The experimental verification of the shielding effect in zirconia

✍ Scribed by Yasuo Kogo; Yutaka Kagawa; Hiroshi Hatta

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 591 KB
• Volume: 176
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/0921-5093(94)90971-7

✦ Synopsis

The toughening mechanism of CeO2-stabilized ZrO: (CeOe-ZrO2) was discussed on the basis of the observation of resistance R curve and the stress intensity factor Kti p at the crack tip. A compression splitting test method, compressing the top of the double cantilever beam specimen, was applied to achieve slow crack growth of CeOe-ZrO 2. The laser caustic method was also applied to observe Kti p. The results showed that K~ was increased with increasing crack extension (R curve behaviour). Crack extension started around K~ of 3 MPa m t/2, and K~ increased to 7 MPa m J/2` where K~ became saturated. On the contrary, Kup exhibited a constant value in the range 2 -3 MPa m ~/2 during the crack extension. From observed K~ and K,p, the contribution AK of transformation toughening was examined on the basis of the relation K~ = Kup + AK With these results, the shielding effect, which is the relaxation mechanism of stress concentration at the crack tip, was experimentally verified.