Fabrication of zirconia- and ceria-based thin-wall tubes by thermoplastic extrusion

Thin-wall tubes made of zirconia stabilized by 8 mol% of yttria and of ceria doped by 10 mol% of gadolinia were prepared by thermoplastic extrusion. The rheological behaviour of the ceramic mixtures prepared and the effect of rheological properties on the deformation of tubes were studied. After sintering, the diameter of tubes was 10.5 mm and their wall thickness ranged from 270 to 420 gm. The deformation and shape irregularity of sintered tubes were determined. The tubes, which were sintered at a temperature of 1500 degreesC, had a relative density of more than 98% t.d. Flexural strength and fracture toughness of sintered ceramics were determined on test bars prepared by injection moulding from thermoplastic mixtures identical to those used for extrusion. The fracture toughness established was 1.7 MPa m(0.5) for yttria-stabilized zirconia, and 1.1 MPa m(0.5) for gadolinia-doped ceria. (C) 2003 Elsevier Ltd. All rights reserved.