beta}-Ca{sub 2}SiO{sub 4} grains. Annealing treatments cause crystallization of the glass and subsequent transformation to the {gamma}-phase.

• Sponsoring Organization: National Science Foundation (NSF); National Science Foundation, Washington, DC (United States)
• OSTI ID: 7088854
• Journal Information: Journal of the American Ceramic Society; (United States), Vol. 75:6; ISSN 0002-7820
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALCIUM SILICATES
PHASE STABILITY
POWDERS
PARTICLE SIZE
CHEMICAL PREPARATION
FABRICATION
FRACTURE PROPERTIES
ORTHORHOMBIC LATTICES
PHASE TRANSFORMATIONS
QUENCHING
THERMODYNAMIC PROPERTIES
THERMOMECHANICAL TREATMENTS
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
HEAT TREATMENTS
MATERIALS WORKING
MECHANICAL PROPERTIES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SILICATES
SILICON COMPOUNDS
SIZE
STABILITY
SYNTHESIS
360102* - Metals & Alloys- Structure & Phase Studies
360104 - Metals & Alloys- Physical Properties
360103 - Metals & Alloys- Mechanical Properties