Applications of X-Ray Microanalysis to the Study and Conservation of Ancient Glasses

X-ray microanalysis can be successfully applied to the study of the chemical composition and weathering processes of ancient glass. The problems concerned with this kind of application are considered. A verification is conducted of the accuracy and sensitivity of this technique, which are sufficient to obtain useful information on technologies and raw materials used and consequently on the origin and dating of ancient glasses. This analytical method also discloses meaningful data for the optimization of restoration and the choice of appropriate conservation operations

Mechanical properties of metal-particulate lead-silicate glass matrix composites obtained by means of powder technology

The great number of waste glasses leads to the need for new applications. The realization of matrices for innovative and cost-effective materials could be an interesting way. In the present work lead silicate glasses from cathode ray tubes (CRTs) dismantling are investigated. A low cost powder processing route is proposed for the manufacture of particulate aluminium reinforced glass matrix composites. These composites exhibit an anomalous mechanical behaviour which is thought to be due to a complex metal/glass interaction. In the case of limited metal/glass interaction good bending strength and fracture toughness are achieved. The obtained KIC level of about 1,20 MPa m0,5, together with observed crack control behaviour, appears to be very promising

Monolithic and cellular sintered glass-ceramics from wastes

Several kinds of wastes have been converted into glasses, successively powdered and sintered with simultaneous crystallisation. The employed \u201csinter-crystallisation\u201d process was useful to obtain glass-ceramics with particular crystal phases (sometimes un-accessible from traditional nucleation/crystal growth treatments, like feldspar crystals). Conventional pressing of fine glass powders led to monoliths, after sintering, with remarkable mechanical properties (for example bending strength exceeding 100 MPa), useful for tile applications; replication processes, by employing sacrificial polymeric materials, after the same thermal treatment employed for the monoliths, led to open-celled glass-ceramic foams, useful for filtering applications. The enhanced specific surface due to porosity was found to have a positive effect on crystallisation

Sintered Wollastonite-based Glass-Ceramics from Mixtures of Wastes

Recycled soda-lime glass, feldspar mining residues and lime from fume abatement systems have been employed for the production of two glasses, later converted into wollastonite-based glass-ceramics. The glass-ceramics were developed by sintercrystallization, starting from fine powders (<37 μm), for short sintering times at 930°C. The properties of the glass-ceramics were due to both the enhanced nucleating activity of glass surfaces and the formation of micro-porosity. The relevant mechanical properties (bending strength and Vickers’ micro-hardness exceeding 130 MPa and 8 GPa, respectively, for samples sintered for only 30 min), make the investigated glass-ceramics suitable for construction applications

Foam glass as a way of recycling glasses from cathode ray tubes

The manufacturing of glass foams is proposed as a way of recycling glasses from cathode ray tubes (CRTs), following a simple and low cost processing route. No melting of CRT glasses is required, and the foaming occurs at relative low temperatures, thus preserving the chemical stability of glasses. The obtained foams have promising mechanical properties

Effect of time and furnace atmosphere on the sintering of glasses from dismantled cathode ray tubes

The dismantling of cathode ray tubes (CRTs) represents a pressing environmental problem. CRTs consist of three distinguished glass parts. The front part is a barium-strontium glass, while the parts hidden inside the TV sets consist of lead silicate glasses. The high quality standards in manufacturing new CRTs impose a very limited amount of glasses to be recycled in the production of the original components. In addition, the presence of easily reducible oxides (like PbO) in the chemical composition of CRT glasses causes the risk of dispersing poisonous substances during remelting. Sintering of powdered glass could be a profitable way to produce new dense glass based materials without remelting. CRT glasses were found to be strongly susceptible to both the duration of the firing at the sintering temperature and the furnace atmosphere (oxygen, air, nitrogen). The evolution of the relatively large amount of dissolved oxygen, typical of CRT glasses, is found to contrast densification. Very short firing times (up to 15 min) are found to limit gas evolution. In addition, oxidative atmospheres lead to high quality sintered materials, capable of optical transparency comparable to that of pristine glasses

Sintered sanidine glass-ceramics from industrial wastes

Glass obtained from melting a mixture of industrial wastes (panel glass from dismantled cathode ray tubes, mining residues from feldspar excavation and lime from fume abatement systems of the glass industry) has been employed for the production of sanidine-based glass-ceramics. The glass-ceramics were developed by a sintering treatment with concurrent crystallization, from fine powders (< 37 micron), at a relatively low temperature (880 degrees C). The enhanced nucleating activity of glass surfaces likely promoted the formation of sanidine, hardly found in glass-ceramics, as the main crystal phase. Due to the achieved mechanical properties (bending strength of about 120 MPa, Vickers' microhardness exceeding 7 GPa) and aesthetic appearance, resulting from a compact and homogeneous microstructure, the obtained sanidine glass-ceramics may find applications as construction materials. (c) 2005 Elsevier Ltd. All rights reserved

Sintered glass-ceramics from mixtures of waste materials

Panel glass from dismantled cathode ray tubes, mining residues from feldspar excavation and lime from fume abatement systems of the glass industry have been employed as raw materials for several glass compositions. The prepared glasses were ground into fine powders and subjected to sintering treatments at low temperatures (880-930\ub0C), with concurrent crystallization, thus obtaining sintered glass-ceramics. The mechanical properties (for example, bending strength exceeding 100 MPa) and the aesthetic appearance of the materials are thought to be promising for applications in the building industry