Activated carbon (AC), extensively used across various industrial sectors, serves as a sponge for different types of gases due to its porous carbon material. These gases are attracted to the carbon substrate via van der Waals forces. In nuclear power plants, AC is commonly used to adsorb radioactive gases such as 86Kr and 134Xe, as well as radioiodine sources like 131I and 133I from gaseous effluents. Even if the adsorbed radioactive gases and radioiodine decay into non-radioactive elements, the spent AC still contains radioactive species with long half-lives, such as 3H (Tritium, T) and 14C (radiocarbon). Minimizing and separating waste that contains long-lived nuclides (e.g., 14C) are pivotal components of an efficient waste management approach. A challenging aspect of effectively managing disposed AC is to minimize long-lived radioactive substances by eliminating them. This paper explores and summarizes the technology used to remove pollutants (3H, 14C) trapped within the pores of Activated carbon through thermochemical vacuum and surface oxidation processes. By recycling and reusing spent Activated carbon, we anticipate a reduction in the volume of radioactive waste, leading to decreased disposal costs. Furthermore, this paper will contribute as a valuable reference in future studies, enhancing the understanding of vacuum thermal desorption and surface oxidation of used Activated carbon.

High-temperature oxidation of a Ni-based superalloy was analyzed with samples taken from gas turbine blades, where the samples were heat-treated and thermally exposed. The effect of Cr/Ti/Al elements in the alloy on high temperature oxidation was investigated using an optical microscope, SEM/EDS, and TEM. A high-Cr/high-Ti oxide layer was formed on the blade surface under the heat-treated state considered to be the initial stage of high-temperature oxidation. In addition, a PFZ (γ’ precipitate free zone) accompanied by Cr carbide of Cr23C6 and high Cr-Co phase as a kind of TCP precipitation was formed under the surface layer. Pits of several μm depth containing high-Al content oxide was observed at the boundary between the oxide layer and PFZ. However, high temperature oxidation formed on the thermally exposed blade surface consisted of the following steps: ① Ti-oxide formation in the center of the oxide layer, ② Cr-oxide formation surrounding the inner oxide layer, and ③ Al-oxide formation in the pits directly under the Cr oxide layer. It is estimated that the Cr content of Ni-based superalloys improves the oxidation resistance of the alloy by forming dense oxide layer, but produced the σ or μ phase of TCP precipitation with the high-Cr component resulting in material brittleness.

This study assessed the changes in the fiber properties of virgin and recovered fibers from lab-scale and pilot-scale depolymerization reactors based on the thermal air oxidation-resistance characteristics. Lab-scale and pilot-scale depolymerization reactors had different depolymerization volumes. Results showed that the lab-scale and pilot-scale peak solvent temperatures were 185 °C and 151 °C, respectively. The lab-scale had highest solvent temperature rate increase because of the small depolymerization volume and the dominant role of the cavitation volume. The structural properties of the recovered and virgin fibers were intact even after the depolymerization and after the pretreatment and oxidation-resistance test. We observed 1.213%, 1.027% and 0.842% weight loss for the recovered (lab-scale), the recovered (pilot-scale) and virgin fibers because of the removal of impurities from the surface and chemisorbed gases. Further, we observed 0.8% mass loss of the recovered fibers (lab-scale) after the oxidative-onset temperature because of the “cavitation erosion effect” from the dominant of the cavitation bubbles. The “cavitation erosion effect” was subdued because of the increased depolymerization volume in the pilot-scale reactor. Therefore, negligible impact of the pilot-scale mechanochemical recycling process on the structure and surface characteristics of the fibers and the possibility of reusing the recovered fibers recycling process were characteristic. Representative functional groups were affected by the thermal oxidation process. We conducted HPLC, HT-XRD, TGA– DSC, XPS, SEM, and AFM analysis and provided an extensive discussion of the test thereof. This study highlighted how misleading and insufficient small-lab-scale results could be in developing viable CFRP depolymerization process.

One-dimensional rutile TiO2 is an important inorganic compound with applicability in sensors, solar cells, and Li-based batteries. However, conventional synthesis methods for TiO2 nanowires are complicated and entail risks of environmental contamination. In this work, we report the growth of TiO2 nanowires on a Ti alloy powder (Ti-6wt%Al- 4wt%V, Ti64) using simple thermal oxidation under a limited supply of O2. The optimum condition for TiO2 nanowire synthesis is studied for variables including temperature, time, and pressure. TiO2 nanowires of ~5 μm in length and 100 nm in thickness are richly synthesized under the optimum condition with single-crystalline rutile phases. The formation of TiO2 nanowires is greatly influenced by synthesis temperature and pressure. The synthesized TiO2 nanowires are characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM).

In order to improve the high temperature oxidation resistance and lifespan of mat type porous carbon insulation, SiC was coated on carbon insulation by solution coating using polycarbosilane solution, curing in an oxidizing atmosphere at 200 oC, and pyrolysis at temperatures up to 1200 oC. The SiOC phase formed during the pyrolysis process was converted into SiC crystals as the heat treatment temperature increased, and a SiC coating with a thickness of 10-15 nm was formed at 1600 oC. The SiC coated specimen showed a weight reduction of 8.6 % when it was kept in an atmospheric environment of 700 oC for 1 hour. On the other hand, the thermal conductivity was 0.17W/mK, and no difference between states before and after coating was observed at all.

Various morphologies of copper oxide (CuO) have been considered to be of both fundamental and practical importance in the field of electronic materials. In this study, using Cu (0.1 μm and 7 μm) particles, flake-type CuO particles were grown via a wet oxidation method for 5min and 60min at 75 oC. Using the prepared CuO, AlN, and silicone base as reagents, thermal interface material (TIM) compounds were synthesized using a high speed paste mixer. The properties of the thermal compounds prepared using the CuO particles were observed by thermal conductivity and breakdown voltage measurement. Most importantly, the volume of thermal compounds created using CuO particles grown from 0.1 μm Cu particles increased by 192.5% and 125 % depending on the growth time. The composition of CuO was confirmed by X-ray diffraction (XRD) analysis; cross sections of the grown CuO particles were observed using focused ion beam (FIB), field emission scanning electron microscopy (FE-SEM), and energy dispersive analysis by X-ray (EDAX). In addition, the thermal compound dispersion of the Cu and Al elements were observed by X-ray elemental mapping.

TiO2 nanowires were grown by thermal oxidation of TiO powder in an oxygen and nitrogen gas environment at 1000 oC. The ratio of O2 to N2 in an ambient gas was changed to investigate the effect of the gas ratio on the growth of TiO2 nanowires. The oxidation process was carried out at different O2/N2 ratios of 0/100, 25/75, 50/50 and 100/0. No nanowires were formed at O2/N2 ratios of less than 25/75. When the O2/N2 ratio was 50/50, nanowires started to form. As the gas ratio increased to 100/0, the diameter and length of the nanowires increased. The X-ray diffraction pattern showed that the nanowires were TiO2 with a rutile crystallographic structure. In the XRD pattern, no peaks from the anatase and brookite structures of TiO2 were observed. The diameter of the nanowires decreased along the growth direction, and no catalytic particles were detected at the tips of the nanowires which suggests that the nanowires were grown with a vapor-solid growth mechanism.

Cu2O nanowires were synthesized at large scale on copper plate by thermal oxidation in air. The effect of oxidation time and temperature on the morphology of the nanowires was examined. The oxidation time had no effect on the diameter of the nanowires, while it had a great effect on the density and the length of the nanowires. The density and the length of the nanowires increased, and then decreased, with increasing oxidation time. The oxidation temperature had a tremendous effect on the size-distribution as well as the density of the nanowires. When the oxidation temperature was 700˚C, uniform size-distribution and high density of the nanowires was achieved. At lower and higher temperatures, the density of the nanowires was lower, and they displayed a broader size-distribution. It is suggested that the Cu2O nanowires were grown via a vapor-solid mechanism because no catalyst particles were observed at the tips of the nanowires.

A simple thermal oxidation of Cu thin films deposited on planar substrates established a growth of vertically aligned copper oxide (CuO) nanorods. DC sputter-deposited Cu thin films with various thicknesses were oxidized in environments of various oxygen partial pressures to control the kinetics of oxidation. This is a method to synthesize vertically aligned CuO nanorods in a relatively shorter time and at a lower cost than those of other methods such as the popular hydrothermal synthesis. Also, this is a method that does not require a catalyst to synthesize CuO nanorods. The grown CuO nanorods had diameters of ~100 nm and lengths of 1~25μm. We examined the morphology of the synthesized CuO nanorods as a function of the thickness of the Cu films, the gas environment, the oxidation time, the oxidation temperature, the oxygen gas flow rate, etc. The parameters all influence the kinetics of the oxidation, and consequently, the volume expansion in the films. Patterned growth was also carried out to confirm the hypothesis of the CuO nanorod protrusion and growth mechanism. It was found that the compressive stress built up in the Cu film while oxygen molecules incorporated into the film drove CuO nanorods out of the film.

유리지방산(FFA), 글리세롤, MAG, 세사몰, 수용성 참깨 박 추출물(ASM) 첨가에 의한 213oC에서 21분 볶아 제조된 참기름의 180oC 열산화 시 세사몰과 세사몰린 함량 변화를 분석하였다. 90분간의 열산화에 의해 FFA와 MAG가 10% 첨가된 시료는 각각 0.94, 0.70 mM의 세사몰이 유의적으로 추가 생성되었으나 대조구는 0.09 mM만 증가하였다(p < 0.05). 세사몰린의 경우 FFA와 MAG 10% 첨가 시료는 대조구에 비해 15 및 18% 유의적으로 감소하였다(p < 0.05). 1.5와 2.5 mM 첨가 세사몰은 세사몰린의 유의적인 변화를 유발하지 않았다(p > 0.05). ASM 첨가 시료에서 세사몰과 세사몰린의 일관적인 변화는 확인되지 않았다. 고온에서 볶은 참깨로부터 착유된 참기름의 가열 산화 시 세사몰 생성 및 세사몰린 분해에는 FFA 및 MAG 같은 유지산화생성물의 함량에 주로 영향을 받는 것으로 사료된다.

We study the relationships between the thermal emissivity of nuclear graphites (IG-110, PCEA, IG-430 and NBG-18) and their surface structural change by oxidation using scanning electron microscope and X-ray diffraction (XRD). The nonoxidized (0% weight loss) specimen had the surface covered with glassy materials and the 5% and 10% oxidized specimens, however, showed high roughness of the surface without glassy materials. During oxidation the binder materials were oxidized first and then graphitic filler particles were subsequently oxidized. The 002 interlayer spacings of the non-oxidized and the oxidized specimens were about 3.38~3.39a. There was a slight change in crystallite size after oxidation compared to the nonoxidized specimens. It was difficult to find a relationship between the thermal emissivity and the structural parameters obtained from the XRD analysis.

Thermal emissivity of nuclear graphite was measured with its oxidation degree. Commercial nuclear graphites (IG-110, PECA, IG-430, and NBG-18) have been used as samples. Concave on graphites surface increased as its oxidation degree increased, and R value (Id/Ig) of the graphites decreased as the oxidation degree increased. The thermal emissivity increased depending on the decrease of the R (Id/Ig) value through Raman spectroscopy analysis. It was determined that the thermal emissivity was influenced by the crystallinity of the nuclear graphite.

Thermal emissivity of commercial nuclear graphites (IG-110, PCEA, IG-430 and NBG-18) following changes in oxidation degrees were examined. Specimens were oxidized to 0%, 5%, and 10% in air flow of 5l/min at 600℃ using a furnace, and the thermal emissivities were measured using an infrared spectrum analyzer. The measuring temperatures for the thermal emissivity were 100℃, 200℃, 300℃, 400℃ 500℃. Also density and porosity of the specimens were observed to compare with thermal emissivity. Results showed that emissivity increased with oxidation, and the 10% oxidized NBG-18 showed the highest emissivity (0.890) which value is larger for 24% than the value of as-received specimen. Investigation of factors affecting the emissivity revealed that increases in the surface roughness and porosity due to oxidation were responsible for the increase in emissivity after oxidation.

Graphite for the nuclear reactor is used to the moderator, reflector and supporter in which fuel rod inside of nuclear reactor. Recently, there are many researches has been performed on the various characteristics of nuclear graphite, however most of them are restricted to the structural and the mechanical properties. Therefore we focused on the thermal property of nuclear graphite. This study investigated the thermal emissivity following the oxidation degree of nuclear graphite with IG-11 used as a sample. IG-11 was oxidized to 6% and 11% in air at 5 l/min at 600˚C. The porosity and thermal emissivity of the sample were measured using a mercury porosimeter and by an IR method, respectively. The thermal emissivity of an oxidized sample was measured at 100˚C, 200˚C, 300˚C, 400˚C and 500˚C. The porosity of the oxidized samples was found to increase as the oxidation degree increased. The thermal emissivity increased as the oxidation degree increased, and the thermal emissivity decreased as the measured temperature increased. It was confirmed that the thermal emissivity of oxidized IG-11 is correlated with the porosity of the sample.

폴리아크릴로나트릴(PAN)계 탄소섬유 및 안정화 PAN섬유를 사용하여 제조한 페놀수지 복합재료의 열주기 산화저항성에 섬유표면의 인산코팅 유.무가 미치는 영향을 조사하였다. 각 복합재료의 열주기 산화저항성은 열중량분석기의 원리를 응용하여, 공기중에서 hot zone과 cold zone을 주기적으로 반복이동하는 열충격조건에 노출되면서 초래되는 복합재료의 중량변화를 측정하여 비교하였다. 시험변수로는 hot zone에 노출된 온도, 시간 및 싸이클횟수를 선정하였다. 이 시험방법은 비교적 단순하며, 작은 크기의 시편으로도 가능하고, 중량변화가 온-라인 모니터에서 직접 감지되므로 데이타의 신뢰성이 ?다. 각 시험조건에서 인산코팅한 섬유를 사용한 복합재료가 그렇지 않은 재료보다 고온에서의 높은 산화저항성 때문에 우수한 열주기저항성을 보여 주었다. 또한 인산코팅의 존재 여부가 열주기시험 후의 탄소섬유-페놀수지 및 안정화 PAN섬유-페놀수지 복합재료의 미세구조에 미치는 영향을 조사하였다.

SiO2초박막(ultrathin film)의 두께 조절 용이성, 두께 균일성, 공정 재현성 및 전기적 특성을 향상시키기 위해 실리콘을 N2O분위기에서 열산화시켰다. N2O분위기에서 박막 성장시 산화와 동시에 질화가 이루어지기 때문에 전기적 특성의 향상을 가져올 수 있었다. 질화 현상에 의해 형성된 Si-N결합 형성은 습식 식각율과 ESCA분석으로 확인할 수 있었다. N2O분위기에서 성장된 SiO2박막은 Fowler-Nordheim(FN)전도 기구를 보여주었으며, 절열파괴 특성과 누설 전류특성 및 산화막의 신뢰성은 건식 산화막에 비해서 우수하였다. 또한 계면 포획밀도는 건식 산화막에 비해 감소하였고, 전하를 주입했을 때 생성되는 계면 준위의 양 또는 크게 감소하였다. 산화막 내부에서의 전하 포획의 양도 감소하였고, 전하를 주입하였을 때 생성되는 전하 포획의 양도 감소하였다. 이와 같은 전기적인 특성의 향상은 산화막 내부에서 약하게 결합하고 있는 Si-O 결합들이 Si-N결합으로의 치환과 스트레스 이완에 의하여 감소하였기 때문이다.

The blended oil was prepared from cottonseed oil and palm olien. The oxidative stability of blended oil after the addition of natural tocopherol and soybean lecithin during heating was investigated and the effects of lecithin were evaluated. The result obtained were as follows: 1. When the concentration of palm olein in blended oil during heating was increased, the oxidative stability was improved. 2. By both addition of natural tocopherol and soybean lecithin during heating in blended oil, induction period was considerably increased and residual ratio of tocopherol was high. 3. The oxidative stability of potato chips prepared from blended oil was higher in the prsence of lecithin than in the absence of it.