粉末注射成形制备TiC0.7N0.3颗粒增强钛基复合材料和零件

以TiC0.7N0.3粉末为颗粒增强体,采用粉末注射成形技术将其与Ti2Ni1Cr0.8Mo0.5Cu基体钛合金(T5)合成,制备了TiC0.7N0.3颗粒增强钛基复合材料.所制备的复合材料,经腐蚀性能试验、磨损性能试验以及显微组织分析,确知其物理力学性能及显微组织为相对密度＞95%,抗弯强度为950～1 150 MPa,硬度HRC35-45;可热处理,并在保持T5合金良好广谱耐蚀特性的基础上,显著提高耐磨性.复合材料中颗粒相仍为TiC0.7N0.3,加入量由3%增加到6%时,耐磨性提高45%;基体相烧结态为条状α+β相,热处理态为纤细针状α+β相.还用该技术直接近净成形制备了均质机用阀芯零件,以评价其制备和应用的技术经济特性.     

氮基气氛的研究进展

简要回顾了国内外研究氮基气氛热处理的历史，概述了氮基气氛在热处理和烧结中的作用，介绍了氮基气氛的主要类型及应用，列举了氮基气氛的成分和供氮方式，着重评述了深冷法、变吸附法和膜分离三种制氮方法。     

表面处理方式对铜/钼/铜复合材料界面结合效果的影响

借助金相显微镜、扫描电镜观察了钼、铜界面的微观组织，研究了采用不同表面处理方式对铜／钼／铜复合材料界面结合效果的影响，并对其界面的结合机制进行了深人的讨论。结果表明，经过喷砂化学处理的材料复合后界面结合最牢固，界面剪切强度最高，达到78．9MPa，形成很强的铜和钼的机械啮合，其主要的结合机制是机械啮合机制和硬化块破裂机制；在同等复合参数条件下，3种处理方法中化学处理法的界面强度最低。     

钕氧化物颗粒增强钛基复合材料的显微组织和性能

采用真空自耗电弧熔炼方法成功地研制了原位生成的稀土钕氧化物颗粒增强钛基复合材料.利用光学显微镜观察分析了显微组织.测试了材料的拉伸、热稳定性、持久和蠕变等力学性能.试验结果表明,稀土钕氧化物颗粒在基体上分布比较均匀,并在高温下具有良好的热稳定性.经过1030℃/0.5 h/AC 800℃/1 h/AC 700℃/2 h/AC处理后的钕氧化物颗粒增强钛基复合材料棒材具有良好的拉伸、持久、蠕变和热稳定性等力学性能.     

稳定化处理对Cu-1Ag-.4Ce原位纳米纤维复合材料的组织及性能的影响

采用透射电子显微镜研究了Cu-10Ag-0.04Ce原位纳米纤维复合材料加工态和不同热处理状态的显微结构. 加工态的Cu-10Ag-0.04Ce的显微结构为 富Ag相呈纤维分布在铜基内, 粗大的Ag纤维尺寸大于50 nm, 而细的Ag纤维尺寸小于30 nm. 在200 ℃时, 显微结构没有明显的变化;在300 ℃时, 少量Ag纤维开始出现球化;400 ℃时开始出现不连续的Ag沉淀, 局部出现再结晶现象;在500 ℃时材料发生明显的再结晶, 晶粒开始长大. 结果表明小于300 ℃时材料的性能是稳定的.     

纳米TiO2-Al2O3复合粉体的电化学合成

用电化学合成方法制备了TiO2-Al2O3的复合粉体材料,借助化学热力学数据库软件系统对体系进行了热力学分析。所得到的TiO2/Al2O3的复合粉体中,氧化铝主要沉积在二氧化钛颗粒的表面,且二氧化钛的成分任意可调。对TiO2-Al2O3复合凝胶进一步高温处理,可获得纳米Al2TiO5。     

Micromechanical Modeling of the Effective Viscoelastic Properties of Inhomogeneous Materials Using Fraction-exponential Operators

A new analytical approach for’ micromechanical modeling of the effective viscoelastic behavior of a’ composite material is presented. Fractionexponential operators are. used to describe the viscoelastic properties of the constituents. To construct the corresponding elastic solution, effective field method is used. Effective viscoelastic operators are obtained from the Volter ra’s elasticity-viscoelasticity correspondence principle. Incompatible deformation that often occurs during the manufacturiig process is taken intp account. All the formulas are obtained in explicit ready-to-use form.     

A simple method for the evaluation of fracture toughness of a multi-layered laminate based on the failure stress of sub-laminates

A simple analytical method is presented that can be used to predict the intralaminar fracture toughness of multilayered composite laminate based on the failure stresses of its sub laminates. MCCI approach is followed to verify the fracture toughness of a base laminate and the method is validated comparing the available test data on the toughness value of the base laminate with the prediction. It is observed that a better representation of carbon —epoxy base laminate by its sub laminate gives very good agreement in prediction within 3%.     

Thermal buckling of cross-ply laminated composite and sandwich plates according to a global higher-order deformation theory

A two-dimensional global higher-order deformation theory is presented for thermal buckling of cross-ply laminated composite and sandwich plates. By using the method of power series expansion of continuous displacement components, a set of fundamental governing equations which can take into account the effects of both transverse shear and normal stresses is derived through the principle of virtual work. Several sets of truncated Mth-order approximate theories are applied to solve the eigenvalue problems of a simply supported multilayered plate. Modal transverse shear and normal stresses can be calculated by integrating the three-dimensional equations of equilibrium in the thickness direction, and satisfying the continuity conditions at the interface between layers and stress boundary conditions at the external surfaces. Numerical results are compared with those of the published three-dimensional layerwise theory in which both in-plane and normal displacements are assumed to be C⁰ continuous in the continuity conditions at the interface between layers. Effects of the difference of displacement continuity conditions between the three-dimensional layerwise theory and the global higher-order theory are clarified in thermal buckling problems of multilayered composite plates.     

SiO2对金属锂盐聚合物电解质导电作用的影响

采用溶液浇注法制备了PEO基聚合物电解质,测定了该类电解质的电导率,并研究了温度、SiO2的颗粒度及表面性能对聚环氧乙烯/高氯酸锂(PEO/LiClO4)聚合物电解质体系电导率的影响.结果表明PEO-LiClO4-10%SiO2复合型聚合物电解质的室温电导率达到了1.033×10-4S/cm,同时对该电解质进行了差热分析,发现加入SiO2后,PEO/LiClO4体系熔融温度降低,非晶相含量增加,有利于提高离子电导率.