Hydrogen embrittlement evlauation of stainless steels in cryogenic temperature

Please click Additional Files below to see the full abstrac

In-situ wear behaviors of various rubbers in low-pressure hydrogen environment

Please click Additional Files below to see the full abstrac

Evaluation of the hydrogen compatigility of material: A comparison with different methodologies

Please click Additional Files below to see the full abstrac

Metal-supported SOFC with an aerosol deposited in-situ LSM and 8YSZ composite cathode

This study reports the micro-structural and electrochemical properties of metal-supported solid oxide fuel cells (MS-SOFCs) with an La0.8Sr0.2MnO3−d (LSM)/8 mol% yttria-stabilized zirconia (8YSZ) composite cathode, fabricated at room temperature using the aerosol deposition process (ADP). The composite cathode fabricated with the ADP technique shows uniform distribution of components and pores and the interface between the cathode and the electrolyte displays excellent joining properties. The area specific resistance (ASR) of the ADP-LSM/8YSZ sample is approximately 1.50 Ω cm2 at 800 °C, so this sample shows a significantly lower ASR value than the values usually reported for samples fabricated by the in-situ treatment method for MS-SOFCs. The power density of the cells with the ADP-LSM/8YSZ cathode coated on MS-SOFCs shows a maximum value of 0.38 mW cm−2 at 800 °C and stable performance in the severe thermal durability test. Therefore, these research results can broaden the opportunities for adoption of the ADP coating processes to fabricate cathode materials in MS-SOFCs

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Influence of Specimen Surface Roughness on Hydrogen Embrittlement Induced in Austenitic Steels during In-Situ Small Punch Testing in High-Pressure Hydrogen Environments

An in-situ small punch (SP) test method has recently been developed as a simple screening technique for evaluating the properties of metallic materials used in high-pressure hydrogen environments. With this method, the test conditions including temperature and gas pressure can easily be adjusted to those used in practice. In this study, specimens of STS316L steel and 18 wt% Mn steel were prepared at two different surface roughness, fabricated using wire-cutting and mechanical polishing. Their effects on hydrogen embrittlement (HE) were evaluated using in-situ SP testing at both room temperature and a lower temperature where HE was shown to occur under 10 MPa hydrogen. Both steels were evaluated using two variables obtained from in-situ SP testing, the SP energy, and the relative reduction of thickness (RRT), to quantitatively determine the effect of specimen surface roughness on HE susceptibility. Their fracture characteristics due to HE under 10 MPa hydrogen showed little difference with surface finish. Surface roughness had a negligible influence on these quantitative factors describing HE, indicating that it is not a dominant factor to be considered in in-situ SP testing when it is used to screen for HE compatibility in steels used in high-pressure hydrogen environments

Volume Dependence of Hydrogen Diffusion for Sorption and Desorption Processes in Cylindrical-Shaped Polymers

In the actual application of gas transport properties under high pressure, the important factors are sample size dependence and permeation efficiency, related to gas sorption. With a modified volumetric analysis technique, we firstly measured the overall diffusion properties and equilibrium times for reaching the saturation of hydrogen content in both hydrogen sorption and desorption processes. The measured parameters of total uptake (C&infin;), total desorbed content (C0), diffusion coefficient in sorption (Ds), diffusion coefficient in desorption (Dd), sorption equilibrium time (ts) and desorption equilibrium time (td) of hydrogen in two polymers were determined relative to the diameter and thickness of the cylindrical-shaped polymers in the two processes. C&infin; and C0 did not demonstrate an appreciable volume dependence for all polymers. The identical values of C&infin; and C0 indicate the reversibility between sorption and desorption, which is interpreted by the occurrence of physisorption by sorbed hydrogen molecules. However, the measured diffusivity of the polymers was found to be increased with increasing thickness above 5 mm. Moreover, the larger Dd values measured in the desorption process compared to Ds may be attributed to an increased amorphous phase and volume swelling caused by increased hydrogen voids and polymer chain scission after decompression. The ts and td were found to be linearly proportional to the square of the thickness above an aspect ratio of 3.7, which was consistent with the numerical simulations based on the solution of Fick&rsquo;s law. This finding could be used to predict the ts in a polymer without any measurement, depending on the sample size

Evaluation of Fracture Properties of Two Metallic Materials under Hydrogen Gas Conditions by Using XFEM

Interest in hydrogen energy is increasing due to its eco-friendliness and ease of use. Research is being conducted to produce and use hydrogen in various fields such as hydrogen vehicles and nuclear power plants. However, considering the purity requirements and the need for containment, experiments with hydrogen have several constraints, such as accounting for the charging and purging time. In this study, the effects of hydrogen gas on the fracture properties of T6 heat-treated 6061 aluminum alloy (Al6061-T6) and Chromium-molybdenum steel (SA372) were investigated using the extended finite element method (XFEM). First, numerical analyses for smooth and notched slow strain rate tensile test specimens under air and hydrogen gas conditions were conducted using a multi-island genetic algorithm and XFEM to derive true stress&ndash;strain data and damage parameters of the two materials based on experimental results. Second, the fracture resistance curves of &frac12;T-compact tension (CT) specimens made of SA372 steel were determined by crack growth analyses using the calibrated parameters. The estimated JQ values were compared with those from experiments to validate the method, of which differences were less than 20%. Finally, the fracture properties of Al6061-T6 alloy were predicted using the same method with &frac12;T-CT specimens

Multiaxial deformation characteristic of a Zr-based bull metallic glass: Variations of the plastic constraint factor underneath a spherical indenter

Multiaxial deformation of Zr55 Al10Ni5 Cu30 metallic glass was investigated by instrumented indentation tests with a spherical indenter. Contrary to the elastic-rigid-plastic behavior of bulk metallic glasses (BMGs), indentation pressure showed a significant increase with increasing indentation strain, and it was ascribed to a rapid transition of the plastic constraint factor (PCF). However, it was impossible to measure the PCF values from the indentation pressures in the Zr-based BMG because information on uniaxial flow stress was insufficient due to the limited flow strain of 2.2%. Here we developed a PCF assessment method using a relative residual depth hf/hmax, which was experimentally confirmed by adopting it to spherical indentations of a steel sample having well-known flow properties. Flow properties of the BMG were calculated using the new PCF assessment method, and the effects of the materials pileup and low strain indentations on PCF and flow properties were discussed.close2