Effect of Cr2O3 addition on crystallization, microstructure and properties of Li2O-Al2O3-SiO2 glass-ceramics

A new glass-ceramic with high flexural strength and low thermal expansion based on Li2O-Al2O3-SiO2 (LAS) was prepared in this study. The effects of Cr2O3 addition on the crystallization, microstructure, flexural strength, thermal expansion, and electrical properties of LAS system were investigated. The crystallization kinetics based on DSC analysis was calculated using Kissinger and Ozawa methods, which showed that the activation energy E decreases from 158.5 to 149.3 kJ/mol, indicating that Cr2O3 is beneficial to the crystallization of LAS; the crystallization index n varies between 4.46 and 5.09, indicating that the crystallization manner is the volumetric crystallization. XRD analysis was estimated by the whole pattern fitting method, demonstrating that Cr2O3 addition could change the phase contents and promote the crystallinity. The crystallization of CaMgSi2O6 and Cr2O3 with higher CTE not only properly adjusted CTE for matching Si, but also dramatically improved the flexural strength for LAS glass-ceramic. Moreover, we provided a modified formula to calculate CTE of glass-ceramic in the acceptable range. LAS glass-ceramic with 3 wt% Cr2O3 sintered at 800 °C exhibited good properties: σ = 208 MPa, α = 2.64 × 10−6/°C, ε = 8.3, tanδ = 3.6 × 10−3, ρ = 8.82 × 1012 Ω cm, indicating its suitability for LTCC application.