Effects Of Al₂O₃on Structures And Properties Of Glass-ceramics Containing Rare-earth Tailings

In recent years, environmental pollution is more and more serious, people attachegreat importance to the secondary utilization of resource and reduce waste emissions so asto realize sustainable development. Every year tailings cause serious pollution, so usingtailings to make high value-added glass ceramics is an important way. Tailingsglass-ceramics is the CaO-Al₂O₃-SiO₂system, Al₂O₃is an important part ofCaO-Al₂O₃-SiO₂system, but excessive Al₂O₃can make the viscosity of the systemincrease, inhibition of crystallization and difficulties in forming, and if the Al₂O₃content istoo low, the stability of glass-ceramics is reduced. So study the effect of Al₂O₃content onthe properties of glass-ceramics is significant.In this paper Bayan Obo rare-earth tailings were used to make the glass-ceramic bymelting method, this paper mainly studied the glass-ceramic with CaO-Al₂O₃-SiO₂system.By means of TG-DTA analysis, SEM, XRD and mechanical property test. the influence ofAl₂O₃content on the heat treating process, crystallization properties, crystal structure andsize, density, resistance to the corrosion, flexural and compressive strength, wear resistanceand thermal expansion coefficient of glass-ceramic were analyzed and then Al₂O₃contentwas determined by analyzing. This research has great academic and practical significancesto make full use of rare-earth tailings to make the glass-ceramic.The research results showed that with Al₂O₃content from3.20%to9.62%, The maincrystals of glass-ceramic were diopside and anorthite. With Al₂O₃content increasing,crystallization temperature of glass-ceramics and crystal size raised gradually, butcrystallization rate decreased; apparent density, flexural strength, acid resistance ofglass-ceramics rose firstly and then decreased, but alkali resistance was present to the exactcontrary. When the content of Al₂O₃was6.43%, flexural strength was200.11MP.andhardness and wear resistance were the best. This paper considers every factor affecting glass-ceramics performance, the optimumcontent of Al₂O₃is6.43%, at this content the properties of glass ceramics are the best, thecrystallization temperature and crystallization temperature of glass-ceramics are relativelylow, and the crystal nucleation and growth are faster.