Residual Stress Analysis of Laser-Drilled Thermal Barrier Coatings Involving Various Bond Coats

Guinard, Caroline; Montay, Guillaume; Guipont, Vincent; Jeandin, Michel; Girardot, Jérémie; Schneider, Matthieu

doi:10.1007/s11666-014-0185-z

Cited by 4 publications

(3 citation statements)

References 22 publications

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“…Once i G reaches its critical value ( ic G ), multilayer delamination may occur in the top-coat [16]. Furthermore, in order to prevent the overheating of the component and to realize further heat protection, numerous cooling holes are drilled throughout the chamber wall [17][18][19]. These holes enable a protective air film to flow from the external side into the internal face of the TBC-coated chamber.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive damage evaluation of localized spallation of thermal barrier coatings

et al. 2017

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Thermal barrier coatings (TBCs) enable the hot section part to work at high temperatures owing to their thermal barrier effect on the base metal components. However, localized spallation in the ceramic top-coat might occur after long duration of thermal exposure or thermal cycling. To comprehensively understand the damage of the top-coat on the overall hot section part, effects of diameter and tilt angle of the spallation on the temperature redistribution of the substrate and the top-coat were investigated. The results show that the spallation diameter and tilt angle both have a significant effect on the temperature redistribution of the top-coat and the substrate. In the case of the substrate, the maximum temperature increment is located at the spallation center. Meanwhile, the surface (depth) maximum temperature increment, having nothing to do with the tilt angle, increases with the increase of the spallation diameter. In contrast, in the case of the top-coat, the maximum temperature increment was located at the sharp corner of the spallation area, and the surface (depth) maximum temperature increment increases with the increase of both the spallation diameter and the tilt angle. Based on the temperature redistribution of the substrate and the top-coat affected by the partial spallation, it is possible to evaluate the damage effect of spalled areas on the thermal capability of TBCs.

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Section: Introductionmentioning

confidence: 99%

Comprehensive damage evaluation of localized spallation of thermal barrier coatings

et al. 2017

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“…The coated material is a thermal-refractory ceramic with a thickness around 200μm. The presence of this coated before the drilling operation induces several defaults such as a macro delamination of the coatings [12] [15]. The holes are more or less inclined (up to 20 • from surface) and are millimetric.…”

Section: Introductionmentioning

confidence: 99%

Modeling laser drilling in percussion regime using constraint natural element method

et al. 2015

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. Abstract The laser drilling process is the main process used in machining procedures on aeronautic engines, especially in the cooling parts. The industrial problematic is to reduce geometrical deviations of the holes and defects during manufacturing. The interaction between a laser beam and an absorbent metallic matter in the laser drilling regime involves thermal and hydrodynamical phenomenon. Their role on the drilling is not yet completely understood and a realistic simulation of the process could contribute to a better understanding of these phenomenon. The simulation of such process induces strong numerical difficulties. This work presents a physical model combined with the use of the original Constraint Natural Element Method to simulate the laser drilling. The physical model includes solid/liquid and liquid/vapor phase transformations, the liquid ejection and the convective and conductive thermal exchanges. It is the first time that all these phenomena are included in a modelling and numerically solved in a 2D axisymmmetric problem. Simulations results predict most of measurements (hole geometry, velocity of the liquid ejection and laser drilling velocity) without adjusting any parameters.

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“…When the ablation area ratio is greater than the critical value, the strength of the material decreased rapidly. During laser ablation, two forms of residual stress are generated: one is that higher power causes material evaporation and the formation of plasma, which generates a stress wave that propagates into the material causing compressive residual stress [18]; and the other is that thermal residual stresses are generated in the heat affected zone due to differences in cooling rates and shrinkage rates between the surface and the inner region. For nanosecond-laser drilling, both residual stresses exist, whereas for millisecond lasers, thermal residual stress is the dominant residual stress around the hole.…”

Section: Yield Strengthmentioning

confidence: 99%

Study of Tensile Strength of Aluminum Alloy Caused by Pulsed Laser Drilling

Gao

Wang

et al. 2022

Metals

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In the process of pulsed laser drilling, the material properties in the heat-affected zone will change due to the thermal effect of the laser. To study the effect of this change on the material tensile strength, two lasers were used to punch the standard 6061 aluminum alloy specimens with millisecond and nanosecond pulse widths, and then the tensile test was carried out on the standard specimens with a tensile tester to measure the ultimate tensile strength of the aluminum alloy. Finally, the micro-morphology of the fracture was photographed by scanning electron microscopy (SEM), and the fracture mechanism of the aluminum alloy was analyzed. The experimental results show that the relationship between the rate of intensity change induced by the millisecond laser and the ablation area ratio is more linear than that of the nanosecond laser; with the increase of ablation area ratio, the rate of intensity changes induced by the nanosecond and millisecond lasers becomes increasingly closer; three types of fractures are produced with two types of laser ablation; the plasticity of the material rapidly decreases with laser drilling, and the main reason for decrease in plasticity was stress concentration. This study provides an important point of reference for how to ensure the strength and plasticity of the components after laser drilling.

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Residual Stress Analysis of Laser-Drilled Thermal Barrier Coatings Involving Various Bond Coats

Cited by 4 publications

References 22 publications

Comprehensive damage evaluation of localized spallation of thermal barrier coatings

Comprehensive damage evaluation of localized spallation of thermal barrier coatings

Modeling laser drilling in percussion regime using constraint natural element method

Study of Tensile Strength of Aluminum Alloy Caused by Pulsed Laser Drilling

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