Effect of TiO2 and CaF2 on the crystallization behavior of Y2O3-Al2O3-SiO2 glass ceramics.

The effects of TiO 2 and CaF 2 on the crystallization kinetics, microstructure, phase evolution and microhardness of Y 2 O 3 -Al 2 O 3 -SiO 2 glass ceramics were investigated by differential scanning calorimetric (DSC), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The results show that the addition of TiO 2 is effective to promote crystallization by decreasing the activation energy, refining the grain size and increasing the microhardness. However, the CaF 2 plays an opposite role by increasing the activation energy, coursing the grain size and decreasing the microhardness. Furthermore, the addition of TiO 2 induces bulk crystallization of Y 2 O 3 -Al 2 O 3 -SiO 2 glass. On the contrary, the addition of CaF 2 leads to surface crystallization and decreasing of thickness of surface crystallized layer. [ABSTRACT FROM AUTHOR]