Development of toughened zirconia laminate materials

陶瓷材料可望成为高温使用材料或高耐磨材料，但其本质的脆性限制了陶瓷材料的实际应用。在本研究中，我们开发了高韧化氧化锆层板，以改善陶瓷的脆性。众所周知，部分稳定氧化锆材料的断裂韧性由于应力诱导相变而提高。但韧性的提高受到相变量饱和的限制。通过控制相变层和非相变层的厚度，制备了ZrO_2-6mol%Y_2O_3、ZrO_2-3mol%Y_2O_3和ZrO_2-2mol%Y_2O_3三种不同厚度的ZrO_2陶瓷层，研制了具有高抗裂纹扩展性能的增韧氧化锆陶瓷层压板。搅拌器里掺了液体。通过控制浆料的粘度，获得了厚度恒定的层。将获得的层堆叠并热压。通过改变叠层方向制备了三种不同加载方向的试样，测试了其四点弯曲强度和断裂韧性。还测量了这些测试期间的声发射信号。最大断裂韧性为9 MPam ^<1/2>。研究了厚度和成分对力学性能的影响。用X射线衍射分析系统测定了主裂纹附近的相变率。通过裂纹扩展过程中的声发射特征和对裂纹的观察，分析了主裂纹附近相变的作用，并对增韧机理进行了评价。

Cermics are expected to be high-temperature use materials or high wear resistance materials, but their essential brittleness interfere the pratical application of ceramics. In this research, we have developed the high-toughened zirconia laminates to improve the brittleness of ceramics. It is well known that the fracture toughness of partially stabilized zirconia materials are enhanced to due the stress induced transformation. However, an increase of toughness is limited by the saturation of transformation quantity. We have developed the toughened zirconia laminates with high crack propagation resistance by stacking non-transformed and transformed layrs and by controlling the thickness of layrs.The thin layrs of ZrO_2-6mol%Y_2O_3, ZrO_2-3mol%Y_2O_3 and ZrO_2-2mol%Y_2O_3 were produced. The pawder was mixed with liquid. Layrs with a constant thickness were obtained by controlling viscosity of slury. The obtained layrs were stacked and hot-pressed. Three types of specimens with different direction of load were prepared by changing the stacking direction.The four-point bending strength and fracture foughness were measured. Acoustic emission signals during these tests were also measured. The maximum fracture toughness was9MPam^<1/2>. The effect of thickness and composition on mechanical properties was investigated. The ratio of transformation near main crack was measured by X-ray diffraction analysis system. The role of transformation near main crack was analyzed by the acoustic emission characteristics during crack propation and the observation of crasks, and the mechanism of toughening was evaluated.