Influence Of Nucleation Agent On Structure And Property Of Blast Furnace Slag Glass Ceramics

Blast furnace slag is form melting iron eduction in blast furnace slag, production crude steel can produce 0.25-0.4 t blast furnace slag per ton. At present, the mainly application is the production of cement, concrete and geological polymer such as low value-added products. The main composition of blast furnace slag were CaO, Al2O3,SiO2,MgO,Fe2O3. And the composition of glass-ceramic is relatively close to the CaO-Al2o3-Sio2 (CAS) system glass. Therefore, the use of blast furnace slag to the preparation of glass ceramics is the feasible way to realize value-added use of blast furnace slag.In this paper, blast furnace slag produced by a large iron and steel enterprises as main raw materials. The blast furnace slag glass ceramics were fabricated with 60?80% content blast furnace slag by a melting method. The main crystalline phase is diopside and gehlenite. The effect of CaO/SiO2 ratio, the slag content and vnucleation agents on the crystallization and properties of blast furnace slag glass ceramics were investigated by differential scanning calorimetry, X-ray diffraction and scanning electron microscopy respectively. The main results summarize as follows:1. With the increase of CaO/SiO2 ratio, the crystallization result of the sample performs better. When CaO/SiO2 ratio is 1.0, the sample can achieve the overall crystallization and physico-chemical properties of the blast furnace slag glass-ceramics is relatively better.2. Blast furnace slag adding amount has a certain impact to microcrystalline glass crystal phase composition, microstructure and performance. In order to maximize the utilization of blast furnace slag and satisfy the various aspects of performance, the optimal solution is that slag adding amount is 67.5 wt%3.When CaF2 or CaF2+TiO2 as nucleation agent, surface crystallization is the only mechanism of high slag glass-ceramic and coarse gehlenite grains can be identified; The CaF2+Fe2O3 can reduce the crystallization activation energy E of blast furnace slag glass-ceramic and change the crystallization mechanism to bulk crystallization; The CaF2+Cr2O3 realize bulk crystallization, which precipitation phase turn to short columnar gehlenite and granular diopside. CaF2+Cr2O3+Fe2O3 ternary nucleation agent can effectively reduce the high slag glass-ceramics crystallization activation energy E, improve crystal growth index n. Small grain size, uniform structure and high phase content of glass ceramics can be obtained finally.4. In this paper, a blast furnace slag glass ceramic with mean grain size of about 100 nm and high bending strength of 168 MPa is obtained when 5wt% CaF2+1wt%Cr2O3+3wt%Fe2O3 is used as a nucleating agent, then nucleated at 780? for 1h, crystallized at 920? for 1.5h.