<i>In-situ</i> laser pelletization of advanced ternary thermal barrier coating system

Jasim, K. Mohammed; Atiyah, Alaa Abdulhasan; Bash, Maryam A. Ali

doi:10.1088/2053-1591/aaf65a

Cited by 5 publications

(4 citation statements)

References 33 publications

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“…During laser treatment, the ceramic materials are heated rapidly to form a molten pool under the action of the high‐energy‐density laser irradiation. Due to the Gaussian distribution of the laser beam, a sharp thermal gradient forms between the center and the edge of the molten pool, which further causes the surface tension gradient and attendant Marangoni flow 41 . Thus, the liquid material is stirred in the molten pool and the gas can easily escape from the molten pool.…”

Section: Resultsmentioning

confidence: 99%

“…Due to the Gaussian distribution of the laser beam, a sharp thermal gradient forms between the center and the edge of the molten pool, which further causes the surface tension gradient and attendant Marangoni flow. 41 Thus, the liquid material is stirred in the molten pool and the gas can easily escape from the molten pool. Finally, the laser-treated zone with a dense microstructure is obtained.…”

Section: Morphology and Microstructurementioning

confidence: 99%

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Thermal shock resistance of thermal barrier coatings modified by selective laser remelting and alloying techniques

et al. 2022

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Aiming to improve the thermal shock resistance of thermal barrier coatings (TBCs), the plasma-sprayed 7YSZ TBCs were modified by selective laser remelting and selective laser alloying, respectively, in this study. A self-healing agent TiAl 3 was introduced into the 7YSZ TBCs by selective laser alloying to fill cracks during thermal cycling. The thermal shock experiments of the plasma-sprayed, laser-remelted, and laser-alloyed TBCs were conducted by a means of heating and water-quenching method. Results revealed that some segmented microcracks were distributed on the surface of the laser-remelted and the laser-alloyed zones, showing a dense columnar crystal structure. After thermal shock tests, the numbers of segmented microcracks on the laser-remelted coating increased, whereas, in the laser-alloyed condition, some irregular particles formed, leading to the decreased numbers of segmented microcracks. The laser-alloyed coating exhibited the best thermal shock resistance, followed by the laser-remelted condition, with the thermal shock lifetime 3.3 and 2.7 times higher than that of the as-sprayed coating, respectively. On the one hand, both columnar grains and segmented microcracks in the laser-treated zone could effectively improve the strain tolerance of coatings. On the other hand, the oxidation products of TiAl 3 under high-temperature condition could seal the microcracks to postpone the crack connection. Thus, the thermal shock resistance of the laser-treated coatings was significantly improved.

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Section: Resultsmentioning

confidence: 99%

Section: Morphology and Microstructurementioning

confidence: 99%

Thermal shock resistance of thermal barrier coatings modified by selective laser remelting and alloying techniques

et al. 2022

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“…During laser treatment, cracks form, which is known to promote strain accommodation during thermal cycling. The effective factors for controlling crack networks are laser power, scanning speed, and track overlapping [17,18].…”

Section: Introductionmentioning

confidence: 99%

A Direct Laser Sintering Approach for the Electrophoretic Deposition Overlay of Yttria-Stabilized Zirconia on the Surface of a Thermal Barrier Coating System

Ali Bash,

Ajeel,

Abbas

et al. 2023

Coatings

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The laser sintering process and modification of yttria-stabilized zirconia (YSZ) coatings subjected to electrophoretic deposition (EPD) on YSZ air-plasma-sprayed (APS) thermal barrier coatings (TBCs) were investigated. A Ni-based superalloy was plasma-sprayed using yttria-stabilized zirconia (YSZ) to create a thermal barrier coating with a 400 μm thickness. The electrophoretic deposition (EPD) technique was used to deposit the nanopowder of YSZ on the surface of YSZ TBCs. In this study, a technology based on the direct sintering of a green EPD layer using a laser beam was employed. The best conditions for the deposition overlay of the YSZ coating using a DC current were obtained with an applied voltage of 40 V, deposition time of 5 min, and suspension concentration of 10 g/L. Iodine was added to the solutions as a stabilizing agent. To overcome the problems of high sintering temperatures, laser sintering was adopted as a new approach. The microstructures of all the specimens were studied using field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDS) analysis. Surface roughness was investigated using atomic force microscopy (AFM) analysis and the central line average (CLA). The direct laser sintering (DLS) process for the EPD overlay on the surface of the TBCs caused a reduction in surface roughness and porosity, and improvements in the microstructural and mechanical properties of the surface coatings were observed.

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“…Laser sealing of the porous YSZ topcoat was also studied [7]. However, during laser sealing of YSZ topcoat, a rapid quenching encourages the formation of the metastable tetragonal-prime phase (ť-ZrO2) [8,9]. Phase ť helps to prevent the phase transformation to equilibrium phases of monoclinic (m) during service.…”

Section: Introductionmentioning

confidence: 99%

Optimizing Coating Thickness of Electrophoretic Deposition Overlay on Plasma Sprayed YSZ Coating Using Taguchi Method

Abbas

Ajeel

Bash

et al. 2022

IOP Conf. Ser.: Earth Environ. Sci.

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In this study, nano sized yttria stabilized zirconia (YSZ) suspension in organic solution was deposited by electrophoretic deposition (EPD) method as a protective layer on substrate that was previously plasma sprayed thermal barrier coating (TBCs). In order to improve the performance of TBC from degradation by melt ingression of fuel impurities. Design of experiments (DOE) by Taguchi method was used to optimize the controlled variables of EPD process. A crack free YSZ overlay coating was carried out at different variables; applied voltage (20, 40, 60) V, deposition time (3, 5, 7) min and suspension concentration (5, 10, 15) g/l using DC current. Morphological appearance and cross section of the investigated coating specimen were done using optical and field emission scanning electron microscope. Optimizing process and analysis of variances (ANOVA) were performed by “Minitab 18” software. The results indicate that best condition of coating thickness can be obtained at 40V, 5min and 10g/l when applying signal-to-noise ratio “Larger is better”.

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In-situ laser pelletization of advanced ternary thermal barrier coating system

Cited by 5 publications

References 33 publications

Thermal shock resistance of thermal barrier coatings modified by selective laser remelting and alloying techniques

Thermal shock resistance of thermal barrier coatings modified by selective laser remelting and alloying techniques

A Direct Laser Sintering Approach for the Electrophoretic Deposition Overlay of Yttria-Stabilized Zirconia on the Surface of a Thermal Barrier Coating System

Optimizing Coating Thickness of Electrophoretic Deposition Overlay on Plasma Sprayed YSZ Coating Using Taguchi Method

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