• Journal of the Korean Ceramic Society
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• v.36 no.3
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• pp.244-254
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• 1999

폐윤활유 재생용 TiO2 한외여과막은 정밀영과용 지르코니아 복합막(즉, 복층담채) 및 알루미나 단층 담체(기공크기 0.1$mu extrm{m}$)상에 졸-겔 코팅법에 의하여 TiO2 분리막 층을 코팅하여 제조 하였다. TiO2 졸의 특성 분석을 통하여 봉입침지(sealed dip-coating) 및 가압 코팅(pressurized coating)법으로 결함이 없는 TiO2 복합막을 제조할 수 있는 코팅조건을 최적화 하였다. 합성 TiO2 한외여과막의 분리막층 두께는 1$\mu\textrm{m}$이하의 범위에서 조절되었으며,기공값을 보여주었으며 75$0^{\circ}C$까지 열처리하여도 80%정도의 용질배제율(기공크기 22.5nm)을 유지하는 점으로 봐서 고온 공정을 요하는 폐윤활유 재생막으로서 충분한 열적 안정성을 갖고 있었다.

• Journal of the Korean Society for Heat Treatment
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• v.15 no.3
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• pp.118-126
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• 2002

TiCN thin films were deposited on tool steels at $510^{\circ}C$ by PECVD from a $TiCl_4+N_2+CH_4+H_2+Ar$ gaseous mixture. The microstructures and preferred orientation were investigated. The micro-scratch tests were performed using a system equipped with an acoustic emission sensor. Critical loads were determined to evaluate the adhesion of TiCN to substrate. The influences of the microstructures of substrates, double layered coatings, and coatings after nitriding(duplex coating) were investigated. The experimental results showed that the microstructures of substrates and double layered coating did not affect the critical loads considerably. By the duplex coating, critical loads were not always increased. In some cases, duplex coatings decreased critical loads significantly despite of absence of black layer. In this study, we tried to relate the results of scratch test to the residual stress analysis. Nitriding before the coating reduces the tensile residual stress in the film, which gives rise to low critical load in scratch test.

• Corrosion Science and Technology
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• v.22 no.4
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• pp.232-241
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• 2023

The mechanical properties of the hydrogen valve responsible for supplying and blocking hydrogen gas in a hydrogen fuel cell electric vehicle (FCEV) were researched. Mechanical properties by hydrogen embrittlement were investigated by coating chromium nitride (CrN) and titanium nitride (TiN) on aluminum alloy by arc ion plating method. The coating layer was deposited to a thickness of about 2 ㎛, and a slow strain rate test (SSRT) was conducted after hydrogen embrittlement to determine the hydrogen embrittlement resistance of the CrN and TiN coating layers. The CrN-coated specimen presented little decrease in mechanical properties until 12 hours of hydrogen charging due to its excellent resistance to hydrogen permeation. However, both the CrN and TiN-coated specimens exhibited deterioration in mechanical properties due to the peeling of the coating layer after 24 hours of hydrogen charging. The specimens coated at 350 ℃ presented a significant decrease in ultimate tensile strength due to abnormal grain growth.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.117-123
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• 2011

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 Ti-series, Cr-series & WC/C and TiAlN+WC/C multilayer coating was investigated under room temperature, normal air pressure and no lubricating condition. Therefore, this study carried out research on the friction coefficient, micro hardness(Hv), surface roughness and wear quantity on the vapor deposited coating layers on the SCM415 steel. As the wear experimental result, the excellence of TiAlN+WC/C multilayer coating has been proven by high micro-hardness, low friction coefficient and wear quantity.

• Korean Journal of Materials Research
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• v.12 no.10
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• pp.809-813
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• 2002

Commercial nano crystalline $TiO_2$ powders were used to characterize photocatalyst, using thermal spray coating technique. The microstructure of coating layers were examined by SEM, FE-SEM and TEM. Also the cross sectional areas of TiO$_2$ coating layers were observed by SEM. The phases were analyzed by X-ray diffraction methed. Surface roughness and hardness were measured. It was found that phase transformation from anatase to rutile occurred, and the melted splats are all rutile, and unmeted nano particles were anatase. These unmelted anatase phase may enhance te play a role of photocatalyst.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.848-854
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• 2012

SCM420 steel cutting gear to improve the durability is quenched. When quenching, increases surface hardness, a change of the physical properties and machinability or fall. This study, using a solid carbide hobs skiving hobbing gear cutting finishing. And cutting tool solid carbide TiAlN coating hove when TiAlN coating on the surface of multi-con polishing hob conducted aero lap nano polishing for each cutting. Experimental results conducted aero lap nano coating on the surface polishing tool machinability was excellent. And aero lap nano polishing tool results were reduced 2.5 times the tool wear compared to TiAlN coated tools. Excellent results were 1.42 times longer tool life.

• Journal of the Korean institute of surface engineering
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• v.35 no.6
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• pp.415-421
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• 2002

Ti-Si-N coating layers were codeposited on silicon wafer substrates by a DC reactive magnetron sputtering technique using separate titanium and silicon targets in $N_2$/Ar gas mixtures. The oxidation behavior of Ti-Si-N coating layers containing 4.0 at.%, 10.0 at.%, and 27.3 at.% Si was investigated at temperatures ranging from 600 to $960^{\circ}C$. The coating layers containing 4.0 at.% Si became fast oxidized from $600^{\circ}C$ while the coating layers containing 10.0 at.% Si had oxidation resistance up to $800^{\circ}C$. It was concluded that an increase in Si content to a level of 10.0 at.% led to the formation of finer TiN grains and a uniformly distributed amorphous Si3N4 phase along grain boundaries, which acted as efficient diffusion barriers against oxidation. However, the coating layers containing 27.3 at.% Si showed relatively low oxidation resistance compared with those containing 10.0 at.% Si. This phenomenon would be explained by the existence of free Si which was not nitrified in the coating layers containing 27.3 at.% Si.

• 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 the Korean Ceramic Society
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• v.51 no.5
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• pp.375-379
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• 2014

Nanocrystalline TiAlN coatings were prepared by reactively sputtering TiAl metal target with $N_2$ gas. This was done using a magnetron sputtering system operated in DC and ICP (inductively coupled plasma) conditions at various power levels. The effect of ICP power (from 0 to 300 W) on the coating microstructure, corrosion and mechanical properties were systematically investigated using FE-SEM, AFM and nanoindentation. The results show that ICP power has a significant influence on coating microstructure and mechanical properties of TiAlN coatings. With increasing ICP power, the coating microstructure evolved from the columnar structure typical of DC sputtering processes to a highly dense one. Average grain size of TiAlN coatings decreased from 15.6 to 5.9 nm with increasing ICP power. The maximum nano-hardness (67.9 GPa) was obtained for the coatings deposited at 300 W of ICP power. The smoothest surface morphology (Ra roughness 5.1 nm) was obtained for the TiAlN coating sputtered at 300 W ICP power.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.89-94
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• 2003

Hard coatings are known to improve the performance of cutting tools in aggressive machining applications, such as high speed machining. New superhard Ti-Al-Si-W films, characterized by a nanocomposite nano-sized (Ti,Al,Si)N crystallites embedded in amorphous $Si_3 N_4$ matrix, could be successfully synthesized on WC-Co substrates by a hybrid coating system of arc ion plating(AIP) and sputtering method. The hardness of Ti-Al-Si-N film increased with incorporation of Si, and had the maximum value ~50 GPa at the Si content of 9 at.%, respectively. And the X-ray diffraction patterns of Ti-Al-Si-N films with various Si content is investigated. In this study, Ti-Al-Si-N coatings were applied to end-mill tools made of WC-Co material by a hybrid coating system. Cutting tests fir the high-hardened material (STD11,$H_R$)C62 and their performances in high speed cutting conditions were studied. Also, the tool wear and tool lift of Ti-Al-Si-N with various si(6, 9, 19) contents were measured.