晶核剂对透明堇青石微晶玻璃析晶与性能的影响

Effect of Nucleating Agent on Crystallization and Properties of Transparent Cordierite Glass-Ceramics

采用熔融法制备了含有不同晶核剂的非化学计量比堇青石微晶玻璃,通过DSC、XRD、FE-SEM、UV-VIS-NIR等测试方法研究了不同晶核剂对微晶玻璃析晶与性能的影响,并用经典动力学方程(Johnson-Mehl-Avrami)分析了微晶玻璃的析晶动力学。结果表明,以P_(2)O_(5)和P_(2)O_(5)+ZrO_(2)为晶核剂的微晶玻璃晶化机制均为表面晶化,而以P_(2)O_(5)+ZrO_(2)+TiO_(2)为晶核剂的微晶玻璃则倾向于整体析晶。三组微晶玻璃在950℃晶化时主晶相为μ-cordierite,当温度升高到980℃时开始转变为α-cordierite,引入TiO_(2)使α-cordierite的含量增加,析出的晶体更加复杂致密。随着晶化时间延长,与其他晶核剂相比,P_(2)O_(5)+ZrO_(2)+TiO_(2)组合晶核剂微晶玻璃在相同晶化时间内结晶度更高,α-cordierite含量的增加显著提升了微晶玻璃的力学性能,但降低了透过率。在800℃/10 h+980℃/3 h热处理制度下,以P_(2)O_(5)+ZrO_(2)+TiO_(2)为晶核剂的微晶玻璃弹性模量可达103 GPa,断裂韧性为1.27 MPa·m1/2,透过率为82.3%,可满足用作移动终端领域的性能要求。

Cordierite silicon glass-ceramics with different nucleating agents were prepared by melting.The effects of different nucleating agents on the crystallization and properties of glass-ceramics were studied by DSC,XRD,FE-SEM,UV-VIS-NIR and other test methods,and the crystallization kinetics of glass-ceramics with different nucleating agents were analyzed using the classical kinetic equation(Johnson-Mehl-Avrami).The results indicate that the crystallization mechanism of glass-ceramics with P_(2)O_(5)or P_(2)O_(5)+ZrO_(2)as nucleating agent is controlled by surface crystallization.However,the glass-ceramics with P_(2)O_(5)+ZrO_(2)+TiO_(2)as nucleating agent has the tendency to be bulk crystallization.With the crystallization temperature increases from 950℃to 980℃,theμ-cordierite in the three groups of glass-ceramics begins to transform intoα-cordierite.While the introduction of TiO_(2)increases theα-cordierite content,the precipitated crystals become dense.With the extension of crystallization time,compared with other nucleating agent,the glass-ceramics with P_(2)O_(5)+ZrO_(2)+TiO_(2)as nucleating agent obtain higher crystallinity within the same crystallization time,the increase ofα-cordierite content significantly improves the mechanical properties of glass-ceramics,but decreases the light transmittance.Under the heat treatment system of 800℃/10 h+980℃/3 h,the elastic modulus of glass-ceramics with P_(2)O_(5)+ZrO_(2)+TiO_(2)as nucleating agent reaches 103 GPa,the fracture toughness is 1.27 MPa·m1/2 and the light transmittance is 82.3%,which meet the performance requirements of mobile terminals.