Enhanced mechanical properties of ZrO₂-Al₂O₃ dental ceramic composites by altering Al₂O₃ form

Objectives: This study evaluates the difference in physical and mechanical properties of ZrO₂ ceramics, commonly used in dental applications, altered by three different forms of Al₂O₃ content; microparticles (m), nanoparticles (n), and microfiber (f). Methods: Three different types of ZrO₂–Al₂O₃ composites were formed using microparticle (m), nanoparticle (n), or microfibre (f) forms of Al₂O₃. The physical and mechanical properties such as sintering shrinkage, relative density, Vickers hardness, fracture toughness, and biaxial strength were evaluated. A Weibull analysis was performed to assess the strength reliability of the specimens. All data were calculated using the t-test and ANOVA. Results: The sintering shrinkage and relative density of all ceramic composite groups were decreased with the addition of Al₂O₃. The mechanical properties of ZrO₂–Al₂O₃ (f) composite were higher than that of ZrO₂–Al₂O₃ (m) composite and ZrO₂–Al₂O₃ (n) composite. The maximum hardness, fracture toughness, and biaxial flexural strength were observed for 10 vol% of Al₂O₃ fibre. When the content of Al₂O₃ fibre in the matrix was increased above 20 vol%, agglomeration occurred and resulted in a decrease of hardness and toughness. The Weibull modulus value of the ZrO₂–Al₂O₃ (f) composite was the lowest compared to that of other groups. However, characteristic strength (σ₀) of ZrO₂–Al₂O₃ (f) the highest value. Significance: The current study demonstrated that the addition of right amount of Al₂O₃ microfibre into the ZrO₂ matrix enhanced the mechanical properties of ZrO₂-Al₂O₃ (f) composite, which would be favourable for dental applications.