Fracture Toughness Measurement by Indentation Fracture Method at Elevated Temperature

Flexure Strength, Fracture Toughness, and Slow Crack Growth of YSZ/Alumina Composites at High Temperatures

“…A similar transition occurring at 400°C was also observed in 6.5 mol% YSZ by Adams et al 18 . Although less defined compared with the current two composite systems, some other zirconia ceramics such as yittria‐stabilized tetragonal zirconia polycrystals (Y‐TZPs) and yittria‐partially stabilized zirconias (Y‐PSZs) 32–35 have also exhibited a transition in elastic modulus around 300°–500°C. This may be due to increase in elastic anisotropy up to the transition point, which is related to changes in ZrO 2 lattice defects 36 .…”

“…This may be due to increase in elastic anisotropy up to the transition point, which is related to changes in ZrO 2 lattice defects 36 . Alumina, silicon nitride, or silicon carbide ceramics, by contrast, have exhibited no or little transition up to 1000° or 1200°C, typified as a monotonic decrease in elastic modulus with increasing temperature 35,37,38 . The previous study, 9 determined with a total of five specimens for each of alumina contents, showed that ambient‐temperature elastic modulus of both particulate and platelet composites increased linearly with alumina content and that difference in elastic modulus for a given alumina content between the two composite systems was negligible.…”

Fractura de materiales cerámicos estructurales avanzados

“…e) No es destructivo.Los inconvenientes son:a) El uso de la técnica a alta tmperatura es en principio complicado(Krell y Bakun 1985, Morscher a al. 1991, Sakaguchi y Murayama 1992. Pueden aparecer fenómenos de recocido del material, plasticidad, enromaniiento y curado de la grieta, cambio en el coeficiente de fricción entre penetrador y material (Lee y Brun 1988), que falseen el valor de la tenacidad obtenido, o hagan inaplicable el método.…”