Effect of Vanadium Oxide on the Crystallization of CaO-Al 2 O 3 -SiO 2 Glass.

This study investigated the effect of vanadium oxide on the crystallization of CaO-Al 2 O 3 -SiO 2 (CAS) glass. Specifically, this study subjected CAS glass-ceramics (GCs) with precipitated hexagonal platy particles of metastable CaAl 2 Si 2 O 8 (CAS GC-H), a layered crystal, that was prepared using metallic molybdenum (Mo) particles as nucleation agents. When the parent glass of CAS GC-H was crystallized with the addition of vanadium oxide in the 0.052-0.21 wt % range, the obtained platy particles of metastable CaAl 2 Si 2 O 8 displayed an increase in the aspect ratio from 20 to 15 compared with conventional CAS GC-Hs. In addition, no crystallization occurred in the CAS glass with vanadium oxide in the 0.052-0.21 wt % range in the absence of metallic Mo particles. Meanwhile, a CAS glass containing 1.0 wt % vanadium oxide without the addition of metallic Mo particles showed the precipitation of metastable CaAl 2 Si 2 O 8 . Therefore, these results indicated that the aspect ratio of layered crystals in glass was controlled by the addition of a relatively small content of vanadium oxide, and a new nucleation agent for the precipitation of metastable CaAl 2 Si 2 O 8 in CAS glass using a relatively high content of vanadium oxide was developed.