Thermodynamic Process And Mechanical Properties Of Alkaline Earth Aluminosilicate Glass

Tempered glass,microcrystalline glass and transparent ceramics are the best choice of cover material for intelligent equipment in recent years,but there are problems of complicated process and high processing cost.Therefore,it is of great significance to develop glass system with high scratch resistance and crack resistance to practical application.For glass,hardness and crack resistance are mutually exclusive properties.In order to study the glass with high hardness and crack resistance at the same time,different series of alkaline earth aluminosilicate glass were prepared by laser-heated aerodynamic levitation method.Glass transition temperature（T_g）,thermal stability,hardness（H_V）,crack resistance（C_R）,crystallization activation energy,fragility,configuration heat capacity and structure were characterized by comprehensive thermal analyzer,micro-Vickers hardness,X-ray diffractometer,Fourier transform infrared spectrometer,laser confocal Raman spectrometer.The conclusions are as follows:（1）A series of xCaO·（49-x）Al₂O₃·51SiO₂（x=0～49.0 mol%）glasses were prepared by laser-heated aerodynamic levitation method.The results show that T_gof peraluminous glasses is higher than that of calcium-rich glasses because of the better network connection.Thermal stability of peraluminous glasses is worse than that of calcium-rich glasses,because the Si-O bond of peraluminous glasses is weaker,and the anti-crystallization ability of peraluminous glass is weaker.H_Vof peraluminous glass is higher than that of calcium-rich glass,which is the result of the joint action of atomic packing density and bond energy density of glasses.C_Rof peraluminous glasses is higher than that of calcium-rich glass,which is the result of the combined effect of atomic packing density,the content of pentagonal Al³⁺and the micro-heterogeneity of the structure.（2）Differential scanning calorimetry（DSC）was used to investigate the thermo-kinetic process of glass formation of 5RO·44Al₂O₃·51SiO₂（R=Mg,Ca,Sr,Ba）glasses.The results show that the order of crystallization activation energy is:E（BAS）>E（Sr AS）>E（CAS）>E（MAS）.The order of strength indexm value is:m（MAS）>m（CAS）>m（Sr AS）>m（BAS）.The order of configuration heat capacity at T_gis:C_p,conf（MAS）>C_p,conf（CAS）>C_p,conf（Sr AS）>C_p,conf（BAS）.The above results show that the glass forming ability from large to small is BAS glass,SAS glass,CAS glass,MAS glass（3）A series of xRO·（49-x）Al₂O₃·51SiO₂（x=0～16.0 mol%;R=Mg,Ca,Sr,Ba）peraluminous glasses were prepared by laser-heated aerodynamic levitation method.The results show that fixed RO type,increase RO content,H_Vgradually decreased and C_Rof glass increased first and then decreased.With fixed RO content,the order of H_Vorder is:H_V（MAS）>H_V（CAS）>H_V（Sr AS）>H_V（BAS）,and the order of C_R:C_R（MAS）>C_R（CAS）>C_R（Sr AS）>C_R（BAS）.H_Vchange is caused by the interactions between the competition and synergism among the packing density,average bond energy,bond energy density of glass network skeleton ions and charge balancer.C_Rchange is due to the interactions between the competition and synergism among atomic packing density,the content of pentagonal Al³⁺and the effect of charge balancer on the micro-inhomogeneity of the structure.