PSZ—Mo系梯度功能材料的热应力缓和设计与制备

对ＰＳＺ－Ｍｏ系梯度功能材料在制备过程中的热应力缓和性能进行了优化设计，用有限元方法解析了ＰＳＺ－Ｍｏ系两层叠层材料（即非梯度功能材料）在制备过程中的热应力分布情况。同时解析了ＰＳＺ－Ｍｏ系ＦＧＭ在制备过程中的热应力分布及缓和规律。揭示了ＰＳＺ－Ｍｏ系ＦＧＭ在制备过程中的热应力大小与组成分布形状指数Ｐ的关系，对所研究的体系通过热应力缓和最佳时的Ｐ值，同时，对ＦＧＭ的制备工艺进行了研究，用粉末法分别     

MgO／Ni系梯度功能材料的设计与制备

对ＭｇＯ／Ｎｉ系梯度功能材料（ＦＧＭ），分别用实验和微观力学模型测定和计算了用于热应力缓和设计的各物性参数。讨论了两种结果之间存在差异的原因。用有限元方法模拟了制备过程中ＦＧＭ的热应力，得到ＭｇＯ／Ｎｉ系ＦＧＭ的综合设计准则。按设计结果进一步调整粉末工艺性质，成功地烧制出ＭｇＯ／Ｎｉ系ＦＧＭ。     

Ni／Ni3Al—TiC系梯度功能材料的热应力缓和特性设计

本文选择Ｎｉ／ＮｉＡｌ－ＴｉＣ体系的ＦＧＭ，对其在制备过程中的残余絷应力进行了计算机有限元模拟。在综合考虑热应力最小，应力强度比值最小以及纯ＴｉＣ侧应力状态等因素的基础上，完成了ＦＧＭ体系的热应力缓和特性设计，得到组成分布指数Ｐ＝１．６的最佳设计结果。     

Ni／Ni1Al—TiC系梯度功能材料的组成结构设计与制备

选择Ｎｉ／Ｎｉ３Ａｌ－ＴｉＣ体系的ＦＧＭ，对其在制备过程的残余热应力进行了计算机用限元模拟，在综合考虑热应力最小，热应力发生位置以及纯ＴｉＣ侧应力状态等因素的基础上，完成了ＦＧＭ的组成结构设计与优化，得到了组成分布指数Ｐ＝１．６的最佳设计结果，按此设计结果，采用热压烧结工艺，制行出完整的，无宏观缺陷的Ｎｉ／Ｎｉ３Ａｌ－ＴｉＣ系ＦＧＭ样品。     

Ni/Ni_3Al-TiC系梯度功能材料的组成结构设计与制备

选择Ｎｉ／Ｎｉ３ＡｌＴｉＣ体系的ＦＧＭ，对其在制备过程中的残余热应力进行了计算机有限元模拟。在综合考虑热应力最小、热应力发生位置以及纯ＴｉＣ侧应力状态等因素的基础上，完成了ＦＧＭ的组成结构设计与优化，得到了组成分布指数Ｐ＝１．６的最佳设计结果。按此设计结果，采用热压烧结工艺，制备出完整的、无宏观缺陷的Ｎｉ／Ｎｉ３ＡｌＴｉＣ系ＦＧＭ样品。     

分步冷却烧成制备Mg—PSZ材料的研究

采用分步冷却烧成工艺制备Ｍｇ－ＰＳＺ材料，也就是将Ｍｇ－ＰＳＺ材料ｃ相区烧结固溶后的降温过程中，当样品通过ｃ＋ｔ二相区时采用较慢的降温速率，当样品进入ＭｇＯ析出相区时采用较愉的降温速率，发现采用这种烧成工艺可以使Ｍｇ－ＰＳＺ材料抗弯强度达到８１０ＭＰａ，断裂韧性达到１１．０ＭＰａ．ｍ＾１／２，对Ｍｇ－ＰＳＺ材料的抗弯强度，断裂韧性和ＭｇＯ含量间的关系进行了研究，用ＸＲＤ对材料的抛光面和断裂面的单斜     

湿化学法制备微晶（Y，Mg）－PSZ／MgAl_2O_4陶瓷的研究

研究了用湿化学法制备Ｙ_２Ｏ_３－ＭｇＯ－ＺｒＯ_２－Ａｌ_２Ｏ_３四元系超细粉末的工艺技术，探讨了包裹沉淀和包裹沉淀－乙酸镁混合两种制备工艺及组成对微晶ＰＳＺ材料结构、性能的影响。经１１００℃适当时间的热处理获得了在ｃ－ＺｒＯ_２中具有ｔ－ＺｒＯ_２梭形析出体的微晶ＰＳＺ复相陶瓷，其室温强度达８００ＭＰａ，断裂韧性在１４ＭＰａ·ｍ１／２左右，１０００℃下高温强度可达４５８ＭＰａ。     

液液界面法测超滤膜孔径及孔径分布

本采用液液界面法，利用毛细管现象测定了截留分子量为２×１０＾４和５×１０＾４聚砜超滤膜ＰＳ－２，ＰＳ－５的孔径及孔径分布。结果表明，利用水－正丁醇体系能测定超滤膜的孔径及孔径分布，并且具有操作简便，测试压力接近膜工作压力的优点，对于ＰＳ－２超滤膜，测试压力达０．５ＭＰａ即能得到膜完整的孔径分布曲线。     

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。     

苯氧化制苯酐催化剂中十五种元素的发射光谱定量分析

以Ｓｒ（ＮＯ３）２：Ｚｎ：ＮａＦ作混合缓冲剂，经粉末法，交流电弧激发直接光谱法测定萘氧化制苯酐催化剂中Ｓｎ、Ｓｂ、Ｍｏ、Ｖ、Ｐｂ、Ｐ、Ａｌ、Ａｇ、Ｍｎ、Ｍｇ、Ｎｉ、Ｂｉ、Ｃｕ、Ｚｎ、Ｃｏ十五种微量元素，最低测定浓度１×１０（－５）％，变动系数１０％～３０％。     

ECBC边界下夹FGM金属/陶瓷复合板稳态热应力

采用有限元法研究ECBC边界下中间夹FGM金属/陶瓷复合板的稳态热应力问题,检验了研究方法的正确性,给出了该材料复合板的稳态热应力场分布(Ta=500K,Tb=1800K)。结果表明,FGM层厚度的增加对ECBC复合板的稳态热应力影响不明显。当M=1时,热应力曲线平缓而光滑;当M=0.1和10时,热应力曲线出现明显的转折点;随着FGM层孔隙率的增大,三层板的衔接界面处,热应力变化增大,曲线出现钝角;与金属/陶瓷二层复合板界面处热应力出现突变相比,夹FGM金属/陶瓷复合板的热应力非常缓和。此结果为该复合板的设计和应用提供了准确的理论计算依据。     

梯度功能陶瓷圆球的抗热震性

推导和提出了第三类边界条件下梯度功能材料(functionally gradient materials,FGM)圆球的瞬态温度场及瞬态热应力场表达式.基于陶瓷材料的临界应力断裂判据,通过求解梯度功能陶瓷圆球表面达到其局部断裂强度的时间,建立了引起其表面临界热应力的临界温差△Tc的表达式,并以此作为梯度功能陶瓷圆球的抗热震参数.通过计算实例并与均质陶瓷圆球对比,分析了材料的热-物理性能分布规律对其抗热震性的影响,并提出了高抗热震性FGM陶瓷圆球的设计原则:线膨胀系数和热扩散率应由表及里增大,而弹性模量应由表及里减小.     

Functionally Graded Materials Under Severe Thermal Environments

Thermal shock strengths of a plate of a functionally graded material (FGM) are analyzed when the plate is suddenly exposed to an environmental medium of different temperature. A finite element/mode superposition method is proposed to solve the time-dependent temperature field. The admissible temperature jump that the material can sustain is studied using the stress-based and fracture mechanics-based criteria. The critical parameters governing the level of the transient thermal stress in the medium are identified. The strength of FGMs under transient thermal stresses is analyzed using both maximum local tensile stress and maximum stress intensity factor criteria.     

TiC／Ni3Al系梯度功能材料在稳定状态下的隔热应力及其组成分布优化

通过实验方法，测定了ＴｉＣ／Ｎｉ３Ａｌ复合材料的诸物性参数，在此基础上，对于ＴｉＣ／Ｎｉ３Ａｌ系梯度材料（ＦＧＭ）在稳定状态下产生的隔热应力，利用有限元方法进行了热弹性模型下的三维解析，在考虑热应力最小，比应力最小以及ＴｉＣ侧应力状态等因素之后，对圆反状ＴｉＣ／Ｎｉ３Ａｌ系梯度材料的组成分布进行了优化。     

Investigation of wall stress and outflow rate in a flat-bottomed bin: A comparison of the DEM model results with the experimental measurements

The present paper provides a discrete element method (DEM) analysis of the filling and discharge processes of granular material in a 3D flat-bottomed bin. A granular aggregate of nearly round particles (20,400 pea grains, 7.2-7.8 mm in diameter) is considered. The numerical results are compared with the experimental data. The DEM analysis provides an accurate prediction of wall stress distribution and the outflow rate of discharge throughout the bottom orifice. The stress distribution developed within the granular material after filling and during the discharge phase is considered, and the transition from the active to passive stress state is discussed. This analysis aims to quantitatively predict the flow parameters related to the careful identification of the material parameters. The investigation presented may be useful for the ongoing development of DEM.     

High sphericity and diameter controllable B4C ceramic pellets prepared via simple low-cost PVA assisted planet-type rotation method

B₄C ceramic pellets with diameter smaller than 0.7 mm have been simply fabricated via polyvinyl alcohol (PVA) assisted planet-type rotation method. Only commercial B₄C powders and tiny amounts of PVA are needed in the experiment. The PVA solution is used to modify the commercial B₄C powders. And the powders with adhesive properties are spheroidized to form green pellets during the rotation process. Results show that the green B₄C pellets exhibit uniform size distribution and high sphericity. The appropriate diameter of 0.61 mm and high sphericity of 97.15% can be obtained by controlling the rotation time and the concentration of PVA solution. This fabrication method provides a low-cost and simple way to prepare B₄C ceramic pellets with various diameters and high sphericity, and also sheds light on the mass production of other ceramic microspheres.     

Design of a C/SiC functionally graded coating for the oxidation protection of C/C composites

To reduce the residual thermal stress between the carbon fiber-reinforced carbon (C/C) composites and the SiC coating layer, functionally graded materials (FGM) consisting of a C/SiC compositionally graded layer (C/SiC interlayer) were adopted. After designing the compositional distribution of the C/SiC interlayer which can relieve the thermal stress effectively, the deposition conditions of the entire compositional range of the C/SiC composites were determined using a thermodynamic calculation. According to the design and calculation the C/SiC interlayer and the SiC outer layer were deposited on the C/C composites by a low pressure chemical vapor deposition (LPCVD) method at deposition temperatures of 1100 and 1300 °C. The stress calculation and the experimental results suggested that the SiC-rich compositional profile in the FGM layer is the most effective for relieving the thermal stress and increasing the oxidation resistance.     

激光与微波协同加热碳纤维的温度与热应力分布规律

利用仿真软件建立微波加热-激光加热-热辐射-流动传热-固体力学多物理场模型，研究了激光加热直径1mm碳纤维丝束的温度场分布与热应力大小，以及不同激光功率对于温度场与热应力的影响。同时，首次提出激光加热与微波加热结合的方式调节温度场分布与热应力大小的方法，仿真结果显示激光加热与微波加热结合的方式可以改善碳纤维丝束温度场的分布，有效降低丝束加热过程中的热应力。