PSZ／Mo功能梯度材料的有限元设计

利用有限元分析的方法，依据拉应力和比应力最小原则对PSZ／Mo功能梯度材料进行了优化设计，确定了FGM的最佳形状分布因子、层数和每一层的厚度。并对最优成分分布FGM在稳态隔热状态下所产生的温度场和热应力进行了计算，得出进行PSZ／Mo功能梯度材料优化设计所需考虑的主要因素。     

MgAl2O4对MgO-PSZ陶瓷的烧结与热学性能的影响

研究了MgO-PSZ和MgAl2O4改进的MgO-PSZ陶瓷制备与性能表征.发现MgO摩尔分数为10%稳定的氧化锆陶瓷样品,在室温下主晶相为单斜相,它是由四方相转变而成.样品中加入适量的MgAl2P4后,相组成中立方相含量增加,可以改变样品的抗循环热震性能,这和MgAl2O4加入后引起的晶粒细化以及致密度适度降低有关;其中在急冷温差△t为1075℃(即急冷最高温度为1100℃)时,在1 mol MgO-PSZ样品配料的基础上再加入0.04 mol MgAl2O4,所获得样品的残余强度率为81%,且在此温度下热震5次后出现裂纹;另外加入MgAl2O4后,样品在热处理过程中的相组成稳定性得到提高.     

Corrosion of type 316L stainless steel in molten LiCl–KCl salt

Pyrochemical reprocessing in molten chloride salt medium has been considered as one of the best options for the reprocessing of spent metallic fuels. The AISI 316L stainless steel (SS) is envisaged as a candidate material for the fabrication of components for various unit operations like salt preparation vessel, electro‐refiner and cathode processor, on which ceramic coatings with metallic bond coat will be applied by the thermal plasma spraying. The unit operation like electro‐refining is carried out in the molten lithium chloride–potassium chloride (LiCl–KCl) eutectic salt at 773 K in argon atmosphere. The corrosion behaviour of the container vessel in molten chloride salts is therefore important, hence corrosion tests were carried out in a molten salt test assembly under argon gas atmosphere. The present paper discusses the corrosion behaviour of 316L SS in the molten LiCl–KCl eutectic salt at 873 K. The 316L SS samples were immersed in the molten LiCl–KCl eutectic for 25, 100 and 250 h, while 316L SS with yttria stabilized zirconia coating was exposed for 1000 h. The exposed samples were examined by optical and scanning electron microscope for corrosion attack. The X‐ray mappings of the cross‐section of the degraded layer onto the 316L SS indicated that the mechanism of corrosion corresponds to the selective diffusion of Cr to the surface with the formation of voids below, and the formation of chromium compounds at the surface. The results of the present study indicated that the yttria stabilized zirconia coating onto the 316L SS exhibits a better corrosion resistance in molten chloride salt than with uncoated 316L SS.     

Discontinuous Coarsening of Tetragonal Precipitates in Partially Stabilized Zirconia Induced by Diffusional Coherency Strain under Applied Stress

When partially stabilized zirconia with 6 mol% MgO and 4 mol% CaO is aged at 1450°C, intragranular precipitation occurs and concurrently the boundaries between the grains migrate, forming a Ca-enriched precipitate-free cubic phase and large tetragonal precipitates behind them. At these compositions and temperature the boundary migration is rapid and shows the characteristics of a discontinuous coarsening. A uniaxial compressive stress applied to this specimen during the aging treatment increases or decreases the migration rate of the boundaries parallel or perpendicular to the stress axis, respectively, in agreement with the prediction that a compressive coherency strain due to the diffusion of Ca atoms is produced at the surface of the retreating grains and drives the migration. The diffusional coherency strain energy is thus expected to be the dominant driving force for the discontinuous coarsening in this solid.     

Investigation of Sintering Technology for Composite of Stainless Steel and Partially Stabilized Zirconia

The sintering technology for mixed powedered extrusion rods of different proportions of stainless steel to magnesia partially stabilized zirconia(PSZ) was investigated..The effects of some sintering parameters including holding time ,atmosphere and protective gas pressure on shrinkage,relative density,micostructure,micro-Vickers hardness and compression strength of sintered samples were mainly researched.The experimental results are as follows(1)The shrinkage and the relative density of the sintered samples decrease as increasing stainless steel content in the composite,except for the xase containing 90 percent of stainless steel;(2)The porosity in PSZ matrix rises as increasing the stainless steel content in the composite;(3)Longer sintering holding time ,higher sintering vacuum and gas-pressure sintering process not only enhance the relative density ,but also improve microstructure of composite;(4)Micre-Vickers hardness of PSZ matrix decreases as increasing stainless steel content,while that of stainless steel particles in sintered samples varies unnoticeably.     

新型陶瓷的开发及其特殊应用

综述了陶瓷的基本性质，新型陶瓷的开发及其特殊应用。     

化学共沉淀法制备微晶PSZ陶瓷的显微结构与力学性能

采用化学共沉淀法制备ＺｒＯ２－ＭｇＯ－Ｙ２Ｏ３系和ＺｒＯ２－ＭｇＯ－Ｙ２Ｏ３系均匀超细活性粉末，经化学组成和显微结构设计，获得了固溶湿度小于等于１５５０℃且致密烧结的微晶ＰＳＺ复相陶瓷，其常温抗弯强度为７６６ＭＰａ，断裂韧性Ｋ１ｃ为１２．５ＭＰａ·ｍ＾１／２。研究了ＭｇＯ和Ａｌ２Ｏ３以及１１００℃热处理时间对材料显微结构、相组成和力学性能的影响。     

Crystal Structures of Two Orthorhombic Zirconias

The crystal structures of orthorhombic zirconias formed by cooling magnesia-partially-stabilized zirconia (Mg-PSZ) (space group Pbc 2₁) and by quenching zirconia powder from 600°C and 6 GPa (space group Pbca ) are compared and contrasted. It is demonstrated that the two structures are easily distinguished by the neutron powder diffraction techniques used to establish them. The occurrence of two distinct phases is hence proved. Structural relationships between these two phases and also with the in situ high-pressure structure proposed from X-ray diffraction (XRD) are discussed. The three structures are virtually indistinguishable by XRD and so the structure of the high-pressure form "in situ" is considered to remain unknown.     

添加剂Y_2O_3对Mg-PSZ显微结构及力学性能的影响

研究了添加Ｙ２Ｏ３对ＭｇＰＳＺ显微结构及力学性能的影响。结果表明,ＭｇＰＳＺ中引入Ｙ２Ｏ３有利于降低烧结温度,促进立方化完全,但烧结体的力学性能有所降低。在１４００℃下热处理,（Ｍｇ,Ｙ）ＰＳＺ材料与ＭｇＰＳＺ一样发生ｃＺｒＯ２→ｔＺｒＯ２的析出过程,析出纺锤状四方ＺｒＯ２晶体。１４００℃热处理１０ｈ获得最大抗弯强度达６４８ＭＰａ,断裂韧性Ｋ１ｃ为８．３ＭＰａ·ｍ１／２。Ｙ２Ｏ３的加入使获得优异力学性能的热处理范围变宽,因而工艺上容易控制。但Ｙ２Ｏ３加入过多使析出困难。最佳加入量为１．０％（摩尔百分数）。Ｙ２Ｏ３的加入还使材料的Ｗｅｉｂｕｌ模数增高至１８．４６,表明（Ｍｇ,Ｙ）ＰＳＺ经热处理后能消除内部缺陷,使材料可靠性提高。     

Thermal plasma CVD of PSZ and double layered TiN/PSZ coatings by injection of alkoxides solutions with H2O

Coatings of partially Y₂O₃-stabilized ZrO₂ (PSZ) (Y > 2 at.%) and double layered TiN/PSZ films were deposited on Si wafers at 700 °C from zirconium tetra-buthoxide (ZTBO), yttrium tri-buthoxide (YTBO) and/or titanium tetra-ethoxide by chemical vapor deposition with H₂O in a thermal Ar/N₂/H₂ plasma. A small amount of H₂O was fed into the plasma to oxidize the ZTBO and YTBO to produce the PSZ coatings. Double layered TiN/PSZ film coatings were deposited without severe oxidation of under-layered TiN by controlling the feeding rate of H₂O. The product phases were identified by grazing incidence X-ray-diffractometry. The surfaces and cross-sections of the PSZ and double layered TiN/PSZ coatings were observed by scanning electron microscopy. An in-depth semi-quantitative analysis of the double layered TiN/PSZ films was performed by X-ray photoelectron spectroscopy, revealing the changes in the concentrations of Zr, Y, Ti, O, and N with depth. The effect of the Y content in mixed solutions of ZTBO and YTBO on the evolution of ZrO₂ is examined. It is proposed that the controlled feed rate of H₂O is effective in producing coatings of PSZ on TiN films without severe oxidation.