含复合晶核剂CaO–MgO–Al_2O_3–SiO_2微晶玻璃析晶与性能

Effect of Composite Nucleation Agents on Crystallization and Properties of CaO–MgO–Al_2O_3–SiO_2 Glass Ceramics

采用高温熔制法制备了含复合晶核剂的CaO–MgO–Al2O3–SiO2(CMAS)微晶玻璃,并借助差热分析、X射线衍射、扫描电子显微镜分析了复合晶核剂组成对CMAS微晶玻璃的析晶和性能的影响规律。结果表明:复合晶核剂CaF2+TiO2能使CMAS玻璃的析晶活化能E降至329.2kJ/mol,且促进晶体快速生长;CaF2+P2O5可促进大量晶核生成,使晶体生长指数n增至2.87,从而实现CMAS玻璃整体析晶;CMAS微晶玻璃的主晶相为钙长石和透辉石,形状为长条状,TiO2和ZrO2的加入对主晶相种类和形状没有影响,但P2O5加入后玻璃不能析出透辉石晶相,而是辉石晶相,并产生许多细小晶粒;含复合晶核剂的微晶玻璃均具有较高Vicker硬度(7.0GPa以上),但引入CaF2+TiO2+P2O5时,微晶玻璃的Vicker硬度较低,这主要是晶粒排列不致密所致。

The CaO-MgO-A12O3-SiO2 （CMAS） glass ceramics containing composite nucleation agents were prepared by a melting method. The effect of complex nucleation agents on the crystallization and properties of CMAS glass ceramics was investigated by means of differential thermal analysis, X-ray diffraction and scanning electron microscopy as well. The results show that the nucleation agents of CaF2＋TiO2 could reduce the activation energy of CMAS glass to 329.2 kJ/mol and accelerate the growth of crystalline phases. The CaF2＋P2O5 could boost the formation of more crystal nucleus, and improve the Avrami index to 2.87, indicating the volumetric crystallization. The main crystallization phases of CMAS glass ceramic are diopside and anorthite with strip-like shape. The addition of TiO2 and ZrO2 had little effect on the compositions and shapes of main crystalline phases, while P2O5 resulted in the precipitation of pyroxene phase instead of diopside phase in the presence of more small crystals. The CMAS glass ceramics containing composite nucleation agents had a higher Vicker hardness （i.e.,〉7.0 GPa）. However, the Vicker hardness decreased with the simultaneous addition of CaF2＋TiO2＋P2O5, resulting from little tight arrangement of crystalline phases.