ZrO_2增韧陶瓷中四方相氧化锆的相变量、相变区宽度及其增韧机理的研究

A STUDY OF TRANSFORMATION VOLUME CHANGE,TRANSFORMATION WIDTH AND MECHANISM OF TRANSFORMATION-TOUGHENING IN ZTG

利用X射线衍射技术研究了氧化锆增韧氧化铝陶瓷(ZTA)和四方氧化锆多晶陶瓷(TZP)的断裂表面上四方氧化锆ZrO_2(t)的相变量和相变宽度。发现在ZrO_2增韧陶瓷(ZTC)中,ZrO_2(t)相变所需应力σ_T随着稳定剂Y_2O_3含量的增加而增大,断裂面上的ZrO_2(t)的相变量和相变宽度随之减小。在此基础上提出了修正的相变增韧公式: ΔK=0.21E_ce^TV_fh^(1/2)/(1-ν)+1.26V_fh^(1/2)σ_T(1-2ν)/(1-ν) 该式表明:(1)ZrO_2相变增韧存在一定的限制;(2)增加基质材料的强度是进一步提高ZTC的K_(Ic)和σ_f的关键。

The transformation volume change and the transformation width of ZrO_2(t) on the fracture surface of ZTA(Zirconia Toughened Alumina)and TZP(Tetragonal Zirconia Polycrystals)are studied by X-ray diffraction. It is found that the critical stress to initiate the ZrO_2(t) to ZrO_2(m) transformation increases with the increasing of the content of Y_2O_3 and the decreasing of the transformation zone volume change and transformation zone width of ZrO_2(t)on the fracture surface. Hence a transformation toughening formula modified by the authors is proposed as following: ΔK=0.21E_cV_te^th^(1/2)/(1-ν)+1.26V_th^(1/2)σ_T(1-2ν)/(1-ν) The formula shows that:(1)there exists a limitation of maximum ΔK of zirconiatoughened ceramics; (2)to increase K_(Ic) and σ_f of ZTC, it is necessary to increase the strength of matrix materials.