Alumina toughened zirconia reinforced with equiaxed and elongated lanthanum hexa-aluminate precipitates. Issue 16 (December 2021)

• Record Type: Journal Article
• Authors: Li, Maoyin; Van Meerbeek, Bart; Tunca, Bensu; Cokic, Stevan; Vleugels, Jef; Zhang, Fei
• Is Part Of: Journal of the European Ceramic Society. Volume 41:Issue 16(2021)
• Page Start: 247
• Page End: 255
• Publication Date: 2021-12
• Subjects: Microstructure -- Alumina-toughened-zirconia -- Alumina precursors -- Elongated lanthanum hexa-aluminate precipitates; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2021.09.038
• Languages: English
• ISSNs: 0955-2219

Abstract

Highlights: Type of alumina precursor considerably influenced the microstructure of 12Ce-TZP based ATZs. The elongated lanthanum hexa-aluminate was much finer when using γ-AlOOH and Al(NO3 )3 ·9H2 O as Al2 O3 precursors. The fine elongated lanthanum hexa-aluminate leading to a strong toughening effect. γ-AlOOH resulted in a fracture resistance of 9.7 MPa m 1/2, biaxial bending strength of σ0 = 976 MPa and reliability of m = 20.7. Abstract: Three different alumina sources (boehmite, aluminium nitrate and α-alumina particles) and 12Ce-TZP powder containing 1 wt% lanthanum oxide were used to prepare 12Ce-TZP-based alumina-toughened-zirconia (ATZ) composites. The obtained ATZs had similar density and phase composition, whereas the microstructures were significantly different. Alumina-particle addition gave rise to a typical ATZ microstructure consisting of equiaxial sub-micrometer zirconia and alumina phases, while the lanthanum hexa-aluminate phase was formed in large and non-homogenously distributed precipitates (∼3.5 μm in length). The boehmite and aluminium nitrate-based composites contained not only sub-micrometer equiaxial alumina and zirconia grains but also small-sized lanthanum hexa-aluminate precipitates (∼1.2 μm in length) that were inter- and transgranularly positioned in the zirconia matrix and effectively promoted crack deflection and toughening. In combination with a higher t -ZrO2 transformability, the boehmite-based composites had a higher indentation fracture resistance, strength and reliability compared to the aluminium-nitrate and alumina-particle based equivalents.