Influence of sintering parameters on the microstructure and mechanical properties of nanosized 3Y-TZP ceramics

Abstract

The fracture toughness of 3Y-TZP ceramics obtained from a nanocrystalline powder with an optimized microstructure and highly transformable tetragonal grains was investigated. Samples of ZrO 2-3 mol% Y 2 O 3 were sintered at temperatures between 1250 and 1400 °C, with isothermal holding times of up to 16 h. Samples sintered at 1250 °C exhibited relative densities ranging between 92% and 98%, which increased with increasing isothermal duration, while samples sintered at 1300, 1350, or 1400 °C achieved densification higher than 98% for all isothermal treatments. Crystallographic analysis indicated the presence of a highly transformable ZrO 2-tetragonal phase (c/a√2= 1.0148-1.0154) for all conditions studied. The average grain size ranged from 0.18±0.04 mm (1250 °C-0 h) to 0.64±0.08 mm (1400 °C-16 h), indicating activation energy of 141.3 kJ/mol for grain growth and a growth exponent of 2.8. Both Vickers hardness (1025 to 1300 HV) and fracture toughness (4.0 to 7.8 MPa.m 1/2) increased with increasing sintering temperature and time due to increased densification, reduced porosity, and maintenance of potentially high fracture toughness by the t m phase transformation.

Heating rate effect during sintering on the technological properties of Brazilian red ceramics

“…Other studies [53,54] rea rm that grain growth reduces the driving force for sintering. This is explained by the increase in the average distance required for diffusion, where mass transfer from the grain contours to the neck formation occurs, which is the mechanism responsible for porosity reduction [55,56].…”