离心-凝胶注模工艺制备双梯度多孔Al_2O_3-ZrO_2陶瓷

Preparation of double gradient porous Al_2O_3-ZrO_2 ceramic by centrifugal-gelcasting technology

以造孔剂PMMA、纳米Al2O3和ZrO2颗粒为主要原料利用离心-凝胶注模成型工艺制备气孔和Al2O3/ZrO2相组成均呈现梯度分布的多孔Al2O3-ZrO2陶瓷。研究了Al2O3-ZrO2浆料的凝胶固化过程,分析了离心加速度和离心时间对生坯密度梯度的影响,观察了烧结产物的显微组织并对其力学性能进行测试。研究结果表明,引发剂含量对Al2O3-ZrO2浆料的凝胶固化过程影响不大。随着催化剂含量的增加,Al2O3-ZrO2浆料的起始凝胶固化时间降低,整个凝胶固化反应过程缩短。随着离心加速度的增加和离心时间的延长,生坯顶部和底部的密度差异增加,梯度分离现象变得明显。当离心加速度为178.9g,离心5min后,制备的梯度多孔Al2O3-ZrO2陶瓷顶部的孔隙度为55.2%,中间为37.6%,底部为14.5%,孔隙和Al2O3/ZrO2相呈现连续的梯度变化。烧结产物的抗压强度和断裂韧性分别为80.7MPa和1.46MPa·m1/2。

In this paper, porous Al2O3-ZrO2 ceramics with gradient pore and gradient phase compositions were prepared by centrifugal-gelcasting technology using PMMA, nano-Al2O3 and nano-ZrO2 particles as initial parti- cles. The gel solidification process was observed. The effects of centrifugal acceleration and time on the gradient of green density were analyzed. The microstructure and mechanical properties of sintering compacts were observed and measured. The results show the amount of initiator has little effect on the gel solidification process. With the increase of catalyst amount, the initial solidification time and whole gel solidification process are shortened. With the increase of centrifugal acceleration and time, the green densities difference or the top and the bottom of the samples both increase and mass segregation phenomenon of three kinds of different patti cles becomes obvious. The porosities of the top, middle and bottom of sintering gradient porous Al2O3 ceramic are 55.2%, 37.6% and 14.5%, respectively, when centrifuged at 178.9g for 5rain. The compressive strength and fracture toughness or sintered compact was 80.7MPa and 1. 46MPa· m^1/2