Several papers on the use of different waste glasses in industrial products have been presented proving that such refuses can be an alternative to the traditional raw materials (Bernardo et al., 2010). Among silica-rich wastes those from bottle banks have attracted much attention. Glass cullets (referred to as soda-lime or soda-lime-silica (SLS) glass) from urban waste consist mainly of silicon, sodium and calcium oxides. Thanks to its potential of low temperature viscous flow sintering, SLS glass can be considered as a good candidate for total, or partial, replacement of the natural fluxes (mainly Na-feldspar) in ceramic manufacturing. Souza et al., 2004 claimed that SLS glasses can substitute feldspar-based fluxes up to 5 wt% without affecting the technological features of the output but reducing the sintering temperature. The use of SLS glass in the vitreous sanitary-ware ceramics provides an environmental safeguard by saving natural resources, and reducing the process energy consumption and CO2 emissions. However it is still a matter of debate how SLS-glass affects the basic ceramic reaction kinetics. Much attention has been paid to porcelain-type technology, but comparatively little has been spent for vitreous sanitary-wares, which result from high-temperature treatments (~1230 °C) of the system clay-kaolinite-feldspar-quartz. In the present paper, we discuss the introduction of SLS glass into the vitreous sanitary-ware ceramic phase-system in partial replacement of the traditional flux agent (Na-feldspar) focussing the attention on: (i) how SLS glass affects the sanitary-ware ceramic transformations at high temperature, in terms of mullite nucleation and growth; (ii) how SLS glass influences the micro-structures formation and the technological properties of the output, as a function of the firing time (tf) and temperature (Tf). The study was performed on samples with classical vitreous sanitary-ware compositions in which a fraction of feldspar is replaced by SLS glass. The mullite kinetics was investigated by isothermal runs using in-situ High Temperature X-Ray Powder Diffraction (HT-XRPD) and Scanning Electron Microscopy (SEM). Samples fired over a tf-Tf grid to mimic a ceramic body were then studied by means of XRPD and technological testing to measure the properties relevant to vitreous sanitary-ware ceramic technology.
Effects of soda-lime-silica waste glass on mullite formation kinetics and microstructures development in vitreous ceramics
2014
Abstract
Several papers on the use of different waste glasses in industrial products have been presented proving that such refuses can be an alternative to the traditional raw materials (Bernardo et al., 2010). Among silica-rich wastes those from bottle banks have attracted much attention. Glass cullets (referred to as soda-lime or soda-lime-silica (SLS) glass) from urban waste consist mainly of silicon, sodium and calcium oxides. Thanks to its potential of low temperature viscous flow sintering, SLS glass can be considered as a good candidate for total, or partial, replacement of the natural fluxes (mainly Na-feldspar) in ceramic manufacturing. Souza et al., 2004 claimed that SLS glasses can substitute feldspar-based fluxes up to 5 wt% without affecting the technological features of the output but reducing the sintering temperature. The use of SLS glass in the vitreous sanitary-ware ceramics provides an environmental safeguard by saving natural resources, and reducing the process energy consumption and CO2 emissions. However it is still a matter of debate how SLS-glass affects the basic ceramic reaction kinetics. Much attention has been paid to porcelain-type technology, but comparatively little has been spent for vitreous sanitary-wares, which result from high-temperature treatments (~1230 °C) of the system clay-kaolinite-feldspar-quartz. In the present paper, we discuss the introduction of SLS glass into the vitreous sanitary-ware ceramic phase-system in partial replacement of the traditional flux agent (Na-feldspar) focussing the attention on: (i) how SLS glass affects the sanitary-ware ceramic transformations at high temperature, in terms of mullite nucleation and growth; (ii) how SLS glass influences the micro-structures formation and the technological properties of the output, as a function of the firing time (tf) and temperature (Tf). The study was performed on samples with classical vitreous sanitary-ware compositions in which a fraction of feldspar is replaced by SLS glass. The mullite kinetics was investigated by isothermal runs using in-situ High Temperature X-Ray Powder Diffraction (HT-XRPD) and Scanning Electron Microscopy (SEM). Samples fired over a tf-Tf grid to mimic a ceramic body were then studied by means of XRPD and technological testing to measure the properties relevant to vitreous sanitary-ware ceramic technology.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
