Effect of TiO2 addition on crystallization and machinability of potassium mica and fluorapatite glass ceramics

In this study, the effect of TiO2 addition as a nucleating agent on the crystallization and machinability of potassium mica and fluorapatite base glass ceramics were investigated. Glass compositions were prepared and casted at predetermined temperatures. Differential thermal analysis and XRD methods were applied to characterize phase precipitation sequence and identification of phases. Disc and cylindrical shaped samples were prepared to determine microstructural and mechanical properties in terms of microhardness and machinability. FEG-SEM was used to characterize variation of microstructural constituents depending on the amount of nucleating agent. The results indicate that optimum microstructure and machinability can be obtained in machinable glass-ceramic by the addition of 1 wt% TiO2 for the composition having 3:7 weight ratio of fluorapatite to potassium mica.