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

Abstract The vitrification and crystallization behavior of melts produced at 1400 °C in the ternary system of K 2 O–B 2 O 3 –TiO 2 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 [TiO 2 ] = 25–57, [K 2 O] = 30–50 and [B 2 O 3 ] = 0–25, the glass-ceramics consisted of the potassium–titanium–borate glassy phase and different crystalline potassium titanates (K 4 Ti 3 O 8 , K 2 Ti 2 O 5 , K 2 Ti 4 O 9 , K 2 Ti 6 O 13 ). The ratio of TiO 2 :K 2 O in the obtained titanates increases with [TiO 2 ] and [B 2 O 3 ]. In the second field, [TiO 2 ] = 7–37, [K 2 O] = 0–25 and [B 2 O 3 ] = 52–93, the obtained glass-ceramics consisted of a similar vitreous phase, as mentioned above, and TiO 2 crystals. During the cooling of the melts, short whiskers-like crystals of anatase formed in the compositions with relatively low [TiO 2 ] and relatively high [K 2 O], whereas long fiber-shaped crystals of rutile appeared with the compositions characterized with relatively high [TiO 2 ] and relatively low [K 2 O]. The possible application of the obtained glass-ceramic materials as a source of fibrous TiO 2 , for composite reinforcement, and as solid lubricants is discussed.