Y₂O₃安定化ZrO₂の引張破壊と破壊じん性

抄録

The tensile strength of yttria-stabilized tetragonal zirconia polycrystals (Y-TZPs) was measured and the fracture surfaces were analyzed by SEM-XMA. The fracture toughness, K_{IC, SEPB}, and the crack extension resistance curve (R-curve) were evaluated by the single-edge-precracked-beam (SEPB) and the double cantilever beam (DCB) methods, respectively. The fracture toughness, K_{IC, slopel}, evaluated from the tensile strength and the fracture surface analysis shows 3.4 to 3.7 MPa√m, which is much smaller than K_{IC, SEPB} (5.0 to 5.2 MPa√m). The type of R-curve is a rising one, and K_{IC, slopel} and K_{IC, SEPB} are close to the initial and the saturated values of the R-curve, respectively. The fracture origins of the SEPB and the tensile test specimens are a relatively large precrack and a small natural flaw, respectivery. Therefore, the value of fracture toughness of the Y-TZPs with a rising R-curve depends on the size of fracture origin.