The gradient porous Al2O3 ceramic was prepared by centrifugal-gelcasting technology using PMMA and nano-Al2O3 particles as initial particles.The effect of pH on Al2 O3 viscosity of slurries was studied.The gel solidification process was observed.The effects of centrifugal rotation and time on gradient of green density were analyzed.The microstructure and compressive strength 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 rotation and time,the green densities of the top and the bottom of the samples both increase and the difference of density gradient becomes obvious.The porosities of the top,middle and bottom of sintering gradient porous Al2O3 ceramic are 52.1％,38.4％ and 15.7％,respectively,when centrifuged at 1000 r/min for 5 min.The compressive strength of sintering compact is 67.2 MPa.%以造孔剂PMMA、纳米Al2O3颗粒为主要原料,利用离心-凝胶注模成型工艺制备梯度多孔Al2O3陶瓷,研究了pH值对Al2O3浆料粘度的影响,观察了Al2O3浆料的凝胶固化过程,分析了离心转速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压缩强度进行测试.研究结果表明引发剂的含量对Al2O3浆料的凝胶固化过程影响不大.随着催化剂含量的增加,Al2O3浆料的起始凝胶固化时间缩短,整个凝胶固化反应过程缩短.随着离心转速的增加和离心时间的延长,试样顶部和底部的生坯密度加大,梯度分离现象变得明显.当离心转速为1000r/min,离心5 min后,制备的梯度多孔Al2O3陶瓷顶部的孔隙度为52.1％,中间为38.4％,底部为15.7％,孔隙呈现连续的梯度变化,烧结产物的抗压强度为67.2MPa.
展开▼
