Preparation And Properties Of AE(Alkaline-Earth Element)-Si-Al-O-N-(F)Glass

Compared with the corresponding oxide glass,oxynitride glass has high hardness,flexural strength,elastic modulus,low thermal expansion coefficient and good chemical stability,which led to the extensive study of oxynitride glass.In the present thesis,alkaline-earth oxynitride glass is chosen as the research object,and the effect of the cations:different alkaline-earth elements,mixed alkaline-earth elements,and anion:different fluorine element content on the internal composition,glass structure,physical properties,thermal properties and mechanical properties of oxynitride glass are systematically studied by means of XRD spectrum,infrared spectrum,nuclear magnetic resonance,Raman spectrum and other performance testing.Main results are as follows:The AE-Si-Al-O-N?AE:Mg,Ca,Sr,Ba?glass was prepared by sol-gel method,and the effects of different alkaline-earth elements on the structure and properties of the glass are systematically studied.The results show that with the increase of the alkaline earth element cationic field strength,the internal structure of the glass changes,the number of structural units with high degree of polymerization gradually increases,and the glass network becomes more densified,the density and molar volume of the glass constantly decrease,the hardness and glass transition temperature gradually increase,and the coefficient of thermal expansion continuously decreases.The mixed alkaline-earth?Mg,Ca?oxynitride glass was prepared by sol-gel method,and the effects of different degrees of mixing on the structure and performance of the oxynitride glass are studied.when the two alkaline-earth elements are mixed,the structural information displayed by infrared and Raman spectroscopy show that the glass structure gradually becomes loose with the continuous substitution of Ca O for Mg O,and the mixed alkaline-earth effect appears obvious.The density,molar volume and thermal expansion coefficient of glass all show regular changes overall as the ratio of Ca O/?Ca O+Mg O?gradually increases,a certain mixed alkaline-earth effect appears and the extreme point is when the molar ratio of Ca O/?Ca O+Mg O?is 0.25;the Tg of mixed alkaline-earth oxynitride glass is lower than the single alkaline earth oxynitride glass,which shows the obvious mixed alkaline earth effect appears on the oxynitride glass,and the minimum point of Tg appears at the Ca O/?Ca O+Mg O?molar ratio of 0.75;the hardness value of glass decreases with the increase of Ca O/?Ca O+Mg O?ratio,and there is no mixed alkaline earth effect.Oxynitride glass with composition Ca₂₀Si₅₀Al₃₀O_90-xN₁₀F_x?x=0,1,3,5,7?was prepared by melt batches,the effects of different contents of fluorine on the structure and properties of oxynitride glass are studied.The results show that the introduction of small amount of fluorine increases the amount of nitrogen introduction into the glass,the introduction of 3 eq%fluorine in the glass increases the nitrogen content from 5.3 eq%to 6.74 eq%;the introduction of fluorine element changes the coordination number of aluminum,part of aluminum changes from four coordination to six coordination;the glass transition temperature gradually decreases with the increase of fluorine;with the introduction of a small amount of fluorine,the oxidation resistance of oxynitride glass is significantly improved,the thickness of the oxide layer is obviously reduced,and the density of the oxide layer is distinctly improved.