【作者】 王玉春；

【导师】 丘泰；

【作者基本信息】 南京工业大学 ， 材料学， 2003， 硕士

【摘要】 本文介绍了陶瓷基复合材料（CMC）基本概念及制备工艺，特别综述了ZrO₂－Al₂O₃系复相陶瓷的特点及目前国内外的研究现状，发现该系材料的性能业已得到了极大的提高。然而，性能优良的ZrO₂－Al₂O₃系复相陶瓷大多以湿化学法制备的超细高纯的均匀分散的活性粉末为原料，采用热压、热等静压等烧结工艺来获得的，其成本高，而且对工艺过程及设备要求都很高。本文用工业氧化锆和工业氧化铝，通过超细化球磨处理，控制起始粉料的颗粒度，采用常规的工艺方法制备复相陶瓷，研究不同制备工艺对ZrO₂－Al₂O₃系复相陶瓷的烧结性能、力学性能及显微结构的影响，以期用低成本制备出高性能的ZrO₂－Al₂O₃系复相陶瓷。采用工业原料来制备低成本高性能的ZrO₂－Al₂O₃系复相陶瓷的关键是选用合适的工业氧化锆和氧化铝原料。通过对不同原料的起始颗粒度及其易磨性的研究发现，原料氧化锆G和氧化铝A3经过最佳工艺条件为：料球比1：4，球磨时间分别为6h和8h的分别研磨工艺超细化处理后可以得到粒径细小、分散性及活性较好的粉料。研究发现，通过控制稳定剂Y2O3以及第二相弥散颗粒Al₂O₃的含量、采用不同来源的原料、改善球磨工艺及烧成制度，控制材料的显微结构，可实现低成本制备高性能材料的目的。在Al₂O₃的含量为20wt％，Y2O3的含量为3.5mol％，1600℃烧成，保温2小时的最佳工艺条件下可以得到致密化程度高、力学性能优良的ZrO₂－Al₂O₃系复相陶瓷，其抗弯强度和断裂韧性分别为：676.7MPa、10MPa?m1/2，其值接近湿化学法制备的复相陶瓷的力学性能。用XRD研究了烧结体的相组成。从相组成分析可以看出，烧结体中只含ZrO₂和Al₂O₃晶相，随着Y2O3稳定剂含量的增加，烧结体内的单斜相含量逐渐减少，但是，根据相图分析可知，过量的稳定剂的加入，提高了立方相的含量，使得发挥应力诱导相变的亚稳态四方相含量降低，从而降低烧结体的力学性能，当Y2O3稳定剂含量为3.5mol％时，可得到性能较佳的烧结体；当Al₂O₃含量为20wt％时，烧结体内的单斜相含量最小，约占ZrO₂含量的32％。表明适量的Al₂O₃可以充分发挥抑制ZrO₂晶粒的长大，使其大部分小于临界相变尺寸，从而使得大<WP=7>部分的四方相氧化锆以亚稳态保留到室温，提高相变增韧的作用效果。用SEM研究了ZrO₂－Al₂O₃系复相陶瓷的显微结构。电镜观察表明， Al₂O₃含量为0、10wt％时，ZrO₂的晶粒相对较大，分别约为1～2um、1.5～2um；Al₂O₃含量为40wt％时，复相材料明显没烧结，有大量尺寸为8～10um的气孔；当Al₂O₃含量为20wt％时，材料烧结致密，未见到明显的缺陷、孔洞，ZrO₂、Al₂O₃ 晶粒发育生长良好。ZrO₂的晶粒相对较小，约为1～1.5um，较多晶粒小于1um ，Al₂O₃在ZrO₂基质中分散较为均匀，团聚较少，其晶粒尺寸为3⁵um。分析结果表明，加入适量的氧化铝可以均匀地分散在氧化锆基体中，不仅对氧化锆晶粒的生长起抑制作用，而且还可以起到颗粒弥散强化的作用，提高ZrO₂－Al₂O₃系复相陶瓷的各项性能。根据相组成和显微结构的分析，初步探讨了ZrO₂－Al₂O₃系复相陶瓷的增韧机理。研究认为，该系材料的高强高韧性能可归结为ZrO₂的应力诱导相变增韧和Al₂O₃颗粒的弥散增韧叠加作用的结果。更多还原

【Abstract】 The essential conception and the technigue preparation of ceramic matrix composite are introduced in this thesis, especially making a summary of the characteristics of ZrO₂－Al₂O₃ system composite and its investigation actuality up to date, and it is demonstrated that prominent improvement on the properties of this system materials have been made. However, the composites of excellent properties were prepared with superfine, high pure, uniformly dispersible and active powders by hot-pressing and hot isostatic pressing et al, the cost of the processing would be high and making rigorous demands on the technical process and equipment. In this thesis, the composites are prepared using industrial ZrO₂and Al₂O₃ powders by traditional process. The powders are ball-grinded in order to control the original particle size. The influence of process routing on the sintering behavior, mechanical properties and microstructure are studied, with the purpose of preparing ZrO₂－Al₂O₃ system composite with high performance and low costs. The key of ZrO₂－Al₂O₃ system composite with high performance and low costs made of industrial material is preparing that with appropriate industrial ZrO₂and Al₂O₃ powders. The result of studying the initiative diameter and the grinding effectiveness of different materials showed that the industrial Zircoina G and Alumina A3 powders with high dispersant and activation could be obtained by finable-grinding under the condition of material-ball ratio 1:4 and the time of grinding for 6h and 8h, respectively.It has been demonstrated that ZrO₂－Al₂O₃ system composite with high performance and low costs could be prepared through the optimization of the content of Al₂O₃ and Y2O3 and the processing of ball-grinding and sintering. The results of the research work showed that ZrO₂－Al₂O₃ system composite having high bulk density and mechanical properties could be obtained at the sintering temperature of 1600℃, the heat preservation time of 2 hours by adding 20wt% Al₂O₃ and 3.5mol% Y2O3. And the bending strength and fracture toughness of the composites were 676.7Mpa and 10MPa?m1/2,respectively, which were close to those of composites made of ZrO₂ and Al₂O₃ powders synthesized by wet chemical approach. The phase composition of sintered bodies were analyzed by XRD. The results indicated that there were only ZrO₂ and Al₂O₃ phases in sintered bodies. The content of monoclinic ZrO₂ decreased gradually with the increasing content of stabilizer Y2O3. But the content of cubic phase increased and the content of metastable tetragonal phase, which associated with the stress-induced transformation decreased when excessive Y2O3 was added, resulted in the mechanical properties of composites decreasing. And the mechanical properties of composites were preferable by adding 3.5mol%Y2O3. The content of monoclinic ZrO₂ were least with 20wt% Al₂O₃ in the composites, which was 32% of the total content of ZrO₂ approximately. The results revealed that the grain growth of ZrO₂ was inhibited with the introduction of Al₂O₃<WP=9>properly in the ZrO₂ matrix ceramic which was in favor of leaving large amount of metastable tetragonal ZrO₂ in the body and resulted in higher effect of transformation. The microstructure of ZrO₂－Al₂O₃ system composite were investigated by SEM. The results revealed that the particle diameters of ZrO₂ were larger relatively by adding 0 and 10wt% Al₂O₃ , which were 1～2um and 1.5～2um respectively; There were large amount of pores whose diameters were 8¹0um and the composites were disinterred obviously with 40wt% Al₂O₃. The grain growth of Al₂O₃ was favorable and there were no pores and disfigurement visibly in the bodies by adding 20wt% Al₂O₃. The particle diameters of ZrO₂ were finer relatively, which were 1¹.5um, and large portion of that were less than 1um, and Al₂O₃ dispersed in the ZrO₂ matrix ceramic uniformly with 3⁵um particle diameters. The results revealed that not only the grain growth of ZrO₂ was inhibited with the introduct更多还原