【作者】 刘祎冉；

【导师】 杨永顺；

【作者基本信息】 河南科技大学 ， 材料加工工程， 2008， 硕士

【摘要】 纳米复相陶瓷具有优良的室温和高温力学性能,使其在切削刀具、轴承、高温发动机部件等诸多方面都有广阔的应用前景。利用纳米复相陶瓷在高温下具有的超塑性进行成形加工是实现复杂形状零件近净成形的重要手段。本文以ZrO₂（3Y）-CaO-SiO₂-TiO₂纳米复相陶瓷为研究对象,按照“粉体合成-块体制备-性能测试”这一工艺路线并结合组织性能分析来研究ZrO₂（3Y）-CaO-SiO₂-TiO₂纳米复相陶瓷。采用醇-水溶液加热法结合共沉淀过程制备了分散性良好的纳米ZrO₂（3Y）-CaO-SiO₂-TiO₂粉体。着重研究了煅烧温度对粉体成分、物相组成、晶粒尺寸以及粉体烧结活性的影响。利用透射电镜、扫描电镜、电子探针、X射线衍射仪、比表面积测定仪等测试手段监测整个制备工艺过程并对粉体进行表征。最终得到了平均粒径为11¹5nm,比表面积为69.15m²·g^-1,各组分均匀分布的ZrO₂（3Y）-CaO-SiO₂-TiO₂纳米复合粉体。采用真空热压烧结方法制备了陶瓷块体,研究了烧结温度对ZrO₂（3Y）-CaO-SiO₂-TiO₂陶瓷块体微观组织和力学性能的影响,结果表明其合适的真空热压烧结温度为1250¹300℃。1300℃烧结时制得的陶瓷块体平均晶粒尺寸为230nm左右,相对密度可达97.8%,硬度值达1400.58kgf·mm^-2。陶瓷的超塑性压缩实验表明,在1400¹450℃的温度范围内,材料表现出良好的超塑成形性能。在整个压缩变形过程中,材料没有出现明显的应变软化,显示出与超塑性拉伸变形截然不同的特性。更多还原

【Abstract】 Owning excellent mechanical properties from ambient to elevated temperature, nanocomposite ceramics are considered as promising materials with their application in cutting-tools, bearing and engine components, et al. Components with complex shape can be made of nanocomposite ceramic by taking advantages of its superplasticity, which is an important way in near-net shape forming. ZrO₂ （3Y）-CaO-SiO₂-TiO₂ nanocomposite ceramic was studied under the route of“powders synthesis—composite sintering—performance testing”. The microstructures and mechanical properties of ZrO₂（3Y）-CaO-SiO₂-TiO₂ nanocomposite ceramic have been investigated systematically.ZrO₂（3Y）-CaO-SiO₂-TiO₂ powders with excellent chemical homogeneity were synthesized by heating of ethanol-aqueous salt solutions combined co-precipitation method. The influences of sintering temperature on compositions, phase composition, particle size and sintering activity were studied. TEM, SEM, XRD, BET and other instruments were used to test the whole process and identify the powder’s characteristic. Nano-scaled ZrO₂（3Y）-CaO-SiO₂-TiO₂ powders with particle size of 15²0nm,specific surface area of 69.15m2·g-1 can be obtained. The powders also showed uniform grain size, less agglomeration and good sintering activity.ZrO₂（3Y）-CaO-SiO₂-TiO₂ ceramic composite was obtained by vacuum hot- pressing sintering. The microstructure and the mechanical properties of the ceramics under different sintering temperature were investigated. After hot-pressing sintering at 1300℃, the average grain size of the ceramic material is about 230nm, the relative density is up to 97.8% and the hardness is 1400.58kgf·mm^-2.Superplastic compressive tests demonstrate that the material behaves good deformability in temperature range of 1400℃to 1450℃. During the compression tests, the material did not show any strain softening, which was quite different from the results obtained in the tensile tests of this kind of material.更多还原