Surface microstructure and high temperature oxidation resistance of thermal sprayed CoCrAlY coating irradiated by high current pulsed electron beam

Cai, Jie; Yang, Shuai; Ji, Le; Guan, Qingfeng; Wang, Z.P.; Han, Zhong

doi:10.1016/j.surfcoat.2014.04.029

Cited by 56 publications

(25 citation statements)

References 45 publications

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“…As seen in figure 6(a), Co matrix shows an FCC structure as indicated by the corresponding SAED pattern ( figure 6(b)), which is in agreement with XRD results. A similar result has been observed by J. Cai who sprayed CoCrAlY coating using high current pulsed electron beam (HCPEB) [24]. It is generally known that HCP and FCC phases of cobalt exist in an equilibrium at temperature T eq (427°C), but heating and cooling transformations can affect this allotropic phase transformation with a considerable hysteresis [25].…”

Section: Phase and Microstructures Of The Cocralyta-10%al 2 O 3 Coatingsupporting

confidence: 78%

Microstructural characterization and evolution under high temperature oxidation of CoCrAlYTa-10%Al₂O₃ coating deposited by high-velocity oxygen fuel thermal spraying

Hong

Yang

et al. 2020

Mater. Res. Express

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The CoCrAlYTa-10%Al 2 O 3 coating was fabricated on H13 steel substrate using high-velocity oxygen fuel (HVOF) thermal spraying. A detail characterization on the microstructures, element distribution and phase composition of the HVOF sprayed CoCrAlYTa-10%Al 2 O 3 coating was conducted using scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS), x-ray diffraction (XRD) and transmission electron microscopy (TEM). The microstructural evolution and microhardness of the coating at different temperatures were investigated. The results showed that the coating had a dense and uniform microstructure with a low porosity of 0.44%. The primary phases for the CoCrAlYTa-10%Al 2 O 3 coating were identified as Co-based solid solution, Cr-based solid solution, Al 2 O 3 phase and TaC particles. Compounds such as Cr 7 C 3 , Al 13 Co 4 and aluminum-yttrium oxides Al 5 Y 3 O 12 were also confirmed by TEM observation results. Owing to the rapidly cooling rates of the molten droplets, nano-crystalline phase was existed in the coating. The average microhardness of the coating was 640 HV 0.1 . Its high microhardness derived from the presence of certain volume fraction of hard Al 2 O 3 , Cr 7 C 3 and TaC grains within the coating. After 1h of oxidation, oxides like CrO 2 and Ta 2 O 5 were formed when the coating exposed at the temperature up to 800°C. At the temperature above 600°C, the hardness of the coating remained at a high level (600 HV 0.1 ). It possessed better high temperature softening resistance than H13 steel, indicated that the coating exhibited good mechanical properties at high temperature.

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Section: Phase and Microstructures Of The Cocralyta-10%al 2 O 3 Coatingsupporting

confidence: 78%

Microstructural characterization and evolution under high temperature oxidation of CoCrAlYTa-10%Al₂O₃ coating deposited by high-velocity oxygen fuel thermal spraying

Hong

Yang

et al. 2020

Mater. Res. Express

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“…Surface treatments modify coating surface condition, which improves coating oxidation performance. Commonly used surface treatment methods include mechanical polishing [92], shot-peening [93,94], electron beam treatment [95][96][97][98], laser-surface treatment [99,100] and so on. The positive effects can be summarized as follows:…”

Section: Role Of Surface Treatmentsmentioning

confidence: 99%

Asset Liability Management for Tanzania Pension Funds

Zhang

2018

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Linköping 2018Front page images: (1) low magnification of snowflake like α-Al 2 O 3 formed on polished coating surface after 10 h oxidation; (2) blade-like transient Al 2 O 3 formed on shot-peened coating surface after 100 min oxidation; (3) spinel island formed on polished coating surface after 10 min oxidation. AbstractMCrAlY coatings (M=Ni and/or Co) have been widely used for the protection of superalloy components against oxidation and hot corrosion in the hot sections of gas turbines. The drive to improve engine combustion efficiency while reducing emissions by increasing the operation temperature brings a big challenge for coating design. As a result, the need for improvement of MCrAlY coatings for better oxidation resistance is essential.Formation of a stable, dense, continuous, and slow-growing α-Al 2 O 3 layer, on the MCrAlY coating surface, is the key to oxidation protection, since the protective α-Al 2 O 3 scale offers superior oxidation resistance due to its lower oxygen-diffusion rate as compared with other oxides. The ability of a MCrAlY coating to form and maintain such a protective scale depends on the coating composition and microstructure, and can be improved through optimization of deposition parameters, modification of coating surface conditions, and so on. Part of this thesis work focuses on studying the effect of post-deposition surface treatments on the oxidation behavior of MCrAlX coatings (X can be yttrium and/or other minor alloying elements). The aim is to gain fundamental understanding of alumina scale evolution during oxidation which is important for achieving improved oxidation resistance of MCrAlX coatings. Oxide scale formed on coatings at initial oxidation stage and the effect of surface treatment were investigated by a multi-approach study combining photo-stimulated luminescence, microstructural observation and weight gain. AcknowledgementsThe present project is financed by Siemens Industrial Turbomachinery AB, Swedish Energy Agency through KME consortium -ELFORSK, and are therefore grateful

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“…There are already some attempts 16,17 on preparation techniques for producing stronger, more ductile and higher conductive Cu-Fe alloys. However, few attentions have been paid to the effect of the HCPEB technique on the surface modification of Cu-Fe alloys, in spite of its well testified effectiveness for other metallic materials [18][19][20] . In this paper, the modification effects of the HCPEB treatment on the surface of Cu-10Fe alloys coated with Al films were studied.…”

Section: Introductionmentioning

confidence: 99%

Surface Modification of Aluminized Cu-10Fe Alloy by High Current Pulsed Electron Beam

et al. 2016

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A Cu-10Fe alloy with magnetron sputtered Al films was irradiated by high current pulsed electron beam (HCPEB) with various pulse numbers, next changes of its microstructure and corrosion property were investigated. Compared with the initial sample, microhardness and corrosion resistance of the aluminized Cu-10Fe alloys after the HCPEB treatment are remarkably improved with increasing pulse numbers. This improvement could be attributed to formation of Al 2 Cu intermetallic compounds, occurrence of liquid phase separation and grain refinement in the surface layer of the Cu-10Fe alloy during the process of rapid remelting and solidification induced by the HCPEB treatment.

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Surface microstructure and high temperature oxidation resistance of thermal sprayed CoCrAlY coating irradiated by high current pulsed electron beam

Cited by 56 publications

References 45 publications

Microstructural characterization and evolution under high temperature oxidation of CoCrAlYTa-10%Al₂O₃ coating deposited by high-velocity oxygen fuel thermal spraying

Microstructural characterization and evolution under high temperature oxidation of CoCrAlYTa-10%Al₂O₃ coating deposited by high-velocity oxygen fuel thermal spraying

Asset Liability Management for Tanzania Pension Funds

Surface Modification of Aluminized Cu-10Fe Alloy by High Current Pulsed Electron Beam

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Surface microstructure and high temperature oxidation resistance of thermal sprayed CoCrAlY coating irradiated by high current pulsed electron beam

Cited by 56 publications

References 45 publications

Microstructural characterization and evolution under high temperature oxidation of CoCrAlYTa-10%Al2O3 coating deposited by high-velocity oxygen fuel thermal spraying

Microstructural characterization and evolution under high temperature oxidation of CoCrAlYTa-10%Al2O3 coating deposited by high-velocity oxygen fuel thermal spraying

Asset Liability Management for Tanzania Pension Funds

Surface Modification of Aluminized Cu-10Fe Alloy by High Current Pulsed Electron Beam

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Microstructural characterization and evolution under high temperature oxidation of CoCrAlYTa-10%Al₂O₃ coating deposited by high-velocity oxygen fuel thermal spraying

Microstructural characterization and evolution under high temperature oxidation of CoCrAlYTa-10%Al₂O₃ coating deposited by high-velocity oxygen fuel thermal spraying