• 센서학회지
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• 제33권5호
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• pp.288-297
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• 2024

Currently, numerous studies are being conducted on metal oxide semiconductor (MOS) gas sensors for hydrogen detection, using Palladium (Pd) and Pd-based alloy nanoparticles (NPs) owing to their hydrogen absorption ability. Furthermore, several studies have reported that Pd-Iridium (Ir) alloys possess high hydrogen absorption capabilities in their bulk state. However, Ir growth is limited to above 2 nm and it does not mix extensively with other metals. Furthermore, as the hydrogen absorption capacity decreases with the reduction in particle size, it is necessary to synthesize nanoparticles of an appropriate size. Therefore, the synthesis of Pd-Ir alloy NPs larger than 10 nm is challenging. In this study, we report the synthesis of Pd-Ir NPs with an average diameter of 19 nm using a hydrothermal technique for the first time and fabricated Pd-Ir alloy NPs through calcination at 500℃ in Ar and air. To confirm alloy formation and oxidation behavior, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were performed. In addition, we synthesized Pd-Ir@CeO₂ core-shell nanoparticles (CSNPs) as hydrogen gas-sensing materials. The Pd-Ir core was partially oxidized during heat treatment at 500℃ in air, and Pd-Ir@CeO₂ CSNPs were finally changed into Pd-Ir(alloy)/PdO-IrO₂@CeO₂ CSNPs, which exhibited higher sensitivity and selectivity toward H₂ gas compared to totally oxidized PdO-IrO₂@CeO₂ CSNPs and pure CeO₂ NPs. The enhanced gas-sensing performance was attributed to the hydrogen absorption effect of the Pd-Ir(alloy) NPs.

• Bulletin of the Korean Chemical Society
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• 제27권12호
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• pp.2064-2066
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• 2006

• 한국재료학회:학술대회논문집
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• 한국재료학회 2007년도 추계학술발표대회 및
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• pp.29.1-29.1
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• 2007

• 한국재료학회:학술대회논문집
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• 한국재료학회 2007년도 추계학술발표대회 및
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• pp.82.2-82.2
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• 2007

• 한국진공학회:학술대회논문집
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• 한국진공학회 1995년도 제9회 학술발표회 논문개요집
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• pp.24-24
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• 1995

• 한국재료학회:학술대회논문집
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• 한국재료학회 1996년도 재료학회 추계학술발표회
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• pp.6-6
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• 1996

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2006년도 추계학술발표회 초록집
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• pp.80-80
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• 2006

• Corrosion Science and Technology
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• 제6권4호
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• pp.159-163
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• 2007

Micron size Co-alloy 800 (T800) powder is coated on the high temperature, oxidation and corrosion resistant super alloy Inconel 718 substrate by the optimal high velocity oxy-fuel (HVOF) thermal spray coating process developed by this laboratory. For the study of durability improvement of high speed spindle operating without lubricants, friction and sliding wear behaviors of the coatings are investigated both at room and at an elevated temperature of $1000^{\circ}F(538^{\circ}C)$. Friction coefficients, wear traces and wear debris of coatings are drastically reduced compared to those of non-coated surface of Inconel 718 substrate both at room temperature and at $538^{\circ}C$. Friction coefficients and wear traces of both coated and non-coated surfaces are drastically reduced at higher temperature of $538^{\circ}C$ compared with those at room temperature. At high temperature, the brittle oxides such as CoO, $Co_{3}O_{4}$, $MoO_2$ and $MoO_3$ are formed rapidly on the sliding surfaces, and the brittle oxide phases are easily attrited by reciprocating slides at high temperature through oxidation and abrasive wear mechanisms. The brittle solid oxide particles, softens, melts and partial-melts play roles as solid and liquid lubricants reducing friction coefficient and wear. These show that the coating is highly recommendable for the durability improvement coating on the machine component surfaces vulnerable to frictional heat and wear.

• 한국분말재료학회지
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• 제22권1호
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• pp.52-59
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• 2015

As well-known wrought stainless steel, sintered stainless steel (STS) has excellent high-temperature anti-corrosion even at high temperature of $800^{\circ}C$, and exhibits good corrosion resistance in air. However, when temperature increases above $900^{\circ}C$, the corrosion resistance of STS begins to deteriorate and dramatically decreases. In this study, the effects of phase and composition of STS on high-temperature corrosion resistances are investigated for STS 316L, STS 304 and STS 434L above $800^{\circ}C$. The morphology of the oxide layers are observed. The oxides phase and composition are identified using X-ray diffractometer and energy dispersive spectroscopy. The results demonstrate that the best corrosion resistance of STS could be improved to that of 434L. The poor corrosion resistance of the austenitic stainless steels is due to the fact that $NiFe_2O_4$ oxides forming poor adhesion between the matrix and oxide film increase the oxidation susceptibility of the material at high temperature.

• Mass Spectrometry Letters
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• 제3권1호
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• pp.10-14
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• 2012

Artificially oxidized cysteine residues in peroxiredoxin 6 (Prx6) were detected by electrospray interface capillary liquid chromatography-linear ion trap mass spectrometry after the preparation of two-dimensional gel electrophoresis (2D-GE). We used Prx6 as a model protein because it possesses only two cysteine residues at the 47th and 91st positions. The spot of Prx6 on 2D-GE undergoes a basic (isoelectric point, pI 6.6) to acidic (pI 6.2) shift by exposure to peroxide due to selective overoxidation of the active-site cysteine Cys-47 but not of Cys-91. However, we detected a tryptic peptide containing cysteine sulfonic acid at the 47th position from the basic spot and a peptide containing both oxidized Cys-47 and oxidized Cys-91 from the acidic spot of Prx6 after the separation by 2D-GE. We prepared two types of oxidized Prx6s: carrying oxidized Cys-47 (single oxidized Prx6), and other carrying both oxidized Cys-47 and Cys-91 (double oxidized Prx6). Using these oxidized Prx6s, the single oxidized Prx6 and double oxidized Prx6 migrated to pIs at 6.2 and 5.9, respectively. These results suggest that oxidized Cys-47 from the basic spot and oxidized Cys-91 from the acidic spot are generated by artificial oxidation during sample handling processes after isoelectric focusing of 2D-GE. Therefore, it is important to make sure of the origin of cysteine oxidation, if it is physiological or artificial, when an oxidized cysteine residue(s) is identified.