Die Diffusion von Wasserstoff durch Metalle

Baukloh, Walter; Wenzel, Werner

doi:10.1002/srin.193701018

Cited by 9 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The data on ST for mild steel (5,6) indicate it is approximately 10 -' at 300~ when dQ/dt is in cc H,~ (STP)/hr, A is in cm ~, d is in ram, and P in atmospheres. Assuming a mild steel container with a wall 0.5 mm in thickness and an internal H~ pressure of 1 atm, rates of H~ effusion equivalent to a corrosion rate of 2700 mg/dm~-mo are obtained based on the reaction 3Fe + 4H~O -~ Fe~O~ § 4H~.…”

Section: Theoretical Considerationsmentioning

confidence: 97%

“…Zinc (1) and aluminum (2)(3)(4) are anodic to steel in many aqueous solutions and often corrode sacrificially to impart partial or complete protection to steel. This tendency of Zn and A1 to protect steel cathodically has been reflected in the good corrosion resistance of galvanized and aluminized steel (5), particularly in marine environments (6,7). Although cases are reported when Zn (8-10) and A1 (3,11,12) reverse their polarity with respect to steel, it is generally true, at least for the zinc-steel couple, that the chance of a polarity reversal is much decreased in the presence of chloride.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Hydrogen Effusion Method for the Determination of Corrosion Rates in Aqueous Systems at Elevated Temperature and Pressure

Bloom

Krulfeld

1957

J. Electrochem. Soc.

View full text Add to dashboard Cite

This paper analyzes the limitations of weight change techniques at elevated temperature and pressure, and presents a description of a new technique based on the measurement of the hydrogen generated by the corrosion reaction. This H, which diffuses through the walls of a test specimen containing the aqueous solution, is collected and measured in a vacuum system of known volume which surrounds the test specimen; the corrosion rate is calculated from the hydrogen effusion rate. Results obtained with the technique show good reproducibility and compare well with results obtained by an independent method.Corrosion rates of metals in aqueous solutions at elevated temperature and pressure have been obtained almost exclusively by weight gain or weight loss measurement of specimens subjected to corrosion in autoclaves of various types (1-4). Such measurements are inherently difficult. Loss of corrosion products by spalling or dissolution introduces serious errors into weight gain data. Weight loss data are reliable only if complete removal of corrosion products without attack on the uncorroded metal beneath can be obtained. Galvanic effects between autoclave and specimens may affect the results obtained if the two differ in composition or treatment history prior to the test. One of the most serious limitations is that from a single specimen only a single value of total corrosion can be obtained from which only an "average" corrosion rate over the period of exposure can be calculated. In the usual case, however, where corrosion resistance depends on the type of protection provided by corrosion product films, such average rates are misleading. The information needed in such cases is the differential corrosion rate. Using weight gain and weight loss methods, differential rates can be obtained only by corroding a large number of samples under the given conditions for varying times, the rates being obtained by differences between the gains or losses of the specimens at the different time intervals. Since reproducibility from sample to sample determines the accuracy of any rates calculated by difference, and since reproducibility using these techniques is usually not good, a large number of samples must be run simultaneously to obtain dependable average values for such calculations. These limitations of weight gain and weight loss methods are particularly serious when the corrosion rates are low.To overcome the difficulties enumerated, a method was developed in which there is no error due to loss of oxide or of metal in the measuring process, the sample constitutes its own autoclave, samples need not be destroyed in the process of measurement, and observation can be continuous on a single sample so that a differential corrosion rate can be determined using only one specimen. Theoretical ConsiderationsExamination of the reaction Metal ~-H~O-~ Metal Oxide + H.~ (I) indicates four possible methods of measuring corrosion rate, i.e., measurement of (a) metal consumed, (b) water consumed, (c) metal oxide formed, and (d) hydrogen form...

show abstract

Section: Theoretical Considerationsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

A Hydrogen Effusion Method for the Determination of Corrosion Rates in Aqueous Systems at Elevated Temperature and Pressure

Bloom

Krulfeld

1957

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…Ham and Sauter (26,28) also reported that diffusion rates of both iron and palladium were changed by the amoxmt of heating. Fuller (27) found that the penetration velocity of nascent hydrogen through iron increased upon successive electrolysis tests or acid picklings. This did not hold if there were intervening rest periods.…”

Section: F6mentioning

confidence: 99%

Heat Transfer Final Technical Report...february 16, 1950, to February 15, 1951

McGill¹,

Sibbitt²,

Wiskind³

et al. 1951

View full text Add to dashboard Cite

show abstract

Diffusivity of hydrogen in pure iron

Bryan

Dodge

1963

AIChE Journal

View full text Add to dashboard Cite

The rate of permeation of hydrogen through a highly purified iron (Ferrovac E) was measured over a pressure range of 1/30 to 300 atm. and a temperature range of 126' to 693OC. The effect of cold working of the annealed metal and of hydrogen purity were also studied. Permeability, diffusivity, and solubility were obtained from the data. Permeation rate was linear with square root of fugacity rather than pressure. No difference in @ or D between the annealed and cold worked tube was observed. Log D vs. 1/T was linear over the whole range of temperature, in disagreement with recent work showing a break in the plot a t about 400OC. The calculated activation energy was lower than values reported in the literature. Solubility agreed well with most previous work and did not show the break in the solubility vs. temperature curve found by some recent investigators. No ageing effect was observed nor any difference between the two grades of hydrogen. All the evidence shows that diffusion through the metal is the controlling rate process in this case.The permeation of gases through metals is a phenomenon of considerable practical importance. The special case of hydrogen and steels has been extensively studied because of the attack by hydrogen at elevated temperatures and the embrittlement caused by it even at ambient temperatures. Two papers dealing with the effect of hydrogen on the structure and the tensile properties of a wide variety of metals have been published from this laboratory (22, 27). The present paper is concerned with the more fundamental question of mechanism and rate of penetration of hydrogen through a metal. DEFINITION OF TERMS AND QUANTITIESTo avoid confusion it is well at this point to define some of the terms and quantities commonly but often loosely used in describing the movement of gases through metals. The term "permeation" will be used to describe the overall process of passage of the gas from one side of a metal barrier to the other.A constant known as the permeability has been defined in various ways. is defined: D can be determined from this equation but C is difficult to measure, and other measures have been developed to circumvent this difficulty. In this work the time-lag method of Barrer ( 4 ) was used. The tirne-lag equation for hollow-cylinder geometry isOr, is the intercept on the time axis of the steady state portion of a graph of quantity diffusing Q vs. time.The solubility of a diatomic, elemental gas in a metal is expressed by c = s dF (4) an equation often referred to as Sievert's law. S is a constant whose value depends on the temperature and the units. If equilibrium can be assumed between the molecular gas and the concentration of gas atoms in the metal (this assumes of course that the surface reactions are rapid relative to the diffusion so that the latter is controlling), one may combine ( 2 ) and (4) to giveand this offers a simple means of obtaining D.Now by analogy to the diffusivity define the steady state permeability for the case of the hollow cylinder by the equation (6)...

show abstract

Die Diffusion von Wasserstoff durch Metalle

Cited by 9 publications

References 0 publications

A Hydrogen Effusion Method for the Determination of Corrosion Rates in Aqueous Systems at Elevated Temperature and Pressure

A Hydrogen Effusion Method for the Determination of Corrosion Rates in Aqueous Systems at Elevated Temperature and Pressure

Heat Transfer Final Technical Report...february 16, 1950, to February 15, 1951

Diffusivity of hydrogen in pure iron

Contact Info

Product

Resources

About