Research On The Technics And Crystallization Mechanism Of Slag Glass-ceramics

Glass-ceramics material is prepared out of the base glass via controlled crystallization and devitrification treatments. In the paper, the development, fabrication technology and present research are widely reviewed.The glass-ceramics of CaO-MgO-Al2O3-SiO2 system, which has excellent microstructure and properties, has been initially prepared by sintering method using wasted glass and the blast furnace slag. This kind of glass-ceramics can be used as decorated material, thus the cost of producing glass-ceramics is reduced and the environment pollution is protected and improved.Researches have shown that crystallization behavior is influenced by the temperatures system of crystallization heat treatment, the variety and content of nucleation agents. The effects of different parameters on crystal phases and crystallization process are studied by means of DTA, XRD and SEM. The technological parameters of heating treatment are confirmed to ensure the nucleation rate and the size of crystals. Optimal heat treatment system is obtained, i.e. the nuclearllization temperature is 920℃for 120min,the crystallization temperature is 1140℃for 75min, the heating rate is 8℃/min. Different nucleation agents have different effect on crystallization behavior of glass. FeS and TiO2 can effectively prompt crystallization of glass with wollastonite as major crystalline. The shape of crystals is apt to be column while taking FeS as nucleation agent, and round grains while applying TiO2.The kinetic parameters are calculated by using Owaza equation, the results have shown that FeS is more effective to reduce the crystallization activation energy than TiO2. The nuclearlization mechanisms of FeS and TiO2 are analyzed deeply.The study of nucleation agent contents indicates that different contents have different effect on glass devitrification degrees, crystal phase amounts and crystal sizes. The content of wollastonite in crystal phases increases and the crystals grow larger with the increasing content of FeS. However, it gives rise to a more difficulty in the sintering of glass into glass-ceramics. It is optimal while the content of FeS is 4wt%.