Comparative studies of the attack of pyrolytic and isotropic graphite by atomic and molecular oxygen at high temperatures.

Allendorf, H. D.; Rosner, Daniel E.

doi:10.2514/3.4558

Cited by 109 publications

(22 citation statements)

References 18 publications

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“…The proposed activation energy is also in agreement with data from Rosner and Allendorf on isotropic graphite [29,30]. It is acknowledged here that any assumption on k f values is easily questionable.…”

Section: Resultssupporting

confidence: 84%

Flow-Tube Oxidation Experiments on the Carbon Preform of a Phenolic-Impregnated Carbon Ablator

Panerai

Martin

Mansour

et al. 2014

Journal of Thermophysics and Heat Transfer

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Oxidation experiments on the carbon preform of a phenolic-impregnated carbon ablator were performed in a flow-tube reactor facility, at temperatures between 700 and 1300 K, under dry air gas at pressures between 1.6 × 10 3 and 6.0 × 10 4 Pa. Mass loss, volumetric recession and density changes were measured at different test conditions. An analysis of the diffusion/reaction competition within the porous material, based on the Thiele number, allows identification of low temperature and low-pressure conditions to be dominated by in-depth volume oxidation. Experiments above 1000 K were found at transition conditions, where diffusion and reaction occur at similar scales. The microscopic oxidation behavior of the fibers was characterized by scanning electron microscopy and energy dispersive x-ray analysis. The material was found to oxidize at specific sites, forming a pitting pattern distributed over the surface of the fibers. Calcium-and oxygen-rich residues from the oxidation reactions were observed at several locations. Nomenclature A = preexponential factor, m∕s D = tube diameter, m D = diffusion coefficient, m 2 ∕s D = binary diffusion coefficient, m 2 ∕s Da = Damköhler number d = fiber or pore diameter, m E = energy, J∕mol G = Gibbs free energy, J∕mol k = reactivity, m∕s k B = Boltzmann constant, 1.3806488 × 10 −23 J∕K L = characteristic length, m l = length, m m = mass (also atomic or molecular mass), kg _ m = mass flow, kg∕s n = number density, m −3 p = pressure, Pa Q = cross section, m 2 R = ideal gas constant, 8.314 J∕mol · K Re = Reynolds number s = specific surface, m 2 ∕m 3 T = temperature, K u = axial velocity, m∕s V = volume, m 3 v = mean molecular velocity (agitation), m∕s w = wall thickness, m x, y, z, t = space and time coordinates, m and s, respectively x = mole fraction Δ = variation δ = thickness, m ε = porosity η = tortuosity λ = mean free path, m μ = dynamic viscosity, mP ρ = density, kg∕m 3 Φ = Thiele number Superscripts 0 = standard (1,1) = diffusion Subscripts a = activation b = bulk end = end e = entrance eff = effective f = fiber g = gas i, j = relative to species i or j K = Knudsen p = pore r = reaction ref = reference s = surface 0 = initial

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Section: Resultssupporting

confidence: 84%

Flow-Tube Oxidation Experiments on the Carbon Preform of a Phenolic-Impregnated Carbon Ablator

Panerai

Martin

Mansour

et al. 2014

Journal of Thermophysics and Heat Transfer

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“…The reaction efficiencies for the O-atom oxidation of graphite far exceed those for N-atom nitridation, by at least one and often 2 orders of magnitude, at all test temperatures in the 873-1273 K temperature range. The O-atom oxidation efficiency also exceeds the O 2 oxidation efficiency, particularly at lower temperatures, a result that has been documented previously in the literature [4,35]. Because of this large reaction efficiency, the limiting effect of O-atom transport to the graphite surface is much more significant than in the case of the N-atom or O 2 surface reactions.…”

Section: Experiments With Molecular and Atomic Oxygensupporting

confidence: 57%

Laboratory Investigation of the Active Nitridation of Graphite by Atomic Nitrogen

Zhang¹,

Pejaković²,

Marschall³

et al. 2012

Journal of Thermophysics and Heat Transfer

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“…Ablation in nitrogen responded with a somewhat lower surface temperature compared to ablation in air, what was especially observed at a higher heat flux of 3 MW=m 2 . Oxidation reactions in air plasma are found by many authors as the dominant contributors to carbon consumption [38][39][40], and led to higher surface temperatures due to their exothermic nature.…”

Section: Visual Inspection Surface Temperature and Recessionmentioning

confidence: 99%

Microstructure and gas-surface interaction studies of a low-density carbon-bonded carbon fiber composite in atmospheric entry plasmas

Helber

Chazot

Hubin

et al. 2015

Composites Part A: Applied Science and Manufacturing

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Comparative studies of the attack of pyrolytic and isotropic graphite by atomic and molecular oxygen at high temperatures.

Cited by 109 publications

References 18 publications

Flow-Tube Oxidation Experiments on the Carbon Preform of a Phenolic-Impregnated Carbon Ablator

Flow-Tube Oxidation Experiments on the Carbon Preform of a Phenolic-Impregnated Carbon Ablator

Laboratory Investigation of the Active Nitridation of Graphite by Atomic Nitrogen

Microstructure and gas-surface interaction studies of a low-density carbon-bonded carbon fiber composite in atmospheric entry plasmas

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