Vitrification and crystallization in the system of K2O–B2O3–TiO2

The vitrification and crystallization behavior of melts produced at 1400 °C in the ternary system of K2O–B2O3–TiO2 is investigated. It is shown that there are two fields of compositions (indicated in mol%) which allow obtaining the glass-ceramic materials with continuous glassy matrix after the cooling of molten compositions. In the first field [TiO2] = 25–57, [K2O] = 30–50 and [B2O3] = 0–25, the glass-ceramics consisted of the potassium–titanium–borate glassy phase and different crystalline potassium titanates (K4Ti3O8, K2Ti2O5, K2Ti4O9, K2Ti6O13). The ratio of TiO2:K2O in the obtained titanates increases with [TiO2] and [B2O3]. In the second field, [TiO2] = 7–37, [K2O] = 0–25 and [B2O3] = 52–93, the obtained glass-ceramics consisted of a similar vitreous phase, as mentioned above, and TiO2 crystals. During the cooling of the melts, short whiskers-like crystals of anatase formed in the compositions with relatively low [TiO2] and relatively high [K2O], whereas long fiber-shaped crystals of rutile appeared with the compositions characterized with relatively high [TiO2] and relatively low [K2O]. The possible application of the obtained glass-ceramic materials as a source of fibrous TiO2, for composite reinforcement, and as solid lubricants is discussed.