http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Bouvard, Vé (검색결과 6 건)
- 무료
- 기관 내 무료
- 유료
-
Numerical simulation of dimensional changes during sintering of tungsten carbides compacts
Bouvard D.,Gillia O. 한국분말야금학회 1997 한국분말야금학회 학술대회논문집 Vol.1997 No.1
During sintering of very porous green bodies, as obtained by compaction of hard powders - such as tungsten carbide or ceramics - or by injection moulding, important shrinkage occurs. Due to heterogeneous green density field, gravity effects, friction on the support, thermal gradients, etc., this shrinkage is often non-uniform, which' may induce significant shape changes. As the ratio of compact dimension to powder size is very high, the mechanics of continuum is relevant to model such phenomena. Thus numerical techniques, such as the finite element method can be used to simulate the sintering process and predict the final shape of the sintered part. Such type of simulation has much been developed in the last decade firstly for hot isostatic pressing and next for die compaction. Finite element modelling has been recently applied to free sintering. The simulation of sintering should be based on constitutive equations describing the thermo-mechanical behaviour of the material under any state of stress and any temperature which may arise within the sintering body. These equations can be drawn either from experimental data or from micromechanical models. The experiments usually consist in free sintering and sinter-forging tests. Indeed applying more complex loading conditions at high temperature under controlled atmosphere is delicate. Micromechanical models describe the constitutive behaviour of aggregates of spheres from the deformation of two-sphere contact either by viscous flow or grain boundary diffusion. Such models are not able to describe complex microstructure and mechanisms as observed in real materials but they can give some basic information on the formulation of constitutive equations. Practically both experimental and theoretical approaches can be coupled to identify the constitutive equations. Such procedure has been performed for modelling the sintering of compacts obtained by die pressing of a mixture of tungsten carbide and cobalt powders. The constitutive behaviour of this material during sintering has been described by a linear viscous constitutive model, whose functions have been fitted from results of free sintering and sinter-forging experiments. This model has next been introduced in ABAQUS finite element code to simulate the sintering of heterogeneous green compacts of various geometries at constant temperature. Examples of simulations are shown and compared with experiments.
-
Analysis of Compression and Permeability Behavior of Porous Ti6Al4V by Computed Microtomography
Luis Olmos,Didier Bouvard,Jose Luis Cabezas‑Villa,Jose Lemus‑Ruiz,Omar Jiménez,Dante Arteaga 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.3
Porous materials were developed as a good alternative to replace different bones in the human body as they improve osseointegration,tissue ingrowth and simulate the mechanical properties of human bones. Such characteristics highly depend on thepore features and volume fraction. Samples with a pore volume fraction between 16 and 60% and a pore size distribution of100–500 μm were analyzed by computed microtomography. 3D images acquisition was performed at 10 μm pixel resolution,which permitted to observe the complete sample. Features like size, shape, orientation, connectivity and pore coordinationwere determined from the 3D image analysis. Compression behavior was evaluated by interrupted compression testing and,after that, new 3D images were acquired. In order to evaluate permeability, numerical simulations of flow throughout the3D images were carried out by using Avizo® software. It was found that shape and pore size distribution was similar in allsamples, showing good distribution of the pore formers inside the matrix. Full connectivity of pores was obtained with 32%volume fraction and above, and the coordination number follows the Artz model. The pores showed a radial orientation,which induces anisotropy in the flow properties. The compression showed two different behaviors, pore closing and porecoalescence. Values of permeability match with those reported for bones as well as the anisotropy in the radial and verticaldirections. It is concluded that the sample with 60 vol% of pores could be consider to be used for bone implants.
-
Microscale Analysis of the Anisotropic Sintering of Metal Powder Compacts
Vagnon Alexandre,Kapelski Georges,Bouvard Didier. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
The behaviour of steel powder compacts during sintering has been investigated by dilatometry and X-ray computed microtomography. Dilatometry measurements showed that the anisotropic deformation results from various phenomena arising at different moments of the cycle including the delubrication stage. Microtomography provided 3D images of the microstructure induced by prior die pressing and its changes throughout sintering. Finally a schematic description of the main phenomena responsible for the deformation of metal powder compacts during sintering is proposed.
-
Schneider L.C.R.,Martin C.L.,Bultel Y.,Kapelski G.,Bouvard D. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Solid Oxide Fuel Cell technology uses powder processes to produce electrodes with residual porosity by partially sintering a mixture of electronically and ionically conducting particles. We model porous fuel cell electrodes with 3D packings of monosized spherical particles. These packings are created by numerical sintering. Each particle-particle contact is characteristic for an ionic, electronic or electrochemical resistance. The numerical packing is then discretized into a resistor network which is solved by using Kirchhoff's current law to evaluate the electrode's electrochemical performance. We investigate in particular percolation effects in functionally graded electrodes as compared to other types of electrodes.
-
Carcinogenicity of fluoro-edenite, silicon carbide fibres and whiskers, and carbon nanotubes
Grosse, Yann,Loomis, Dana,Guyton, Kathryn Z,Lauby-Secretan, Bé,atrice,El Ghissassi, Fatiha,Bouvard, Vé,ronique,Benbrahim-Tallaa, Lamia,Guha, Neela,Scoccianti, Chiara,Mattock, Heidi,Straif, Elsevier 2014 The Lancet. Oncology Vol.15 No.13
-
Jorge Chávez,Omar Jiménez Alemán,Martín Flores Martínez,Héctor J. Vergara‑Hernández,Luis Olmos,Pedro Garnica‑González,Didier Bouvard 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.2
The design and fabrication of a bilayer Ti6Al4V–Ti6Al4V/30Ta component were performed by using the powder metallurgyprocess and solid-state sintering as the consolidation step. Phase change and sintering densifcation of the component werestudied by dilatometry. The addition of 30 vol% of Ta to the Ti6Al4V matrix had a noticeable efect over the microstructuraland mechanical properties of the alloy, which showed decrements of up to 12.2 and 21.5% in nano-hardness and elastic modulus, respectively. The decrement of these properties strongly afected the wear and corrosion performance of the component. Special attention was focused on the intermediate zone between layers denoted by a transition zone, which presented betterwear response because of the properties and microstructure caused by the gradient difusion of Ta. Ti6Al4V/30Ta alloyshowed an improved corrosion behaviour compared to Ti6Al4V alloy, decreasing 2.4 times their susceptibility to corrosionand about two orders of magnitude their corrosion rate. The bilayer component in this study is proposed as an alternative todecrease the consumption of expensive materials with improved properties.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
