Hydrogen Permeation of Multi-Layered-Coatings

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1152.9 ◽

2019 ◽

Vol 1152 ◽

pp. 9-18

Author(s):

Motonori Tamura

Keyword(s):

Grain Boundaries ◽

Hydrogen Permeation ◽

Single Layer ◽

Barrier Properties ◽

Hydrogen Trapping ◽

Fine Crystal ◽

Layered Coating ◽

Plating Method ◽

316L Austenitic Stainless Steel ◽

Hydrogen Systems

Using a substrate of AISI 316L austenitic stainless steel, which is used for components in high-pressure hydrogen systems, the hydrogen barrier properties of samples with single-layer coatings of TiC, TiN, and TiAlN as well as a multi-layered coating of TiAlN and TiMoN were evaluated. The ion plating method was used, and coating thicknesses of 2.0–2.6 μm were obtained. Hydrogen permeation tests were carried out under a differential hydrogen pressure of 400 kPa and at a temperature between 573 and 773 K, and the quantities of hydrogen that permeated the samples were measured. This study aimed at elucidating the relationship between the microstructures of the coatings and the hydrogen permeation properties. Coatings of TiC, TiN, TiAlN, and TiAlN/TiMoN facilitated reductions of the hydrogen permeabilities to 1/100 or less of that of the uncoated substrate. The samples coated with TiN and TiC that developed columnar crystals vertical to the substrate exhibited higher hydrogen permeabilities. The experiment confirmed that the coatings composed of fine crystal grains were highly effective as hydrogen barriers, and that this barrier property became even more efficient if multiple layers of the coatings were applied. The crystal grain boundaries of the coating and interfaces of each film in a multi-layered coating may serve as hydrogen trapping sites. We speculate that fine crystal structures with multiple crystal grain boundaries and multi-layered coating interfaces will contribute to the development of hydrogen barriers.

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High Temperature Radiation Heat Transfer Performance of Thermal Barrier Coatings With Multiple Layered Structures

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2967495 ◽

2008 ◽

Vol 131 (1) ◽

Cited By ~ 6

Author(s):

Xiao Huang

Keyword(s):

Heat Transfer ◽

Thermal Radiation ◽

Thermal Barrier Coatings ◽

Wavelength Range ◽

Coating Thickness ◽

Single Layer ◽

Layered Structures ◽

Thermal Barrier ◽

Barrier Coatings ◽

Layered Coating

Meeting the demands for ever increasing operating temperatures in gas turbines requires concurrent development in cooling technologies, new generations of superalloys, and thermal barrier coatings (TBCs) with increased insulation capability. In the case of the latter, considerable research continues to focus on new coating material compositions, the alloying/doping of existing yttria stabilized zirconia ceramics, and the development of improved coating microstructures. The advent of the electron beam physical vapor deposition coating process has made it possible to consider the creation of multiple layered coating structures to meet specific performance requirements. In this paper, the advantages of layered structures are first reviewed in terms of their functions in impeding thermal conduction (via phonons) and thermal radiation (via photons). Subsequently, the design and performance of new multiple layered coating structures based on multiple layered stacks will be detailed. Designed with the primary objective to reduce thermal radiation transport through TBC systems, the multiple layered structures consist of several highly reflective multiple layered stacks, with each stack used to reflect a targeted radiation wavelength range. Two ceramic materials with alternating high and low refractive indices are used in the stacks to provide multiple-beam interference. A broadband reflection of the required wavelength range is obtained using a sufficient number of stacks. In order to achieve an 80% reflectance to thermal radiation in the wavelength range 0.3–5.3μm, 12 stacks, each containing 12 layers, are needed, resulting in a total thickness of 44.9μm. Using a one dimensional heat transfer model, the steady state heat transfer through the multiple layered TBC system is computed. Various coating configurations combining multiple layered stacks along with a single layer are evaluated in terms of the temperature profile in the TBC system. When compared with a base line single layered coating structure of the same thickness, it is estimated that the temperature on the metal surface can be reduced by as much as 90°C due to the use of multiple layered coating configurations. This reduction in metal surface temperature, however, diminishes with increasing the scattering coefficient of the coating and the total coating thickness. It is also apparent that using a multiple layered structure throughout the coating thickness may not offer the best thermal insulation; rather, placing multiple layered stacks on top of a single layer can provide a more efficient approach to reducing the heat transport of the TBC system.

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

ISRN Materials Science ◽

10.5402/2012/945235 ◽

2012 ◽

Vol 2012 ◽

pp. 1-14 ◽

Cited By ~ 6

Author(s):

Patricia Castaño-Rivera ◽

Viviana P. Ramunni ◽

Pablo Bruzzoni

Keyword(s):

Hydrogen Permeation ◽

Numerical Study ◽

Local Equilibrium ◽

Binding Energies ◽

Hydrogen Trapping ◽

Free Energies ◽

Least Squares Fit ◽

Permeation Transient ◽

C 50 ◽

Trapping Sites

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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Pure Ni and Pd-Ni Alloy Membranes Prepared by Electroless Plating for Hydrogen Separation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.179-180.1309 ◽

2011 ◽

Vol 179-180 ◽

pp. 1309-1313 ◽

Cited By ~ 2

Author(s):

Xiao Liang Zhang ◽

Xu Feng Xie ◽

Yan Huang

Keyword(s):

Electroless Plating ◽

Hydrogen Permeation ◽

Hydrogen Permeability ◽

Composite Membranes ◽

Hydrogen Separation ◽

High Hydrogen ◽

Ni Alloy ◽

Plating Method ◽

Fcc Phase ◽

The Ideal

Pd-based composite membranes are the attractive membrane materials for hydrogen separation due to their high hydrogen permeability and infinite permselectivity. Thin pure Ni and Pd-Ni alloy membranes with high hydrogen permeation were prepared by the electroless plating method. It is difficult to prepare the dense pure Ni membranes with 1-2 μm thickness for hydrogen separation. However, Pd-Ni alloy membranes with several micrometers thickness showed good permeation performance. Hydrogen permeance of the Pd95Ni5 alloy membrane with fcc phase up to 3.1×10-6 mol/m2 s Pa and the ideal permselectivity over 600 were obtained at 773 K.

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Numerical Evaluation on Analysis Methods of Trapping Site Density in Steels Based on Hydrogen Permeation Curve

Materials ◽

10.3390/ma13173712 ◽

2020 ◽

Vol 13 (17) ◽

pp. 3712

Author(s):

Bangshu Yang ◽

Li Li ◽

Lin Cheng

Keyword(s):

Hydrogen Permeation ◽

Effective Diffusivity ◽

Trapping Site ◽

Hydrogen Trapping ◽

Site Density ◽

Site Characteristics ◽

Inappropriate Utilization ◽

Magnitude Difference ◽

Trapping Sites ◽

Permeation Test

Hydrogen permeation techniques have been widely utilized to extract hydrogen effective diffusivity, as well as hydrogen trapping site characteristics in steels. Several methods have been proposed to examine reversible and irreversible trapping site characteristics. However, the inappropriate utilization of these simplified models, as well as incorrect value assignment to the key parameters, can result in several orders of magnitude difference in hydrogen trapping site density. Therefore, in order to evaluate these models and verify their application prerequisites, a serial of hydrogen permeation tests were numerically simulated and examined, separately considering reversible and irreversible hydrogen trapping sites. In the meantime, suggestions were given to conduct hydrogen permeation test more effectively, and evaluate hydrogen trapping site characteristics more precisely.

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First-principles investigation of hydrogen trapping and diffusion at grain boundaries in nickel

Acta Materialia ◽

10.1016/j.actamat.2015.07.031 ◽

2015 ◽

Vol 98 ◽

pp. 306-312 ◽

Cited By ~ 73

Author(s):

Davide Di Stefano ◽

Matous Mrovec ◽

Christian Elsässer

Keyword(s):

Grain Boundaries ◽

First Principles ◽

Hydrogen Trapping ◽

And Diffusion

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Grains and grain boundaries in single-layer graphene atomic patchwork quilts

Nature ◽

10.1038/nature09718 ◽

2011 ◽

Vol 469 (7330) ◽

pp. 389-392 ◽

Cited By ~ 1392

Author(s):

Pinshane Y. Huang ◽

Carlos S. Ruiz-Vargas ◽

Arend M. van der Zande ◽

William S. Whitney ◽

Mark P. Levendorf ◽

...

Keyword(s):

Grain Boundaries ◽

Single Layer ◽

Single Layer Graphene ◽

Layer Graphene

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High Temperature Radiation Heat Transfer Performance of Thermal Barrier Coatings With Multiple Layered Structures

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Manufacturing, Materials and Metallurgy; Microturbines and Small Turbomachinery ◽

10.1115/gt2008-50047 ◽

2008 ◽

Author(s):

Xiao Huang

Keyword(s):

Heat Transfer ◽

Thermal Radiation ◽

Thermal Barrier Coatings ◽

Wavelength Range ◽

Coating Thickness ◽

Single Layer ◽

Layered Structures ◽

Thermal Barrier ◽

Barrier Coatings ◽

Layered Coating

Meeting the demands for ever increasing operating temperatures in gas turbines requires concurrent development in cooling technologies, new generations of superalloys, and thermal barrier coatings (TBCs) with increased insulation capability. In the case of the latter, considerable research continues to focus on new coating material compositions, alloying/doping existing yttria stabilized zirconia ceramics, and the development of improved coating microstructures. The advent of the EB-PVD coating process has made it possible to consider the creation of multiple layered coating structures to meet specific performance requirements. In this paper, the advantages of layered structures are first reviewed in terms of their functions in impeding thermal conduction (via phonons) and thermal radiation (via photons). Subsequently, the design and performance of new multiple layered coating structures based on multiple layered stacks will be detailed. Designed with the primary objective to reduce thermal radiation transport through TBC systems, the multiple layered structures consist of several highly reflective multiple layered stacks, with each stack used to reflect a targeted radiation wavelength range. Two ceramic materials with alternating high and low refractive indices are used in the stacks to provide multiple-beam interference. A broadband reflection of the required wavelength range is obtained using a sufficient number of stacks. In order to achieve 80% reflectance to thermal radiation in the wavelength range of 0.3 ∼ 5.3 μm, 12 stacks, each containing 12 layers, are needed, resulting in a total thickness of 44.9 μm. Using a one dimensional heat transfer model, steady state heat transfer through the multiple layered TBC system is computed. Various coating configurations combining multiple layered stacks along with a single layer are evaluated in terms of the temperature profile in the TBC system. When compared to a baseline single layered coating structure of the same thickness, it is estimated that the temperature on the metal surface can be reduced by as much as 90°C due to the use of multiple layered coating configurations. This reduction in metal surface temperature, however, diminishes with increasing scattering coefficient of the coating and total coating thickness. It is also apparent that using a multiple layered structure throughout the coating thickness may not offer the best thermal insulation; rather, placing multiple layered stacks on top of a single layer can provide a more efficient approach to reduce the heat transport of the TBC system.

Download Full-text