• Journal of the Korean institute of surface engineering
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• v.52 no.4
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• pp.227-232
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• 2019

Mo-N based coatings have been studied for enhancing mechanical characteristics of thin films. In the case of Mo-X-N coatings, the microstructure and mechanical properties can be affected by the addition of the third element. In this work, Mo-Cu-N coatings were successfully fabricated with varying the Cu content from 4.5 at% to 31 at% by the co-sputtering method. Thus, properties of the coatings were analyzed by EDS, SEM, XRD, AFM, nano indentation and scratch test techniques. From observed results, MoxN bonds were made in a nitrogen atmosphere and Cu elements were present at grain boundaries. In addition, coatings with the Cu content above 14 at% had a Cu3N peak in the XRD results. Thus, it is suggested that the formation of Cu3N phase affected the microstructure and mechanical properties of Mo-Cu-N coatings. Mechanical properties of Mo-Cu-N coatings were found to be relatively better at Cu content of about 12 at%.

• Journal of Powder Materials
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• v.30 no.4
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• pp.310-317
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• 2023

Small-film-type ion sensors are garnering considerable interest in the fields of wearable healthcare and home-based monitoring systems. The performance of these sensors primarily relies on electrode capacitance, often employing nanocomposite materials composed of nano- and sub-micrometer particles. Traditional techniques for enhancing capacitance involve the creation of nanoparticles on film electrodes, which require cost-intensive and complex chemical synthesis processes, followed by additional coating optimization. In this study, we introduce a simple one-step electrochemical method for fabricating gold nanoparticles on a carbon nanotube (Au NP-CNT) electrode surface through cyclic voltammetry deposition. Furthermore, we assess the improvement in capacitance by distinguishing between the electrical double-layer capacitance and diffusion-controlled capacitance, thereby clarifying the principles underpinning the material design. The Au NP-CNT electrode maintains its stability and sensitivity for up to 50 d, signifying its potential for advanced ion sensing. Additionally, integration with a mobile wireless data system highlights the versatility of the sensor for health applications.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.502-507
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• 2016

This study was conducted to develop novel antimicrobial nano-composites, with the aim of fully utilizing antimicrobial properties of multi-walled carbon nanotubes (MWCNTs), nickel (Ni) and zinc oxide (ZnO). Ni coated-MWCNTs (Ni-CNT) were prepared and evaluated for their potential application as an antimicrobial material for inactivating bacteria. Field emission scanning electron microscopy (FE-SEM), and X-ray energy dispersive spectroscopy (EDS) were used to characterize the Ni coating and morphology of Ni-CNT. Staphylococcus aureus (S. aureus) and Escherichia coil (E. coil) were employed as the target bacterium on antimicrobial activities. Comparing with the nitric acid treated MWCNTs and Ni-CNT which have been previously reported to possess antimicrobial activity towards S. aureus and E. coil, Ni-CNT/ZnO exhibited a stronger antimicrobial ability. The nickel coating was confirmed to play an important role in the bactericidal action of Ni-CNTs/ZnO composites. Also, the addition of ZnO to the developed nanocomposite is suggested to improve the antimicrobial property.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.501-501
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• 2011

산업이 고도화, 다원화, 세계화되고 있는 현대사회는 다기능성, 고물성, 극한 내구성을 가지며 환경 친화적이면서 에너지 효율을 극대화시킬 수 있는 다기능 소재의 개발을 요구하고 있다. 이러한 시점에서 다양한 물성을 동시에 발현이 가능한 코팅 소재는 향후 미래에 중요한 원천소재로서 주목되고 있다. 특히, 환경에 의해 쉽게 물성 및 구조의 변화가 쉬운 종래의 코팅소재와는 달리, 다양한 외부환경에서도 미세 구조 및 물성을 안정적으로 유지할 수 있는 신개념의 코팅 소재의 개발이 절실히 요구되고 있다. 이를 위해서는 코팅소재의 다 성분화가 필수적이다. 최근의 코팅 기술은 2가지 이상의 물성, 특히 서로 상반되는 물성을 동시에 구현할 수 있는 소재의 개발을 요구하고 있다. 이러한 물성의 구현을 위하여 더 많은 성분으로 구성되며 더욱 복잡한 조직으로 구성된 코팅층에 대한 개발이 필요하다. 본 연구에서 목표로 하는 신 개념의 원천소재기술은 4 성분계 이상의 원료 물질을 단일 타겟으로 제조하여, 단순한 코팅공정으로서 단일 코팅층 내에 다양한 성분상이 10 nm 미만 크기의 나노 결정립/나노 비정질로 구성된 나노 복합 구조로 형성되도록 하는 기술을 개발하고자 하는 것이다. 이는 복합기능 3 이상의 다기능성 부여는 물론, 그림 1에 명시되어 있는 극한 기능성(광대역 윤활성, 전자 이동 제어에 의한 온도 저항 계수 및 전기 저항 조절, 고온 열적 안정성, 내산화성, 고열전도율, 초저마찰/내구성/초고경도성 등)이 구현되도록 하는 소재 개발과 원하는 물성을 구현할 수 있는 나노 복합 코팅층의 형성 공정으로 구성된다. 다성분계 모물질의 개발이 중요한 이유는 다수의 성분 원소를 합금 상태로 형성시킴으로서, 단일 소스에 의해 다양한 원소를 동시에 스퍼터링 및 증착이 가능하도록 할 수 있다는 장점을 가지기 때문이다. 특히, 타겟의 미세구조를 나노구조화 하는것을 통해, 스퍼터링 yield의 차이가 큰 원소일지라도 균일하게 증착시킬 수 있는 방법을 제시하고자한다. 이러한 연구는 다수의 성분 타겟을 사용함으로서 장비의 복잡성, 코팅의 재현성, 대형화 등의 문제점을 본질적으로 갖고 있는 기존 PVD 공정의 문제점을 해결하기 위한 최적의 대안이라할 수 있다. 본 발표에서는 3가지 이상의 다기능성 구현을 위한 가장 중요한 원천기술이라 할 수 있는 다성분계 타겟 모물질 제조 기술에 대해 소개하고자 한다.

• Clean Technology
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• v.20 no.2
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• pp.141-145
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• 2014

In this study, we studied optical properties on the layer-by-layer (LbL) assemblies consisting of Au nanorods and organic dyes. For this purpose, poly (allylamine hydrochloride), PAH and poly (styrene sulfonate), PSS were selected as ionic polymers and rhodamine B isothiocyanate (RB) was utilized as an organic dye based on its spectral overlap with plasmon band of Au nanorods. In the view point of assembling methods, RB was covalently attached to PAH, then, LbL structure of Au [PSS/PAH]2/PSS/PAH-RB was prepared by sequential coating of PAH, PSS, PAH-RB on Au nanorods. Since the prepared LbL assembly exhibits both plasmonic and fluorescent properties, we studied the mutual nanorod-dye properties by dissolving Au nanorods.

• Journal of the Korean institute of surface engineering
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• v.38 no.3
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• pp.106-111
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• 2005

Ternary Ti-B-C coatings were synthesized on WC-Co and Si wafers substrates by a PECVD technique using a gaseous mixture of $TiCl_4,\;BCl_3,\;CH_4,\;Ar,\;and\; H_2$. The effects of deposition variables such as substrate temperature, gas ratio, $R_x=[BCl_3/(CH_4+BCl_3)]$ on the microstructure and mechanical properties of Ti-B-C coatings were investigated. From our instrumental analyses, the synthesized Ti-B-C coatings was confirmed to be composites consisting of nanocrystallites TiC, quasi-amorphous TiB2, and amorphous carbon at low boron content, on the contrary, nanocrystallites $TiB_2$, quasi-amorphous TiC, and amorphous carbon at relatively high boron content. The microhardness of the Ti-B-C coatings increased from $\~23 GPa$ of TiC to $\~38 GPa$ of $Ti_{0.33}B_{0.55}C_{0.11}$ coatings with increasing the boron content. The $Ti_{0.33}B_{0.55}C_{0.11}$ coatings showed lower average friction coefficient of 0.45, in addition, it showed relatively better wear behavior compared to other binary coatings of $TiB_2$ and TiC. The microstruture and microhardness value of Ti-B-C coatings were largely depend on the deposition temperature.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.293-296
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• 2012

Nanocomposites were fabricated as titanium dioxide ($TiO_2$) doped with nanometals (Au, Ag) by sonochemical reduction method and sol-gel method in order to investigate their antimicrobial activities. Then, the antimicrobial activity of the resulting samples was compared by the measurement of colony numbers survived on the agar plate incubated for 24 h after the loading E. coli on the solid-state media with the nanocomposites. The initial antimicrobial activity of the metal (Au, Ag)-doped $TiO_2$ was higher than that of the pristine $TiO_2$. Afterwards the nanocomposite samples were kept at $4^{\circ}C$ for a long time and the aged samples exhibited the different antimicrobial activity. With the elapse of aging times, Ag-doped $TiO_2$ with $TiO_2$ coating ($Ag-TiO_2$@$TiO_x$) exhibited the higher antimicrobial activity than those of $Ag-TiO_2$and $Au-TiO_2$. The $TiO_2$ coating on the $Ag-TiO_2$ may prevent the oxidation of Ag nanometals and stabilize colloidal nanocomposites.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.410-418
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• 2016

In this study, we prepared electrically conducting composites using epoxy resin of diglycidyl ether of bisphenol A (DGEBA) as a matrix, triethylenetetramine (TETA) as a hardener and nickel powder or multi-walled carbon nanotubes (MWCNTs) grafted with $-NH_2$ groups (MWCNT-$NH_2$) as electrically conducting fillers. Electrical conductivity of composite films were measured by coating on the slide glass with a doctor blade. We measured modification reactions of MWCNT and reaction of MWCNT-$NH_2$ with DGEBA epoxy resin by fourier transform infrared spectrometer (FTIR), thermogravimetric analyzer (TGA) and elemental analyzer (EA). Morphology of composites was investigated by scanning electron microscope (SEM) and sheet resistances of composites were measured by 4-point probe. We found $(9.87{\pm}1.09){\times}10^4{\Omega}/sq$ of sheet resistance for epoxy composite containing both 40 wt% nickel powder and 0.5 wt% of MWCNT-$NH_2$ as fillers, equivalent to epoxy composite containing 53.3 wt% nickel powder only as a filler.