Investigation of Indentation Fracture Toughness (KIC) and Weibull Parameters of 0.25Li2O.2SiO2-0.75BaO.2SiO2 Glass-Ceramic

摘要

In the present study, mechanical properties of 0.25Li2O.2SiO2-0.75BaO.2SiO2 glass-ceramic were investigated. The trans-formations‘ temperatures were determined by DTA instrument. The optimum nucleation temperature was found to be 540°C. This suggested the crystallization temperatures as 675, 720 and 800°C. After carrying out crystallization heat treatments, Vickers indentation test was applied. In order to determine the indentation fracture toughness (KIC), crack half-length ?c‘ of the samples was measured. To calculate KIC, Young’s modulus, E and the measured hardness, Hv were used. Using KIC and probability of fracture ?P‘, ln ln[1/(1 ? P)] – ln KIC graph was drawn based on the Weibull distribution equation. Consequently, Weibull modulus, ?m‘ and scale parameter, ?K0‘ were determined and compared with each other.