Optimal pressures and temperatures for isobaric, isothermal chemical vapor infiltration

Ofori, John Y.; Sotirchos, Stratis V.

doi:10.1002/aic.690421013

Cited by 23 publications

(16 citation statements)

References 15 publications

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“…Recent theoretical results [14][15][16] have shown that processes that use convective flow (forced-flow CVI or pulse-CVI) to enhance the rate of transport of the reactive species in the pore space perform much better when they are operated at high pressures. Moreover, studies on the optimization of the conventional isobaric, isothermal CVI process 17,18 have revealed that the optimal pressure of operation is located in the part of the transition regime of diffusion that is close to the bulk diffusion regime, which for the typical pore sizes that are encountered in porous media used as preforms in CVI is close to atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of atmospheric pressure chemical vapor deposition of silicon carbide from methyltrichlorosilane

Papasouliotis

Sotirchos

1999

J. Mater. Res.

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A comprehensive study of the chemical vapor deposition of SiC from methyltrichlorosilane at atmospheric pressure was conducted in this study; its main objectives were to identify the range of operating parameters in which stoichiometric SiC could be deposited and the generation of reliable kinetic data that could be used for the design of atmospheric pressure processes of chemical vapor deposition or chemical vapor infiltration of SiC. Deposition experiments were conducted in a hot-wall, cylindrical reactor at temperature ranging from 1273 to 573 K on flat graphite substrates or thin molybdenum wires aligned with the axis of the reactor. The obtained results showed that the deposition rate and the deposit stoichiometry varied markedly with the distance from the entrance of the reactor. The deposition rate exhibited, depending on the reaction temperature, one or two pronounced maxima before the beginning of the isothermal zone of the reaction, whereas the deposit stoichiometry showed an abrupt transition from almost silicon to stoichiometric silicon carbide after the first maximum. Experiments with HCl added in the feed showed that the presence of HCl could cause complete suppression of the deposition of silicon and lead to smoother variation of the SiC deposition rate with the residence time in the reactor. It is believed that this effect could be exploited to improve the uniformity of SiC deposition in chemical vapor deposition reactors or in the interior of porous preforms.

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Section: Introductionmentioning

confidence: 99%

Experimental study of atmospheric pressure chemical vapor deposition of silicon carbide from methyltrichlorosilane

Papasouliotis

Sotirchos

1999

J. Mater. Res.

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“…They usually range between 1 and 10, growing higher when close to percolation thresholds. If the medium is anisotropic, then their inverses have to be considered as tensors [24].…”

Section: Gas Transport and Reaction In The Porous Mediummentioning

confidence: 99%

Modeling of isobaric–isothermal chemical vapor infiltration: effects of reactor control parameters on a densification

Reuge

Vignoles

2005

Journal of Materials Processing Technology

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“…Note that η is proportional to S v , so η can be viewed as a dimensionless surface area per volume. Values of the constants in equations (9)(10)(11)(12) are given in Table 1, for the case of carbon CVI from methane, with a preform thickness of 2L = 3 mm.…”

Section: Formulationmentioning

confidence: 99%

On the Mathematical Analysis and Optimization of Chemical Vapor Infiltration in Materials Science

2000

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Abstract. In this paper we present an analysis of the partial differential equations that describe the Chemical Vapor Infiltration (CVI) processes. The mathematical model requires at least two partial differential equations, one describing the gas phase and one corresponding to the solid phase. A key difficulty in the process is the long processing times that are typically required. We address here the issue of optimization and show that we can choose appropriate pressure and temperature to minimize these processing times.Mathematics Subject Classification. 76S05.

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Optimal pressures and temperatures for isobaric, isothermal chemical vapor infiltration

Cited by 23 publications

References 15 publications

Experimental study of atmospheric pressure chemical vapor deposition of silicon carbide from methyltrichlorosilane

Experimental study of atmospheric pressure chemical vapor deposition of silicon carbide from methyltrichlorosilane

Modeling of isobaric–isothermal chemical vapor infiltration: effects of reactor control parameters on a densification

On the Mathematical Analysis and Optimization of Chemical Vapor Infiltration in Materials Science

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