• Journal of Surface Science and Engineering
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• v.42 no.2
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• pp.86-94
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• 2009

Various types of multilayer coatings including Al/$Al_2O_3$ structure have been prepared on Nd-Fe-B permanent magnet to modify the morphology of the coating and to enhance the corrosion resistance of the magnet. Magnetron sputtering has been employed to make the multilayer coatings. $Al_2O_3$sputtering conditions were optimized in reactive sputtering by varying the deposition parameters. The formation of $Al_2O_3$ film was confirmed from the binding energy shift measured by electron spectroscopy for chemical analysis. 3 types of coating structures were designed and prepared by magnetron sputtering. The coating structures consist of (1) single Al coating, (2) modified coatings having oxide or plasma treated layer in the middle of coating structure, and (3) Al/$Al_2O_3$ multilayer coatings. Surface and cross-sectional morphologies showed that Al/$Al_2O_3$ multilayer grew as a layered structure, and that very compact Zone 3 like structure were formed. X-ray diffraction peak showed that the crystal orientations of multilayer coatings were similar to that of the bulk powder pattern. Hardness increased drastically when the Al thickness was around 1im in the Al/$Al_2O_3$ multilayer. From the salt spray test and pressure cooker test, it has been shown that the multilayer coatings showed good corrosion resistance compared to Al single or modified layer coatings.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.658-659
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• 2006

Magnetron sputtered TiN, (Ti, Al)N and TiN/(Ti, Al)N multilayer coatings grown on cemented carbide substrates have been characterized by using electron probe microanalysis (EPMA), X-ray diffraction (XRD), scanning electron spectroscopy (SEM), nanoindentation, scratcher and cutting tests. Results show that TiN coating is bell mouth columnar structures, (Ti, Al)N coating is straight columnar structures and the modulation structure has been formed in the TiN/(Ti, Al)N multilayer coating. TiN/(Ti, Al)N multilayer coating exhibited higher hardness, better adhesion with substrate and excellent cutting performance compared with TiN and (Ti, Al)N coating.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.783-791
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• 2000

Increasing demands in productivity are propelling the development of new manufacturing methods like hard machining, high speed cutting (HSC) or machining of difficult to machine materials. In these processes the toois are subjected to very severe mechanical, tribological and thermal loads. They fail prematurely by abrasion, cratering, edge breakage and cold welding. The performance of such tools will be enhanced by better and more wear resistant coatings. The development of these new coatings shows a clear trend towards complex multi-component and multi-layer configurations. TiAIN multilayer coating belongs to these coatings for the new cutting tool generation. This paper tries to explain the benefits of the new coatings. TiAIN multilayer coating offers the following advantages: reduction of manufacturing costs. boost productivity, and lower coolant procurement, conditioning and disposal costs.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.2
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• pp.40-46
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• 2010

The purpose of this study is to show the friction and wear characteristics on the vapor deposited coating layers on the SCM415 steel. In this research, frictional wear characteristic of coating materials such as TiAlN+WC/C Multilayer Coating was investigated under room temperature, normal air pressure and nothing lubricating condition. Therefore this study carried out research on the friction coefficient, micro hardness(Hv), roughness, EPMA on the vapor deposited coating layers on the SCM415 steel. As the wear experimental result, the coefficient of friction decreased according to experimental load increases.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.78-87
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• 2001

The friction and wear behaviors of WC/C multilayer coating were investigated by using a pin on disk type tester. The experiment was conducted by using silicon nitride (S $i_{3}$ $N_{4}$) as a pin material and WC/C multilayer coating on bearing steel (STB2) as a disk material, under various environments that are atmospheric conditions of high vacuum( 1,3$\times$10$^{-4}$ Pa), medium vacuum( 1.3$\times$10$^{-l}$Pa). ambient air( 10$^{5}$ pa)(3 types) and relative humidity(2~98%) conditions. The results showed that WC/C coating fracture was suddenly increased with increasing degree of vacuum, because of high adhesion. So, WC/C coating could not be displayed their ability as solid lubricant. WC/C coating could be displayed better abilitv as solid lubricant with increasing relative humidity. because of oxide film, size and shape of wear debris. The friction coefficient and specific wear rate became better about RH 50%.%.

• Journal of Surface Science and Engineering
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• v.53 no.6
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• pp.360-368
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• 2020

Wear resistance of cutting tools is one of the most important requirements in terms of the durability of cutting tool itself as well as the machining accuracy of the workpiece. Generally, tungsten carbide ball end mills have been processed with hard coatings for high durability and wear resistance such as diamond coating and tetrahedral amorphous carbon(ta-C) coating. In this study, we developed multilayer ta-C coatings whose wear resistance is comparable to that of diamond coating. First, we prepared single layer ta-C coatings according to the substrate bias voltage and Ar gas flow, and the surface microstructure, raman characteristics, hardness and wear characteristics were evaluated. Then, considering the hardness and wear resistance of the single layer ta-C, we fabricated multilayer coatings consisting of hard and soft layers. As a result, it was confirmed that the wear resistance of the multilayer ta-C coating with hardness of 51 GPa, and elastic recovery rate of 85% improved to 97% compared to that of the diamond coated ball end mill.

• Journal of Surface Science and Engineering
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• v.57 no.1
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• pp.14-21
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• 2024

For this study, CrAlN multilayer coatings were deposited on SKD61 substrates using a multi-arc ion plating technique. The structural characteristics of the CrAlN multilayer coatings were evaluated using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Additionally, the adhesion of the coatings was assessed through scratch testing, and the mechanical strength was evaluated using nanoindentation and tribometric tests for frictional properties. The results show that the CrAlN multilayer coatings possess a uniform and dense structure with excellent mechanical strength. Hardness measurements indicated that the CrAlN coatings have high hardness values, and both the coating adhesion and wear resistance were found to be improved compared to CrN. The addition of aluminum is anticipated to contribute to enhanced durability and wear resistance.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.47-47
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• 2008

Cr and AlSi (Si=20 and 66 at.%) target들을 이용하여 Closed-field unbalanced magnetron sputtering (CFUBMS)으로 증착된 주기($\Lambda$)가 2.3 nm에서 8.0nm인 CrN/AlSiN multilayer coatings의 crystal structure, 화학적 조성, 및 기계적 특성을 glow discharge optical emission spectroscopy (GDOES), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and nano-indenter 등의 분석장비를 이용하여 분석하였다. 고온안정성을 시험하기 위하여 $800^{\circ}C$와 $1000^{\circ}C$ 공기중 에서 30분 열처리하였다. CrN/AlSiN multilayer coatings의 고온안정성은 Si조성이 증가함에 따라 향상되었다. Si이 18.2 at.%함유된 coating이 가장 우수한 고온안정성을 갖고 있다.

• Tribology and Lubricants
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• v.37 no.6
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• pp.240-245
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• 2021

Ceramic coatings with high hardness and excellent chemical stability have been successfully applied to various machine elements, tools, and implants. However, in the case of monolayer coating on soft substrates, a high-stress concentration at the interface between the coating and the substrate causes delamination of the coating layer. Recently, to overcome this problem, multilayer coatings with a metal layer with a low modulus of elasticity added between the ceramic and the substrate have been widely applied. This study presents the third part of a recent study and focuses on the effect of the number of coating layers on the Brinell hardness of multilayered coating with TiN/Ti, following the two previous studies on a new Brinell hardness test method for a coated surface and on the influence of substrate and coating thickness. Indentation analyses are performed using finite element analysis software, von Mises stress and equivalent plastic strain distributions, load-displacement curves, and residual indentation shapes are presented. The number of TiN/Ti layers considerably affect the stress distributions and indentation shapes. Moreover, the greater the number of TiN/Ti layers, the higher is the Brinell hardness. The stress and plastic strain distributions confirm that the multilayer coatings improve the wear resistance. The results are expected to be used to design and evaluate various coating systems, and additional study is required.

• Journal of Microbiology and Biotechnology
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• v.33 no.10
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• pp.1309-1316
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• 2023

To exert their beneficial effects, it is essential for the commensal bacteria of probiotic supplements to be sufficiently protected as they pass through the low pH environment of the stomach, and effectively colonize the intestinal epithelium downstream. Here, we investigated the effect of a multilayer coating containing red ginseng dietary fiber, on the acid tolerance, and the adhesion and proliferation capacities of three Lactobacillus strains (Limosilactobacillus reuteri KGC1901, Lacticaseibacillus casei KGC1201, Limosilactobacillus fermentum KGC1601) isolated from Panax ginseng, using HT-29 cells, mucin-coated plates, and human pluripotent stem cell-derived intestinal epithelial cells as in vitro models of human gut physiology. We observed that the multilayer-coated strains displayed improved survival rates after passage through gastric juice, as well as high adhesion and proliferation capacities within the various gut epithelial systems tested, compared to their uncoated counterparts. Our findings demonstrated that the multilayer coat effectively protected commensal microbiota and led to improved adhesion and colonization of intestinal epithelial cells, and consequently to higher probiotic efficacy.