PREPARATION OF NOVEL CALCIA-STABILIZED TZP CERAMICS

D. LAMAS; R.E. JUAREZ; A. CANEIRO; B. WALSOE DE RECA

NANOSTRUCTURED MATERIALS

Elsevia Scicne Ltd

Año: 1998 vol. 7 p. 1199 - 1207

0965-9773

The preparation of tetragonal zirconiapolycrystal (TZP) ceramics stabilized bythe addition of calcia is presented. These novel ceramics were obtained by means of a fast-firingtreatment applied to compacts of nanocrystalline powders with a composition of ZrOz - 4 mol%CaO. Powders were synthesized by a nitrate-citrate gel-combustion process and they exhibited thetetragonalphase at room temperature due to their small crystallite size (12-13 nm). These powderswere compacted by uniaxial pressing and fired at 1400.1500°C for 3-5 min, obtaining finegrained,dense ceramics, which also retained the metastable tetragonal phase. Longer heattreatments increased the average grain size leading to large amounts of the monoclinic phase. Itwas alsofound that the critical grain sizefor the tetragonal-to-monoclinic transformation is about150 nm for this composition. This small value explains the necessity of a fast-firing treatment ofthe samples, allowing densification but avoiding a significant grain growth.