T. Endo et al., MULTIPHASE COMPOSITES OF TETRAGONAL ZIRCONIA AGGLOMERATE DISPERSED INTO ALUMINA AND ALUMINA-ZIRCONIA MATRICES, Journal of Materials Science, 29(9), 1994, pp. 2395-2400
Multiphase composites of yttria- and ceria-doped tetragonal zirconia a
gglomerates (10-50 mum) dispersed into an alumina or alumina-zirconia
matrix were sintered at 1500-1600-degrees-C in air, followed by post-H
ot Isostatic Pressing (HIP) at 1450-degrees-C and 150 MPa in an Ar gas
atmosphere. The relative density of the recovered composites was abov
e 98% of the theoretical density. By chemically etching on the surface
of zirconia agglomerates, the sinterability of composites was apparen
tly improved; and no microcracks nor pores were observed at the interf
ace of agglomerate and matrix. According to scanning electron microsco
py (SEM) observation, tetragonal and tetragonal monoclinic zirconia ag
glomerates were highly dispersed into the alumina or alumina zirconia
matrix. The multiphase composites containing 10 vol% spherical agglome
rates demonstrate the relatively low value of bending strength, < 400
MPa, and a high value of fracture toughness, > 11 MPa m1/2. The crack
propagation introduced by Vickers indentation was efficiently suppress
ed and deflected by the agglomerates.