EFFECT OF TITANIA ADDITION ON THE MICROSTRUCTURE AND CRYSTALLIZATION BEHAVIOUR OF GLASS-CERAMICS PREPARED FROM LOCAL RAW MATERIALS
The effect of titania and composition on the microstructure of glass-ceramics prepared from local raw materials was investigated using two-step heat treatment at 321-621 as nucleation and crystal growth temperature, respectively. The crystallization behaviour was investigated using X-ray diffraction (XRD) and emission scanning microscopy (SEM). The phases assemblage was precipitated and identified as wollastonite, andradite, monticellite and titanate dispersed in the matrix of residual glassy phase. The microstructure is characterized by dense, needle, circular, ellipsoidal, flake and lamellar twinning-like crystals dispersed in the amorphous phase. Also, fewer micro sized pores were detected between grains. The glass-ceramics showed excellent resistance to acid and alkali attack due to prolong heat treatment and the presence of crystalline phases that were dispersed in the matrix of residual glass. The glass-ceramics to which 10wt% TiO2 was incorporated and heat treated for 4 hours showed excellent chemical durability.