Chemical vapor infiltration (CVI) is a frequent processing method for the tailoring of high-quality ceramic-matrix composites. It involves rarefied gas transfer in a disordered fibrous array and heterogeneous depositi...
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Chemical vapor infiltration (CVI) is a frequent processing method for the tailoring of high-quality ceramic-matrix composites. It involves rarefied gas transfer in a disordered fibrous array and heterogeneous deposition reactions. Optimization of CVI by experimental means is prohibited by important fabrication costs andduration;triggering the need for a numerical model. Our tow scale computational tool reproduces gas transport by an Ito-Taylor random walk scheme whilst chemical reaction is handled by a Monte Carlo routine. Numerical validations of the code with respect to analytical estimates are presented. Finally, applications to 3dimages are depicted and the influence of operating conditions on matrix deposition is discussed. (C) 2011 Elsevier B.V. All rights reserved.
A numerical solution for the simulation of chemical vapor infiltration (CVI) of ceramic matrix composites is presented. This computational model requires a 3d representation of the preform. Gas transport and chemical ...
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A numerical solution for the simulation of chemical vapor infiltration (CVI) of ceramic matrix composites is presented. This computational model requires a 3d representation of the preform. Gas transport and chemical reaction are simulated by a Monte Carlo random walk technique. The developed algorithm can also be used for the determination of effective transport and reaction properties in a porous medium. It is firstly validated by considering the simple case of diffusion and reaction in a flat pore. Results of infiltration of an actual fiber arrangement are described anddiscussed. Extension to deposition on a thin substrate with asperities is also studied
Chemical Vapor Infiltration (CVI) is a popular processing route for the preparation of high-quality Ceramic-Matrix Composites which involves rarefied gas transfer in a disordered fibrous array and heterogeneous deposi...
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Chemical Vapor Infiltration (CVI) is a popular processing route for the preparation of high-quality Ceramic-Matrix Composites which involves rarefied gas transfer in a disordered fibrous array and heterogeneous deposition reactions. The fiber-scale modeling of CVI in large 3dimages of actual porous media (e.g. tomographic images) is a challenging task. We address it with a numerical methodbased on Pearson random walks for transport/reaction of gases, on a Simplified Marching Cubes technique for the surface discretization, and on a pseudo-VOF technique for surface growth. Two different chemical situations are considered, depending on whether the gas precursor is synthesized inside the pores or not. Numerical validations of the code with respect to analytical estimates are presented;finally, in applications to large 3dimages of fibrous media, we discuss the consequences of the competition between diffusion and reaction on the deposit morphology. (C) 2010 Elsevier B.V. All rights reserved.
The paper examines the research methodology and technology used at Milan Malpensa International Airport (Varese, Italy) throughout the construction of the public transportation railway link between Terminal 1 and Term...
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ISBN:
(纸本)9781728102924
The paper examines the research methodology and technology used at Milan Malpensa International Airport (Varese, Italy) throughout the construction of the public transportation railway link between Terminal 1 and Terminal 2, during which excavation works revealed a necropolis of the Final Bronze Age. The project was carried out through the recording and presentation of the 3ddata of the necropolis and the exhibition of the archaeological finds brought to light during the excavations. This research examines the use and potentials of modern digital 3d modelling techniques applied at archaeological heritage to increase research, study and presentation of the archaeological heritage.
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