Preparation and Hot Isostatic Pressing of ZrO_2 Solid Solution Powders in the System ZrO_2-Al_2O_3

摘要

Special attention has been given to partially stabilized ZrO_2 (PSZ), tetragonal polycrystal ZrO_2 (TZP), and ZrO_2-toughened Al_2O_3 (ZTA) to improve the fracture toughness (K_(IC)) and bending strength (#sigma#_b) of ceramics. In a recent study, it was shown that in the system ZrO_2-Al_2O_3, ZrO_2 solid solutions (ss) are formed metastably up to ≈40 mol percent Al_2O_3 from amorphous materials prepared by the alkoxy-method. Isostatically hot-pressed ZrO_2(ss) ceramics exhibit very high K_(IC) (23 MPa centre dot m~(1/2)) and plastic deformation at room temperature, although their #sigma#_b is weak (<=700 MPa). The texture consists of a homogeneous microstructure with a grain size of ≈50nm. To improve #sigma#_b, two kinds of ceramics have been fabricated by the addition of a small amount of Y_2O_3: (1) perfect ZrO_2(ss) ceramics and (2) composite ceramics of ZrO_2(ss) and #alpha#-Al_2O_3. Composites with a homogeneous dispersed #alpha#-Al_2O_3 result in a remarkable increase of #sigma#_b (1445 MPa). The ratio of ZrO_2(ss) and #alpha#-Al_2O_3 can be controlled by the amount of Y_2O_3 addition and sintering temperature. A new method for preparing solid solutions from chlorides using hydrazine monohydrate has been developed in some systems. This paper describes the mechanical properties of PSZ, TZP and ZTA ceramics fabricated using ZrO_2(ss) powders prepared by some sol-gel techniques.