사용된 IN738LC 가스 터빈 블레이드 코팅층의 고온 부식 및 Thermally Grown Oxide 형성 거동

최병학,한성희,김대현,안종기,이재현,최광수 한국재료학회 2022 한국재료학회지 Vol.32 No.4

In this study, defects generated in the YSZ coating layer of the IN738LC turbine blade are investigated using an optical microscope and SEM/EDS. The blade YSZ coating layer is composed of a Y-Zr component top coat layer and a Co component bond coat layer. A large amount of Cr/Ni component that diffused from the base is also measured in the bond coat. The blade hot corrosion is concentrated on the surface of the concave part, accompanied by separation of the coating layer due to the concentration of combustion gas collisions here. In the top coating layer of the blade, cracks occur in the vertical and horizontal directions, along with pits in the top coating layer. Combustion gas components such as Na and S are contained inside the pits and cracks, so it is considered that the pits/cracks are caused by the corrosion of the combustion gases. Also, a thermally grown oxide (TGO) layer of several μm thick composed of Al oxide is observed between the top coat and the bond coat, and a similar inner TGO with a thickness of several μm is also observed between the bond coat and the matrix. A PFZ (precipitate free zone) deficient in γ' (Ni3Al) forms as a band around the TGO, in which the Al component is integrated. Although TGO can resist high temperature corrosion of the top coat, it should also be considered that if its shape is irregular and contains pore defects, it may degrade the blade high temperature creep properties. Compositional and microstructural analysis results for hightemperature corrosion and TGO defects in the blade coating layer used at high temperatures are expected to be applied to sound YSZ coating and blade design technology.

대면적 유체 코팅을 위한 기계학습 기반의 블레이드 코팅 조건 최적화

송륜근(Ryungeun Song),어솔(Sole Eo),이진기(Jinkee Lee) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11

Large-scale liquid coating is an important technique in various industrial fields such as the fabricating of functional panels or surfaces. Blade coating with continuous liquid supply is one of the most cost-effective methods for large-scale coating. In order to coat liquid without defects, it is essential to stably maintain the coating bead trapped under the blade, but numerous experiments are required to obtain coating conditions that guide the appropriate operating parameters. To relieve the burden on this laborious work, we present a novel strategy to acquire coating conditions via physics-informed neural networks (PINNs). Whereas standard neural networks (NNs) predict the coating performance directly from the operating parameters, the PINNs predict parameters related to the state of the coating bead to enhance the coating performance. When the data collected from the experiments under the various parameters were trained on both networks, it was revealed that the PINNs predict with a superior performance than the purely data-driven NNs. Finally, a parametric study was performed with a well-trained PINN-based model to present the optimal coating conditional zones, and we experimentally demonstrated that the stable coating was achieved by using the operating parameters from the found optimal coating conditional zones.

Sand particle-Induced deterioration of thermal barrier coatings on gas turbine blades

Murugan, Muthuvel,Ghoshal, Anindya,Walock, Michael J.,Barnett, Blake B.,Pepi, Marc S.,Kerner, Kevin A. Techno-Press 2017 Advances in aircraft and spacecraft science Vol.4 No.1

Gas turbines operating in dusty or sandy environment polluted with micron-sized solid particles are highly prone to blade surface erosion damage in compressor stages and molten sand attack in the hot-sections of turbine stages. Commercial/Military fixed-wing aircraft engines and helicopter engines often have to operate over sandy terrains in the middle eastern countries or in volcanic zones; on the other hand gas turbines in marine applications are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly-ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, Calcia-Magnesia-Alumina-Silicate (CMAS) attack, oxidation, plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. The focus of this research work is to simulate particle-surface kinetic interaction on typical turbomachinery material targets using non-linear dynamic impact analysis. The objective of this research is to understand the interfacial kinetic behaviors that can provide insights into the physics of particle interactions and to enable leap ahead technologies in material choices and to develop sand-phobic thermal barrier coatings for turbine blades. This paper outlines the research efforts at the U.S Army Research Laboratory to come up with novel turbine blade multifunctional protective coatings that are sand-phobic, sand impact wear resistant, as well as have very low thermal conductivity for improved performance of future gas turbine engines. The research scope includes development of protective coatings for both nickel-based super alloys and ceramic matrix composites.

Experimental and numerical investigation on gas turbine blade with the application of thermal barrier coatings

Aabid, Abdul,Jyothi, Jyothi,Zayan, Jalal Mohammed,Khan, Sher Afghan Techno-Press 2019 Advances in materials research Vol.8 No.4

The engine parts material used in gas turbines (GTs) should be resistant to high-temperature variations. Thermal barrier coatings (TBCs) for gas turbine blades are found to have a significant effect on prolonging the life cycle of turbine blades by providing additional heat resistance. This work is to study the performance of TBCs on the high-temperature environment of the turbine blades. It is understood that this coating will increase the lifecycles of blade parts and decrease maintainence and repair costs. Experiments were performed on the gas turbine blade to see the effect of TBCs in different combinations of materials through the air plasma method. Three-layered coatings using materials INCONEL 718 as base coating, NiCoCrAIY as middle coating, and La₂Ce₂O₇ as the top coating was applied. Finite element analysis was performed using a two-dimensional method to optimize the suitable formulation of coatings on the blade. Temperature distributions for different combinations of coatings layers with different materials and thickness were studied. Additionally, three-dimensional thermal stress analysis was performed on the blade with a commercial code. Results on the effect of TBCs shows a significant improvement in thermal resistance compared to the uncoated gas turbine blade.

Evaluation on Thermal Gradient Fatigue Characteristics of Thermal Barrier Coating through Finite Element Analysis

이정민(Jeong-Min Lee),송현우(Hyunwoo Song),윤정한(Junghan Yun),위성욱(Sunguk Wee),김용석(Youngseok Kim),구재민(Jae-Mean Koo),석창성(Chang-Sung Seok) Korean Society for Precision Engineering 2017 한국정밀공학회지 Vol.34 No.7

A gas turbine is a power plant unit that converts thermal energy into rotational energy by rotating a blade using hightemperature and high-pressure combustion gas. A gas turbine blade is directly exposed to a high-temperature flame. Various studies have aimed to improve the durability of the blade in harsh conditions. One proposes coating the blade with a thermal barrier to protect it from the flame, using a ceramic material with better thermal insulation. Another proposes using internal cooling, by creating an air flow path inside the blade to lower its temperature. Because both these techniques create a thermal gradient in the cross section of the blade, they amplify the difference in thermal expansion, thereby producing thermal stress in the blade and the thermal barrier coating. This study investigates the internal cooling effect on thermal gradient fatigue by using finite element analysis.

Analysis and structural design of various turbine blades under variable conditions: A review

Saif, Mohd,Mullick, Parth,Imam, Ashhad Techno-Press 2019 Advances in materials research Vol.8 No.1

This paper presents a review study for energy-efficient gas turbines (GTs) with cycles which contributes significantly towards sustainable usage. Nonetheless, these progressive engines, operative at turbine inlet temperatures as high as $1600^{\circ}C$, require the employment of highly creep resistant materials for use in hotter section components of gas turbines like combustion chamber and blades. However, the gas turbine obtain its driving power by utilizing the energy of treated gases and air which is at piercing temperature and pushing by expanding through the several rings of steady and vibratory blades. Since the turbine blades works at very high temperature and pressure, high stress concentration are observed on the blades. With the increasing demand of service, to provide adequate efficiency and power within the optimized level, turbine blades are to be made of those materials which can withstand high thermal and working load condition for longer cycle time. This paper depicts the recent developments in the field of implementing the best suited materials for the GTs, selection of proper Thermal Barrier Coating (TBC), fracture analysis and experiments on failed or used turbine blades and several other designing and operating factors which are effecting the blade life and efficiency. It is revealed that Nickel based Superalloys were promising, Cast Iron with Zirconium and Pt-Al coatings are used as best TBC material, material defects are the foremost and prominent reason for blade failure.

1300℃급 가스터빈 1단 블레이드의 코팅분석을 이용한 열화평가

송태훈 ( Tae Hoon Song ),장성용 ( Sung Yong Chang ),김범수 ( Beom Soo Kim ),장중철 ( Jung Chel Chang ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.10

The first stage blade of a gas turbine was operated under a severe environment which included both 1300℃ hot gas and thermal stress. To obtain high efficiency, a thermal barrier coating (TBC) and an internal cooling system were used to increase the firing temperature. The TBC consists of multi-layer coatings of a ceramic outer layer (top coating) and a metallic inner layer (bond coat) between the ceramic and the substrate. The top and bond coating layer respectively act as a thermal barrier against hot gas and a buffer against the thermal stress caused by the difference in the thermal expansion coefficient between the ceramic and the substrate. Particularly, the bondcoating layer improves the resistance against oxidation and corrosion. An inter-diffusion layer is generated between the bond coat and the substrate due to the exposure at a high temperature and the diffusion phenomenon. A thickness measurement result showed that the bond coat of the suction side was thicker than that of the pressure side. The thickest inter-diffusion zone was noted at SS1 (Suction Side point 1). A chemical composition analysis of the bond coat showed aluminum depletion around the inter-diffusion layer. In this study, we evaluated the properties of the bond coat and the degradation of the coating layer used on a 1300℃-class gas turbine blade. Moreover, the operation temperature of the blade was estimated using the Arrhenius equation and this was compared with the result of a thermal analysis.

Tailored Morphology Control of Rapid Drying Blade-coated Organic Solar Cells

정요섭,정재웅 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

The printable solar cells are the most attracting photovoltaic technologies suitable for large area and low-temperature processing. The state-of-the-art organic solar cells achieve power conversion efficiency higher than 16% via spin coating of a polymer donor and a nonfullerene acceptor. However, the spin coating is an uneconomical process because the amount of solution used is very large compared to the coating area. In addition, the uniform film area from spin coating is limited. In this regard, we herein investigate uniform film coating of a blend of polymer donor and non-fullerene acceptor via blade coating with controlled solution temperature. We demonstrate that the chilled solution of a polymer donor and a non-fullerene acceptor facilitates self-assembly of the conjugated molecules, which significantly improves optoelectronic properties of the blend film. The optimized bulk heterojunction morphology led to promising power conversion efficiency of 11.22% of organic solar cells.

Doctor Blade-Coated Polymer Solar Cells

Namchul Cho(조남철),Jong H. Kim(김종현) 한국고분자학회 2016 폴리머 Vol.40 No.5

본 연구에서는 대면적 용액 인쇄장비인 닥터블레이드 코터를 이용하여 형성된 P3HT:PC71BM 및 PBDTTTEFT:PC71BM 벌크헤테로 졍션을 기반으로 하는 고분자 태양전지를 보고한다. 블레이드 코팅 인쇄공정으로 제작된 정구조와 역구조의 P3HT:PC71BM 고분자 태양전지로부터 기존 스핀코팅법으로 제작된 태양전지 성능보다 우수한 2.75, 3.03%의 광전변환효율을 얻을 수 있었을 뿐만 아니라, 개선된 소자 성능의 균일도가 확보됨을 확인하였다. 나아가 블레이드 코팅 공정을 이용하여 3.10%의 광전변환효율을 나타내는 PBDTTT-EFT:PC71BM 기반의 플렉시블고분자 태양전지를 구현함으로써 블레이드 코팅법이 향후 대면적 고속 롤투롤 프린팅 인쇄공정에 효과적으로 활용될 수 있음을 제시하였다. In this work, we report polymer solar cells based on blade-coated P3HT:PC71BM and PBDTTT-EFT:PC71BM bulk heterojunction photoactive layers. Enhanced power conversion efficiency of 2.75 (conventional structure) and 3.03%(inverted structure) with improved reproducibility was obtained from blade-coated P3HT:PC71BM solar cells, compared to spin-coated ones. Furthermore, by demonstrating 3.10% efficiency flexible solar cells using blade-coated PBDTTT-EFT:PC71BM films on the plastic substrates, we suggest the potential applicability of blade coating technique to the high-throughput roll-to-roll fabrication systems.

점착필름 절단용 다이 칼날 소재에 적용된 점착 방지 코팅의 물 접촉각 및 박리강도에 관한 연구

하유진,김민욱,김욱배 한국트라이볼로지학회 2023 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.39 No.5

Anti-adhesion coatings are very important in the processing of adhesive materials such as optical clear adhesive (OCA) films. Choosing the appropriate release coating material for dies and tools can be quite challenging. Hydrophobic surface treatment is usually performed, and its performance is often estimated by the static water contact angle (CA). However, the relationship between the release performance and the CA is not well understood. In this study, the water CAs of surfaces coated with anti-adhesion materials and the peel strengths of the acrylic-based adhesive films are evaluated. STC5 and SUS304 are selected as the base materials. Base materials with different surface roughnesses are produced by hairline finishing, mirror-polishing, and end milling. Four fluoropolymer compounds, including a self-assembled monolayer, are selected to make the base surface hydrophobic. Static, advancing, and receding CAs are mostly increased due to the coating, but the CA hysteresis is found to increase or decrease depending on the coating material. The peel strengths all decreased after coating and are largely dependent on the coating material, with significantly lower values observed for fluorosilane and perfluoropolyether silane coatings. The peel strength is observed to correlate better with the static CA and advancing CA than with the receding CA or hysteresis. However, it is not possible to accurately predict the anti-adhesion performance based on water CA alone, as the peel strengths are not fully proportional to the CAs.