Fast Sinter-Crystallization of Glasses from Mixtures of Wastes

摘要

Several glasses, belonging to the CaO-Al_2O_3-SiO_2 system and corresponding to the melting of mixtures of industrial wastes (recycled glasses, mining residues, ashes, asbestos-containing cements ecc.), have been successfully converted into dense glass-ceramics by sintering with concurrent crystallization. The usage of fine glass powders (<37 μm) allowed very short sintering treatments, due to the enhanced nucleating activity of glass surfaces. In particular, dense glassceramics could be produced by direct insertion of pressed glass powders in furnace at the sintering temperature, followed by sudden cooling at room temperature after a 30 min holding time. The proposed approach evidences the feasibility of sintered glassceramics by the fast and economic processes employed for traditional ceramics, with the advantage of superior mechanical properties (bending strength exceeding 100 MPa, Vickers' microhardness exceeding 6 GPa). Like in traditional ceramics, clay and water could be used for the shaping of pressed tiles, thus posing the conditions for massive industrial production.