功能梯度材料

介绍了功能梯度材料的提出，开发流程，研究现状，对于当前功能梯度材料的设计过程，制备方法，性能评价方法和实验手段进行了详细叙述，提出了功能梯度材料应进一步发展的方向。     

梯度功能材料

梯度功能材料是一种新型的复合材料,其特点是界面的成分和组织连续变化,使材料的热应力大为缓和。本文叙述了梯度功能材料的进展以及在航天、核能源、生物医学工程、电子工程等领域的应用和制备方法。     

功能梯度材料的制备方法研究进展

在对功能梯度材料的制备方法进行综述的基础上，比较了几种实验方法的优缺点，并讨论了FGM材料的试验研究前景。采用粉末冶金法制备了SiCp／A1FGM，测量其密度并观察了其微观组织形貌，结果表明材料层间没有明显裂纹和孔隙，致密度良好，相对密度达到97％，与设计要求吻合。     

功能梯度材料最近的研究进展

本文综述了功能梯度材料最近的研究进展，包括这种材料的理论研究重点，制造工艺以及它的潜在应用。     

密度功能梯度材料的探讨EI

梯度功能材料是一种新型材料，它的特点是利用特殊的工艺使两种材料按成分或同种材料按密度逐渐地变化，从而使其性能无界面地、连续地改变。本文对密度功能梯度材料的制备方法、性能和潜在应用做了一些探讨性的研究。     

功能梯度材料的研究现状及展望

功能梯度材料(FGMs)是一种全新的非匀质复合材料,因其优异的结构性能和潜在的应用价值受到人们的高度重视。简要阐述了功能梯度材料的发展历程、研究现状、应用,详细总结和分析了功能梯度材料的制备方法,最后展望了功能梯度材料的发展前景。     

新型梯度功能材料的研究现状与展望

主要介绍了梯度功能材料的研究现状，对国内外制备梯度材料的各项技术进行科学的分类并其原理和优缺点，同时展望了梯度功能材料的发展方向。     

梯度功能材料的研究

梯度功能材料是五年前由日本科学家提出的新概念和新思想,其两侧由不同性能的材料组成,以对付苛刻的使用环境;而中间部分的组成和结构又是连续变化的,使其内部界面消失,以减小和克服结合部位的性能不匹配因素。这类材料在航天事业和核工业中有看广阔的应用前景和极高的使用价值。本文着重介绍了梯度功能材料的设计思想、目前的研究现状、以及我们在这方面做的一些工作。并综述和比较了各类制备工艺技术。     

梯度功能材料表征技术研究进展

梯度功能材料是一种非均匀材料,其表征方法与均匀材料之间存在较大差异.综述了显微镜分析、热分析、光谱分析、能谱分析、元素分析、X射线衍射、电子探针等测试方法在梯度功能材料表征技术中的应用,分析了表征这种非均质材料存在的困难,同时展望了梯度功能材料表征技术的发展趋势.     

功能梯度材料的制备与应用进展

功能梯度材料(FGM)是由日本人首先提出的一种新型复合材料,从提出后到现在已经得到了深入的研究和广泛的应用.阐述了功能梯度材料的概念及其产生背景,重点评述了功能梯度材料各种制备技术的原理和特点,以及国内外在应用方面取得的各种成果,探讨了功能梯度材料的发展方向.     

Evaluation of Thermophysical Properties of Functionally Graded Materials

In this work, by considering four-layered functionally graded material (FGM) specimens of Cu/Ni and PSZ/NiCrAlY, the transient characteristics and homogeneity of heat conduction media have been studied. The thermal diffusivities of the considered specimens have been measured by the laser flash method. As the temperature response curve of a FGM is very similar to that of a homogeneous material, it is difficult to distinguish a FGM from a homogeneous material by the shape of the temperature responses. Therefore, the thermal diffusivity obtained from the half-time method is usually taken as the corresponding value of the thermal diffusivity. The apparent thermal conductivity, obtained from the corresponding value of the thermal diffusivity and the average of the heat capacity of each layer, is different from the effective thermal conductivity, obtained from the sum of the heat resistances of each layer. As the values of the heat capacity of materials exist over a certain range, and the heat capacity distribution can be predicted when the materials in a FGM are known, the amount of error that will be caused when the effective thermal conductivity is replaced by the apparent value can be determined. Also, the heterogeneity of a FGM, based on an evaluation of thermophysical properties, has been discussed.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui,P. R. China.     

流延法制备梯度功能材料的研究进展

简要介绍了梯度功能材料的产牛背景和发展历程,综述了梯度功能材料的制备方法的原理及优缺点.重点阐述了梯度功能材料的流延法制备及流延法制备梯度功能材料的国内外的研究动态和进展.     

梯度热电材料的研究进展

热电材料梯度化是在保证各组分单一材料的热电性能的基础上,拓宽其应用温度范围,使各组分材料都能工作在最佳温区,以确保热电材料在一定的工作温度范围内具有较高的ZT值,保证其高的热电转换效率.介绍了热电材料的研究基础及其梯度化设计,对梯度热电材料在国内外的研究进展进行了综述并对未来的研究趋势进行了展望.     

梯度结构热电材料的研究动态

为了获得高的热电能量转换效率,可以把不同单体联接制成多段热电装置形成梯度结构(FGM),能有效扩大工作温度区间;同时又可以使每段材料工作在其最佳温度范围内,获得最佳的热电优值,有效提高热电转换效率.概述了梯度结构热电材料的设计与研究现状,并简要介绍了梯度结构中的界面稳定性和性能表征.     

A Note for the Crack Problem of Functionally Graded Materials

Employing the power-type function of material properties, a crack lying between the functionally graded materials (FGMs) and homogeneous substrate is studied by an asymptotic analysis from that of bimaterials, J-integral and the numerical calculations. The present results show that when the curve of the material property is concave, i.e. the power (m) of function of material property is great than 1, the stress distribution near the crack-tip is the same as that of homogeneous materials, which is in agreement with previous findings. However, if the curve of the material property is convex corresponding to 0< m <1, our results show that the stress distribution is strongly affected by m and it can be obtained asymptotically from that of bimaterials.     

Alumina/Ce-Tzp Functionally Graded Materials by Electrophoretic Deposition

Cylindrical Al2O3/Ce-TZP functionally graded composites were fabricated by electrophoretic deposition and pressureless sintering in air. A continuous change in composition was realized by changing the composition of the suspension during deposition. In order to achieve full densification, a temperature above 1550℃ was necessary. The resultant FGM cylinder with a diameter of 5.6 mm shows the following structure: a central hole with a diameter less than 0.5 mm, a tough Ce-ZrO2 core with a diameter of about 3 mm, a gradient layer of about 1 mm, and a hard Al2O3-rich surface layer. The Ce-ZrO2 core has a Vickers hardness between 10and 11 GPa and an excellent toughness (＞10 MPa√m). In the gradient layer, hardness and toughness vary continuously along the radius. The surface layer has a hardness of 15.5 GPa and a modest toughness of 2.5MPa√m.     

A Review of Dynamic Fracture Studies in Functionally Graded Materials

Abstract:  This article presents a review of dynamic fracture studies on functionally graded materials. A brief literature review on the fracture mechanics of graded materials is presented first. This is followed by a discussion on the higher-order asymptotic analysis of the transient elastic field surrounding the tip of a dynamically growing crack in a functionally graded material. A comprehensive experimental study of dynamic crack growth in model functionally graded material using the optical method of reflection photoelasticity and high-speed photography is then presented. The results are analysed to establish a generalised relationship between the crack velocity and the dynamic mode-I stress intensity factor (SIF). This relationship is found to be unique and is distinctly different from that previously established for the matrix material (polyester). Finally, an innovative experimental procedure is used to demonstrate the necessity of employing a fully transient stress-field representation in the analysis of optical data for an accurate prediction of the dynamic SIF history.     

Numerical Calculation of Stress Intensity Factors in Functionally Graded Materials

The finite element method is studied for its use in cracked and uncracked plates made of functionally graded materials. The material property variation is discretized by assigning different homogeneous elastic properties to each element. Finite Element results are compared to existing analytical results and the effect of mesh size is discussed. Stress intensity factors are calculated for an edge-cracked plate using both the strain energy release rate and the J-contour integral. The contour dependence of J in an inhomogeneous material is discussed. An alternative, contour independent integral is calculated and it is shown numerically that , the strain energy release rate G, and the limit of J as approaches the crack tip (where is the contour of integration) are all approximately equal. A simple method, using a relatively coarse mesh, is introduced to calculate the stress intensity factors directly from classical J-integrals by obtaining lim_{#x0393; 0} J.     

梯度热电材料的优化设计及研究进展

将2种不同的单体材料连接起来,制备成梯度结构热电材料(FGTM),不仅能扩大材料的应用温区,而且能极大地提高材料的热电转换效率.介绍了梯度热电材料优化设计的理论基础及方法,综述了梯度热电材料的研究进展及应用前景.