• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.256-256
• /
• 2013

Carbon nanotubes (CNT) / polyvinylidene fluoride (PVDF) piezoelectric composite films for nanogenerator devices were fabricated by spray coating method. When the CNT/PVDF mixture solution passes through the spray nozzle with small diameter by the compressed nitrogen gas, electric charges are generated in the liquid by a triboelectric effect. Then randomly distributed ${\beta}$ phase PVDF film could be re-oriented by the electric field resulting from the accumulated electrical charges, and might be resulted in extremely one-directionally aligned ${\beta}$ phase PVDF film without additional electric field for poling. X-ray diffraction patterns were used to investigate crystal structure of the CNT/PVDF composite films. It was confirmed that they revealed extremely large portion of the ${\beta}$ phase PVDF crystalline in the film. Therefore we could obtain the poled CNT/PVDF piezoelectric composite films by the spray coating method without additional poling process. Charge accumulation and resulting electric field generation mechanism by spray coating method were shown in Fig. 1. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the I-V curves didn't show any saturation effect in the CNT concentration range of 0~4 wt%. Therefore we can control the performance of the devices fabricated from the CNT/PVDF composite film by adjusting the current level resulted from the CNT concentration with the uniform capacitance value.

• Journal of Ceramic Processing Research
• /
• 제19권6호
• /
• pp.450-454
• /
• 2018

In recent years, thermal insulation coating technology for automotive engine parts has received significant attention as a means of improving the thermal efficiency of automotive engines. One of the characteristics of thermal insulation coatings is their low thermal conductivity, and, materials such as YSZ (Yttria-stabilized zirconia), which have low thermal conductivity, are used for this purpose. This research presents a study of the changes in the microstructure and thermal conductivity of $8YSZ/SiO_2$ multi compositional thermal insulation coating for different compositions, and particle size distributions of suspension, when it is subjected to suspension plasma spraying. To obtain a porous coating structure, the mixing ratio of 8YSZ and $SiO_2$ particles and the particle sizes of the $SiO_2$ were changed. The microstructure, phase formation behavior, porosity and thermal conductivity of the coatings were analyzed. The porosities were found to be 1.2-32.1%, and the thermal conductivities of the coatings were 0.797-0.369 W/mK. The results of the study showed that the microstructures of the coatings were strongly influenced by the particle size distributions, and that the thermal conductivities of the coatings were greatly impacted by the microstructures of the coatings.

• Korean Chemical Engineering Research
• /
• 제59권1호
• /
• pp.100-105
• /
• 2021

본 연구는 적은 비용으로 분석 장치 없이 질병 진단 및 경과를 모니터링할 수 있는 종이-기반 분석 장치(paper-based analytical device, PAD)를 제작하기 위해 polydimethylsiloxane (PDMS) 블레이드 코팅 방법을 제안하였다. PAD 디자인은 레이저 커팅 기술로 쉽게 몰드에 적용할 수 있으며, 제작된 몰드로 블레이드 코팅을 수행하여 완전한 소수성 장벽 형성에 필요한 조건을 확립하였다. 코팅 조건인 잉크의 두께와 종이와의 접촉시간에 따라 PDMS 소수성 장벽의 구조와 친수성 채널의 크기 변화를 분석하여 안정적으로 소수성 장벽을 형성할 수 있는 조건을 최적화하였다. 최적화된 방법을 바탕으로 PAD를 제작하여 특별한 분석기기 없이 단백질, 당, 메탈이온을 검출하여 바이오센서에 응용가능함을 증명하였다.

• Membrane and Water Treatment
• /
• 제13권4호
• /
• pp.191-199
• /
• 2022

In industrial production, the development of traditional polyamide nanofiltration (NF) membrane was limited due to its poor oxidation resistance, complex preparation process and high cost. In this study, a composite NF membrane with high flux, high separation performance, high oxidation resistance and simple process preparation was prepared by the method of dilute solution dip coating. And the sulfonated polysulfone was used for dip coating. The results indicated that the concentration of glycerin, the pore size of the based membrane, the composition of the coating solution, and the post-treatment process had important effects on the structure and performance of the composite NF membrane. The composite NF membrane prepared without glycerol protecting based membrane had a low flux, when the concentration of glycerin increased from 5% to 15%, the pure water flux of the composite NF membrane increased from 46.4 LMH to 108.2 LMH, and the salt rejection rate did not change much. By optimizing the coating system, the rejection rate of Na₂SO₄ and PEG1000 was higher than 90%, the pure water flux was higher than 40 LMH (60psi), and it can withstand 20,000 ppm.h NaClO solution cleaning. When the post treatment processes was adjusted, the salt rejection rate of NaCl solution (250 ppm) reached 45.5%, and the flux reached 62.2 LMH.

• 센서학회지
• /
• 제31권4호
• /
• pp.255-259
• /
• 2022

In this study, we fabricated ZnS substrates with excellent transmittance in the mid-infrared region (3-5 ㎛) using hot pressing instead of conventional chemical vapor deposition (CVD). Diamond-like carbon (DLC) was coated on either one or both sides of the ZnS substrates to improve their mechanical properties and transmittance efficiency. To reduce the reflectance and further improve transmittance in the mid-infrared region, anti-reflection (AR) coating was designed for DLC/ZnS /AR and AR/ ZnS /AR structures. The coating structure, microstructure, and optical properties of the AR-coated ZnS substrates were subsequently investigated by employing energy dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier-transform infrared (FTIR) spectroscopy. The FTIR spectroscopy results demonstrated that, in the mid-infrared region, the average transmittance of the samples with AR coating on one and both sides increased by approximately 18% and 27%, respectively. Thus, AR coating improved the transmittance of the ZnS substrates.

• 센서학회지
• /
• 제32권3호
• /
• pp.154-158
• /
• 2023

This study aimed to improve the moisture resistance of salt cores by investigating the suitability of a two-dimensional kaolinite colloidal solution and a commercially available SiO₂ ink solution as coating agents. X-ray diffraction analysis (XRD) results showed that the intercalation of urea into kaolinite did not significantly change its layer structure. Scanning electron microscopy (SEM) images revealed that the dip-coating only affected the surface of the salt core, and the texture of the surface is differ depending on the coating solution. The humidity absorption test results showed that both coatings reduced the hygroscopicity of the salt core by more than 50%. However, in the water-solubility test, the kaolinite dissolved with the salt core, whereas the SiO₂-coated salt core left a residue. These results strongly suggest that with the coating of the exfoliated kaolinite solution, salt core will remain stable in humid environments.

• 한국표면공학회지
• /
• 제38권1호
• /
• pp.37-43
• /
• 2005

Nanosized titanium-colloid particles were prepared by sol-gel method. The physical properties, such as thermal stability, crystallite size and crystallinity according to synthesis condition have been investigated by TEM, XRD, SEM, TGA and DTA. In addition, Zinc phosphating has been studied in order to compare the phosphating characterization of prepared nanosized titanium-colloid particles. The major phase of all the prepared titanium-colloid particles was an amorphous structure regardless of synthesis temperature and the structure was composed of phoshate complex and titanium. The micrographs of HR- TEM showed that nanosized titanium-colloid particles possessed a spherical morphology with a narrow size distribution. The crystallite size of the titanium-colloid particles synthesized at 80℃ was 4-5 nm and increased to 8-10 nm with an increase of synthesis temperature (150℃). In addition, the coating weight increased with an increase of temperature of phosphating solution and when the concentration of titanium-colloid was 2.0 g/l, the coating weight was 1.0 g/㎡.

• 한국태양에너지학회 논문집
• /
• 제31권4호
• /
• pp.48-56
• /
• 2011

Black cobalt solar selective coatings were prepared by thermal oxidation of electroplated cobalt metal on copper and nickel substrates. The optical properties and structure of the black cobalt selective coating for solar energy utilizations were characterized by glow discharge spectrometry (GDS), ultraviolet-visible-near infrared (UV-VIS-NIR) spectrometer, atom force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS). The optical properties of optimum black cobalt selective coating prepared on copper substrate were a solar absorptance of 0.82 and a thermal emittance of 0.01. From the GDS depth profile analysis of these coatings, the concentration of cobalt particles near the interface was higher than at the surface, but oxygen concentration at the surface was higher than at the interface. These results suggest that the selective absorption was dominated by this chemical composition variation in the coating. The surface of this film exhibited morphology with root-mean-square(rms) roughness of about 144.3nm. XPS measurements data showed that several phases of Co coexist($Co_3O_4$,CoO) in the film.

• 한국표면공학회지
• /
• 제34권2호
• /
• pp.97-104
• /
• 2001

($Ti_{ 1-x}$$Al_{ x}$)N has been deposited on high speed steel (HSS) substrate using PECVD from the gas mixture of $TiC1_4$, $AlC1_4$, $NH_3$, $H_2$, and Ar. The correlation between the microstructure and the mechanical properties was investigated. ($Ti_{1-x}$$Al_{ x}$)N showed single phase NaCl-structure up to X=0.87, while a mixed phase of NaCl Type (Ti, Al) N and wurtzite structure AlN was observed for 0.87$Ti_{1-x}$ $Al_{x}$ )N became by degrees as increasing X, which made the hardness of the coating higher by Al addition. When the coating was composed of a mixed phase, however, the hardness decreased abruptly due to the effect of soft AlN phase. The wear volume of the coatings could be obtained as the concentration of the coating was varied, and the relation between the wear volume and hardness or the adhesion strength was discussed.

• Corrosion Science and Technology
• /
• 제23권1호
• /
• pp.72-81
• /
• 2024

The Ti-6Al-4V alloy is widely used as an implant material due to its higher fatigue strength and strengthto-weight ratio compared to pure titanium, excellent corrosion resistance, and bone-like properties that promote osseointegration. For rapid osseointegration, the adhesion between the titanium surface and cellular biomolecules is crucial because adhesion, morphology, function, and proliferation are influenced by surface characteristics. Polymeric peptides and similar coating technologies have limited effectiveness, prompting a demand for alternative materials. There is growing interest in 2D nanomaterials, such as MoS₂, for good corrosion resistance and antibacterial, and bioactive properties. However, to coat MoS₂ thin films onto titanium, typically a low-temperature hydrothermal synthesis method is required, resulting in the synthesis of films with a toxic 1T@2H crystalline structure. In this study, through high-temperature annealing, we transformed them into a non-toxic 2H structure. The implant coating technique proposed in this study has good corrosion resistance and biocompatibility, and antibacterial properties.