Microscopic Observations of SOFC Anodes Under Operation With Hydrocarbon Fuels

2004 ◽  
Author(s):  
Tatsuya Kawada ◽  
Keiji Yashiro ◽  
Tomoaki Taura ◽  
Kenichiro Takeda ◽  
Atsushi Kaimai ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Carbon Deposition ◽  
Optical Microscope ◽  
Open Circuit ◽  
In Situ Observation ◽  
Nickel Surface ◽  
Operation Condition ◽  
Grid Electrode ◽  
Laser Raman

Carbon deposition on a SOFC anode was investigated under direct hydrocarbon fueling condition. Microscopic behaviors were observed with a newly designed sample holder that enabled in-situ observation of an electrode in operation under controlled atmosphere at elevated temperatures. The preferential carbon deposition site, the structure of the deposited carbon, and the chemical or electrochemical re-oxidation processes were investigated with an optical microscope combined with a laser Raman microscope. Color and morphology change of the electrode surface was recorded with a CCD camera, and the deposited materials were identified with a laser Raman microscope. A nickel micro grid was used as a model electrode of a well-defined microstructure. When the cell was kept at an open circuit condition in methane, carbon started to deposit on the surface of Ni grid electrode. The deposition of carbon was clearly observed as the change in the reflection on the nickel surface by optical microscope as well as by the appearance of the specific peak at ∼ 1560 cm−1 in Raman spectroscopy. The deposited carbon was in the form of graphite on the nickel grid electrode. The carbon coverage on the surface was not uniform but varied from grain to grain. When a certain anodic overpotential (e.g. 200 mV) was applied to the electrode, the carbon disappeared gradually from the edge of the electrode i.e. from the electrode/electrolyte boundary where oxygen was supplied electrochemically. It is the first in-situ observation of the electrochemical carbon oxidation in a real operation condition.

scholarly journals In-situ observation of graphene using an optical microscope

2021 ◽  
Vol 6 ◽  
pp. 100138
Author(s):  
Mikihiro Kato ◽  
Sujun Guan ◽  
Xinwei Zhao
Keyword(s):  
Optical Microscope ◽  
In Situ Observation

scholarly journals In-Situ Monitoring and Analysis of the Pitting Corrosion of Carbon Steel by Acoustic Emission

2019 ◽  
Vol 9 (4) ◽  
pp. 706 ◽  
Author(s):  
Junlei Tang ◽  
Junyang Li ◽  
Hu Wang ◽  
Yingying Wang ◽  
Geng Chen
Keyword(s):  
Acoustic Emission ◽  
Carbon Steel ◽  
Pitting Corrosion ◽  
Optical Microscope ◽  
Open Circuit ◽  
In Situ Monitoring ◽  
Localized Corrosion ◽  
Uniform Corrosion ◽  
Corrosion Morphology

The acoustic emission (AE) technique was applied to monitor the pitting corrosion of carbon steel in NaHCO3 + NaCl solutions. The open circuit potential (OCP) measurement and corrosion morphology in-situ capturing using an optical microscope were conducted during AE monitoring. The corrosion micromorphology was characterized with a scanning electron microscope (SEM). The propagation behavior and AE features of natural pitting on carbon steel were investigated. After completion of the signal processing, including pre-treatment, shape preserving interpolation, and denoising, for raw AE waveforms, three types of AE signals were classified in the correlation diagrams of the new waveform parameters. Finally, a 2D pattern recognition method was established to calculate the similarity of different continuous AE graphics, which is quite effective to distinguish the localized corrosion from uniform corrosion.

scholarly journals ANNEALING OF POLYCRYSTALLINE THIN FILM SILICON SOLAR CELLS IN WATER VAPOUR AT SUB-ATMOSPHERIC PRESSURES

2014 ◽  
Vol 54 (5) ◽  
pp. 341-347
Author(s):  
Peter Pikna ◽  
Vlastimil Píč ◽  
Vítězslav Benda ◽  
Antonín Fejfar
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Water Vapour ◽  
Elevated Temperatures ◽  
Voltage Response ◽  
In Situ Observation ◽  
Polycrystalline Thin Film ◽  
Cell Parameters

Thin film polycrystalline silicon (poly-Si) solar cells were annealed in water vapour at pressures below atmospheric pressure. PN junction of the sample was contacted by measuring probes directly in the pressure chamber filled with steam during passivation. Suns-VOC method and a Lock-in detector were used to monitor an effect of water vapour to VOC of the solar cell during whole passivation process (in-situ). Tested temperature of the sample (55°C – 110°C) was constant during the procedure. Open-circuit voltage of a solar cell at these temperatures is lower than at room temperature. Nevertheless, voltage response of the solar cell to the light flash used during Suns-VOC measurements was good observable. Temperature dependences for multicrystalline wafer-based and polycrystalline thin film solar cells were measured and compared. While no significant improvement of thin film poly-Si solar cell parameters by annealing in water vapour at under-atmospheric pressures was observed up to now, in-situ observation proved required sensitivity to changing VOC at elevated temperatures during the process.

scholarly journals Very Low Nucleation Rates of Glucose Isomerase Crystals under Microgravity in the International Space Station

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 90
Author(s):  
Yoshihisa Suzuki ◽  
Takahisa Fujiwara ◽  
Katsuo Tsukamoto ◽  
Seijiro Fukuyama ◽  
Taro Shimaoka ◽  
...  
Keyword(s):  
International Space Station ◽  
Growth Rates ◽  
Space Station ◽  
Glucose Isomerase ◽  
Optical Microscope ◽  
In Situ Observation ◽  
International Space ◽  
High Supersaturation ◽  
Very High

In situ observation of the nucleation and growth of glucose isomerase (GI) crystals under microgravity was conducted using an optical microscope during the first flight of the Advanced Nano Step project undertaken in the International Space Station (ISS). Very low apparent nucleation rates (J’) of GI crystals in the solution and on the substrate of the growth container were confirmed compared with those on the ground. In particular, J’ of GI crystals in the solution were a few times lower than that on the substrate. The growth rates (R) of the {101} faces of GI crystals on the substrate and the apparent growth rates (R’) in the solution were measured. The very low nucleation rates allowed us to successfully measure R at a very high supersaturation region (up to ln(C/Ce) = 6), at which R cannot be measured on the ground.

Study of dynamic compressive behaviors of 2D C/SiC composites at elevated temperatures based on in-situ observation

2020 ◽  
Vol 40 (15) ◽  
pp. 5103-5119
Author(s):  
Chao Zhang ◽  
Tengfei Ren ◽  
Xinyue Zhang ◽  
Wei Hu ◽  
Zhen Wang ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
In Situ Observation ◽  
Sic Composites

scholarly journals Dendritic Growth in Si1−xGex Melts

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 761
Author(s):  
Genki Takakura ◽  
Mukannan Arivanandhan ◽  
Kensaku Maeda ◽  
Lu-Chung Chuang ◽  
Keiji Shiga ◽  
...  
Keyword(s):  
Dendritic Growth ◽  
Elevated Temperatures ◽  
Electronic Devices ◽  
Solidification Process ◽  
Dendrite Growth ◽  
In Situ Observation ◽  
Wide Range ◽  
Solidification Processes ◽  
Semiconductor Alloy

We investigated the types of dendrites grown in Si1−xGex (0 < x < 1) melts, and also investigated the initiation of dendrite growth during unidirectional growth of Si1-xGex alloys. Si1−xGex (0 < x < 1) is a semiconductor alloy with a completely miscible-type binary phase diagram. Therefore, Si1−xGex alloys are promising for use as epitaxial substrates for electronic devices owing to the fact that their band gap and lattice constant can be tuned by selecting the proper composition, and also for thermoelectric applications at elevated temperatures. On the other hand, regarding the fundamentals of solidification, some phenomena during the solidification process have not been clarified completely. Dendrite growth is a well-known phenomenon, which appears during the solidification processes of various materials. However, the details of dendrite growth in Si1−xGex (0 < x < 1) melts have not yet been reported. We attempted to observe dendritic growth in Si1−xGex (0 < x < 1) melts over a wide range of composition by an in situ observation technique. It was found that twin-related dendrites appear in Si1−xGex (0 < x < 1) melts. It was also found that faceted dendrites can be grown in directional solidification before instability of the crystal/melt interface occurs, when a growing crystal contains parallel twin boundaries.

scholarly journals In-situ study of electrochemical migration of tin in the presence of bromide ion

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ee Lynn Lee ◽  
A. S. M. A. Haseeb ◽  
Wan Jeffrey Basirun ◽  
Yew Hoong Wong ◽  
Mohd Faizul Mohd Sabri ◽  
...  
Keyword(s):  
Water Drop ◽  
Short Circuit ◽  
Optical Microscope ◽  
In Situ Observation ◽  
Electrochemical Migration ◽  
X Rays ◽  
Corrosion Properties ◽  
Bromide Ion ◽  
Ionic Contaminants

AbstractThe miniaturization of electronic devices and the consequent decrease in the distance between conductive lines have increased the risk of short circuit failure due to electrochemical migration (ECM). The presence of ionic contaminants affects the ECM process. This work systematically investigates the ECM of tin (Sn) in the presence of bromide ions (Br−) in the range of 10−6 M to 1.0 M. Water drop test (WDT) was conducted in the two-probe semiconductor characterization system under an optical microscope as an in-situ observation. Polarization test was carried out to study the correlation between the corrosion properties of Sn and its ECM behaviour. The products of ECM were characterized by scanning electron microscope coupled with an energy dispersive X-rays spectrometer (SEM/EDX) and X-ray photoelectron spectrometer (XPS). The results confirm that the rate of anodic dissolution of Sn monotonously increases with the Br− concentration. However, the probability of ECM failure follows a normal distribution initially, but later increases with the Br− concentration. The main products of the ECM reactions are identified as Sn dendrites and tin hydroxide precipitates. The mechanisms of the ECM process of Sn in the presence of Br− are also suggested.

scholarly journals In-Situ Monitoring and Analyzing Pitting Corrosion of Carbon Steel by Acoustic Emission

2018 ◽  
Author(s):  
Junlei Tang ◽  
Junyang Li ◽  
Hu Wang ◽  
Yingying Wang ◽  
Geng Chen
Keyword(s):  
Acoustic Emission ◽  
Carbon Steel ◽  
Pitting Corrosion ◽  
Optical Microscope ◽  
Open Circuit ◽  
In Situ Monitoring ◽  
Localized Corrosion ◽  
Uniform Corrosion ◽  
Corrosion Morphology

The acoustic emission (AE) technique was applied to monitor the pitting corrosion of carbon steel in NaHCO3 + NaCl solutions. The open circuit potential (OCP) measurement and the corrosion morphology in-situ capturing using optical microscope were conducted during AE monitoring. The corrosion micromorphology was characterized with scanning electron microscope (SEM). The propagation behavior and AE features of natural pitting on carbon steel were investigated. After the performing of signal processing including pre-treatment, shape preserving interpolation and denoising for raw AE waveforms, three types of AE signals can be classified in the correlation diagrams of new waveform parameters. Finally, a 2D pattern recognition method was established to calculate the similarity of different continuous AE graphics, which is quite effective to distinguish the localized corrosion from uniform corrosion.

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