Comparison of fracture toughness measurements for zirconia materials using two test methods

抄録

To determine the influence of the fracture toughness (K_IC) methods [single-edge-V-notch-beam (SEVNB) and chevron-notch-beam (CNB)] as well as an optional heat treatment on the K_IC of three different zirconia generations (1st: ZI, 3rd: FX, 4th: HT). One hundred and twenty specimens each (3×4×45 mm) were fabricated, sintered, notched (n=360) and half of them heat treated before K_IC measurements with 4-point-flexural-strength test. SEM images of the notches were recorded. Highest K_IC was found for ZI followed by HT and FX. SEVNB resulted in significantly higher K_IC than CNB. Heat treatment resulted in decrease for SEVNB and increase for CNB of K_IC (except for FX). Groups tested using CNB showed higher reliability of values (Weibull modulus) than tested using SEVNB. SEM images present crack path and fracture surface. Different zirconia materials lead to different K_IC values. The test method and a prior heat treatment showed an influence on the K_IC values and their reliability.