Effect of Li2O/Na2O on Structure,Crystallization and Mechanical Properties of YAS Glass-Ceramics
Transparent glass-ceramics are widely used in the electronic field due to their excellent mechanical properties.Y2O3-Al2O3-SiO2(YAS)glass-ceramics with different mass fractions of Li2O and Na2O were prepared by melting method,and the structural characteristics,crystallization and mechanical properties were investigated by Raman,DSC,XRD,FESEM,UV-VIS-NIR.The results show that when the total content of R2O(R=Li,Na)remains unchanged,the transition temperature,softening temperature and crystallization peak temperature of YAS glass-ceramics decrease as the content of Li2O replacing Na2O increases,the content of structure units Q4 gradually decreases,indicating that Li2O as a network modifier gradually depolymerizes the structure of YAS glass-ceramics and promotes the crystallization ability of glass.It is also found that with the increase of Li2O content,the Vickers hardness of YAS glass-ceramics increases significantly,while the transmittance decreases significantly at the same heat treatment.Under the heat treatment at 680℃ for 10 h and 750 ℃ for 1 h,YAS glass-ceramics with uniform crystal size and distribution and yttrium stabilized zirconia as the main crystalline phase can be prepared.At present,YAS glass-ceramics containing 2％(mass fraction,the same below)Na2O and 4％Li2O exhibits favorable overall performance.The Vickers hardness is 646 HV,the fracture toughness is 1.07 MPa·m1/2 and the transmittance is 85.7％,which has great potential for many applications.
Y2O3-Al2O3-SiO2transparent glass-ceramicsalkali metal oxidestructurecrystallizationVickers hardness
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