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The effect of high-pressure gaseous H2 on the fracture behavior of pipeline steel X70 and austenitic stainless steel type 304L and 316L was investigated by means of notched-tensile tests at 10 MPa H2 gas and various test speed. The notch tensile strength of pipeline X70 steel and austenitic stainless steels were degraded by gaseous H2, and the deterioration was accompanied by noticeable changes in fracture morphology. The loss of notch tensile strength of type 316L and X70 steels was comparable, but type 304L was more susceptible to hydrogen embrittlement than the others. In the X70 steel, hydrogen embrittlement increased as test speed decreased until the test speed reached 1.2 × 10−3 mm/s, but the effect of test speed was not significant in 304L and 316L steels.

Metal additive manufacturing (AM) technology as the emerging future manufacturing technology can be applied to the hydrogen service including hydrogen energy utilized industry. Direct metal tooling (DMT), one of the 3-D printing technologies, was used to manufacture an austenitic stainless steel part, and its mechanical properties and hydrogen embrittlement (HE) behavior were studied using the small specimen test technique under 10-MPa pressurized hydrogen gas. This part showed high HE resistance with minimal strain-induced transformation of austenite to martensite. This result indicates that parts produced using DMT are suitable for use in facilities for hydrogen service and hydrogen infrastructure.

A simple method that uses magnetic field induction for the disentanglement of bundled multiwall carbon nanotubes (MWCNTs) that are massively aggregated in a single and intact form was investigated. MWCNTs exposed to a 1 Tesla (T) field periodically switched on and off were separated into individual MWCNTs using 4,4′-azobis(4-cyanovaleric acid) as a radical initiator with iron oxide nanoparticles. The study results show that, in accordance with the dissipation working principle, MWCNT bundles under 40 nN achieved complete disentanglement within a few hours, and these results were theoretically verified by an Opera 3D simulation. We anticipate that single CNTs obtained using our method will have applications in several CNT research areas ranging from electronic devices to biocomputers.

The susceptibility of 316L-type austenite stainless steel to hydrogen was quantified by means of SSRT results and low-cycle fatigue life measurement. Both tests were conducted in the air condition after being charged with high-pressure hydrogen gas of 10 MPa and a temperature of 300°C for 120 hours. In addition, SSRT tests in gaseous hydrogen at a pressure of 10 MPa were also performed and compared to the tests conducted in hydrogen pre-charged and as-received conditions. The 0.2% yield strength and tensile strength did not show there to be a considerable difference between hydrogen pre-charging and the as-received conditions, whereas the gaseous hydrogen condition revealed a remarkable degradation in tensile properties, especially in terms of fracture elongation. In the case of fatigue life test, a considerable influence of hydrogen pre-charging in fatigue life properties was observed in the high strain amplitude regime whereas the measured values in the low strain deformation region are consistently comparable to that in the as-received condition. Fatigue limit was not affected by hydrogen pre-charging.

In this study, a simple screening technique using an in-situ small-punch (SP) test and based on the hydrogen embrittlement (HE) sensitivity of austenitic stainless steels was developed for use in hydrogen energy facilities. To investigate the HE behaviors of metallic materials, the in-situ SP tests were carried out under high-pressure hydrogen gas environments. The reductions of thickness at the fractured parts of the specimen were measured. The relative reductions of thickness (RRT) were determined after conducting SP tests in both hydrogen and inert gas environments. Similar to the relative reduction of area (RRA) obtained using the slow strain-rate tensile test, RRT obtained using the in-situ SP test is a quantitative measure of the influence of the HE behaviors. The influence of punch velocity on HE sensitivity was examined. The HE behaviors of austenitic steels were evaluated qualitatively and quantitatively. The high-Mn steels were also evaluated because they are candidates for storage and transportation of hydrogen gas. A screening technique for determining the practical environmental conditions at the point of use could be established by confirming the effectiveness of the influencing factor, RRT, using this in-situ SP test method.

Paper-based sensors fabricated using the pencil-on-paper method are expected to find wide usage in many fields owing to their low cost and high reproducibility. Here, hydrogen (H2) detection was realized by applying palladium (Pd) nanoparticles (NPs) to electronic circuits printed on paper using a metal mask and a pencil. We confirmed that multilayered graphene was produced by the pencil, and then characterized Pd NPs were added to the pencil marks. To evaluate the gas-sensing ability of the sensor, its sensitivities and reaction rates in the presence and absence of H2 were measured. In addition, sensing tests performed over a wide range of H2 concentrations confirmed that the sensor had a detection limit as low as 1 ppm. Furthermore, the sensor reacted within approximately 50 s at all H2 concentrations tested. The recovery time of the sensor was 32 s at 1 ppm and 78 s at 1000 ppm. Sensing tests were also performed using Pd NPs of different sizes to elucidate the relationship between the sensing rate and catalyst size. The experimental results confirmed the possibility of fabricating paper-based gas sensors with a superior sensing capability and response rate.

A sudden change in the geometrical parameters of a material, such as bends, T-branches, and welded joints may increase the stress concentration, which in turn may enhance the diffusible hydrogen concentration. In this study, quantitative evaluations of the effect of stress concentration factors on hydrogen environmental embrittlement (HEE) will be studied based on the mechanical performance of notched tensile specimens with variations in the stress concentration factors (Kt) of the X70 pipeline base and weld metal. To highlight the role of stress concentration, the tests are performed under a 10 MPa gas mixture condition with a low partial hydrogen pressure. The maximum strengths of the notched specimens were nearly consistent across all Kt values. The degree of HEE susceptibility of the base metal increased with increasing Kt value. However, in the weld metal, prominent reductions in the RA occurred at all Kt values. The complex HEE susceptibility of the weld metal can be attributed to the synergistic action of the microstructure heterogeneity and Kt values.

The proposed study investigates the potential damage in an actual hydrogen vessel and the mechanical performance of Cr-Mo steel used in high-pressure hydrogen vessels. The hydrogen vessel exhibited defects, such as small fissures and various types of inclusions, which may have a detrimental effect on its performance under hydrogen gas. The maximum tensile strength of the steel under high-pressure hydrogen met the design standard requirement (i.e., it did not exceed 915 MPa), and hydrogen had a significant effect on the strain at fracture and reduction in area. The occurrence of intergranular fracture was more pronounced in the specimens exposed to 99 MPa of hydrogen than those exposed to 10 MPa of hydrogen, resulting in a slightly higher embrittlement index.

We designed a model composed a ring type magnet, a yoke, and a sensing coil buried in a projectile for calculating the muzzle velocity based on the voltage induced from sensing coil by simulation. The muzzle velocity was calculated from the master curve obtained through the voltage induced from sensing coil by simulation. The induced voltage increased with increasing the diameter of sensing coil. The projectile’s velocity was proportional to the induced voltage when the sensing coil was buried in projectile. The projectile will be surely exploded at the target region by inputting the information of muzzle velocity variation corrected the diameter effect of induced voltage of sensing coil.

Large-scale graphene or carbon nanotube (CNT) films are good candidates for transparent flexible electrodes, and the strong interest in graphene and CNT films has motivated the scalable production of a good-conductivity and an optically transmitting film. Unzipping techniques for converting CNTs to graphene are especially worthy of notice. Here, we performed nanotube unzipping of the spun multi-walled carbon nanotubes (MWCNTs) to produce networked graphene nanoribbon (GNR) sheet films using an 02 plasma etching method, after which we produced the spun MWCNT film by continually pulling MWCNTs down from the vertical well aligned MWCNTs on the substrate. The electrical resistance was slightly decreased and the optical transmittance was significantly increased when the spun MWCNT films were etched for 20 min by O2 plasma of 100 mA. Plasma etching for the optimized time, which does not change the thickness of the spun MWCNT films, improved the electrical resistance and the optical transmittance.

In this study, the susceptibility of API X70 weld joints to hydrogen gas was investigated using slow strain rate tensile (SSRT) tests. The microstructure of the subregion of the actual heat-affected zone (HAZ) weld joint was reproduced by weld thermal-cycle simulation techniques. The SSRT results showed that the weld and cross-weld specimens had the highest hydrogen embrittlement (HE) susceptibility, followed by the subregions of the fine-grained heat-affected zone (FGHAZ) and coarse-grained heat-affected zone (CGHAZ) specimens and the base metal. The HE index ranking of the samples was as follows (in increasing sequence): weld, cross-weld, simulated FGHAZ, simulated CGHAZ, and base metal specimens. The rupture location of the cross-weld specimen in ambient air is different to that tested in 10 MPa H2. The higher susceptibility of the weld and cross-weld specimens was primarily attributed to synergic effects between the microstructural characteristics, stress localization, and microhardness distribution – particularly, microhardness plays an important role in the nucleation of microcracks and the hydrogen diffusion rate induced by stress/strain localization.

This study examined the effects of cold rolling ratio and cryogenic temperatures on the mechanical properties of a 1.5 mm SUS304L sheet, the original material used in membrane-type liquefied natural gas (LNG) storage tanks. The original sheet was cold rolled to reduce its thickness in order to examine the effect of cold rolling ratio. And to identify the effect of cryogenic temperatures, very high cycle fatigue (VHCF) characteristics were obtained at −162 °C, using the ultrasonic fatigue tester. The fatigue limit of a 1.5 mm specimen, measured at −162 °C in the ultrasonic fatigue test (UFT) was 252 MPa, while that of 1.3 mm and 1.1 mm cold rolled specimens was 503 MPa and 597 MPa, up by about 99.6% and 137% respectively. The fatigue limit of 1.3 mm and 1.1 mm cold rolled specimens measured at −196 °C was 550 MPa and 690 MPa, up by about 88.4% and 136.3% respectively. As such, the fatigue strength of the cold rolled specimen in the UFT tend to increase in a nearly linear manner, compared to that of the original material, as the cold rolling ratio and the effect of cryogenic temperatures.

A series of small punch (SP) tests was conducted to investigate the effect of natural/hydrogen gas mixture conditions on the mechanical properties of X70 pipeline steel. The various gas mixture conditions included 0.1, 0.5, 1, 3, and 5 vol% hydrogen blends and three typical pipeline pressure levels (5, 7, and 10 MPa). The hydrogen embrittlement (HE) susceptibility grades depend on the hydrogen concentration and tend to increase with hydrogen concentration. The hydrogen gas mixture conditions have an insignificant effect on the yield load of the elastic bending region, whereas the maximal load decreases significantly when the hydrogen concentrations increase. Moreover, the quantitative parameters obtained from the SP load displacement curves and fracture morphologies were analyzed to characterize the HE behavior. By evaluating the SP absorption energy as a function of the hydrogen pressure, the ductile–brittle transition and saturated hydrogen pressures of the HE were determined. According to the results, the strength degradation grades of the mechanical properties of X70 pipeline steel in the gaseous hydrogen environment were not affected by the exposure time.

Mn5O8 nanoparticles (NPs) were obtained via the controlled oxidation of MnO NPs. The oxygen evolution reaction (OER) properties of Mn5O8 NPs were evaluated using cyclic voltammetry (CV). A current density of 5 mA/cm2 was reached when 580 mV of overpotential was applied at pH 7.8. Electron paramagnetic resonance (EPR) analysis was conducted to investigate the origin of high OER activity of Mn5O8 NPs. From the EPR analysis, Mn3+ was found to be involved in the OER process of the Mn5O8 materials.

This paper reports the use of Au films to improve the performance of the stacked solid oxide fuel cell (SOFC) based on the characterization of the interface and the adhesion between the electrodes of the SOFCs and the Ag paste. The specimens were manufactured to perform the experiment as follows. A SiO2 wafer with a 300 μm notch was attached to the electrodes of a SOFC by a Ag paste and Au film, which were deposited on the electrodes by sputtering for 1 min or 5 min deposition time and annealed at 300 °C for 1 h. The four-point bending test was performed, which resulted in the formation of an extended crack at the tip on the wafer notch, and the crack propagation was observed using a stereo microscope equipped with a charge-coupled device (CCD). Consequently, the interfacial adhesion energy and the effect of the Au film between the each electrode and the Ag paste can be evaluated. On the cathode, the interfacial adhesion energy without Au film was 2.59 J/m2 (upper value) and the adhesion energy increased to 11.59 J/m2 (upper value) and 15.89 J/m2 (lower value) with the Au film. On the anode, the interfacial adhesion energy without Au film was 1.74 J/m2 (upper value), which increased to 11.07 J/m2 (upper value) and 14.74 J/m2 (lower value) with the Au film. In addition, the interface areas were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) to estimate the interface delamination.

During the use of API X70 steel as a pipeline structural material for the transportation of natural gas, hydrogen embrittlement can occur due to the hydrogen contained in natural gas. The aim of this study is to investigate the effects of the hydrogen content under high-pressure hydrogen gas conditions on the hydrogen embrittlement of air-cooled API X70 steel. The air-cooled API X70 steel was manufactured by hot rolling and was then air-cooled to room temperature. Tensile test specimens were held for 0 h, 1000 h, and 2000 h within a pressure vessel filled with 100% hydrogen gas at a gas pressure of 10 MPa, with the tensile tests then performed at room temperature. The microstructure of the API X70 steel consists of coarse polygonal ferrite, coarse pearlite, and fine acicular ferrite. The yield and tensile strength increased and elongation decreased considerably after a holding time of 2000 h compared to those of 0 h and 1000 h within the pressure vessel. The morphology of the fracture surface changed from ductile to brittle upon hydrogen gas charging. Secondary cracks were observed in both of the hydrogen-gas-charged specimens. No external cracks were formed on the surface of the tensile-tested specimen with a 0 h holding time; however, many external cracks were observed on the specimen surface subjected to hydrogen gas charging.

WO3 nanoigloos decorated with Ag-, Pd-, and Au nanoparticles are fabricated by soft-template method and self-agglomeration of metal films. The responses of WO3 nanoigloos decorated with metal nanoparticles to various gases such as NO2, CH3COCH3, C2H5OH, and H2 are much higher than those of bare WO3 nanoigloos. According to the surface decoration, WO3 nanoigloos show significantly different behaviors in the response enhancement, revealing that Pd-decorated WO3 nanoigloos exhibit the highest response to H2 together with fast response time to H2, C2H5OH, and CH3COCH3 (below 10 s), Au-decorated WO3 nanoigloos exhibit the highest response to NO2. The catalytic effect of Ag is relatively weaker than Pd and Au nanoparticles, however, it exhibit the fastest response time to NO2. These are attributed to not only the varied catalytic activities of the metal nanoparticles, but also the different work function energies of them. Our results show that highly sensitive and selective WO3 nanoigloos decorated with metal nanoparticles can be an effective platform to fabricate an electronic nose for the further application of semiconducting metal oxide gas sensors.

The objective of this research is to study the effect of various hydrogen charging quantities in austenitic stainless steel using nondestructive technique. The hydrogen charging equipment was designed to make charging the steel, and the specimens were charged for 2, 4, 10 and 24 hours in the equipment. An acoustic emission (AE) technique, nondestructive test, was used to evaluate the dynamic behavior of the hydrogen charged austenitic stainless steel specimen. The tensile load was applied the charged specimen with the attached AE sensor, and elastic waves caused plastic deformation and cracking in the specimen by external tensile loading were caught at the AE sensor and analyzed by the AE parameters such as count, energy, duration time, event and amplitude. In addition, ultrasonic wave was also used to evaluate the degree of hydrogen charging. The velocity and the attenuation ratio of the ultrasonic wave on the specimen with different hydrogen charging conditions were measured. The velocity was not changed but the attenuation ratio was linearly increased with the hydrogen charging time. The relationship between the results of nondestructive test including AE test and ultrasonic test and fractographic analysis by using SEM was discussed.

We explored the influences of hydrogen on small-scale strength of a linepipe steel through nanoindentation experiments with four pyramidal indenters. Interestingly, a transition from hydrogen-induced hardening to softening was observed as indenter sharpness increases. The transition was analyzed based on the enhancement in hydrogen's elastic shielding effects for a sharper indenter, which could be indirectly evidenced by the stress effects on indentation pile-up, dislocation density, and rate dependency of hardness.

When using hydrogen gas as an ecofriendly energy sources, it is necessary to conduct a safety assessment and ensure thereliability of the hydrogen pressure vessel against hydrogen embrittlement expected in the steel materials. In this study, by applying the in-situ SP test method, the gas hydrogen embrittlement behaviors in SA372 steel, which is commonly used as a pressurized hydrogen gas storage container, were evaluated. To investigate the hydrogen embrittlement behavior, SP tests at different punch velocities were conducted for specimens with differently fabricated surfaces at atmospheric pressure and under high-pressure hydrogen gas conditions. As a result, the SA372 steel showed significant hydrogen embrittlement under pressurized hydrogen gas conditions. The effect of punch velocity on the hydrogen embrittlement appeared clearly; the lower punch velocity case indicated significant hydrogen embrittlement resulting in lower SP energy. The fractographic morphologies observed after SP test also revealed the hydrogen embrittlement behavior corresponding to the punch velocity adopted. Under this pressurized gas hydrogen test condition, the influence of specimen surface condition on the extent of hydrogen embrittlement could not be determined clearly.

We fabricate almost crack-free 1.5 μm thick nanoporous gold thin films using free-corrosion dealloying and transfer processes from sputter-deposited precursors. By controlling the temperature and the concentration of the nitric acid solution during free-corrosion dealloying, we obtain ligament sizes in nanoporous gold between 22 and 155 nm. We investigate the effects of dissolution rate of Ag atoms, surface diffusivity of Au atoms and formation of Ag oxide on nanoporosity evolution.

The magnetic, electrical and elastic properties of 3Cr-1Mo-0.25 V steel were investigated using heat treatment procedures (as-quenched→tempered→PWHT). The mechanical properties were determined for the respective specimens with three types of heat histories. The mechanical properties (yield stress, hardness) and magnetic properties (permeability, coercive force, remanence) were inversely proportional to the heat treatment procedures. The permeability decreased linearly with an increase in the grain size; however, the yield stress, hardness, coercive force and remanence did not vary greatly with grain size. The electrical resistivity and ultrasonic velocity of the as-quenched material differed from those of the tempered/PWHT material. This trend was due to the defects, precipitates and carbides in the grain and at the grain boundary caused by the heat treatment procedures. However, the electrical resistivity and ultrasonic velocity did not vary greatly with grain size.

In this study, hydrogen effects on the impact toughness of simulated coarse-grained heat-affected zones (CGHAZs) in a linepipe steel were investigated in search of the possible “local brittle zone phenomenon” in hydrogen pipeline welds. After hydrogen charging, the inter-critically reheated and unaltered CGHAZ exhibited very low impact energies as well as occurrence of splitting. This hydrogen-induced toughness drop is discussed in terms of combined effects of brittle microstructures and hydrogen trapping.

Apocynin is known to suppress the production of reactive oxygen species (ROS) by inhibiting NADPH oxidases, specifically phagocytic NADPH oxidase (PHOX or NOX2). Given the pro-inflammatory effects of ROS, apocynin has been studied extensively for its use as a therapeutic agent in various disease models. While the effects of apocynin on neutrophils and monocytes have been investigated, it remains to be elucidated whether apocynin modulates the effector function of T cells. In the present study, we examined the effect of apocynin on CD8(+) T cells and further investigated its mechanism of action. We found that apocynin directly inhibited the production of pro-inflammatory cytokines such as TNF-α, IFN-γ, and IL-2 in anti-CD3/anti-CD28-stimulated CD8(+) T cells. The action of apocynin was upstream of the protein kinase C and calcium signaling in the T cell receptor signaling pathway because apocynin did not inhibit cytokine production in phorbol 12-myristate 13-acetate/ionomycin-stimulated CD8(+) T cells. Electrophoretic mobility shift assays revealed that apocynin attenuated anti-CD3/anti-CD28-induced NF-κB activation in CD8(+) T cells. In the experiments with NOX2-deficient mice, we demonstrated that apocynin inhibited TNF-α production of CD8(+) T cells in a NOX2-independent manner. Taken together, we demonstrated that apocynin, a well-known NOX2 inhibitor, suppressed the cytokine production of CD8(+) T cells. We also showed the NOX2-independent action of apocynin in the inhibition of TNF-α production in CD8(+) T cells.

The ultrasonic characteristics of 2.25Cr-1Mo steel were investigated in relation to the isothermal heat treatment temperature and time. Charpy impact tests and hardness tests were conducted on individual specimens with three different heat treatment conditions. A pulse-echo method with longitudinal waves was used to measure the attenuation and velocity of ultrasonic waves. The FATT (fracture appearance transition temperature) increased with an increase in the isothermal heat treatment time, which implies that the toughness decreased. As the isothermal heat treatment time and temperature increased, the longitudinal wave velocity and ultrasonic attenuation coefficient were raised.

Hydrogen penetration into a metal leads to damages and mechanical degradations and its content measurement is of importance. For a precise measurement, a sample preparation procedure must be optimized through a series of studies on sample washing and drying. In this study, two-step washing with organic solvents and thermal soaking in inert gas were tried with a rod-shaped, API X65 steel sample. The samples were machined from a steel plate and then washed in acetone and etyl-alcohol for 5 minute each and dried with compressed air. After then, the samples were thermally soaked in a home-made nitrogen gas chamber during 10 minute at different heat gun temperatures from 100 to and corresponding temperature range in the soaking chamber was from 77 to according to the temperature calibration. Hydrogen residue in the samples was measured with a hot extraction system after each soaking step; hydrogen residue of wppm after the thermal soaking at decayed with increase of the soaking temperature. By adopting the heat transfer model, decay behavior of the hydrogen residue was fitted into an exponential decay function of the soaking temperature. Saturated value or lower bound of the hydrogen residue was 0.36 wppm and chamber temperature required to lower the hydrogen residue about 95% of the lower bound was . Furthermore, a thermal desorption spectroscopy was done for the fully soaked samples at . Weak hydrogen peak was observed for whole temperature range and it means that hydrogen-related contaminants of the sample surface are steadily removed by heating. In addition, a broad peak found around means that parts of the hydrogen residue are irreversibly trapped in the steel microstructure.

Carbon nanofibers (CNFs) are good candidates for nano-system applications because they have the excellent mechanical and the electrical properties. The mechanical and electrical properties of a single CNF were measured. A tensile test and a measurement of the electrical resistance of CNFs during elongation were performed inside a scanning electron microscope. We confirmed that the CNFs used in this experiment consisted of a polycrystalline structure and an amorphous phase by a result of Raman. Additionally, we observed that the crystal structure in nanofibers exhibits brittle fracture behavior and the amorphous phase make them relatively ductile. The elastic moduli of the CNFs were 9.57 to 13.6 GPa in the elastic section. The electrical resistance of the CNFs exhibited unusual behavior during elongation. The electrical resistance of the CNFs exhibited stable resistance increase like as the tensile results in the initial region. But the electrical resistance exhibited generally irregular increase after initial region because of the polycrystalline structure and amorphous phase. The strain sensitivity of the CNFs exhibited a much lower value.

The effect of He-injection on irradiation-induced segregation of aging treated Fe–12%Cr–15%Mn austenitic steels, which are candidate materials as the reduced radio-activation of structure material for nuclear and/or fusion reactors was investigated by using the 1250 kV high voltage electron microscope (HVEM) connected with an ion accelerator. The Fe–Mn–Cr steel has been irradiated at 573 K by three irradiation modes of single electron-beam irradiation, electron-beam irradiation after He-injection and electron/He+-ion dual-beam irradiation in a HVEM. Irradiation-induced segregation analyses were carried out by an energy dispersive X-ray analyzer (EDX) in a 200 kV FE-TEM with beam diameter of about 0.5 nm. Dislocation loops with strain contrast were formed during irradiation and the loop numbers density increased rapidly with irradiation dose for He-pre-injected specimens. Voids were not observed after irradiations with three irradiation modes up to 5.4 dpa at 573 K. Irradiation-induced segregations of Cr and Mn near grain boundary were observed in each irradiation condition, but the amounts of Mn segregation decreased in the cases of electron/He+-ion dual-beam irradiation compared with single electron-beam and electron-beam irradiation after He-injection conditions.

SNG (synthetic natural gas or substitute natural gas) could contribute greatly toward energy security. In addition, HCNG (or H2CNG) is expected to be used as a fuel gas for internal combustion engines and home appliances because it has extremely low emissions and high thermal efficiency. However, the hydrogen contained in SNG or HCNG can deteriorate the mechanical properties of the materials used in existing natural gas infrastructure. Therefore, it is necessary to investigate the effect of hydrogen on the mechanical properties of such materials so that SNG or HCNG can be transported and distributed safely and reliably. In this study, the effect of highly pressurized hydrogen gas on the tensile properties of a low-alloy steel used for manufacturing CNG storage vessels was investigated using the so-called hollow tensile specimen technique.

Tensile tests of an individual ZnS nanowire with a cubic structure were performed with a nano-manipulator inside a scanning electron microscope (SEM). To perform the tensile test of ZnS nanowires, a mechanical testing system was installed in the SEM. A nano-manipulator was set up in the SEM, and a cantilever force sensor was mounted on the nano-manipulator. The force sensor could be controlled with the nano-manipulator. The ZnS nanowires were dispersed on the transmission electron microscope (TEM) grid; then, the ends of the ZnS nanowires were welded to the TEM grid and the tip of force sensor by exposing them to the E-beam of the SEM. The tensile tests of the ZnS nanowires were performed by controlling the nano-manipulator in the SEM. The load response during the tensile tests was obtained with a force sensor. The strain-stress curve was obtained from the tensile load-displacement curve after the tensile test. The tensile strengths for nanowires 1, 2, and 3 were 364.7 ± 5.2, 146.2 ± 5.2, and 234.4 ± 5.2 MPa, respectively, and the elastic moduli for nanowires 1, 2, and 3 were 39 ± 5.2, 33.4 ± 5.2, and 37.4 ± 5.2 GPa, respectively.

This study aims to investigate the effects of hybrid carbon fillers on the physical properties of polymer composites for bipolar plates of fuel cells. Hybrid carbon-filled poly(phenylene sulfide) (PPS) composites have been prepared via compression molding with graphite as main filler and different shaped supplementary filler such as carbon black, carbon fiber and multi-walled carbon nanotubes. Different types of conducting fillers, such as fibrous and particulate fillers, or different sizes of fillers show synergistic effects on the flexural strengths and electrical conductivities of the PPS based composites. Materials selection windows of hybrid fillers for desired flexural strength and electrical conductivity obtained by simple linear interpolation of the measured values provide useful tools for the development of PPS based composites for bipolar plate application.

This paper reports that the Barkhausen noise method can be used to accurately characterize forged reactor vessels. The Charpy V-notch impact tests were conducted on the respective specimens with three different types of heat history. Various test results including fracture appearance transition temperature (FATT) were obtained. The Barkhausen noise voltage changed with heat treatment temperature (870~1000°C) and conditions (Tempered, PWHT). The fracture appearance transition temperature can be predicted using the Barkhausen noise voltage.

We performed the tensile test of an individual carbon nanofiber (CNF) inside a scanning electron microscope. The mechanical testing system was installed in a scanning electron microscope (SEM). The nano-manipulator was set up in the SEM, and the force sensor, which is formed as a cantilever, was mounted on the nano-manipulator. Then, the force sensor can be controlled by using the nano-manipulator. The CNFs were dispersed on the transmission electron microscope (TEM) grid, and the both end of the CNFs were welded on the TEM grid and the tip of force sensor by exposing electron-beam of the SEM. The tensile test of the CNFs was performed by controlling the nano-manipulator. The load response during the tensile test was obtained by force sensor. Stess-strain curve was obtained from force-displacement curve of CNF after tensile test. The elastic modulus of CNFs was calculated at ~12.5 GPa.

Recently, alternative and novel energy resources have been developed for use in the future because of the current environmental problems and exhaustion of fossil energy resources. Hydrogen energy has many merits, such as its environmental friendliness, easy storage, and easy production, but it also has disadvantages, in that it is highly combustible and explosive. In this study, a test procedure using a simple SP test under highly pressurized hydrogen gas conditions was established. In order to evaluate its applicability, SP tests were carried out using a stainless steel (SUS316L) sample under atmospheric, pressurized helium, and pressurized hydrogen gas conditions. The results under the pressurized hydrogen gas condition showed fissuring and produced a reduction of the elongation in the plastic instability region due to hydrogen embrittlement, showing the effectiveness of the current in-situ SP test.

Hydrogen-induced degradations have generally been investigated through the ex situ testing of cathodically hydrogen-charged specimens. However, the cathodic charging cannot realize damage accumulation by gaseous hydrogen in transportation pipelines. Thus, we designed an ampule specimen which enables an in situ tensile test containing gaseous hydrogen. Ampule specimens made of API (American Petroleum Institute) X65 pipeline steel showed significant reductions of 3.4 % and 4.1 %, respectively, in their ultimate tensile strength and fracture strain after exposure to 20 MPa of hydrogen gas. The resulting fracture surface showed quasi-cleavage perpendicular to the loading direction and a fracture thickness close to the initial wall thickness, significantly different from the complex dimples and highly reduced fracture thickness by shear deformations in nitrogen gas and air environments.

The present work studies a nondestructive evaluation of the degradation of modified 9Cr-1Mo steel using a magnetic method based on the existence of the peaks of reversible permeability (RP) in the differential magnetization around the coercive force. The apparatus is based on detection of the voltage induced in a coil using a lock-in amplifier tuned to the frequency of the AC perturbing field. Results obtained for the reversible permeability and Vickers hardness on the aged samples showed the peak interval of reversible permeability (PIRP) and Vickers hardness decrease as aging time increased. The correlation between Vickes hardness and the PIRP could be used to evaluate degradation of modified 9Cr-1Mo steel.

We present a magnetic and nondestructive method to evaluate the remanent life of modified 9Cr–1Mo steel by measuring the reversible magnetic permeability. Specimens with ten different kinds of aging periods were prepared using an isothermal heat treatment at 690 °C. The Larson–Miller parameter (LMP) was calculated and the peak interval of reversible magnetic permeability (PIRMP) was measured using the surface type probe. PIRMP was inversely proportional to LMP. We can evaluate the remanent life of modified 9Cr–1Mo steel using the relationship between PIRMP and LMP. Also, we present the possibility that the tensile strength and yield strength measured by destructive methods could be estimated by PIRMP measured nondestructively.

A flexible, transparent heater was manufactured by spinning multi-walled carbon nanotubes (MWCNTs). MWCNT sheets were produced by continuously pulling on well-aligned MWCNTs, and films were produced by directly coating a flexible film. Single and double sheets were produced with sheet resistances of ∼699 Ω/sq and ∼349 Ω/sq and transmittances of 81% to 85% and 67% to 72%, respectively. Both films were heated by applying a direct current, and showed rapid thermal responses and uniform temperature distribution. The rate of temperature change was found to depend on the power applied. Frost on the surface of these films was rapidly removed so that they may have applications as automatic defrosters in vehicles of goggles.

The bending and tensile tests of the ZnO nanorods were carried out by controlling a force sensor and a nano-manipulator inside a scanning electron microscope (SEM). The force sensor was mounted on the nano-manipulator, was controlled with the nano-manipulate. The load response during the mechanical test for the ZnO nanorod was obtained by using the force sensor which is formed as a cantilever. The elastic modulus of the ZnO nanorods after the tensile and bending tests were calculated and compared. The elastic modulus of ZnO nanorods was depended on a size and an aspect ratio of the ZnO nanorods. The difference of the elastic modulus of ZnO nanorods was obtained with a difference of test methods performed along crystal facets direction of the ZnO nanorods. The average elastic modulus calculated after the tensile test was approximately 57.15 GPa. In case of the bending test, the average elastic modulus was approximately 29.37 GPa.

Tensile properties are the most fundamental properties for the mechanical structure design. Due to industrial development in all areas requires sophisticated and smart, lightweight, high-quality products continues to increase appetite. Therefore, designer was necessary more accurate mechanical properties. To meet these requirements, In the field of mechanical engineering has a lot of effort. In this study, several testing laboratory ware proficiency testing(PT) in Korea to the ability of the tensile test, to the reliability of testing machine and to assessment the skill level of a tester. Also propose each laboratory problems and improvements on the basis of PT test results.

Multi-walled carbon nanotube (MWCNT) yarns were prepared by spinning a bundle of MWCNTs from vertically super-aligned MWCNTs on a substrate, and field emission from the tip and side of the yarns was induced in a scanning electron microscope. We found that the field emission behavior from the tip of the yarn was better than the field emission from the side. The field emission turn-on voltages from the tip and side of MWCNT yarns were 1.6 and 1.7 V/μm, respectively, after the yarn was subjected to an aging process. Both the configuration of the tip end and the body of the yarn were changed remarkably during the field emission. Both the field emission of the tip and side exhibited a transition of the Fowler–Nordheim slope from the region of low voltage to the region of high voltage. From the Fowler–Nordheim plots, the field enhancement factors of field emission from the tip and side, γtip and γside, in the region of high voltage were determined to be 5430 ± 5 and 3940 ± 5, respectively, and their ratio was approximately 1.38:1.

In order to study elastic stress effects on the surface deformability of BMGs, indentations with a Berkovich diamond pyramid were done on an artificially bent Zr-based metallic glass stripe (Vitreloy-1). Residual indentation marks formed with a peak load of 500 mN were observed with an atomic force microscope for 7 artificial stress steps. Significant pile-ups (or surface upheavals around indents) and shear bands were observed at low stress levels less than 244 MPa and disappeared with an increase of the tensile stress. From a 3D morphological viewpoint, the tensile stress in elastic regime is understood to be beneficial to the surface formability of the Zr-based BMG, because the tensile stress invokes deeper indentations with slight elastic recovery and reduces the irregular pile-ups with shear bands.

Mechanically polished surface of Zr55Al10Ni5Cu30metallic glass was indented with a rigid ball 0.5 mm in diameter and its corresponding load-depth curve was recorded automatically. Although a stress-strain relationship beneath the indenter can be analyzed from the raw indentation curve, the current analysis developed for crystalline solids can mislead erroneous properties because it does not consider significant material pile-ups in amorphous metallic glasses. Thus, we proposed a novel indent image processing technique for characterizing the contact and flow properties in the metallic glasses; the contact area was measured by differentiating a three-dimensional indent morphology digitized by a surface profiler and a surface-stretching strain was newly defined in order to estimate the flow properties. Finally, the work-hardening index estimated was about 0.05, comparable with the typical value measured from uniaxial compression in the Zr -based metallic glass.

It is advantageous to use a non-destructive evaluation (NDE) method to assess the mechanical properties of materials since conventional methods are time-consuming and usually require sampling from the material or component. In this study, an electrical resistivity method was attempted for the estimation of the creep damage of degraded 9 Cr steel. The specimens with six different kinds of aging periods were prepared by an isothermal heat treatment at 690 °C. The electrical resistivity was determined by a standard DC four-point probe method at 24±0.5 °C. The home-made probe station and Burster 2304 were utilized for the resistance measurement. A correlation between the measured electrical resistivity and the tensile properties was studied. The electrical resistivity showed a declining tendency with the increase of aging time because the electrical resistivity is strongly dependent on the microstructural changes. A correlation between the electrical resistivity and aging parameter was established, which allows one to estimate the material degradation of 9 Cr steel.