Densification and grain growth of nanocrystalline 3Y-TZP during two-step sintering

• Published in: Journal of the European Ceramic Society 2008-11, Vol.28 (15), p.2933-2939
• Main Authors: Mazaheri, Mehdi, Simchi, A., Golestani-Fard, F.
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Densification; Exact sciences and technology; Grain growth; Nanocrystalline 3Y-TZP; Structural ceramics; Technical ceramics; Two-step sintering
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2008.04.030

Two-step sintering (TSS) was applied on nanocrystalline yttria tetragonal stabilized zirconia (3Y-TZP) to control the grain growth during the final stage of sintering. The process involves firing at a high temperature (T1) followed by rapid cooling to a lower temperature (T2) and soaking for a prolonged time ( t). It is shown that for nanocrystalline 3Y-TZP (27 nm) the optimum processing condition is T1 = 1300 °C, T2 = 1150 °C and t = 30 h. Firing at T1 for 1 min yields 0.83 fractional density and renders pores unstable, leading to further densification at the lower temperature (T2) without remarkable grain growth. Consequently, full density zirconia ceramic with an average grain size of 110 nm is obtained. XRD analysis indicated that the ceramic is fully stabilized. Single-step sintering of the ceramic compact yields grain size of 275 nm with approximately 3 wt.% monoclinic phase. This observation indicates that at a critical grain size lower than 275 nm, phase stabilization is induced by the ultrafine grain structure.