Mechanical properties of (Y-TZP) — alumina-silicon carbide nanocomposites and the phase stability of Y-TZP particles in it

✍ Scribed by K. Niihara; N. Ünal; A. Nakahira

• Publisher: Springer
• Year: 1994
• Tongue: English
• Weight: 900 KB
• Volume: 29
• Category: Article
• ISSN: 0022-2461
• DOI: 10.1007/bf00356588

✦ Synopsis

AI203-SiC-ZrO 2 composites were investigated to obtain a better understanding of the effect of SiC particles and the stress-induced transformation of Y-TZP on its mechanical properties. The AI203-SiC-ZrO 2 composites were fabricated by hot pressing using y-AI203, SiC and Zr02 mixtures. Fracture toughness and strength of AI203 were greatly improved by incorporating SiC and Zr02 particles which were located mainly inside and between AI203 grains, respectively. The toughening and strengthening mechanism of these composites and the phase stability of the tetragonal Zr02 in the composites before and after high-temperature annealing were investigated by scanning electron microscopy, transmission electron microscopy and Xray diffraction. It was observed that there is a critical volume fraction of zirconia, above which the phase stability of the tetragonal zirconia increases, despite the grain growth of the zirconia. It is considered that another phenomenon, the residual stresses, affect the phase stability of the tetragonal zirconia. To remove the residual stresses the composites were annealed at 11 O0 ~ After slow cooling, the tetragonal zirconia became very unstable, especially in samples with the highest fabrication temperature and increasing zirconia content. Even quenching from 11 O0 ~ caused an increase in the monoclinic phase of these samples.