Ceramic and composite materials based on Y-TZP and metastable Al2 O3 nanofibers were manufactured by uniaxial single-axis pressing followed by free sintering in the temperature range of 1350 –1600°C. The addition of 1 vol.% Al2 O3 nanofibers makes it possible to produce ceramics with 196 nm grain and a relative density of 98% at 1400°C. For samples without nanofibers, the density value approaches 98% only at a sintering temperature of 1500°C and is accompanied by an increase in the average grain size by 25%. It was found that the introduction of Al2 O3 nanofibers into Y-TZP is accompanied by an increase in hydrothermal resistance: the content of the monocline phase after 40 hours of testing at 134°C water vapour temperature and a pressure of 0.2 MPa does not exceed 3.5 vol.% in samples manufactured in the sintering temperature range of 1400 –1500°C, while in samples without nanofibers sintered at 1500°C, the content of the monocline phase after such tests exceeds 60%. A regular relationship has been found between the degree of tetragonality the source material and the formation of the monoclinic phase after accelerated ageing. After the ageing test at a vapour temperature of 180°C and a pressure of 1 MPa, the phase content of the studied ceramics remains stable with the degree of tetragonality not exceeding 1.0145. The discovered regularity expands the possibilities for optimization of manufacturing modes and achievement of the required balance of various operating properties of Y-TZP ceramics used as implants or responsible products working in a humid environment.
ASJC Scopus subject areas
- Materials Science(all)