Objectives: To verify if there is a relationship among physical properties (density and elastic modulus) and the flexural strength of two poycristalline ceramics (yttria stabilized tetragonal zirconia polycrystal, Y-TPZ and polycrystalline alumina, AL). Methods: Bar-shaped specimens (2mmx4mmx16mm) of Y-TZP and AL, were obtained by sectioning commercial blocks and sintering them with subsequent polishing step up to 2 micrometer. Density (D) was determined by Archimedean principle. Elastic constants (E and P) were determined by the ultrasonic pulse-echo method. Flexure strength was obtained by testing the specimens in three-point flexure using a universal testing machine (n=10/37°C/water/1.0MPa/s) with the polished side in tension. All data were analyzed with ANOVA (alpha=0.05). Results: The results are presented in the Table. Y-TZP showed density values that were 53% higher than those obtained for AL. Also, the values of P and flexural strength were respectively 30% and 87% higher for Y-TZP compared to those obtained for AL. As for E, the mean values obtained for AL was 87% higher than that obtained for Y-TZP. Conclusions: The polycrystalline ceramic with higher density and poissons' ratio obtained the highest flexural strength. However for these materials the highest elastic modulus did not translate into the highest strength values.
Material | Properties | |||
D (g/cm3) | E (GPa) | P | σ (MPa) | |
Y-TZP | 6.062 ± 0.009 a (0.14%) | 209.3 ± 2.1 b (1%) | 0.316 ± 0.005 a (1.58%) | 869.0 ± 92.3 a (10.62%) |
AL | 3.953 ± 0.004 b (0.10%) | 390.4 ± 8.3 a (2.12%) | 0.244 ± 0.012 b (4.91%) | 462.8 ± 59.0 b (12.74%) |