共查询到18条相似文献,搜索用时 140 毫秒
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研究了反应物起始条件对非化学计量碳化钛SHS过程燃烧动力学的影响。用燃烧波淬火法分析了燃烧产物组织形成过程,并计算了SHS过程的激活能。 研究SHS—准热等静压工艺表明,制备非化学计量碳化钛基金属陶瓷时,存在一有利于致密化的最佳施压滞后时间。增大外加压力有利于提高最终产物密度,直到压力大于160MPa后产物密度不再增大,施加压力的保持时间超过1.5min后,延长时间亦不能增加最终产物密度。 在C/Ti=0.42~0.50范围内,用SHS—准热等静压工艺制备了致密化的非化学计量碳化钛基金属陶瓷。金属陶瓷经800℃、0.5h处理后,其中的非化学计量碳化钛相发生有序化转变,金属陶瓷的抗弯强度增大。 根据材料设计知识,添加Ni、TaC、Mo有效地细化了金属陶瓷晶粒,提高了金属陶瓷性能。并且添加Mo使粘结相由α-Ti(hcp)转化为β-Ti(bcc),提高粘结相变形能力。在C/Ti=0.45时,同时添加7wt%的Mo和4wt%TaC的复合作用使金属陶瓷抗弯强度达884.0MPa,硬度HRA87.3。 自蔓延高温合成的非化学计量碳化钛基金属陶瓷,具有较好的红硬性和优良的耐腐蚀性能。 相似文献
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功能梯度材料:回顾与展望 总被引:2,自引:0,他引:2
本文阐述了功能梯度材料的种类、主要制备方法以及国内外研究进展和应用,对该领域的几个重要热点问题进行了讨论。此外,提出了一种新的梯度材料制备方法——等离子喷焊法,分析了该法的特点。 相似文献
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研究了间隙波在功能梯度压电板和压电半空间结构中的传播性质.功能梯度压电板的材料性能沿x2方向呈指数变化,首先推导了间隙波传播时的解析解,利用界面条件得到了间隙波的频散方程,基于推导的频散方程,结合数值算例分析了功能梯度压电材料的梯度、压电层厚度以及材料性能对间隙波相速度的影响,研究结果对功能梯度压电材料的覆层结构在声波器件中的应用具有重要的参考价值. 相似文献
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The microstructure and composition of TiC-A12O3/Fe functionally graded materials (FGM) prepared by self-propagating high temperature synthesis and pseudo-hot isostatic pressing (SHS/ PHIP) were studied, and the resisting thermal shock behaviors were analyzed. The results show that TiC-A12O3/Fe FGM has graded composition distribution. No cross-section crack through the layers was found in the tests of thermal shock and fatigue. 相似文献
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Al—TiO2自蔓延高温合成和热爆合成金属陶瓷宏观动力学差异 总被引:1,自引:0,他引:1
通过试验观察了Al-TiO_2自蔓延高温合成(SHS)和热爆合成Ti-Al_2O_3金属陶瓷复合材料宏观结构差异,并结合冶金学原理对此作了分析。发现Al-TiO_2反应系统以SHS方式进行时,能合成组成、结构均匀的Ti-Al_2O_3金属陶瓷复合材料,而热爆方式进行时则不能做到。 相似文献
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Nand Jee Kanu Umesh Kumar Vates Gyanendra Kumar Singh Sachin Chavan 《Particulate Science and Technology》2019,37(5):579-604
Composite materials fail under extreme working conditions, particularly at high temperature, due to delamination (separation of fibers from matrix). And therefore it is needed to switch over functionally graded materials (FGMs) which can sustain at high temperature conditions (250–2000°C). There is a need to analyze the fracture and fatigue characteristics of FGM structures and so through this review the emphasis is given on fracture analysis of FGM materials. It has been reported that a combination of extended finite element method and isogeometric analysis methodologies has been used for general mixed-mode crack propagation problems after the introduction of extended isogeometric analysis. Furthermore, recent computational advances have been in the form of multiscale simulations where the part of model is simulated by a finer modeling scale, which can represent details of the material behavior and the interacting effects of material constituents in the finest way. The review is also focused on new advances in analytical and numerical methods for the stress, vibration, and buckling analyses of FGMs. Emphasis has been primarily on to restrict 2D analysis with sorts of compromise in the accuracy of results. First shear deformation theory (FSDT) and third-order shear deformation theory have been extensively used among the various 2D plate theories. FSDT can help us in terms of getting reasonably accurate results with less computational afford. This paper also outlines review on carbon nanotubes (CNT) reinforced FGMs, functionally graded nanocomposites, functionally graded single-walled CNT, FG nanobeam as well as functionally graded piezoelectric materials. Future applications would be based on these smart materials which are supposed to serve us in adverse conditions. Of course, with rise and advent of promising nanotechnology and its potential impact on aerospace industry as well as on other areas, it becomes important to us to compile this review article. 相似文献
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Linhui Zhang 《Engineering Fracture Mechanics》2009,76(16):2512-2525
This paper addresses asymptotic full crack-tip fields for an anti-plane (Mode-III) stationary crack in an anisotropic functionally graded material. A monoclinic material that has a material symmetry plane is considered. The complex variable approach and the asymptotic analysis are used to solve a perturbed Laplace equation resulting from material anisotropy and gradation. The out-of-plane displacement and stress solutions are provided for a crack in exponentially and linearly graded anisotropic materials by considering material gradation either parallel or perpendicular to the crack. The characteristics of the asymptotic solutions in an anisotropic functionally graded material are compared with those for anisotropic homogeneous and isotropic graded materials. Finally, engineering significance of the present work is discussed. 相似文献