Microstructure, Fracture Toughness, and Strength of (Ultra)Fine-GrainedTetragonal Zirconic Ceramics

摘要

A study to improve the bulk and interface properties of ceramic materials basedon tetragonal zirconia is presented. The preparation and compaction behavior of yttria doped zirconia powders is treated. The microstructure of the powders is compared with a commercially available powder. The microstructure development during sintering of Y-TZP is treated. The synthesized powders are very reactive resulting in fast densification at low temperatures. When employing isothermal sintering experiments it could be shown that a dense nanoscale ceramic is obtained (grain size less than 100 nm) after short sintering or sintering at very low temperature. Surface and grain boundary analysis on Y, Ce, and Ti doped zirconia ceramics are presented. This was done using AES (Auger Electron Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy). Grain growth models are considered for grain growth control on ytteria doped zirconia ceramics. It is shown that the experimental observations point to grain growth control by means of an impurity drag mechanism. The influence of other dopants like cerium and titanium on the thermal and chemical stability of the tetragonal phase is presented, and experimental results in the compaction and sintering behavior of these powders are presented. The oxidation state of cerium in ceria doped zirconia ceramics and its influence on grain growth are investigated.