• Korean Chemical Engineering Research
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• 제52권3호
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• pp.388-394
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• 2014

출발물질인 TTIP로부터 이산화티탄 졸을 합성하여 무기물로 사용하고 유기물로서 실란커플링제인 methacryloxypropyl trimethoxysilane (MPTMS), aminopropyl triethoxysilane (APS), glycidoxypropyl trimethoxysilane (GPTMS), vinyltriethoxysilane (VTES)을 2종 혹은 3종씩 복합 사용하여 유-무기 하이브리드 코팅 용액을 제조하였다. 그 후 코팅 용액을 기재인 PC시트 위에 스핀 코팅시키고, 열경화 시켜 하드코팅 막을 제조하였다. 2종 실란커플링제를 혼합하여 제조된 코팅 막들은 기재와의 부착력과 연필경도가 우수하지 못했으나, 3종 실란커플링제를 혼합하여 제조한 코팅 막은 2H~4H의 향상된 연필경도와 5B의 우수한 부착력을 나타내었다. 이산화티탄 졸의 첨가량이 20 g인 코팅 막의 굴절률은 550 nm에서 1.56을 나타내었으나 이산화티탄 졸의 첨가량을 20 g에서 30 g으로 증가시킨 경우, 코팅 막의 굴절률이 1.63으로 향상되었다.

• Tribology and Lubricants
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• 제37권2호
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• pp.54-61
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• 2021

The effect of the sand blasting before TiAlN coating in the manufacture of WC hard metal alloy tips have been studied. For four different tips, according to the status of processing of the sand blasting and the coating, residual stress measurement by X-ray diffraction and several tests for mechanical properties have been conducted. The results suggest that there was no difference in static mechanical properties, such as hardness, surface roughness and elastic modulus, between two coatings. Furthermore, compressive residual stress was generated equally on their surfaces. Additionally, the compressive residual stress in substrate WC was found to increase greatly when subjected to sand blasting treatment. However, the compressive residual stress decrease after coating regardless of sand blasting treatment. Nevertheless, it is confirmed that the compressive residual stress generated in the coating after sand blasting is less than that in the non-sandblasting coating. This was attributed to the plastic deformation occurring in the WC substrate during coating after sand blasting. In contrast to the scratch test results, sand blasting was assumed to have a negative effect on the adhesion between the coating and substrate. This is because there is a high possibility of microcracks due to plastic deformation in the WC substrate under the coating after sand blasting.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.162-168
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• 2018

유기 및 무기 폴리실라잔을 우레탄 아크릴레이트와 혼합시킴에 따라 UV 경화형 하드 코팅 용액을 제조하였다. 이용액을 polymethylmethacrylate (PMMA) 시트에 흐름 코팅한 후 UV 경화시킴에 의해 UV 경화형 하드 코팅 도막을 제조하였다. 이 과정 중 폴리실라잔의 종류 및 첨가량을 변화시켜 코팅 도막의 물성에 미치는 영향을 살펴보았다. 그 결과 유기 폴리실라잔의 경우 $95^{\circ}$의 수접촉각을 보여 높은 소수성을 나타내었으며, 7H의 연필경도와 92%의 가시광선 투과율을 보였다. 반면에 무기 폴리실라잔을 코팅한 도막은 8H의 높은 연필경도와 기재와의 우수한 접착력 및 $82^{\circ}$의 수접촉각을 나타내었다.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.1928-1937
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• 2003

Effect of elastic modulus mismatch on the contact crack initiation is investigated to find major parameters in designing desirable surface-coated system. Silicon nitride coated soft materials with various elastic modulus mismatch, E$\_$c//E$\_$s/＝1.06∼356 are prepared for the analysis. Hertzian contact test is conducted for producing contact cracks and the acoustic emission detecting technique for measuring the critical load of crack initiation. The implication is that coating thickness and material strength are controllable parameters to prevent the initiation of contact cracks resulted from the elastic modulus mismatch in the hard ceramic coating layer on the soft materials.

• 대한기계학회논문집A
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• 제30권10호
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• pp.1179-1186
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• 2006

This paper was designed to assess the adhesive properties of hard coatings on non-nitrided and nitrided various tool steels. Estimations of adhesion were done to scratch test which is mainly used in hard coating. The critical load$(L_c)$ between coating and substrate is defined through analysis of frictional load vs. normal load curve, signals of acoustic emission and optical observations. Coatings employed in this study are TiN, CrN and TiAlN, tools as substrates are STD11, STD61 and SKH51. It was classified to substrates with/without intermediate nitrided layer and hard coatings on substrate were deposited by arc PVD. Results showed that harder substrates and coatings give higher values of critical loads.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.186-189
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• 2005

This paper was designed to assess the adhesive properties of hard coatings on non-nitrided and nitrided various tool steels. Estimations of adhesion were done to scratch test which is mainly used in hard coating. The critical load(Lc) between coating and substrate is defined through analysis of frictional load vs. normal load curve, signals of acoustic emission and optical observations. Coatings employed in this study are TiN, CrN and TiAlN, tools as substrates are STD11, STD61 and SKH51. It was classified to substrates with/without nitrided layer and hard coatings on substrate were deposited by arc PVD. Results showed that harder substrates and coatings give higher values of critical loads.

• The Korean Journal of Ceramics
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• 제4권4호
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• pp.356-362
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• 1998

Hertzian crack suppression phenomena and relatively high damage tolerance were investigated in hard/soft silicon nitride ($Si_3N_4$) bilayers. Coarse $\alpha}-Si_3N_4$ powder was wsed for the hard coating layer and fine $\alpha}-Si_3N_4$ powder was used for the soft substrate layer. The two layers were designed with a strong interface. Hertzian indentation was used to investigate contact fracture and damage tolerance property. Hertzian crack suppression has occurred with increasing applied load and decreasing coating thickness. The crack suppression contributed strength improvement, especially in the bilayers with thinner coatings. Ultimately, the combination of hard coating with soft but tough underlayer improved the damage tolerance of brittle $Si_3N_4$ ceramics.

• Bulletin of the Korean Chemical Society
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• 제21권8호
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• pp.817-822
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• 2000

Crack-free hard coating siIica films were prepared by sol-gel processfrom twokinds of silicon alkoxide (tetra-ethoxysilane and methyltrimethoxysilane) and two kinds of alcohol (methanol and isopropyl alcohol) with an acid catalyst,acetic acid. A silicate framework of the precursor solution was investigated by infrared spectros-copy (IR) in the process of hydrolysis and condensation. Theextent of the condensation in the intermediates was elucidated by gel permeation chromatography (GPC) and 29Si-NMR spectroscopy. The hard coating films werecharacterized by IR,scanning electron microscope (SEM), thermo gravimetric analyzer (TGA) and dif-ferential scanning calroimeter (DSC). The synthetic condition for the crack-free and transparent silica film for-mation was optimized interms of starting materials for the precursor solution as well as preparation method of the silica film.

• 접착 및 계면
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• 제8권2호
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• pp.1-8
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• 2007

자동차의 유리를 폴리카보네이트로 대체하기 위하여 폴리카보네이트 판 위에 하드 코팅을 시도하였다. 본 연구에서는 (3-glycidoxypropyl)trimethoxysilane (GPTMS), colloidal silica (CS), (3-aminopropyl) triethoxysilane (APS)으로부터 졸-겔 과정을 이용하여 코팅을 형성하였는데, 이 때 가장 우수한 물성을 갖는 조건들을 찾아보았다. GPTMS와 CS를 에탄올 용매 안에서 가수분해 시킨 후에, APS를 첨가하여 코팅 액을 제조하고 이 코팅 액을 가지고 폴리카보네이트 판 위에 코팅을 실시하였다. 제조된 코팅 액으로부터 경도 2H의 투명하고 고른 면을 갖는 코팅 막을 형성할 수 있었으며, 형성된 코팅 막은 매우 우수한 내마모성과 접착력을 나타내었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.105-105
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• 2016

Recently, high power impulse magnetron sputtering (HIPIMS) has attracted considerable attentions due to its high potential for industrial applications. By pulsing the sputtering target with high power density and short duration pulses, a high plasma density and high ionization of the sputtered species can be obtained. HIPIMS has exhibited several merits such as increased coating density, good adhesion, microparticle-free and smooth surface, which make the HIPIMS technique desirable for synthesizing hard coatings. However, hard coatings present intrinsic defects (columnar structures, pinholes, pores, discontinuities) which can affect the corrosion behavior, especially when substrates are active alloys like steel or in a wear-corrosion process. Atomic layer deposition (ALD), a CVD derived method with a broad spectrum of applications, has shown great potential for corrosion protection of high-precision metallic parts or systems. In ALD deposition, the growth proceeds through cyclic repetition of self-limiting surface reactions, which leads to the thin films possess high quality, low defect density, uniformity, low-temperature processing and exquisite thickness control. These merits make ALD an ideal candidate for the fabrication of excellent oxide barrier layer which can block the pinhole and other defects left in the coating structure to improve the corrosion protection of hard coatings. In this work, CrN/Al2O3/CrN multilayered coatings were synthesized by a hybrid process of HIPIMS and ALD techniques, aiming to improve the CrN hard coating properties. The influence of the Al2O3 interlayer addition, the thickness and intercalation position of the Al2O3 layer in the coatings on the microstructure, surface roughness, mechanical properties and corrosion behaviors were investigated. The results indicated that the dense Al2O3 interlayer addition by ALD lead to a significant decrease of the average grain size and surface roughness and greatly improved the mechanical properties and corrosion resistance of the CrN coatings. The thickness increase of the Al2O3 layer and intercalation position change to near the coating surface resulted in improved mechanical properties and corrosion resistance. The mechanism can be explained by that the dense Al2O3 interlayer acted as an excellent barrier for dislocation motion and diffusion of the corrosive substance.