Sushil R. Kanel
,
Heath Misak
,
Dhriti Nepal
,
Shankar Mall
,
Seth W. Brittle
,
Ioana Sizemore
,
David M. Kempisty
,
Mark N. Goltz
新型炭材料
doi:10.1016/S1872-5805(16)60021-5
碳纳米管纱( CNTY)因具有优异的力学强度、化学稳定性、热稳定性和高比表面积而成为去除废水中有机污染物的潜在材料。本文将CNTY用于含2,4-二硝基甲苯(DNT)的污水处理。 CNTY对DNT的吸附能力与文献报道值作对比研究,同时探讨吸附动力学。采用SEM-EDX、HRTEM、Raman与XPS表征CNTY吸附DNT前后的尺寸、表面形貌及表面化学。结果表明,经CNTY对DNT污水处理后的水质达到实验室无离子水级纯度。 CNTY对DNT吸附符合Freundlich吸附等温线, Freundlich参数由KF 为55.0 mg/g (L/mg)1/n,指数1/n为0.737得到,表明其比活性炭吸附性弱,但更易再生。 CNTY比活性炭的吸附性速率更快,遵循拟二级动力学模型。 CNTY吸附DNT引起D、G常偏移,归因于CNTs与DNT间电子受体和供体效应。
关键词:
碳纳米管纱
,
2,4-二硝基甲苯
,
吸附
,
Freundlich吸附等温线
,
新兴技术
Guangwei HAN
,
Di FENG
,
Wujun YE and Heli LUO (Dept. of Superalloy
,
Central Iron and Steel Research Institute
,
Beijing 100081
,
China)
材料科学技术（英文）
A mechanical model is presented in this paper to describe the initiating and propagating of brittle cracks. Two criteria have been deduced from the model to determine the effects of such factors as local stress state, surface and grain boundary energies as well as local grain boundary orientation on the initiating and propagating of both intergranular and transgranular brittle cracks. By which the role of adding B in Ni3Al base alloys to improve their ductility,temper and hydrogen embrittlements in steels and other alloys as well as the random feature of brittle crack initiation could be explained
关键词:
Journal of Applied Physics
A systematic study on the fracture surface of brittle Mg-, Fe-, and Co-based metallic glasses under compressive loading is approached and a fracture mechanism is proposed. Experimentally, the metallic glass samples are compressed into many small fragments, displaying an explosion fracture feature. Therefore, an energy equilibrium model is employed to describe the fracture processes of those brittle metallic glasses. Furthermore, some regular nanoscale steps, which were scarcely discovered, are found on the mirror region on their fracture surfaces. It is suggested that such nanoscale steps are associated with the energy distribution in metallic glasses and are created by the shear waves generated by the instability of crack propagation during the explosion rupture processes. Based on the comparison of experimental observations with numerical calculations, we recommend a novel model for interpreting the development of nanoscale steps on the dynamic fracture surfaces of these brittle metallic glasses, which appropriately describes the experimental findings.
关键词:
brittle fracture;brittleness;cobalt alloys;cracks;elastic waves;iron alloys;magnesium alloys;metallic glasses;bulk amorphous-alloys;energy-dissipation;crack-propagation;dynamic;fracture;instability;strength
H. Y. Jing
,
L. X. Huo
,
Y. F. Zhang and F. Minami( 1) College of Material Science
,
Tianjin University
,
Tianjin 300072
,
China 2) Osaka University
,
Japan)
金属学报(英文版)
A computation framework for brittle fracture which incorporates weakest link statistics and a microme- chanics model reflecting reflecting local damage of the material is described.The Weibull stress W emerges as a probabilistic fracture parameter to define the condition leading material failure. Unstable crack propa- gation occurs at a critical value of W which may be attained paior to or following some amount of duc- tile crack extension. A realistic model of ductile crack growth using the computation cell methodology is used to define the evolution of near tip stress fields during crack extension. An application of proposed framework to predict the measured geometry and ductile tearing effects on the statistical distributio of fracture toughness for the pipe line steel welded joint is described.
关键词:
fracture toughness
,
null
,
null
Xifeng LI
,
Kaifeng ZHANG
,
Guofeng WANG
材料科学技术（英文）
The paper reports on the observation of nanoscale morphology on the tensile fracture surface of a brittle amorphous Fe-based ribbon. The formation of nanoscale damage cavity structure is a main characteristic morphology on the fracture surfaces. Approaching the ribbon boundary, these damage cavities assemble and form the nanoscale periodic corrugations, which are neither Wallner lines nor crack front waves. The periodic corrugations result from the interactions between the reflected elastic waves by the boundaries of amorphous ribbon and the stress fields of the crack tip.
关键词:
Nanoscale periodic corrugation
,
断裂空洞
,
拉伸断裂
Physics Letters A
Two-dimension spring square network model involving the nearest and second neighbour bonds is studied by numerical simulation with Gauss-Seidel iteration for brittle fracture Mode 1. The material-dependent parameter, G(0)/G, is introduced in this simulation, G and G(0) are the parameters related to the elastic moduli of the nearest and second neighbour, bonds, respectively. Brittle fracture of materials with different G(0)/G are simulated under the same quenched disorder. The fractal dimension of crack fluctuates with G(0)/G. It seems that it is impossible for different materials to have a universal fractal dimension of crack in brittle fracture. However, it is possible to have different so-called universal fractal dimensions. (C) 2003 Elsevier Science B.V All rights reserved.
关键词:
fracture;crack;fractal dimension;scanning-tunneling-microscopy;surfaces;roughness;geometry;metals;model
Physica a-Statistical Mechanics and Its Applications
Two-dimensional spring square network model involving the nearest and second neighbour bonds is studied by numerical simulation with Gauss-Seidel iteration for brittle fracture Mode I. The material-dependent parameter, G(0)/G(1) is introduced in this simulation, and G and G(0) are the parameters related to the elastic moduli of the nearest and second neighbour bonds, respectively. Brittle fracture of the same material with different quenched disorders is simulated. Fractal dimension of crack fluctuates with quenched disorder. It seems that it is impossible to have a universal fractal dimension of crack in brittle fracture for the same material with different quenched disorders. However, it is possible to have different so-called universal fractal dimensions in some cases. (C) 2003 Published by Elsevier B.V.
关键词:
disorder;fracture;crack;fractal dimension;scanning-tunneling-microscopy;surfaces;breakdown;lattices;metals
Materials Letters
By employing a pulsed laser source to produce microcracks, typical features of brittle fracture of nanocrystalline FeMoSiB ribbon have been investigated. From the energy viewpoint, explanation for the branching behavior of a moving crack front was proposed. Static and dynamic fracture toughness of the material were calculated to be on average 3.3 and 15.2 MPa m(0.5), respectively, and the difference between these two values was elucidated in comparison with experimental results in the literature. (C) 2001 Elsevier Science B.V. All rights reserved.
关键词:
nanocrystalline;SEM;brittle fracture;branching;fracture toughness;mechanical-properties;wire
