非晶晶化法制备Si-Al-Zr-O系超微细晶复相陶瓷

Preparation of Si-Al-Zr-O Composite Ceramics with Ultra Fine Grains by in situ Controlled Crystallizing from the Amorphous Bulk

在1650-1700℃下制备了Si-Al-Zr-O(SAZ)溶胶,经快速冷却获得均匀致密的SAZ系非晶体,经梯度热处理得到SAZ系超微细晶复相陶瓷．结合示差扫描量热分析(DSC)、红外光谱(IR)、X射线衍射(XRD)和扫描电镜(SEM)等技术以及Vicker压痕法,研究了相关超微细晶复相陶瓷结构和性能随热处理温度的变化．结果表明,SAZ系非晶体在950℃时开始析出四方氧化铬,1100℃时晶化基本完成,主晶相为莫来石和四方氧化锫,晶粒尺寸为10-40nm;温度升高至1200℃,晶粒迅速长大至0．5μm左右,部分四方氧化锆向单斜氧化锆的转变．样品的显微硬度和断裂韧性经1150℃热处理后均达到最大,分别为12．6GPa和4．32MPa·m1/2．

The homogeneous SiO2-Al2O3-ZrO2（SAZ） sol was prepared at 1650- 1700℃ and transparent amorphous bulk was obtained by controlling the cooling process. The bulk was treated at 950℃ for 2h to nucleate and at 1100- 1250℃ for lh to crystallize, and SAZ composite ceramics with ultra fine grains were prepared. The effects of heat treatment on the structure and properties of the composite caramics were analyzed by using DSC, IR, XRD, SEM and Vickers indentation techniques. The results show that crystallization of SAZ amorphous bulk begins with t-ZrO2 at about 950℃ and completes at about 1100℃. The main phases are mullite, t-ZrO2. With the increase of crystallization temperatures, the gains grow rapidly from 10-40nm to 0.5μm, and the transformation of zirconia from tetragonal into monoclinic occurs. The values of microhardness and fracture toughness are largest at 1150℃, those are 12.6GPa and 4.32MPa·m^1/2 respectively.