Investigation On The Performance Of Li₂O-Al₂O₃-SiO₂ System Glass-ceramics Doped With Rare Earth

In this thesis, the research object is Li₂O-Al₂O₃-SiO₂ system glass-ceramics. According Li₂O-Al₂O₃-SiO₂ system glass phase diagram, a set of compositions are designed, and without the change of compositions La₂O₃ and other 4 rare earth are doped in the compositions for extra ingredient, then the glass-ceramics is produced by fusion. The influence of doping with rare earth on the viscosity and the melting temperature is studied and the influence of doping with La₂O₃ on the crystallization, the structure and the performance is studied;the heat treatment was optimized.In the experiment, the viscosity is studied by means of High Temperature Viscometer, the structure and the appearance are studied by means of DTA, XRD, SEM and IR and so on. The performances are studied by means of heat expansion testing, intension testing and visible light transmission testing and so on.The results indicate that with La₂O₃ and other 4 rare earth addition, the viscosity decreases, especially doping with La₂O₃. With a small amount of La₂O₃ addition, the structure of the LAS system glass-ceramics doesn't show obvious transformation. La₂O₃ doesn't enter the network of glass, but to be the modifier of the network which changes the bond length of Si-0 and the bond angle of Si-O-Si slightly. Because of this, the viscosity, the glass melting temperature(1610℃) decrease, also La₂O₃ can accelerate the crystallization, but there is no influence on the main crystal phase which is β-quartz, and with adding La₂O₃ the dimension of the crystal and heat expansion coefficient increase, intension performance becomes lower. By repetitive experiment, in order to achieve the integrated performance with 0.5mol% La₂O₃ addition is suitable, and the best heat treatment is 590℃/1h→790℃/2h.