• Korean Journal of Metals and Materials
• /
• v.49 no.4
• /
• pp.321-328
• /
• 2011

The 30 nm-thick Ni layers was deposited on a flexible polyimide substrate with an e-beam evaporation. Subsequently, we deposited a Si layer using a catalytic CVD (Cat-CVD) in a hydride amorphous silicon (${\alpha}$-Si:H) process of $T_{s}=180^{\circ}C$ with varying thicknesses of 55, 75, 145, and 220 nm. The sheet resistance, phase, degree of the crystallization, microstructure, composition, and surface roughness were measured by a four-point probe, HRXRD, micro-Raman spectroscopy, FE-SEM, TEM, AES, and SPM. We confirmed that our newly proposed Cat-CVD process simultaneously formed both NiSi and crystallized Si without additional annealing. The NiSi showed low sheet resistance of < $13{\Omega}$□, while carbon (C) diffused from the substrate led the resistance fluctuation with silicon deposition thickness. HRXRD and micro-Raman analysis also supported the existence of NiSi and crystallized (>66%) Si layers. TEM analysis showed uniform NiSi and silicon layers, and the thickness of the NiSi increased as Si deposition time increased. Based on the AES depth profiling, we confirmed that the carbon from the polyimide substrate diffused into the NiSi and Si layers during the Cat-CVD, which caused a pile-up of C at the interface. This carbon diffusion might lessen NiSi formation and increase the resistance of the NiSi.

• Korean Journal of Metals and Materials
• /
• v.46 no.5
• /
• pp.321-327
• /
• 2008

Cu based amorphous ($Cu_{54}Zr_{22}Ti_{18}Ni_6$) coating was produced by cold spraying as a new fabrication process. The microstructure and macroscopic properties of amorphous coating layer was investigated and compared with those of cold sprayed pure Cu coating. Amorphous powders were prepared by gas atomization and Al 6061 was used as the substrate plate. X-ray diffraction results showed that Cu based amorphous powder could be successfully deposited by cold spraying without any crystallization. The Cu based amorphous coating layer ($300{\sim}400{\mu}m$ thickness) contained 4.87% porosity. The hardness of Cu based amorphous coating represented $412.8H_v$, which was correspond to 68% of the hardness of injection casted bulk amorphous material. The wear resistance of Cu based amorphous coating was found to be three times higher than that of pure Cu coating. The 3-point bending test results showed that the adhesion strength of Cu based amorphous coating layer was higher than that pure Cu coating. It was also observed that hard Cu base amorphous particle could easily deform soft substrate by particle collisions and thus generated strong adhesion between coating and substrate. However, the amorphous coating layer unexpectedly represented lower corrosion resistance than pure Cu coating, which might be resulted from the higher content of porosity in the cold sprayed amorphous coating.

• Journal of the Semiconductor & Display Technology
• /
• v.20 no.2
• /
• pp.61-66
• /
• 2021

In this study, we studied the alternative of plasma resistant ceramic parts that constitute plasma chambers in the semiconductor dry etching process. MgO-Al₂O₃-SiO₂(MAS) glass was made of 13 types of glass using the Design Of Experiments(DOE) and the effect on thermal properties such as glass transition temperature and crystallization temperature depending on the content of each composition and etching resistance to CF₄/O₂/Ar plasma gas. MAS glass showed excellent plasma resistance and surface roughness up to 20 times higher than quartz glass. As the content of Al₂O₃ and MgO increases, the plasma resistance is improved, and it has been confirmed that it has an inverse relationship with SiO₂.

• Membrane Journal
• /
• v.31 no.1
• /
• pp.67-79
• /
• 2021

Mesoporous polystyrene (PS) and polyethersulfone (PES) membranes have been fabricated by reverse-thermally induced phase separation (RTIPS) process, using flash freezing. The mesoporous pores can be created by the nano-scaled phase separation induced by the formation and growth of solvent crystals in the dope solution in RTIPS process. RTIPS process has been characterized through analysis on the enthalpy change in the solvent of the dope solution, the morphology of the membrane fabricated with different polymer content, and the pore size distribution and its standard deviation of pore size of the membrane with polymer content via DSC, SEM, and BET, respectively. It is found that the kinetic aspect of the dope solution, i.e., the crystallization of solvent is a crucial factor to determine the structure of membrane fabricated in RTIPS rather than the thermodynamic aspect of the dope solution.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.27 no.3
• /
• pp.159-167
• /
• 2021

The need for biodegradable plastic continues to increase, improvement of physical properties is necessary for actual use in the market. In this study, composite film was produced by adding peroxide additives to bioplastic according to concentration to investigate changes in the melt index, elongation, morphology, and TGA of the composite film. The addition of peroxide compatibilizer showed superior elongation of film and TGA compared to those of control. The added amount of compatibilizer affected the extrusion process, and it was revealed that adding an appropriate amount of peroxidizer is important. Analysis of the composite film's morphology revealed a heterogeneous dispersion sequence due to different rates of crystallization depending on the resin, and surface physical properties were best in the group added with 4% peroxide. The results above showed that the test group added with 4% peroxide compatibilizer was superior in the production of composite biodegradable film.

• Journal of the Semiconductor & Display Technology
• /
• v.21 no.2
• /
• pp.85-89
• /
• 2022

We reported on annealing effect on Ga₂O₃/Al₂O₃/SiC devices grown by radio frequency sputtering method. Post-deposition annealing at 900 ℃ was performed, which results in crystallization in the Ga₂O₃ films. The major peaks (-401) and (403) of Ga₂O₃ which was thermally treated at 900 ℃ appears in the x-ray diffraction (XRD) results. Auger electron spectroscopy (AES) shows that Ga and Al atoms seems to be diffused into the opposite direction Al₂O₃ and Ga₂O₃ after annealing. Transfer and output characteristics of back-gate transistor were analyzed where SiC substrate is used as gate material. On-state current and on/off ratio increased almost 10⁹ and 10⁶ times higher in the 900 ℃ annealed sample.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.2
• /
• pp.349-354
• /
• 2022

This research was conducted in order to improve the hydrolysis resistance and mechanical properties of a resin compound and biodegradable mulching film, produced through the use of PBAT(Poly Butylene Adipate-co-Terephthalate) and PLA(Poly Lactic Acid). Various ratios of chain extenders and mechanical properties according to the annealing temperature conditions were investigated. The annealing process showed that compound resin can improve the crystallization capacity. In addition, incorporation of the chain extender was shown to improve and increase the tensile strength and hydrolysis resistance of the film. In the case of 0.6phr chain extender, the tensile strength was 383.0Kgf/cm², which was improved by 155% compared to the control films. When the blow up ratio(BUR) was 2.5, the optimal tensile strength of the film increased greatly, expanding up to 379.0/195.2kgf/cm² in the both machine direction (MD) and transverse direction (TD).

• Nuclear Engineering and Technology
• /
• v.53 no.12
• /
• pp.3952-3965
• /
• 2021

In this study, volcanic ash was used as raw material to prepare waste forms with different silicon/aluminum (Si/Al) molar ratios to immobilize sodium-salt waste (SSW) containing simulated ¹³⁷Cs. Effects of Si/Al molar ratios (3:1 and 2:1) and sodium salts on sintering behavior of waste forms and immobilization mechanism of Cs⁺ were investigated. Results indicated that the main mineral phase of sintered waste-form matrixes was albite, and the formation of major phases was found to depend on Si/Al molar ratios. Si/Al molar ratio of 2 was favorable for the formation of pollucite, and the formation and crystallization of mineral phases were also decided based on physicochemical characteristics of sodium salts. Furthermore, product consistency test results indicated that the immobilization of Cs⁺ was related to Si/Al molar ratio, types of sodium salts, and glassy phase. Waste forms with Si/Al molar ratio of 2 exhibited better ability to immobilize Cs⁺, whereas the influence of sodium salts and glassy phases on the immobilization of SSW showed more complicated relationship. In waste forms with Si/Al molar ratio of 2, Cs⁺ leaching concentrations of samples containing Na₂B₄O₇·10H₂O and NaOH were low. Na₂B₄O₇·10H₂O easily transformed into liquid phase during sintering to consequently achieve low temperature liquid-phase sintering, which is beneficial to avoid the volatilization of Cs⁺ at high temperature. Results clearly reveal that waste forms with Si/Al molar ratio of 2 and containing Na₂B₄O₇·10H₂O show excellent immobilization of Cs⁺.

• Korean Chemical Engineering Research
• /
• v.60 no.4
• /
• pp.499-505
• /
• 2022

This study presents a conceptual design of vanillin production from Kraft lignin. Most of the existing Kraft lignin is used as low-quality boiler fuel or discarded as wastewater, and only 2% or less of lignin has been refined into high-quality products. We propose the process developed in this study to utilize discarded Kraft lignin. The existing vanillin production concept process consisted of alkali oxidation using NaOH, filtration, chromatography, and crystallization. Chromatography, which is difficult to commercialize, was changed to a solvent extraction process. The recovery rate of vanillin of the proposed solvent extraction process is 92.9%, and the purity is 99.5%, which is similar to the existing chromatography process. The reason why the solvent extraction process showing similar results to chromatography can replace the existing chromatography process was analyzed.

• Composites Research
• /
• v.35 no.5
• /
• pp.309-316
• /
• 2022

The demand for cold-resistant cable material is increasing due to the rapid increase in the development of devices that operate in a low temperature environment. Cold tolerance of a thermoplastic polymer largely depends on the type and content of about 20 or more additives used to make the polymer. The phenomenon of polymer hardening at low temperature can be classified into hardening by simple temperature effect, embrittlement at the glass transition temperature, and hardening by crystallization of polymers that tend to crystallize. In this study, a thermoplastic polymer having a low glass transition temperature, a flame retardant, and an additive were mixed to evaluate the mechanical properties of a thermoplastic polymer composite material for electric wires. It has been confirmed that mechanical properties and processability are determined depending on the additives and compatibilizers added, and this study is considered to be useful as basic data for optimization to meet the performance requirements of wires developed for low-temperature use.