Molecular Dynamics Simulation Of Microstructure Of CaO-Al₂O₃-SiO₂-TiO₂ Glass-ceramics

Glass-ceramic is an advanced inorganic material,which has excellent mechanical properties,chemical stability,thermal stability and electrical properties.It has good application prospect in military,electronics,instrumentation,optics and architecture.CaO-Al2O3-SiO2-TiO2(CAST)system is one of the most promising green building materials.It has become a hotspot in the research of new building materials.However,most of the preparation of glass-ceramics requires more than 1500 degrees of high temperature,it is difficult to characterize the microstructure of the crystallized glass system,which affects the deep research on the microstructure and properties of the glass-ceramics.Therefore,it is of great significance to study the computer simulation of CAST glass-ceramic system,to understand the microstructure of glass-ceramics and to restrict the development and application of glass-ceramics.In this paper,the molecular dynamics of the microstructure of CAST system glass was simulated by molecular dynamics method.The microstructure of the system was obtained.The influence of TiO2 content and SiO2 content on the microstructure of the system was studied.In this paper,the effect of TiO2 on the microstructure of CAST system was simulated.From the results of radial distribution function curve shows that Si-O and Al-O first peak position in the 1.61? and 1.75?,consistent with the reported value of the literature.Ti-O also has the first sharp peak,we can see that the binding capacity of Ti-O and Al-O binding ability similar.With the increasing content of TiO2,the diffusion rate of Ti decreases first and then increases,and the reason of this result is related to the network characteristics of Ti.The Si-O-Al content in the system increases at first,Then stabilized,and finally showed a downward trend.While the content of Si-O-Si showed a tendency to decrease gradually.When the amount of TiO2 was more than 5.5%,the content of Si-O-Si began to increase.Al-O-Al content is first reduced,and then continue to rise,when the TiO2 addition of more than 5.5%,Al-O-Al content began to decrease rapidly.The results of statistical analysis show that with the increase of TiO2 content,the formation rate of tetrahedral [SiO4] in the system does not change much,and the number of [AlO4] increases with the increase of TiO2,and the maximum value reached 91%.The formation rate of [TiO4] showed a rising trend with the increase of TiO2.The results show that with the increasing content of SiO2,the mean square displacement of Ti decreases first and then increases.From the variation law of skeleton bridge oxygen in the system,it can be seen that the influence of SiO2 content on the microstructure of CAST system is simulated.With the increase of SiO2,there is a tendency of 2(Si-O-Al)→(Si-O-Si)+(AlO-Al)in the network structure,but when the SiO2 content continues to increase to 52.5% Reverse.The results show that the change of SiO2 content has no effect on the structure of TiO2,and most of them are in the presence of [TiO4],indicating that the TiO2 with their nucleating agent can be uniformly and stable in the high temperature silicate melt.The results show that the distribution of O-Si-O bond angle is more concentrated than that of O-Al-O,indicating that the addition of SiO2 in the CAST system does not affect the O-Si-O,while the O-Al-O has a certain degree of influence.