• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1431-1434
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• 2014

The thermal barrier coating (TBC) applied to a gas turbine can be damaged by repeated thermal fatigue during operation, so an evaluation of its durability is needed. Thermally grown oxide (TGO) is generated inside the TBC in a high-temperature environment. The growth of TGO is known to be the main cause of damage to the TBC. Therefore, the durability of TBC should be evaluated according to the growth of TGO. In this research, Kim et al.'s work on the growth of TGO with aging was used as a basis for finite element analysis. The relationship between stress and aging was derived from the finite element analysis results. The durability of the TBC with aging was evaluated through a comparison between the results of the finite element analysis and a bond strength test.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.193.2-193.2
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• 2014

열차폐 코팅(Thermal Barrier Coating)은 주로 항공기 엔진이나 화력발전용 터빈 등의 $1300^{\circ}C$ 이상의 고온에서 사용되는 부품에 적용되어 모재(내열합금)의 손상 방지 및 에너지 효율 향상을 위해 사용되고 있다. 열차폐 코팅의 경우 Plasma Spray 공법과 EB-PVD(전자빔 물리 증착법) 공법이 가장 많이 사용되고 있다. Plasma Spray에 의한 열차폐 코팅 공정은 생산 비용이 저렴하고 수평형 적층 구조를 통한 높은 열전도율을 가지는 장점이 있으며, EB-PVD 공정은 수직형 구조의 열차폐막을 통해 내열 충격성과 내열 사이클성이 양호하다는 장점이 있다. 본 연구에서는 열 사이클의 내구성이 뛰어난EB-PVD를 이용하여 열차폐 코팅 공정연구를 진행하였다. 본 연구소에서 사용하고 있는 EB-PVD 는 종래의 장치와는 달리 70 kW급 전자총 5기가 장착 되어 있으며, 각각 시편 가열용 전자총 2기 및 피코팅용 가열 전자총 3기로 구성되어 있다. 이런 구성을 통해 다양한 종류의 열차폐 박막과 높은 결정성과 치밀도를 가지는 박막 형성할 수 있을 것이다. 본 발표에서는 EB-PVD 공정 연구결과 및 향후 실용화를 위한 개발 연구 방향에 대해서 기술하였다.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.3
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• pp.202-210
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• 2016

A thermal barrier coating (TBC) has been widely applied to machine components working under high temperature as a thermal insulator owing to its critical financial and safety benefits to the industry. However, the nondestructive evaluation of TBC damage is not easy since sensing of the microscopic change that occurs on the TBC is required during an evaluation. We designed an eddy current probe for evaluating damage on a TBC based on the finite element method (FEM) and validated its performance through an experiment. An FEM analysis predicted the sensitivity of the probe, showing that impedance change increases as the TBC thermally degrades. In addition, the effect of the magnetic shield concentrating magnetic flux density was also observed. Finally, experimental validation showed good agreement with the simulation result.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.466-466
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• 2007

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1427-1430
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• 2014

A thermal barrier coating (TBC) prevents heat directly transferring from a high-temperature flame to a substrate. The TBC system comprises a top coating and bond coating. TBC technology reduces the substrate surface temperature by about $100{\sim}170^{\circ}C$. In the TBC system, internal stress is generated by the difference in thermal expansion coefficients of the substrate and coating. The internal stress also differs according to the shape and position of the blade. In this study, finite element analysis was performed for different curvatures of coin-shaped specimens, which are commonly used for thermal fatigue tests, and the changes in internal stress of the TBC system were compared. Based on the results, the curvature at which the minimum stress occurs was derived, and the thermal stress was confirmed to increase with the difference between a given curvature and the curvature with the minimum stress.

• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.138-143
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• 2009

Thermal barrier efficiency and endurance of coatings in liquid rocket engine combustor were evaluated for air plasma spray coating and electro/electroless plating. The result of firing tests has revealed occasional occurrence of local delamination of $ZrO_2$, NiCrAlY coating obtained by the method of air plasma spray in the region of supersonic flow and it necessitated a new coating method as a substitution. It was found that Ni-Cr coating by means of electro/electroless plating can substitute $ZrO_2$, NiCrAlY coatings of air plasma spray in terms of thermal barrier efficiency and endurance.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.47-52
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• 1998

최근에 세라믹-금속 접합, 열차폐코팅(Thermal Barrier Coating), 마모저항코팅등 이종재료접합의 이용이 급증하고 있다. 열차폐코팅의 경우, 고온환경쪽에 세라믹을 배치하여 내열성을 부여하고, 냉각환경쪽은 금속재료를 사용하여 열전도성과 기계적 강도를 부여한다. 이 때 두 재료의 경계부에서는 열적, 기계적 특성 차이로 인하여 제조과정이나 사용중에 열적, 기계적 부하에 의하여 내부잔류응력이 생기게 되며, 이는 재료의 강도, 파괴특성에 많은 영향을 미치기 때문에 잔류응력의 감소기술이 중요시되고 있다. (중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.421-425
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• 2009

A study has been performed to investigate the thermo-mechanical effects of thermal barrier coating on liquid rocket regenerative cooling chamber using finite element analysis. Two kinds of thermal barrier coatings were studied on the same loading condition: first, NiCrAlY-$ZrO_2$, coating which is currently applied to the developing combustion chamber and second, Ni-Cr coating which might be applied in the future. Analysis results showed that NiCrAlY-$ZrO_2$ coating has better decreasing effect of temperature than the Ni-Cr coating. As a results, temperature and deformation of the cooling channel in the NiCrAlY-$ZrO_2$ coating were also less than those of the Ni-Cr coating. The Ni-Cr coating has no effect on a structural stability of the outer jacket but the NiCrAlY-$ZrO_2$ coating reduced the effective stress of the outer jacket and enhanced the structural stability of the chamber.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.2
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• pp.52-59
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• 2014

The effect of ceramic thermal barrier coating thickness on the cooling performance of a liquid-propellant rocket engine combustor has been investigated through combustion/cooling performance analysis whose results verified against measured data from hot-firing tests. Also have been confirmed the effects of film cooling amount near the face plate on the coolant temperature and on the thermal barrier coating surface temperature. Some important points to be considered for designing cooling schemes for regeneratively cooled rocket engine combustor have been drawn and reviewed from present study and further verification of the analysis tool should be performed in the future.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.392-394
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• 2017

In this study, the surface heat transfer coefficient of the 3D model of a thruster regulator in the high temperature and high pressure environment was estimated using the CFD. The thermal barrier coating (TBC) on the surface of the thruster regulator was modeled and the effect of the thickness of the TBC on the temperature of the thruster regulator was investigated. The thickness of the TBC was varied from $100{\mu}m$ to $500{\mu}m$. Results showed that the temperature of the surface and the inside the thruster regulator was lower for the thicker TBS case.