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Influence of Water Vapor on the Isothermal Oxidation Behavior of thermal barrier coatings

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Journal of Materials Science & Technology 2004年第1期20卷 38-40页

作者： Chungen ZHOU, Jingsheng YU, Shengkai GONG and Huibin XUDepartment of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, China Dept. of Mat. Sci. and Eng. Beijing Univ. of Aero. and Astron. Beijing 100083 China

The oxidation of specimens with thermal barrier coating (TBC) consisted of nickel-base superalloy, low-pressure plasma sprayed Ni-28Cr-6AI-0.4Y (wt pct) bond coating and electron beam physical vapor deposited 7.5 wt pct yttria stabilized zirconia (YSZ) top coating was studied at 1050℃ respectively in flows of 02, and mixture of O2 and 5%H2O under atmospheric pressure. The thermal barrier coating has relatively low oxidation rate at 1050℃ in pure O2. Oxidation rate of thermal barrier coating in the atmosphere of O% and 5%H2O is increased The oxidation kinetics obeys almost linear law after long exposure time in the presence of 5% water vapor. Oxide formed along the interface between bond coat and top coat after oxidation at 1050℃ in pure O2 consisted of Al2O3, whereas interfacial scales formed after oxidation at 1050℃ in a mixture of O2 and 5%H2O were mainly composed of Ni(AI,Cr)2O4,NiO and AI2O3. It is suggested that the effect of water vapor on the oxidation of the NiCrAlY coating may be attributed to the increase in Ni and Cr ions transport in the oxides.

关键词： Oxidation Water vapor thermal barrier coating

Failure Behavior of thermal barrier coatings on Cylindrical Superalloy Tube Under Thermomechanical Fatigue

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Acta Metallurgica Sinica(English Letters) 2013年第4期26卷 404-408页

作者： Zhubing CHEN Zhongguang WANG Shijie ZHU Shenyang Aeroengine Research Institute Aviation Industry Corporation of China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences Department of Intelligent Mechanical Engineering Fukuoka Institute of Technology

Failure behavior of thermal barrier coatings on cylindrical superalloy tube was investigated under thermome- chanical fatigue （TMF）. Two types of TMF tests, i.e. in phase （IP） and out of phase （OP）, were performed in the temperature range of 450-850℃. All tests were carried out under mechanical strain control at a given period of 300 s. The bond coat NiCrAIY was produced by high velocity oxygen fuel （HVOF）, and the top coat 7%Y203-ZrO2 was deposited by air plasma spraying （APS）. The testing results showed that the OP TMF life was longer than the IP TMF one under the same mechanical strain amplitude. Observations of the fractured specimens revealed that the interface damage and cracking behavior in the two phasing conditions were different. In OP loading, the top coat was cracked and detached from the bond coat while no spallation was found in the IP loading.

关键词： thermal barrier coating Air plasma spraying High velocity oxygen fuel Thermomechanical fatigue

Finite Element Analysis of thermal Stresses in Ceramic/Metal Gradient thermal barrier coatings

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Journal of Wuhan University of Technology(Materials Science) 2005年第3期20卷 44-47页

作者：明平顺肖金生 School of Automotive Engineering Wuhan University of Technology State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

This paper studied the thermal stresses of ceramicl metal gradient thermal barrier coating which combines the conceptions of ceramic thermal barrier coating （TBC） and functionally gradient material （FGM）. thermal stresses and residual thermal stresses were calculated by an ANSYS finite element analysis software. Negative thermal expansion coefficient method was proposed and element birth and death method was applied to analyze the residual thermal stresses which have non-uniform initial temperature field. The numerical results show a good agreement with the analytical results and the experimental results.

关键词： functionally gradient material thermal barrier coating thermal stress finite element analysis ANSYS

High temperature cyclic oxidation behavior of Y_2O_3-ZrO_2 thermal barrier coatings irradiated by high-intensity pulsed ion beam

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Journal of Central South University 2009年第1期16卷 13-17页

作者：王一奇雷明凯 AFSAR A M SONG J I Department of Mechanical Engineering Changwon National University School of Materials Science and Engineering Dalian University of Technology

The high-temperature oxidation resistance behavior of 7% （mass fraction） Y203-ZrO2 thermal barrier coatings （TBCs） irradiated by high-intensity pulsed ion beam （HIPIB） was investigated under the cyclic oxidation condition of 1 050 ℃ and 1 h. The columnar grains in the TBCs disappear after the HIPIB irradiation at ion current densities of 100-200 A/cm^2 and the irradiated surface becomes smooth and densified after remelting and ablation due to the HIPIB irradiation. The thermally grown oxide （TGO） layer thickness of the irradiated TBCs is smaller than that of the original TBCs. After 15 cycles, the mass gains of the original TBCs and those irradiated by ion current densities of 100 and 200 A/cm^2 due to the oxidation are found to be 0.8-0.9, 0.6-0.7, and 0.3-0.4 mg/cm^2, respectively. The inward diffusion of oxygen through the irradiated TBCs is significantly impeded by the densified top layer formed due to irradiation, which is the main reason for the improved overall oxidation resistance of the irradiated TBCs.

关键词： Y2O3 ZrO2 thermal barrier coating high-intensity pulsed ion beam electron beam physical vapor deposition oxidation resistance cyclic oxidation

thermal insulation and cooling properties of thermal barrier coatings of flame baffles

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Journal of Beijing Institute of Technology 2011年第4期20卷 558-563页

作者：许卫宝刘保果宋遒志 School of Shipbuilding Engineering Harbin Engineering University Navy Armament Department School of MechatronicalEngineering Beijing Institute of Technology

In order to study the thermal insulation and cooling properties of thermal barrier coatings of a flame baffle,several ZrO2 thermal barrier coatings with different thicknesses were prepared on the surface of aluminium-alloy flame-baffle samples by plasma *** relations between temperature and time of these samples were tested when they were heated by combustion *** relations between temperature of the coatings and the sample bodies and time were also tested when the samples at high temperatures were cooled by *** experimental results indicated that ① the thicker the thermal barrier coatings,the better the thermal insulation effect of the thermal barrier;② the higher the temperature,the more significant of the thermal insulation of the thermal ***,in the case of water-cooling,the cooling rate of the coatings was greatly subject to the plate body and the cooling rate of coatings below 1.0mm was equivalent to that of the plate body.

关键词： flame baffle thermal barrier coating cooling factors

Interface fracture toughness and fracture mechanisms of thermal barrier coatings investigated by indentation test and acoustic emission technique

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China Welding 2016年第3期25卷 63-70页

作者： Han Jiceng Guo Ping Luo Jianxia Zhang Zhichao Li Qiang College of Materials Science and Engineering Fuzhou University Fuzhou 350108 Fujian Special Equipment Inspection and Research Institute Fuzhou 350008

Interface fracture toughness and fracture mechanisms of plasma-/sprayed thermal barrier coatings （TBCs） were investigated by interfacial indentation test （ HT） in combination with acoustic emission （ AE ） measurement. Critical load and AE energy were employed to calculate interface fracture toughness. The critical point at which crack appears at the interface was determined by the HT. AE signals produced during total indentation test not only are used to investigate the interface cracking behavior by Fast Fourier Transform （FFT） and wavelet transforms but also supply the mechanical information. The result shows that the AE signals associated with coating plastic deformation during indentation are of a more continuous type with a lower characteristic frequency content （30 -60 kHz） , whereas the instantaneous relaxation associated with interface crack initiation produces burst type AE signals with a characteristic frequency in the range 70 - 200 kHz. The AE signals energy is concentrated on different scales for the coating plastic deformation, interface crack initiation and interface crack propagation. Interface fracture toughness calculated by AE energy was 1. 19 MPam1/2 close to 1.58 MPam1/2 calculated by critical load. It indicates that the acoustic emission energy is suitable to reflect the interface fracture toughness.

关键词： thermal barrier coating acoustic emission interface indentation test interface fracture toughness

Residual stress evolution regularity in thermal barrier coatings under thermal shock loading

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Theoretical & Applied Mechanics Letters 2014年第2期4卷 52-58页

作者： Ximin Chen Zhanwei Liu Yang Yang School of Aerospace Engineering Beijing Institute of Technology

Residual stress evolution regularity in thermal barrier ceramic coatings （TBCs） under different cycles of thermal shock loading of 1 100℃ was investi- gated by the microscopic digital image correlation （DIC） and micro-Raman spec- troscopy, respectively. The obtained results showed that, as the cycle number of the thermal shock loading increases, the evolution of the residual stress under- goes three distinct stages： a sharp increase, a gradual change, and a reduction. The extension stress near the TBC surface is fast transformed to compressive one through just one thermal cycle. After different thermal shock cycles with peak temperature of 1 100℃, phase transformation in TBC does not happen, whereas the generation, development, evolution of the thermally grown oxide （TGO） layer and micro-cracks are the main reasons causing the evolution regularity of the residual stress.

关键词： thermal barrier coating residual stress DIC hole-drilling method micro-Raman spectroscopy

Preparation of Al2O3 nanowires on 7YSZ thermal barrier coatings against CMAS corrosion

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Transactions of Nonferrous Metals Society of China 2019年第11期29卷 2362-2370页

作者： Xiao-feng ZHANG Shao-peng NIU Zi-qian DENG Min LIU Hong LI Chun-ming DENG Chang-guang DENG Ke-song ZHOU National Engineering Laboratory for Modern Materials Surface Engineering Technology Key Laboratory of Guangdong for Modern Surface Engineering TechnologyGuangdong Institute of New MaterialsGuangzhou 510650China

The commonly-employed material for thermal barrier coatings(TBCs)is 7 wt.%Y2O3 ZrO2(7YSZ),generally deposited by electron beam-physical vapor deposition(EB-PVD).Due to the increasing demand for higher operating temperature in aero-derivative gas turbines,a lot of effort has been made to prevent the premature failure of columnar 7YSZ TBCs,which is induced by the microstructure degradation,sintering and spallation after the deposition of infiltrated siliceous mineral(consisting of calcium magnesium aluminum silicate(CaO MgO Al2O3 SiO2,i.e.,CMAS)).A new method called Al-modification for columnar 7YSZ TBCs against CMAS corrosion was *** Al film was magnetron-sputtered on the surface of the columnar 7YSZ TBCs,followed by performing vacuum heat treatment of the Al-deposited *** the heat treatment,the molten Al reacted with ZrO2 to formα-Al2O3 overlay that effectively hindered CMAS ***,the Al film could evaporate and re-nucleate,leading to the generation of Al2O3 nanowires,which further restrained the moving of molten CMAS.

关键词： thermal barrier coating CMAS corrosion Al-modification Al2O3 nanowires

thermal stability and mechanical properties of thick thermal barrier coatings with vertical type cracks

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Transactions of Nonferrous Metals Society of China 2014年第S1期24卷 29-35页

作者： Zhe LU Min-Sik KIM Sang-Won MYOUNG Je-Hyun LEE Yeon-Gil JUNG In-Soo KIM Chang-Yong JO School of Nano & Advanced Materials Engineering Changwon National University High Temperature Materials Research Group Korea Institute of Materials Science

The thermal stability and failure mechanism of thick thermal barrier coatings(TBCs) with and without vertical type cracks were investigated through the cyclic thermal exposure and thermal-shock tests. The TBC systems with thickness of about 2000 μm in the top coat were prepared by an air plasma spray(APS) on the bond coat of about 150 μm in thickness prepared by APS. The adhesive strength values of the as-prepared TBCs with and without vertical type cracks were determined to be 24.7 and 11.0 MPa, respectively, indicating the better interface stability in the TBC with vertical type cracks. The TBC with vertical type cracks shows a better thermal durability than that without vertical type cracks in the thermal cyclic exposure and thermal-shock tests. The hardness values of the as-prepared TBCs with and without vertical type cracks were found to be 6.6 and 5.3 GPa, respectively, which were increased to 9.5 and 5.5 GPa, respectively, after the cyclic thermal exposure tests. These results indicate that the vertical type cracks developed in the top coat are important in improving the lifetime performance of thick TBC in high temperature environment.

关键词： thermal barrier coating air plasma spray vertical type crack thermal durability