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

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 (K_IC), crack half-length ‚c‘ of the samples was measured. To calculate K_IC, Young’s modulus, E and the measured hardness, H_v were used. Using K_IC and probability of fracture ‚P‘, ln ln[1/(1 − P)] – ln K_IC graph was drawn based on the Weibull distribution equation. Consequently, Weibull modulus, ‚m‘ and scale parameter, ‚K₀‘ were determined and compared with each other.