Fracture behaviour of microcrack-free alumina–aluminium titanate ceramics with second phase nanoparticles at alumina grain boundaries

• Published in: Journal of the European Ceramic Society Vol. 28; no. 10; pp. 1961 - 1971
• Main Authors: Bueno, S., Berger, M.H., Moreno, R., Baudín, C.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2008; Elsevier
• Subjects: Applied sciences; B. Nanocomposites; Building materials. Ceramics. Glasses; C. Mechanical properties; C. Toughening; Ceramic industries; Cermets, ceramic and refractory composites; Chemical industry and chemicals; Condensed Matter; Cross-disciplinary physics: materials science; rheology; D. Al 2O 3; D. Al 2TiO 5; Exact sciences and technology; Materials Science; Other materials; Physics; Specific materials; Structural ceramics; Technical ceramics; D. Al 2O 3; C. Mechanical properties; D. Al 2TiO 5; C. Toughening; B. Nanocomposites; Ceramic matrix composite; Scanning electron microscopy; Nanoparticle; Mechanical properties; Titanates; Fracture; Dispersion reinforced material; Experimental study; Oxide ceramics; Composite material; Structural ceramic; Grain boundary; Reaction sintering; D. Al2TiO5; D. Al2O3; Manufacturing; Scanning transmission electron microscopy; Alumina; Aluminium Titanates; Al2TiO5; Nanocomposites; Toughening; Al2O3
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2008.01.017

Alumina + 10 vol.% aluminium titanate composites were obtained by colloidal filtration and reaction sintering of alumina and titania. The materials were dense with aluminium titanate grains of average sizes 2.2–2.4 μm located mainly at alumina triple points. The reaction sintering schedule promoted the formation of additional nanometric grains, identified as aluminium titanate using STEM–EDX analysis between the alumina grains. This special microstructure led to a change of the toughening mechanism from the typical crack bridging reported for microcrack-free composites fabricated from alumina and aluminium titanate powders to microcracking. The identification of microcracking as the main toughening mechanism was done from the analysis of stable fracture tests of SENVB samples in three points bending and fractographic observations. Monophase alumina materials with similar grain sizes were used as reference. Different fracture toughness parameters were derived from the load–displacement curves: the critical stress intensity factor, K IC, the critical energy release rate, G IC, the J-Integral and the work of fracture, γ WOF, and the R curves were also built. The comparison between the linear elastic fracture parameters and the non-linear ones revealed significant toughening and flaw tolerance.