Effect Of CeO₂ On Crystallization Mechanism And Corrosion Resistance Of The Glass Ceramic From Blast Furnace Slag Of Baogang Group

With the rapid development of the national economy,the demand for domestic market for iron and steel products is increasing,and the blast furnace slag produced by blast furnace ironmaking is also increasing.At present,the comprehensive utilization of blast furnace slag resources includes the preparation of cement,slag bricks,silica fertilizer,and glass ceramics.Among them,the rare earth-containing glass ceramics have been prepared from Baogang Group's blast furnace slag.The glass ceramics have excellent comprehensive physical and chemical properties,and have been widely used as new industrial wear-resistant and corrosion-resistant structural materials.However,the existence state of the co-rare earth in glass ceramics and its influence on the crystallization characteristics remain to be analyzed in depth,especially,the mechanism of co-rare earth on the corrosion resistance of blast furnace slag glass ceramics was studied from the perspective of microstructure.Therefore,in this paper,the glass ceramics containing rare-earth elements were prepared from the blast furnace slag of Baogang Group as the main raw material,revealing the existence state of co-rare earth cerium in glass ceramics and its effect on the crystallization characteristics and corrosion mechanism of glass ceramics.This research provides theoretical support for the high value,high efficiency and green utilization of the blast furnace slag of Baogang Group.Based on the Ca O-Mg O-Al2O3-Si O2(CMAS)quaternary phase diagram,the basic experimental formula of this study was determined with the industrial waste furnace slag of Baogang Group as the main raw material.The crystal structure,phase composition,microstructure,physical and chemical properties of blast furnace slag glass ceramic in different blast furnace slag content,the additive content of cerium oxide and different corrosive environment,respectively by differential thermal analyzer,Raman spectrometer,X-ray diffraction,field emission electron microscope,X-ray energy dispersive spectrometer,electron back scattering diffraction and the evaluation of the universal testing machine and other equipment testing.The main research contents and results of this paper are as follows:In this paper,the glass ceramics with different blast furnace slag contents(60,70,80and 90 wt.%)were prepared by traditional melting method.And its influence on the structure and properties of glass ceramics was studied.The results show that with the increase of blast furnace slag content,the content of network modified ions in glass network increases correspondingly,the structural units of glass network gradually change from aggregate state to monomer form.At the same time,the introduction of blast furnace slag can inhibit the precipitation of pyroxene phase to a certain extent,but it can promote the growth of gehlenite.It is found in the backscattered electron image that a small amount of Ce O2 crystal phase is precipitated at the phase boundary.The density,Vickers hardness,bending strength and acid resistance of glass ceramics decrease with the increase of the amount of the blast furnace slag.When the blast furnace slag is 60 wt.%,the pyroxene-based blast furnace slag glass ceramics has the best physical and chemical properties.Its density,Vickers hardness,bending strength and acid resistance are 3.00 g/cm³,10.86 GPa,114.9 MPa and 93.77%,respectively.On the premise of determining the optimal amount of blast furnace slag introduced(60wt.%),the content of cerium in glass ceramics was changed by adding Ce O2(0,0.5,1.0,1.5,2.0,2.5 wt.%).The existence of cerium in glass ceramics and its influence on the nucleation and crystallization of glass ceramics were studied.The results indicate that the Ce⁴⁺in the glass network structure can modify the glass network of the blast furnace slag glass ceramics.The accumulation effect of high coordination Ce⁴⁺can strengthen the stability of the glass network,increase the content of bridging oxygen bond in the glass network,and improve the degree of polymerization and densification of the glass ceramics.In addition,Ce⁴⁺can enter diopside crystal by substituting Ca²⁺with similar ion radius.Cerium also exists stably at the phase boundary in the form of Rare Earth second phase Ce O2.Under the premise of determining the optimal amount of blast furnace slag(60 wt.%),the content of cerium in the glass ceramics was changed by adding Ce O2(0,0.5,1.0,1.5,2.0and 2.5 wt.%).The cerium state of existence in glass ceramics and its effect on the nucleation and crystallization of glass-ceramics were studied.The results suggest that Ce⁴⁺in the glass network structure can modify the glass network of blast furnace slag glass ceramics.The accumulation effect of high-coordination Ce⁴⁺can strengthen the stability of the glass network,increase the content of bridge oxygen bonds in the glass network and improve the degree of polymerization of glass ceramics.In addition,Ce⁴⁺can enter diopside crystals by substituting Ca²⁺with a similar ion radius.At the same time,cerium also stably exists in the position of the phase boundary in the form of the rare earth second phase Ce O2.On the basis of determining the position of rare earth cerium in pyroxene-based glass ceramics,the influence of the co-rare earth cerium on the microstructure of pyroxene-based glass ceramics with the content of 60 wt.%of blast furnace slag was investigated,under different corrosion conditions(soaking at room temperature and dynamic scour).The results show that with the increase of corrosion time and the concentration of sulfuric acid solution,the Ce-O bond formed by high field strength Ce⁴⁺and O^2-can stably exist on the surface of the sample,and improve the connectivity of the network to a certain extent,so that the corrosion resistance of glass ceramics is improved.The corrosion process under different corrosion methods is basically the same.When corrosion begins,signs of corrosion appear gradually at the position of the phase boundary and defects on the surface of the sample.Under the action of the sulfuric acid solution,the phase boundary will become the diffusion channel of H⁺ions and continue to expand.Then the glass phase is gradually peeled off from the phase boundary,and the glass network structure is gradually destroyed,so that it eventually forms isolated silicate units,which are then dissolved by sulfuric acid solution.