Improvement of hydrogen permeation barrier performance by iron sulphide surface films

Fe–S compounds with hexagonal crystal structure are potential hydrogen permeation barrier during H2S corrosion. Hexagonal system Fe–S films were prepared on carbon steel through corrosion and CVD deposition, and the barrier effect of different Fe–S films on hydrogen permeation was tested using electrochemical hydrogen permeation method. After that, the electrical properties of Fe–S compound during phase transformation were measured using thermoelectric measurement system. Results show that the mackinawite has no obvious barrier effect on hydrogen penetration, as a p-type semiconductor, and pyrrhotite (including troilite) has obvious barrier effect on hydrogen penetration,as an n-type semiconductor. Hydrogen permeation tests showed peak permeation performance when the surface was deposited with a continuous film of pyrrhotite (Fe_(1–x)S) and troilite. The FeS compounds suppressed hydrogen permeation by the promotion of the hydrogen evolution reaction, semiconducting inversion from p-to n-type, and the migration of ions at the interface.

Electrochemical investigation on the hydrogen permeation behavior of 7075-T6 Al alloy and its influence on stress corrosion cracking

The hydrogen permeation behavior and stress corrosion cracking （SCC） susceptibility of precharged 7075-T6 A1 alloy were inves- tigated in this paper. Devanthan-Stachurski （D-S） cell tests were used to measure the apparent hydrogen diffusivity and hydrogen permeation current density of specimens immersed in 3.5wt% NaCl solution. Electrochemical experiment results show that the SCC susceptibility is low during anodic polarization. Both corrosion pits and hydrogen-induced cracking are evident in scanning electron microscope images after the specimens have been charging for 24 h.

Hydrogen Permeation Properties of Perovskite-type BaCe_(0.9)Mn_(0.1)O_(3-δ)Dense Ceramic Membrane

The electrical conduction properties of dense BaCe0.9Mn0.1O3-d (BCM10) membrane were investigated in the temperature range of 600-900oC. High ionic and electronic conductivities at elevated temperatures make BCM10 a potential ceramic material for hydrogen separation. Hydrogen permeation through BCM10 membranes was studied using a high- temperature permeation cell. Little hydrogen could be detected at the sweep side. However, appreciable hydrogen can permeate through BCM10 membrane coated with porous platinum black, which shows that the process of hydrogen permeation through BCM10 membranes was controlled by the catalytic decomposition and recomposition of hydrogen on the surfaces of BCM10 membranes.

HYDROGEN PERMEATION AND DIFFUSION IN ALLOY INCOLOY 903

Permeability and diffusivity of hydrogen in Fe-Ni-Co based superalloy lncoloy 903 were measured over the temperature range of 220 to 420℃ using a gaseous permeation technique. The effect of strengthening phase γ' precipitated after being aged on the hydrogen permeation and diffusion was investigated.It was indicated that the permeability and diffusivity of hydrogen in the alloy hardly depend on heat treatment condition and are not af- fected by γ' phase precipitated after being aged.The relationships between the permeability and diffusivity of hydrogen and the temperature can be respectively expressed as Φ=9.36×10^(-5)exp[-54.20(kJ/mol)/RT]mol/m·s·MPa^(1/2)and D=4.24×10^(-7)exp[-49.07(kJ/mol)/RT]m^2/s.

Hydrogen Permeation Behaviors of X52 Pipeline Steel in NACE A Solution with Saturated H_2S/CO_2

With the aid of hydrogen permeating devices, the hydrogen permeation behaviors of X52 pipeline steel in NACE A solution with saturated H2S/CO2 were studied under the conditions of different ambient temperatures and pH values, and the hydrogen permeation behaviors of X52 pipeline steel in weld seam zone were comparatively studied. The experimental results show that the hydrogen permeation coefficient value is directly proportional to the time required for reaching the saturation anode current and inversely proportional to the saturation anode current, and the hydrogen permeation coefficient is influenced by the corrosion scales; the temperature is directly proportional to the saturation anode current, and the hydrogen permeation coefficient is influenced by the temperature and corrosion scales, heat-affected zone and matrix zone in NACE A solution with saturated H2S/CO2 at normal temperature. The hydrogen permeation coefficient in weld seam zone is larger than that in heat-affected zone which is further larger than that in matrix zone.

Mitigation of hydrogen permeation into steel by bacteria:a new research proposal

A new research proposal was introduced aiming at solving the fundamental theory for reducing the risk of hydrogen embrittlement(HE)in high-strength steels by utilizing hydrogen-consuming microorganisms.The superior performance of high-strength steel can meet the material strength requirements for remote deep-sea marine engineering development.Due to the heavy corrosive marine environment,steel structures must be protected by cathodic protection.However,high-strength steel is sensitive to stress corrosion cracking and HE,and cathodic protection can promote hydrogen permeation into steel.Hydrogen-consuming microorganisms are widespread in the natural environment and they utilize the energy of hydrogen oxidation to survive.If we could make use of the hydrogen-consuming function of microorganisms to consume the hydrogen generated during the cathodic protection process,then the potential for cathodic protection can be reasonably lowered,ideally protecting the steel and simultaneously reducing the possibility of HE.

Properties of passive nano films on zircaloy-4 affected by defects induced by hydrogen permeation

In this work, hydrogen absorption and the permeation behavior of the passive layer formed on zircaloy-4 are in- vestigated. Potentiodynamic polarization, Mott-Schottky analysis, electrochemical impedance spectroscopy, and Raman scattering spectroscopy are employed to characterize the passive defects before and after hydrogen permeation. It is found that the nanoscale passive ZrO2 films play an important role in the resistance against corrosion; hydrogen impingement, however, reduces the passive impedance towards hydrothermal oxidation. The increase of defects （vacancies） in passive film is probably attributed to the degradation. We believe that this finding will provide valuable insight into the understanding of the corrosion mechanism of zircaloys used in light water reactors.

Hydrogen Permeation and Diffusion in Amorphous Alloy Ni_(68)Cr7_Si_8B_(14)Fe_3 at Elevated Temperature

The behaviour of hydrogen permeation and diffusion in amorphous alloy Ni68Cr7Si8B14Fe3 hasbeen investigated by an ultrahigh vacuum gas permeation technique. A comparison experimentwas carried out between the as-quenched and annealed States (400℃/2h) of the amorphousalloy. The results show that, for both states of the amorphous alloy in the temperature rangeof 200～350℃, the diffusivity and permeability of hydrogen are in agreement with Arrheniusrelationship, there does not exist H-trapping effect, and the activation energies of diffusion andpermeation almost keep the same.

Hydrogen Permeation and Diffusion in Low-carbon Steels and 16Mn Steel

In the present work. the hydrogen permeation and diffusion in two low-carbon steels. # 10 and #20. and 16Mn stee1 over the temperature range of 80 to 330℃ were investigated using gaseous permeation technique. The temperature dependence of hydrogen permeability. diffusivity and solubility for the three steels was obtained in the form of the Arrhenius equations. It was shown that the hydrogen permeability of the 16Mn steel is somewhat lower than that of the two low-carbon steels.whereas the hydrogen diffusivity is lowered in the order of #10, #20 and 16Mn but the activation energy of diffusion is much the same for the three steels. The difference in the diffusivity was attributed to the increase of ferrite-cementite interface areas with the refinement of pearlitic structure in the steels

Hydrogen permeation resistance and characterization of Si–Al and Si–Zr composite sol oxide coating on surface of zirconium hydride

The hydrogen permeation resistance of Si–Zr(SZ) and Si–Al(SA) composite sol oxide coating on zirconium hydride blocks(Zr H) was studied. SZ and SA composite sol were prepared by sol–gel method. SZ and SA composite oxide coatings were prepared on the surface of Zr H(in situ oxidized or not) in turns by dip-coating and heat treatment. Hydrogen permeation of Zr Hwith and without composite oxide coating was compared.Hydrogen desorption experiments in thermal vacuum show that hydrogen permeation resistance of SA composite oxide coating is better than that of SZ, to a certain extent,which could decrease hydrogen thermal loss. Experimental results in the working condition show that the SA composite oxide coating can not only prevent hydrogen permeation, but also retard contact and reaction between COand Zr Hmatrix, which could mitigate excessive oxidation of in situ oxide film. Differential scanning calorimetry and thermogravimetry(DSC–TG) analysis was performed to investigate the decomposition behavior of SA and SZ liquid sol in heat treatment process. X-ray diffraction(XRD) and scanning electron microscopy(SEM) analysis were employed to characterize the phase composition,surface and cross-section morphology of the coatings.

Effect of Sintering Temperature on Microstructure and Hydrogen Permeation Properties of Perovskite Membrane

The BaCe0.9Y0.1O3-δ （BCY） perovskite membrane was successfully synthesized by liquid citrate method. The phase structure of the powder was characterized by X-ray diffraction （XRD）. Scanning electron microscopy （SEM） was used to characterize microstructures of the membrane sintered under various conditions. Sintering temperatures and dwell time during sintering influence the final microstructure of the ceramic. Results showed that increasing sintering temperature resulted in a dense membrane with clear grains. An increase of dwell time was favorable to produce membranes with larger grains in the sintered ceramics. A density of 5.87 g/cm3 was reached for the membrane after sintering at 1200 ℃ with dwell time of 10 h. This resulted in the formation of dense membranes with clear structure and average grain size of 0.27 μm. The influence of microstructure on the hydrogen permeation flux through BCY was observed by measuring the hydrogen permeation flux, and the results showed that hydrogen permeation flux increases with increasing the average grain size of the membrane. From H2 permeation rates, it was found that bulk diffusion rather than surface reaction played the dominant role in H2 transport.

Layer-structured Cr/Cr_(x)N coating via electroplating-based nitridation achieving high deuterium resistance as the hydrogen permeation barrier

Hydrogen isotope permeation through structural materials is a key issue for developing nuclear fusion energy,which will cause fuel loss and radioactive pollution.Developing ceramic coatings with high thermal shock and hydrogen resistance is an effective strategy to solve this issue.In this work,a layer-structured Cr/Cr_(x)N coating was successfully fabricated by a facile electroplatingbased nitridation technique,which is easy,facile,and applicable to coating complex-shaped substrates.The Cr/Cr_(x)N coating,composed of a bottom Fe/Cr interdiffusion zone,a middle Cr layer,and a top Cr_(x)N layer,exhibits high bonding strength,high anti-thermal-shock ability,and high deuterium permeation resistance.Its bonding strength achieves 43.6 MPa.The Cr/Cr_(x)N coating remains intact even after suffering 300 thermal shock cycles under a 600℃–water condition.Through optimizing the nitridation temperature,the Cr/Cr_(x)N coating achieves a deuterium permeation reduction factor(PRF)as high as 3599 at 500℃.Considering its scalable fabrication technique and considerable properties,the developed Cr/Cr_(x)N coating may serve as a novel high-performance hydrogen permeation barrier in various fields.

Novel SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) membrane for hydrogen separation

Dense ceramic membranes with protonic and electronic conductivity have attracted considerable interest in recent years.In this paper,the powders of SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) were synthesized via the liquid citrate method,and the membranes of SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) were prepared by pressing followed by sintering.X-ray diffraction(XRD) was used to characterize the phase structure of both the powder and sintered membrane.The microstructure of the sintered membranes was studied by scann...

Preparation Methods and Properties of PdCu Alloy Membrane for Hydrogen Transition

Pd and Pd alloy membranes are of increasing interest for hydrogen separation and purification due to their good thermal stability, high permeability and perfect selectivity. PdCu alloy (60wt% Pd) membranes have similar hydrogen permeability compared with PdAg alloy; meanwhile, it is cheaper than PdAg alloy. Furthermore, it has been reported that PdCu membrane has better resistance to poisoning and deactivation by H 2 S impurity. This paper reviews the properties and manufacturing methods of PdCu alloy membrane, finally, introduced some achievement made by us on PdCu alloy membrane.

A METHOD FOR DETERMINATION OF CONCENTRATION OF ATOMIC HYDROGEN PERMEATED IN MULTI-LAYER STRUCTURE WALL OF HYDROGENATION REACTORS

It was proposed how the concentration distribution was calculated in the treble lager wall of hgdrogenation reactor according to the principle of hydrogen diffusion at the steady state in this paper. Based on the steady hydrogen permeation current density i∞ measund with the hydrogen probe at a given temperature, the hydmpen concentrationson the key interfaces and hydrogen distribution at any given mdial profile in the single, double or treble layer wall of hydrogenation reactor could be found by applying the presented equations throoph suitable parmeters ioput. The theoretical bases were provided for developing the nondestructive probing technique of the concentration of atomic hydmpen in the wallS of hydrogenation reactors.

脉冲频率和电流密度对钢板表面洁净度和渗氢的影响(英文)

The effect of pulse frequency and current density on the effectiveness ofbiphasic pulse electrocleaning is discussed. Moderate frequency (5Hz) is found to be more effectivethan lower or higher frequency on steel surface cleanliness. A novel interpretation of cyclicvoltammagrams is used to estimate the surface cleanliness. This correlates very well with XPSdetermination of surface carbon levels. This result is discussed in terms of mechanisms ofelectrocleaning. Moderate frequency (5-10Hz) is more effective than lower frequency for inhibitinghydrogen permeation. This method can prevent hydrogen brittleness on the electrocleaninghigh-strength steel.

The influence of adding niobium and vanadium on hydrogen diffusion in 22MnB5 hot stamping steel

Adding alloying elements is always considered as an effective method to enhance the resistance against hydrogen embrittlement in steels.Nb and V were added into 22MnB5 hot stamping steel,and then their influences on hydrogen permeation of 22MnB5 steel suffering from corrosion in 3.5%NaCl aqueous solution were investigated.The results showed that the addition of Nb/V could reduce the hydrogen permeation content due to solution corrosion.Electrochemical techniques including electrochemical impedance spectroscopy and overpotential stepping hydrogen permeation test con-firmed that compared to the original 22MnB5 steel,22MnB5-NbN steel owned a higher corrosion resistance and a higher hydrogen diffusion resistance.Furthermore,it was confirmed that Nb-V-alloyed 22MnB5 steel showed higher resistance against hydrogen embrittlement than the Nb-V-free counterpart,which should be related to the presentence of nanoscaled Nb/V-containing precipitates as the irreversible trapping sites for hydrogen detected by thermal desorption spectroscopy.Finally,the lattice diffusion coefficient of hydrogen DL was determined in steels with and without Nb and V.

Synergistic effects of Nb and Mo on hydrogen-induced cracking of pipeline steels:A combined experimental and numerical study

The synergistic effects of Nb and Mo on hydrogen-induced cracking(HIC)of pipeline steels were studied experimentally and numerically.The results showed that Mo was primarily segregated at grain-boundaries(GBs)or solid-dissolved in the matrix,while most Nb and a small amount of Mo formed dis-persed(Nb,Mo)C nano-precipitates and refined the microstructure.Compared with Nb alloying,the multi-ple additions of Nb-Mo played dual roles in affecting H diffusion:primarily,the H-traps densities such as GBs,precipitates,and solute Mo atoms increased,providing an advantage;however,Mo slightly reduced the H-trapping capacity of precipitates,playing an adverse role.Nonetheless,the beneficial effects far outweighed the adverse effects,thereby reducing H diffusivity and inhibiting crack initiation.Addition-ally,Nb and Mo hindered crack propagation synergistically as follows:(i)Mo enhanced GB cohesion by repelling H,impeding intergranular cracking and hydrogen-enhanced decohesion(HEDE);(ii)Nb reduced the proportion of3/high-angle grain boundaries,increasing cracking resistance;(iii)(Nb,Mo)C precip-itates impeded H-dislocation interactions,reducing the hydrogen-enhanced localized plasticity(HELP).

Hydrogen transport in metals: Integration of permeation, thermal desorption and degassing

A modelling suite for hydrogen transport during electrochemical permeation, degassing and thermal desorption spectroscopy is presented. The approach is based on Fick＇s diffusion laws, where the initial concentration and diffusion coefficients depend on microstructure and charging conditions. The evolution equations are shown to reduce to classical models for hydrogen diffusion and thermal desorption spectroscopy. The number density of trapping sites is found to be proportional to the mean spacing of each microstructural feature, including dislocations, grain boundaries and various precipitates. The model is validated with several steel grades and polycrystalline nickel for a wide range of processing conditions and microstructures. A systematic study of the factors affecting hydrogen mobility in martensitic steels showed that dislocations control the effective diffusion coefficient of hydrogen. However,they also release hydrogen into the lattice more rapidly than other kind of traps. It is suggested that these effects contribute to the increased susceptibility to hydrogen embrittlement in martensitic and other high-strength steels. These results show that the methodology can be employed as a tool for alloy and process design, and that dislocation kinematics play a crucial role in such design.