【作者】 王凤霞；

【导师】 蔡舒；

【作者基本信息】 天津大学 ， 材料学， 2007， 硕士

【摘要】 本文以MgO/ZrO₂为10/90（mol）为基材,添加不同含量的ZnO ,在1580℃烧结,并对部分样品进行热处理,制得（Zn,Mg）-ZrO₂陶瓷。用SEM、XRD等方法研究其微观结构及相组成。比较了不同ZnO含量对材料微观结构和力学性能的影响。本文还研究了线材拉制环境下不同PSZ体系的摩擦学性能,分析了不同摩擦介质、转速、载荷对其摩擦学性能的影响规律和作用机理。实验结果表明,ZnO可以与ZrO₂生成固溶化合物,引起晶格畸变,从而促进烧结,降低烧结温度,形成具有较小晶粒和更加致密的烧结体。另外,含有ZnO的样品在烧成冷却过程中会形成大量的四方相,并能稳定至室温,突破了传统Mg-PSZ必须经长时间热处理才能析出较多四方相的限制,简化了生产工艺,降低了成本。ZnO的含量对Mg-PSZ中析出体的形貌具有调控作用,随着ZnO加入量的增加,晶粒内析出体粒径增大,其形状也由球形逐渐转变为具有特定晶向的各向异性,这对于进一步控制和开发陶瓷性能提供了很好的依据。当ZnO含量为0.4mol%时,PSZ具有较高的抗弯强度,数值达到703.5±47.3MPa,但由于其中四方相形成机理的不同,其韧性比Mg-PSZ低很多,只能达到7.8±0.8MPam^1/2。因此实际应用中,只能用于对于韧性要求不是很高的环境。通过研究线材拉制环境下,0.4ZnO-10MgO-ZrO₂ ,10MgO-ZrO₂,Y-TZP三种材料与65Mn钢丝进行摩擦的情况,说明氧化锆基陶瓷材料在此条件下具有较好的摩擦磨损性能,在摩擦介质,转速,载荷等因素不断变化的情况下,磨损率均能在10小时后达到平稳,数量级在10^-6～10^-7范围,其中Y-TZP具有各种条件下最佳的摩擦磨损性能。由于水与氧化锆基陶瓷间会发生复杂反应,在水为摩擦介质条件下其磨损性能发生恶化,尤其是Mg-PSZ材料在水介质摩擦时中会发生磨损突变。通过实验还发现以下规律:转速的提高可以降低陶瓷的磨损率;载荷的增加使陶瓷材料的磨损率增加,但不会有数量级的变化。这些都为氧化锆基陶瓷材料作为线材拉制中的拉丝模提供了参考依据。更多还原

【Abstract】 PSZ ceramics based on Mg-PSZ with a molar rate of 10:90 of MgO: ZrO₂ were prepared by adding different content of ZnO. Mechanical properties were measured by three point flexural test and hardness test. Tribology properties were also examined under a simulated circumstance of wire drawing. The microstructure characteristics and phases constitute were identified by SEM and XRD. The effects of different content of ZnO on microstructures and mechanical properties were investigated. The tribology properties of different PSZ systems under different frictional rings, rotation rate, and normal load were also analyzed.The experiment results show that a new compound were formed by the reaction of ZnO and ZrO₂ and induced the aberration of crystal lattice, which lead to a low sintering temperature and small grain size. Compared with the traditional Mg-PSZ, a amount of t-ZrO₂ phase precipitated directly from the （Zn,Mg）-ZrO₂ matrix during the cooling process without a long-time heat-annealing. It simplified the producing process and decreased the cost.The ZnO content had an effect on the shape of t-ZrO₂ precipitates. As the increasing of the ZnO content, the size of the grain became bigger, and its shape changed from sphere to multi-sides one which was anisotropism. The mechanism provided evidence for the controlling and exploitation of the properties of the ceramics.Among the samples doped with zinc oxide, the average bending strength of samples with 0.4mol% ZnO reached to 703.5±47.3MPa. but for the different forming mechanism of t-ZrO₂, it showed a lower toughness than that of Mg-PSZ, which was 7.8MPam^1/2 . Considering the lower toughness, Mg-PSZ ceramics doped with ZnO can only be used in such an environment that does not require a high toughness.The friction behaviour between steel wire of 65Mn and different zirconia based ceramic rings, such as 0.4ZnO-10MgO-ZrO₂,10MgO-ZrO₂ and Y-TZP, is done respectively under a simulated circumstance of wire drawing. It showed that zirconia based ceramics had good properties of tribology that wear rate came to a stabilization after 10h with a value between 10^-6～10^-7. And Y-TZP is the best one. Because of the complicated reactions between water and zirconia based ceramics, wear rate value is smaller in the oil than in the water. And Mg-PSZ had a break of wear rate when sliding in the water. Through the research, we also found the following rules: the increasing of rotational rate decreased the wear rate of ceramics; the bigger of the normal load, the higher of the wear rate. They can all provide reference when the ceramics with zirconia matrix are used as module of wire drawing. The results can be used to guide the application of zirconia based ceramic parts in different environments.更多还原