IADR Abstract Archives
Effect of Sintering Temperature on Crystalline Phase Fractions in 3Y-TZP
Objectives: It is well established that the fraction of cubic phase in 3Y-TZP increases with sintering temperature. This in turn strongly influences the mechanical properties, including fracture toughness. Our goal was to determine crystalline phase volume fractions and grain size as a function of sintering temperature in 3Y-TZP for dental applications.
Methods: Disc-shaped specimens were sectioned from 3Y-TZP blanks and sintered at temperatures ranging from 1350 to 1650°C/2h. Crystalline phases were analyzed by x-ray diffraction (XRD) over the range 72 to 75 two-theta degrees (n=5 per group). The grain size was measured on polished and thermally etched specimens (n=5) by the lineal intercept method on scanning electron micrographs. Atomic force micrographs were also acquired in contact mode. The grain size was determined using the particle size analysis feature of the atomic force microscope image analysis software. Particle size distributions were obtained as a function of sintering temperature.
Results: XRD revealed the presence of cubic phase after sintering at 1350°C and a mix of non-transformable tetragonal t’ phase and cubic phase starting at 1450°C, up to 1650°C. There was a linear increase in combined amounts of t’ and c-phase with sintering temperature, starting at 10.8±1.4% at 1350°C and reaching 28.2±0.3% at 1650°C (R2=0.985). The mean real grain size by the intercept method increased from 0.35±0.03µm at 1350°C to 2.24±0.52µm at 1650°C. There were no statistically significant differences between the two techniques used to measure grain size (p>0.05). Groups sintered at 1600 or 1650°C were characterized by dual particle size distributions attributed to the presence of large cubic grains.
Conclusions: There was a linear relationship between sintering temperature and combined amounts of non-transformable t’ and c-phases. The two techniques used to measure mean grain size both revealed a linear increase with sintering temperature up to 1550°C.
Methods: Disc-shaped specimens were sectioned from 3Y-TZP blanks and sintered at temperatures ranging from 1350 to 1650°C/2h. Crystalline phases were analyzed by x-ray diffraction (XRD) over the range 72 to 75 two-theta degrees (n=5 per group). The grain size was measured on polished and thermally etched specimens (n=5) by the lineal intercept method on scanning electron micrographs. Atomic force micrographs were also acquired in contact mode. The grain size was determined using the particle size analysis feature of the atomic force microscope image analysis software. Particle size distributions were obtained as a function of sintering temperature.
Results: XRD revealed the presence of cubic phase after sintering at 1350°C and a mix of non-transformable tetragonal t’ phase and cubic phase starting at 1450°C, up to 1650°C. There was a linear increase in combined amounts of t’ and c-phase with sintering temperature, starting at 10.8±1.4% at 1350°C and reaching 28.2±0.3% at 1650°C (R2=0.985). The mean real grain size by the intercept method increased from 0.35±0.03µm at 1350°C to 2.24±0.52µm at 1650°C. There were no statistically significant differences between the two techniques used to measure grain size (p>0.05). Groups sintered at 1600 or 1650°C were characterized by dual particle size distributions attributed to the presence of large cubic grains.
Conclusions: There was a linear relationship between sintering temperature and combined amounts of non-transformable t’ and c-phases. The two techniques used to measure mean grain size both revealed a linear increase with sintering temperature up to 1550°C.