• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.3-8
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• 1996

To enhance the cutting performance of the tool, single or multilayer coating is applied on the substrate of the tool. Coating material reduces cutting force and heat generation in tool-chip contact zone and enhances resistance against abrasive wear. This paper presents that the effect of different coatings on abrasive wear resistance varies with work material and the flank wear rate is different with depth of cut. Crater wear rate is also found to decrease with higher thermal diffusivity of coating material. It is verified that the estimated thermal diffusivity of multilayer coating has consistent effect on the crater wear.

• 한국세라믹학회지
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• 제33권2호
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• pp.155-162
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• 1996

A Taguchi methodology study of the plasma spraying thermal barrier coating (TBC) layer is presented. The experiment parameters were designed by a L8-style orthogonal arrays approach. A Taguchi analysis was conduc-ted through the results of the coating properties which were affected by plasma spraying parameters. Zirconia (partially stbilized with ytrria: PSZ) was sprayed on TiAl intermetallic compound substrates, The coating layer was characterized by thickness microstructure and porosity using SEM and Image analyzer. The coating quali-ties are discussed with respect to thermal barrier effect thermal cycling test6 and adhesion strength test. An optimum condition of plasma spraying process which are derived from the Taguchi analysis could be found for high quality TBC.

• 대한기계학회논문집A
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• 제22권1호
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• pp.73-79
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• 1998

The development of a new material which should be continuously usable under severe environment of very high temperature has been urgently requested. The conventional thermal barrier coating(TBC) is a two layer coating, but a composition and a microstructure of functionally graded material(FGM) are varied continuously from place to place in ways designed to provide it with the maximum function of mitigating the induced thermal stress. The purpose of this study is to evaluate the heat-resistant characteristics by thermal shock of laser and furnace heating. The fracture behaviors of non-FGM(NFGM) and FGM were investigated based on acoustic emission(AE) technique during thermal shock test. Therefore, it can be concluded that FGM gives higher thermal resistance compared to NFGM by AE signal and fracture surface analysis.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.7-13
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• 1999

An experimental study was performed to discover the effect of silver coating on the frictional behavior of SM45C steel at sliding surfaces. Pure silver was coated the SM45C disk surfaces by a thermal evaporation method. Experiments using a pin-on-disk test-rig was performed under dry air and various humidity conditions. Friction coefficients increased to a high and unstable value after failure of coating, and friction coefficients increased with increasing the thickness of silver coated layer. But optimum coating thickness was not observed.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.27-34
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• 2001

A new functionally gradient metal coating method using an atomic mixing technique was developed. In this work the effect of silver atomic mixing on the tribological characteristics of silver$.$ films. has been investigated experimentally. Atomic mixing was implemented by using the, bombardment .of accelerated Ar ions during the thermal evaporation coating process of silver films. Experiments were performed in dry conditions using a ball-on-disk test rig at a load range of 19.6 mN - 17.64 N and a sliding velocity of 20 mm/sec. Results showed that the life of functionally gradient silver coating was enhanced about 100 times more than that of thermally evaporated silver coating and 2 times more than that of IBAD silver coating. The functionally gradient. film also showed low friction and wear compared to those of the evaporated silver and

• 한국세라믹학회지
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• 제37권3호
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• pp.288-293
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• 2000

Effects of contact damage and residual stress for two kinds of dental restorative layered ceramics, porcelain/alumina and porcelain/zirconia bilayers, were observed with Hertzian and Vickers indentation methods. Indentation stress-strain behavior of each material, strength degradation of the coating material, and crack propagation behavior in the coating layer after Vickers indentation were examined by an optical microscope. As a result, porcelain as coating materials showed the classical brittleness. It was inferred that damage and strength in two bilayer system were dependent on thermal expansion mismatch between the coating material and the substrate, which affected the strength degradation. Residual stress resulting from thermal expansion mismtch was formed in the coating layer, and specially in the case of porcelain/zirconia, residual stress was eliminated as coating thickness decreased.

• 한국산학기술학회논문지
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• 제14권12호
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• pp.6098-6105
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• 2013

본 연구에서는 해수용 열교환기 적용을 위한 열분사코팅의 종류에 따른 부식특성 및 열전도 성능을 조사하기 위해 실험이 수행되었다. 코팅은 아연과 알루미늄을 열분사코팅한 뒤 실리콘 및 에폭시 수지를 추가 도포한 시편을 선정하였다. 코팅의 부식특성 변화를 관찰하기 위하여 사이클릭 선도변화 측정 및 SEM촬영을 이용하였다. 시편의 열전도 성능을 측정하기 위해서 레이저 확산법을 이용하여 열전도도를 비교하였으며 추가도포를 실리콘으로 한 경우 3 ~ 4% 에폭시로 한 경우 70 ~ 75%의 열전도도 하락이 발생하였다.

• 한국표면공학회지
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• 제32권2호
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• pp.144-156
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• 1999

Thermal Barrier Coating with Functional Gradient Materials (FGM-TBC) can play an important role to protect the parts from harmful environments in high temperatures such as oxidation, corrosion, and wear and to improve the efficiency of aircraft engine by lowering the surface temperature on turbine blade. FGM-TBC can increase the life spans of product and improve the operating properties. Therfore, in this study the evaluations of mechanical and thermal properties of FGM-TBC such as fatigue, oxidation and wear-resistance at high temperatures have been conducted. The samples of both the TBC with 2, 3, 5 layers (YSZ/NiCrAlY) to be produced by Air Plasma Spray method (APS) and the bulk TBC with 6 layers to be produced by Plasma Assisted Sintering method (PAS) were used. Furthermore, residual stress, bond strength, and thermal conductivity were evaluated. The average thickness of the APS was 500$\mu\textrm{m}$ to 600$\mu\textrm{m}$ and the average thickness of the PAS was 3mm. The hardness number of the top layer of APS was 750 Hv to 810Hv and that of PAS was 950 Hv to 1440Hv. The $ZrO_2$ coating layer of APS was composed of tetragonal structure after spraying as the result of XRD analysis. As shown in the results of the high temperature wear test, the 3 layer coating of APS had the best wear resistance at $800^{\circ}C$ and the 5 layer coating of APS had the best wear resistance at $600^{\circ}C$. But, these coatings had the tendency of the low-temperature softening at $300^{\circ}C$. The main mechanism of wear was the adhesive wear and the friction coefficient of coatings was increased as increasing the test temperatures. A s results of thermal conductivity test, the ${\Delta}T$ of the APS coating was increased as number of layer and the range of thermal conductivity of the PAS was $800^{\circ}C$ to $1000^{\circ}C$.

• 한국산학기술학회논문지
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• 제21권8호
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• pp.248-255
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• 2020

경사화 두께를 갖는 열차폐 코팅의 열적 내구성과 열적 안정성에 대한 코팅층 두께의 영향을 화염 열피로 시험과 열충격 시험을 통해서 조사하였다. Bond 층과 top 층은 각각 Ni-Cr계 상용 MCrAlY 분말과 상용 이트리아 안정화 지르코니아 (YSZ) 분말을 사용하여 니켈기지의 초내열합금 모재 (GTD-111)에 대기 플라즈마 용사법 (APS)으로 코팅층을 형성하였다. 1100 ℃의 화염으로 1429회 열피로 시험 후 bond 층이 일부 산화되고 top 층과 bond 층 계면에서 열화에 의한 산화층 (TGO)이 관찰되었으나, 코팅층 부위와 관계없이 균열이나 박리현상 없는 양호한 미세구조를 나타내었다. 1100 ℃ 열충격 시험결과, 37회 열충격 테스트 후 코팅층의 얇은 부위에서 박리가 시작되어 98회 시험 후 코팅층의 50% 이상이 박리되었으며, 코팅층의 두께가 얇게 형성된 부위는 코팅층이 두껍게 형성된 부위에 비해, top 층의 박리와 함께 bond 층의 산화가 많이 진행되었으며, 코팅층 두께가 상대적으로 두껍게 형성된 부위에서 열차폐 효과의 증가로 인해 bond 층의 내산화성과 열적 안정성이 우수한 것으로 나타났다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1453-1456
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• 2009

Transparent sol-gel hybrid dielectric material (hybrimer) coating films were fabricated by spin coating and photo or thermal curing of sol-gel derived oligosiloxane resins. Hybrimer coating films are suitable as the passivation layer of TFT in AMLCD due to low dielectric constant, small loss tangent, low leakage current density, high transmittance and thermal stability.