| 摘要 |
Zirconium oxide ceramic which is partly stabilised by 3.3-4.7 wt.% CaO. The ceramic is pref. employed as a refractory possessing a fine-flaked microstructure with two phases: (a) a metastable tetragonal phase of critical size dispersed in (b) a matrix of cubic grains, where zones (a) are irreversibly converted into the normal monoclinic form when the refractory is exposed to high stress. The ceramic pref. contains 3.4-4.2% Ca, esp. 4% Ca, and the ceramic is baked at 1700-1950 degrees C., followed by cooling at min. 175 degrees C./h, esp. 175-600 degrees C./h to 1200-1450 degrees C., then ageing at this temp., but esp. 1300 degrees C. to obtain max. strength. Ageing may occur by slow cooling from 1400 degrees to 1000 degrees C. Pref. a mixt. of ZrO2 and CaO is moulded, baked 3-5 h at 1700-1950 degrees C., cooled rapidly as above and then either (a) aged; or (b) cooled to room temp. then reheated for ageing. |
