Contributions of CaO and SrO in crystallization and properties of some glasses based on stoichiometric tetra-silicic fluoromica. Issue 12 (15th August 2017)

• Record Type: Journal Article
• Authors: Salman, S.M.; Salama, S.N.; Abo-Mosallam, H.A.
• Is Part Of: Ceramics international. Volume 43:Issue 12(2017)
• Page Start: 9424
• Page End: 9430
• Publication Date: 2017-08-15
• Subjects: Glass -- Tetra-silicic fluormica -- Crystallization -- Microhardness -- Durability; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2017.04.116
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Glass-ceramic materials based on the stoichiometric composition of tetra-silicic fluoromica K2 Mg5 Si8 O20 F4 modified by partially CaO/MgO or SrO/MgO replacement were prepared and characterized. Generally, the addition of different ratios of CaO or SrO instead of MgO led to improved glass crystallinity. At low CaO/MgO replacement, diopside phase was crystallized together with tetra-silicic mica. By increasing the replacement ratio, diopside and fluorite phases were developed and no tetra-silicic mica phase could be detected. The tetra silicic mica was transformed to fluoramphibole (Sr-fluororichterite) at low SrO/MgO replacement. However, at high SrO content, strontium metasilicate, Sr-akermanite, and strontium fluoride phases were developed at the expense of tetra-silicic mica. The chemical stability and microhardness of the glass-ceramics were improved due to the formation of Sr-fluororichterite or diopside phases, while their values decreased with the crystallization of the calcium or strontium fluoride phases, dissolved in aqueous solutions to form the hydrofluoric acid. The density of glass–ceramics specimens ranged from 2.74 to 3.16 g/cm 3 while the microhardness ranged from 4013 MPa to 5731 MPa.