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Preparation and properties of glass-ceramics from wastes (Kira) of silica sand and kaolin clay refining

2003; Elsevier BV; Volume: 24; Issue: 8 Linguagem: Inglês

10.1016/s0955-2219(03)00628-9

1873-619X

Tomohiro Toya, Yoshikazu Kameshima, Atsuo Yasumori, Kiyoshi Okada,

Nuclear materials and radiation effects

Glass-ceramics were prepared from wastes generated from refining of silica sand and kaolin clay, called Kira. Several kinds of Kira were melted at 1300–1550 °C with additions of CaCO3 and quenched in air or water to obtain glasses. The quenched glasses were ground to <48 mesh and used to prepare glass-ceramics. Crystallization of the parent glass occurred above 950 °C, producing wollastonite as a major crystalline phase which gradually transformed to pseudowollastonite above 1150 °C. The macroscopic appearance of the samples changed from transparent pale green glass to smooth-textured shiny white upon crystallization. The thermal expansion coefficient of the glass-ceramics was 5.2×10−6/°C (30–380 °C). The four-point bending strengths of the as-fired glass-ceramics ranged from 76 to 86 MPa. Vickers microhardness was found to be 6.6–7.5 GPa. Since the chemical durability for acid and alkali was excellent in these glass-ceramics, they are considered to be candidates for applications such as building materials, ceramic tiles, etc.