Characterization of Ce-TZP annealed in vacuum atmosphere

Abstract

12 mol% CeO[subscript 2]-doped tetragonal zirconia polycrystals (12Ce-TZP) has been considered as a candidate material for engineering application because of its outstanding mechanical properties. Furthermore, mechanical properties of Ce-TZP can be improved by heat treatment in reduction atmosphere. In this experiment, specimens were sintered at various temperatures to reach full density. After that, specimens were heat treated by annealing at 1100 to 1400 ํC in vacuum in a high temperature furnace (hot pressed furnace). The mechanical properties of specimens before and after heat treatment were studies. After annealing, the color of specimen changed from yellowish white to dark brown since the reduction atmosphere reduced Ce[superscript 4+] to Ce[superscript 3+]. However, the weight loss after heat treatment was too small (less 0.02%). The phase of specimen annealed at 1100 ํC remained tetragonal which was the same as the sintered one. On the otherhand, specimens after annealing at 1200 ํC showed pure monoclinic phase. The bending strength of this specimen increased from 555 to 621 MPa. The monoclinic phase on the surface of specimen increased the volume of the specimen surface hence induced the compressive layer on the surface. In indentation loading of 10 to 50 kgf, no cracks occurred from the indent corners. Hardness before and after annealing did not change so much in every heat treatment condition