微波处理条件下含氧化钇稳定氧化锆增韧氧化铝陶瓷中的相变行为研究

本文采用XRD方法对微波热处理前后具有不同含量的氧化钇稳定氧化锆增韧氧化铝陶瓷的相变行为进行了研究。实验结果表明微波处理过程中,低含量Y_2O_3稳定ZTA陶瓷表面几乎皆为单斜相,当Y_2O_3含量超过2mol％时则四方相含量剧增,其原因在于ZTA陶瓷微波处理引起体积性加热造成较大的内外温差,使得内应力缓解了基质对ZrO_2的约束而发生t—ZrO_2=m—ZrO_2相变。同时如果调节稳定剂含量适中(如2mol％Y_2O_3),并对瓷体进行微波特殊处理后可获得较高的断裂相变量,有利于相变增韧陶瓷力学性能改善及损伤部件的性能自回复。

Study on Phase Transformation Behaviour of Zirconia Toughened Alumina Ceramic Containing Y_2O_3 under Microwave Treatment

The transformation behaviour of zirconia toughened alumina ceramic containing different content of Y2O3 under microwave treatment was investigated with XRD method. The experimental results indicated that the amount of monoclinic phase accounts for a considerable proportion of zirconia on surface of ZTA stabilized with less content of Y2O3, whereas the amount of tetragonal phase rises sharply as the content of Y2O3 is more than 2mol% during microwave treatment. The above-mentioned phenomena may be attributed to that large thermal interal stresses.which originate from a difference of temperatures between inner part and outer part in the same specimen due to volume heating of materials in microwave process, and subsequent relax of the constrained zirconia in matrix, is available on the behaviour of phase transformation from t-ZrO2 to m-ZrO2. Therefore,high strength of zirconia toughened ceramics can be obtained and self-recovery of used or microcracked ceramic component can be easily made for the sake of an evident increase of phase transformation of t-ZrO2,which could again constribute to fracture toughness under load,only if the zirconia toughened ceramic is designed to contain the moderate content of yttrium oxide such as 2.0mol% in synthesising process through such special treatment.