Effects of Cr2O3 and CaF2 on the structure, crystal growth behavior, and properties of augite-based glass ceramics

Glass ceramics were synthetized using Cr2O3 and CaF2 as additives, and their structure, crystal growth behavior, and physicochemical properties were investigated. The results showed that an excessive amount of Cr2O3 leads to the formation of a spinel structure in the glass matrix and an increase in the number of Q3Si units. The addition of CaF2 promoted the decomposition of Q2Si into Q1Si and Q3Si. Compared with the sample with Cr2O3 alone, the addition of CaF2 helped reduce the glass transition and crystallization temperatures, forming sharper crystallization peaks. Although CaF2 increased the activation energy of crystallization, it increased the degree of crystallinity and Avrami parameter (2.019). In terms of the microstructure, the sample added with CaF2 formed a snowflake-like structure with a spinel core. An excessive amount of spinel reduced the strength of the samples. The samples (1.5Cr2O3-3.5CaF2) exhibited a maximum flexural strength of 149.85 MPa and a good chemical resistance.