Modeling of chemical vapor infiltration processes

Vignoles, Gérard L.

doi:10.1016/b978-1-78242-307-2.00017-8

Cited by 14 publications

(19 citation statements)

References 130 publications

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“…Numerous studies (outlined in Ref. 1) have been performed focusing on the large-scale phenomena such as gas phase reactions, flow, heat, and mass transfer. The basic modeling strategy in such approaches is similar to that used by Kim et al, 4 Starr and Smith, 5 Probst et al, 6 Jones, 7 or Reuge and…”

Section: Related Workmentioning

confidence: 99%

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Chemical vapor infiltration of additively manufactured preforms: Pore‐resolved simulations and experimental validation

et al. 2021

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The densification of additively manufactured porous preforms by chemical vapor infiltration (CVI) is studied using pore-resolved simulations and experiments. Experimentally, 3D printed silicon carbide (SiC) preforms are subject to CVI synthesis using methyltrichlorosilane (MTS) precursor to obtain high purity SiC/SiC composites. Optical images of the cross sections of the processed preforms are analyzed to obtain the spatial porosity distribution. The numerical method is based on a level set formulation to capture the spatial distribution and time evolution of the pore scale microstructural characteristics. The coupled transport and kinetic effects are represented using a dimensionless Thiele modulus. Simulations are initialized using representative synthetic preform geometries comprising of packed particles based on the size distribution of the powder used for 3D printing. The simulation results are validated against the experimental observations in terms of total density and the distribution of residual porosity. The densification characteristics, porosity classification, concentration profiles, and structure functions are analyzed as functions of processing temperature and Thiele modulus. K E Y W O R D S chemical vapor infiltration (CVI), direct numerical simulations (DNS), level set, Thiele modulusThis manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

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Section: Related Workmentioning

confidence: 99%

“…There have been various attempts at numerically modeling CVI as summarized in Ref. 1. However, most computational analyses were performed at reactor scale focusing on the large-scale phenomena such as temperature nonuniformity, gas compositions, and pressures.…”

Section: Introductionmentioning

confidence: 99%

Chemical vapor infiltration of additively manufactured preforms: Pore‐resolved simulations and experimental validation

et al. 2021

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“…In order to optimize and upscale this process, modeling is an essential tool. Many studies have been conducted to achieve these goals [20]. For instance, models for the forcedflow CVI with temperature gradients [21], the CVI process with radio-frequency heating (RF-CVI) [22] and the'film-boiling TG-CVI process [23] have been developed and validated experimentally.…”

Section: Introductionmentioning

confidence: 99%

“…Depending on the precise setup and conditions, it has been shown that an infiltration front can appear and travel through the porous preform, achieving a correct inside-out infiltration [24,25]. This front requires a minimal thermal gradient to exist [26], a criterion that is not always obtained in practice [20].…”

Section: Introductionmentioning

confidence: 99%

Chemical Supercritical Fluid Infiltration of Pyrocarbon with Thermal Gradients: Deposition Kinetics and Multiphysics Modeling

et al. 2022

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The chemical supercritical fluid infiltration process is a recent variation of the chemical vapor infiltration (CVI) process that allows rapid and efficient manufacturing of ceramic-matrix composites (CMCs), albeit still needing optimization. This article proposes a quantitative assessment of the process dynamics through experiments and modeling. The kinetics of carbon deposition were determined through two sets of experiments: CVD on a single filament at pressures between 10 and 50 bar and infiltration at pressures ranging between 50 and 120 bar. The CVI experiments were conducted under important thermal gradients and were interpreted using a model-based reconstitution of these gradients. We found that (i) the kinetic law has to incorporate the potential effect of the reverse reaction (i.e., etching of C by H2); (ii) the activation energy and pre-exponential factor both decrease with pressure up to 50 bar, then remain roughly constant, and (iii) although the apparent activation energy is modest, a favorable situation occurs in which an infiltration front builds up and travels from the hottest to the coldest part of the preform due to the presence of sufficient heat flux. A numerical simulation of the process, based on the solution of momentum, heat, and mass balance equations, fed with appropriate laws for the effective transfer properties of the porous medium and their evolution with infiltration progress, was performed and validated by comparing the simulated and actual infiltration profiles.

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“…For now, relatively few numerical studies [ 7 , 8 , 9 , 10 ] have been carried out on this problem. For instance, considering the fiber and matrix as the same material and pores as non-conductive, Tomadakis and Sotirchos [ 7 , 11 ] used Monte Carlo algorithm to calculate the thermal transport properties of 1-D partially overlapping and randomly overlapping fiber structure.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Thermal Conductivity of CVI-Densified Composites at Fiber and Bundle Level

Guan

Cheng

2016

Materials

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The evolution of the thermal conductivities of the unidirectional, 2D woven and 3D braided composites during the CVI (chemical vapor infiltration) process have been numerically studied by the finite element method. The results show that the dual-scale pores play an important role in the thermal conduction of the CVI-densified composites. According to our results, two thermal conductivity models applicable for CVI process have been developed. The sensitivity analysis demonstrates the parameter with the most influence on the CVI-densified composites’ thermal conductivity is matrix cracking’s density, followed by volume fraction of the bundle and thermal conductance of the matrix cracks, finally by micro-porosity inside the bundles and macro-porosity between the bundles. The obtained results are well consistent with the reported data, thus our models could be useful for designing the processing and performance of the CVI-densified composites.

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Modeling of chemical vapor infiltration processes

Cited by 14 publications

References 130 publications

Chemical vapor infiltration of additively manufactured preforms: Pore‐resolved simulations and experimental validation

Chemical vapor infiltration of additively manufactured preforms: Pore‐resolved simulations and experimental validation

Chemical Supercritical Fluid Infiltration of Pyrocarbon with Thermal Gradients: Deposition Kinetics and Multiphysics Modeling

Modeling of Thermal Conductivity of CVI-Densified Composites at Fiber and Bundle Level

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