The Protectiveness of Thermally Grown Oxides on Cold Sprayed CoNiCrAlY Bond Coat in Thermal Barrier Coating

Manap, Abreeza; Nakano, Atsushi; Ogawa, Kōichi

doi:10.1007/s11666-012-9749-y

Cited by 39 publications

(19 citation statements)

References 25 publications

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“…TBC system, traditionally, consists of four layers . The 1st is a Ni‐based superalloy substrate to sustain strength, toughness, and creep resistance at high operating temperatures . The 2nd layer is the oxidation resistant metallic bond coat.…”

Section: Introductionmentioning

confidence: 99%

“…Several researchers used Al 2 O 3 as a protective layer using several techniques of coating. Chen et al modified the microstructure of TGO by forming a thin α‐Al 2 O 3 layer in a low pressure oxidation treatment (LPOT) for the bond coat before top coat deposition, which promotes formation of a nearly continuous alumina layer to act as a diffusion barrier to suppress the formation of detrimental oxides during service.…”

Section: Introductionmentioning

confidence: 99%

“…Heating is used in all previous techniques to introduce alumina protective layer. These techniques produce coatings with initial oxide layer, depending on the Al content within bond coat, which accelerates Al depletion . After the depletion of the Al in the bond coat, other non‐protective scales will start to form .…”

Section: Introductionmentioning

confidence: 99%

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Protective pre‐deposited slurry dip‐coating alumina layer on TBC system

Abdeldaim

Mahallawy

2017

Materials & Corrosion

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In the present study, a thin intermediate protective α‐alumina layer was pre‐deposited by slurry dip‐coating technique on APS–CoNiCrAlY bond coat prior depositing APS–YSZ as top coat. The alumina layer acts as barrier for oxygen diffusion to protect the metallic bond coat from excessive oxidation. The new TBC was compared with the standard TBC system which comprises of Ni‐superalloy substrate, CoNiCrAlY bond coat and YSZ top coat concerning the behavior under thermal cycling at 1150 °C. The samples were investigated before and after thermal cycling by optical microscopy, scanning electron microscopy (SEM) equipped with energy dispersive X‐ray spectroscopy (EDS), and X‐ray diffraction analysis (XRD). Image analysis was used to compare between the microstructure by measuring the crack lengths and the thermally grown oxide layer (TGO) average thickness after thermal cycling. It was observed that a more uniform and compact α‐Al2O3 TGO was formed in the new TBC system after thermal cycling comparing to the commercial one. It was, also, found that the alumina intermediate layer has the potential to reduce the length of the cracks and the average thickness of TGO by suppressing the detrimental mixed oxides, like Cr2O3, CoO, NiO, and (Ni, Co)(Cr, Al)2O4, thus, improving the TBC durability.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Protective pre‐deposited slurry dip‐coating alumina layer on TBC system

Abdeldaim

Mahallawy

2017

Materials & Corrosion

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“…For example, dense and thick metallic coatings can be obtained via the CS, without the occurrence of high-temperature oxidation and phase transformations 3,4) . Soft metallic coatings such as aluminum and copper 5,6) , and hard metallic alloy coatings such as MCrAlY alloy and Ti-6Al-4V alloy are routinely obtained via this technique 7,8) . Therefore, the CS process is expected to replace conventional thermal spray techniques, as the preferred method for repairing structural components.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Analyses on the Deposition Behavior of Spherical Aluminum Particles in the Cold-Spray-Emulated High-Velocity Impact Process

2016

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Understanding the deposition mechanism of ne solid particles is essential for the effective use of the cold spray (CS) technique, which is used to synthesize dense and thick metallic coatings. As such, in this study, the deposition behaviors of spherical pure aluminum particles were investigated in detail in order to understand the deposition mechanism; these particles had a diameter of 1 mm and were deposited on ve metallic substrate materials, during the CS-emulated high-velocity impact process. A single particle impact testing system, which is a modi ed single-stage light gas gun, was used to evaluate the deposition process. This evaluation con rmed that the critical velocities of Al particles vary signi cantly with the substrate material. In order to identify the dominant factors, the bonding energies, rebound velocities, plastic deformation experienced by the particles and substrates, and removability of the natural oxide lms were evaluated. The results revealed that the critical velocities increased signi cantly with increasing Ar sputtering time required for complete removal of the natural oxide lm; this time represents the removability of the lm. This result con rms that, of the factors considered, the removability of the natural oxide lm exerts the most in uence on Al particle deposition on metallic substrates.

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“…This induces intimate bonding assisted by adiabatic shear instability at the particle-particle and particle-substrate interface . Such characteristic of kinetic spray process, using kinetic energy rather than thermal energy for the particle deposition, provides specific properties to the resultant coating layer (Ref 3,(14)(15)(16)(17)(18)(19)(20)(21)(22)(23). Accordingly, kinetic spray process has been applied to various industrial fields such as automotive, aviation, defense, energy, etc.…”

Section: Introductionmentioning

confidence: 99%

Microstructure of Kinetic Spray Coatings: A Review

2015

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Kinetic spray process has been applied to various industrial fields such as automotive, aviation, and defense industries due to its availability to produce high-performing coating layer. However, since the properties of kinetic-sprayed coating layer are significantly affected by the microstructures of deposit, the microstructures of the deposit should be controlled to acquire advanced coating layer and, accordingly, deep understanding of microstructural evolution must be achieved before controlling the microstructure of the coating layer. This paper gives an overview of contents related to the microstructure of kineticsprayed deposition. The most powerful influencing factors in microstructural evolution of kinetic-sprayed coating layer are instant generation of thermal energy and high-strain, high-strain-rate plastic deformation at the moment of particle impact. A high-density coating layer with low porosity can be produced, although some micro-cracks are occasionally induced at the interparticle boundary or at the inner region of the particles. Also, a microstructure which is distinct from the inner particle region is created in the vicinity of the particle-particle or particle-substrate interface region. However, almost no crystal phase transformation or chemical reaction is induced since the deposited particles are not heated directly by a thermal energy source.

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The Protectiveness of Thermally Grown Oxides on Cold Sprayed CoNiCrAlY Bond Coat in Thermal Barrier Coating

Cited by 39 publications

References 25 publications

Protective pre‐deposited slurry dip‐coating alumina layer on TBC system

Protective pre‐deposited slurry dip‐coating alumina layer on TBC system

Experimental and Numerical Analyses on the Deposition Behavior of Spherical Aluminum Particles in the Cold-Spray-Emulated High-Velocity Impact Process

Microstructure of Kinetic Spray Coatings: A Review

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