Effect of trapping on hydrogen permeation

Caskey, G.R.; Pillinger, W. L.

doi:10.1007/bf02658404

Cited by 93 publications

(23 citation statements)

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“…In Section 3 we show that a single permeation transient is enough to describe trapping sites. Sections 4 and 5 describe the numerical method developed here to solve (1) and (2) and present a theoretical discussion in which we establish the range of trap energies which can be determined trough a single permeation transient. Then, we present simulated hydrogen permeation transients to support this conclusion.…”

Section: Isrn Materials Sciencementioning

confidence: 99%

“…Reference [1] supplies analytical expressions for the time lag as a function of k, p and the diffusion coefficient D. However, no analytical expressions for the permeation transient (hydrogen flux at the exit side of the permeation membrane as a function of time) are given, since the presented coupled differential equations are not solved. The McNabb and Foster equations are solved numerically (finite difference method) by Caskey and Pillinger [2] and later by Thomas and Stern [3]. Simulated permeation transients are obtained for different sets of parameters D, k, p, and N x , where N x is the trap population measured either in sites per unit volume or in moles per unit volume.…”

Section: Introductionmentioning

confidence: 99%

“…Simulated permeation transients are obtained for different sets of parameters D, k, p, and N x , where N x is the trap population measured either in sites per unit volume or in moles per unit volume. These authors [2,3] do not compare simulated transients with experimental ones. One attempt to fit simulated permeation transients to experimental data is that of Johnson and Lin [4], which assumes the simplification of local equilibrium theory proposed in 1970 by Oriani [5].…”

Section: Introductionmentioning

confidence: 99%

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Numerical Study of Hydrogen Trapping: Application to an API 5L X60 Steel

Castaño-Rivera¹,

Ramunni²,

Bruzzoni³

2012

ISRN Materials Science

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A numerical finite difference method is developed here to solve the diffusion equation for hydrogen in presence of trapping sites. A feature of our software is that an optimization of diffusion and trapping parameters is achieved via a non linear least squares fit. On the other hand, we have demonstrated that usual electrochemical hydrogen permeation tests are enough to assess hydrogen free energies of trapping in the range of −35 kJ/mol to −70 kJ/mol. These conclusions are obtained by assuming the presence of saturable traps in local equilibrium with hydrogen and are validated by means of simulated permeation and degassing transients. In addition, we check our model performing electrochemical hydrogen permeation tests at 30 • C, 50 • C, and 70 • C, on an API 5L X60 as received steel state to study its trapping and diffusion properties considering only one type of trapping site. The binding energies (ΔG) and the trap densities (N) are determined by fitting the theoretical model to the experimental permeation data. The steel presents a high density of weak traps, |ΔG| < 35 KJ/mol, namely, N = 1.4 × 10 −5 mol cm −3 . Strong trapping sites which alter the shape of the permeation transient are also detected; their ΔG values ranged from 57 to 72 KJ/mol.

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Section: Isrn Materials Sciencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical Study of Hydrogen Trapping: Application to an API 5L X60 Steel

Castaño-Rivera¹,

Ramunni²,

Bruzzoni³

2012

ISRN Materials Science

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“…Caskey and Pillingerl (30) have given an approximate solution of McNabbFoster's equation (4) using the finite difference method for boundary conditions appropriate to hydrogen permeation and evolution. Iino(31) (32) has analyzed the influence of reversible and irreversible traps on the apparent diffusivity, examining the kinetics of coverage of traps of possible various depths, i.e., the influence of traps of varying trapping rates and release rates on the McNabb-Foster theory (4) from the point of view that there should generally be active hydrogen traps of varying depths in steels.…”

Section: Introductionmentioning

confidence: 99%

“…(30) Now, we also consider a generalized expression of the diffusion flux equations for individual jumping processes due to the gradient of hydrogen concentration. All the possible fluxes can be written as follows: (31 Here, we also assume that there is a system of the low occupation probability of hydrogen in the normal and trapping sites, i.e., C1<<1, Ct1<<1, Ct2<<1,...Cti<<1.…”

Section: Introductionmentioning

confidence: 99%

An Analysis of a Trapping Model for the Diffusion of Hydrogen in Metals

Sakamoto

1984

Trans. JIM

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An analysis of the apparent diffusivity of hydrogen in mixed trap and multiple physical trap models was carried out based on the assumption of a system of low occupation probability of hydrogen in a normal lattice and trapping sites and by taking into consideration that the trapping sites have not only the characteristic trap density and depth but also a trap "width" and that the "normal" lattice sites and individual traps have characteristic trapping and release rates.In this work the diffusivity in a lattice with mixed trap and multiple physical traps can be expressed by closed equations. The theory predicts that the enhancement of diffusivity might occur at low temperature, even if hydrogen is substantially trapped. Such behavior can be explained in terms of an enhanced jump rates due to lower barriers at trap sites compared with those of normal lattice sites. On the other hand, if all the trap sites are already saturated and do not influence the diffusion flux, the resulting diffusion equation is identical with that of McNabb and Foster and that of Oriani.

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Hydrogen Ingress during Corrosion

Pound

2003

Encyclopedia of Electrochemistry

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The sections in this article are Introduction Hydrogen Evolution General Mechanisms Reaction Kinetics Hydrogen Absorption Mechanisms Promoters of Hydrogen Entry Inhibitors of Hydrogen Entry Solubility of Hydrogen Hydrogen Diffusion Diffusion Kinetics Hydrogen Trapping Hydrogen Antitrapping Methods to Study Trapping Electrochemical Techniques Permeation Techniques Potentiostatic Charging Galvanostatic Charging Time‐dependent Entry Kinetics Effect of Trapping Pulse Techniques Potentiostatic Pulse Galvanostatic Pulse Triangular Pulse Potentiometric Techniques Alternating Current Technique Surface Effects of the Metal and Films Diffusion Control Experimental Issues Selected Metals Palladium Iron and Steel Nickel Hydrogen Degradation Classification Hydrogen Trapping Theories Internal Pressure Surface Energy Decohesion Slip Softening Hydrogen‐related Phase Changes Alloys Steels Stainless Steels Nickel Alloys Titanium Alloys

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Effect of trapping on hydrogen permeation

Cited by 93 publications

References 7 publications

Numerical Study of Hydrogen Trapping: Application to an API 5L X60 Steel

Numerical Study of Hydrogen Trapping: Application to an API 5L X60 Steel

An Analysis of a Trapping Model for the Diffusion of Hydrogen in Metals

Hydrogen Ingress during Corrosion

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