Modelling the fracture behaviour of thermal barrier coatings containing healing particles

Krishnasamy, Jayaprakash; Ponnusami, Sathiskumar A.; Turteltaub, Sergio; Zwaag, Sybrand van der

doi:10.1016/j.matdes.2018.07.026

Cited by 17 publications

(14 citation statements)

References 47 publications

(57 reference statements)

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“…Thus, in [7], thermal shock failure was controlled when glass beads were added in an epoxy coating; and in [8,9], graphene oxide (GO) was incorporated into polyurethane and epoxy coatings to improve their corrosion resistance. Moreover, in [10], the effects of geometry and material properties of the fillers on the crack pattern in the coating were also examined. However, not all material parameters were investigated in these previous investigations [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation of Failure of Composite Coatings due to Thermal and Hygroscopic Stresses

Zhou

Liu

et al. 2019

Coatings

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Due to the higher thermal and moisture expansions of epoxy coatings than the rigid substrate, these coatings suffer from high thermal and hygroscopic stresses, leading to coating/substrate interfacial crack growth. Herein, a parametric study was conducted systematically on epoxy coatings incorporated with fillers, in order to understand their effects on coating/substrate interface delamination caused by thermal and hygroscopic stresses. A finite element model (FEM) was developed to determine an indicator J-integral value (Ji), in comparison with a critical JC value to interpret the obtained interface delamination experimental results. FE simulations showed that interfacial pre-cracks located at coating edges were more serious than those at the centre. Once delamination was triggered by thermal shock or moisture absorption, it propagated rapidly along the coating/substrate interface. However, by adding suitable micro-/nano-fillers to the coating the thermal and hygroscopic stresses give lower Ji values, so that delamination crack growth can be effectively controlled. The simulation results demonstrate that the incorporation of fillers with lower Young’s modulus, lower thermal expansion and moisture absorption coefficients, smaller size for soft fillers, larger size for rigid fillers, and suitable aspect ratios for rod-shape fillers to the coatings, are more effective against interface delamination. Hence, useful guidelines for improving the design of epoxy composite coatings against delamination growth can be obtained for different engineering applications.

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Section: Introductionmentioning

confidence: 99%

“…Moreover, in [10], the effects of geometry and material properties of the fillers on the crack pattern in the coating were also examined. However, not all material parameters were investigated in these previous investigations [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Failure of Composite Coatings due to Thermal and Hygroscopic Stresses

Zhou

Liu

et al. 2019

Coatings

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“…Although the crack healing mechanism in the self‐healing TBC system has been rationalised in theory, unambiguous experimental evidence showing crack healing in real self‐healing APS TBCs has not been reported yet. Figure A shows a healing particle cut through by a crack from the topcoat matrix near the topcoat/bond coat interface after 320 cycles.…”

Section: Resultsmentioning

confidence: 99%

Damage evolution in a self‐healing air plasma sprayed thermal barrier coating containing self‐shielding MoSi₂ particles

et al. 2019

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A self-healing thermal barrier coating (TBC) system is manufactured by air plasma spraying (APS) and tested by thermal cycling. The ceramic topcoat in the self-healing APS TBC system consists of an yttria stabilised zirconia (YSZ) matrix and contains self-shielding aluminium containing MoSi 2 healing particles dispersed close to the topcoat/bond coat interface. After spraying the healing particles the material was annealed to promote the formation of an oxygen impermeable Al 2 O 3 shell at the MoSi 2 -TBC interfaces by selective oxidation of the aluminium fraction. The samples were subsequently thermally cycled between room temperature and 1100°C. The study focussed on the spontaneous formation of the Al 2 O 3 shell as well as the subsequent damage evolution in the APS produced TBC during thermal cycling. Experimental evidence showing characteristic signs of crack healing in the topcoat is identified and analysed. The study shows that while the concept of the self-healing APS TBCs containing self-shielding MoSi 2 particles is promising, future study is needed to improve the protectiveness of the Al 2 O 3 shells by further tailoring the aluminium content in the MoSi 2 and the particle shape to avoid the premature oxidation of the healing particles and maximise crack healing efficiency. K E Y W O R D SAl-containing MoSi 2 ,

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“…Predefined initiation length is defined as the minimum total length of consecutively failed cohesive elements required to form a measurable microcrack. Based on the convergence analysis carried out in (Ref 18,24), a predefined length of 3 lm is used to define the crack initiation temperature for all the parametric simulations. The failure of the cohesive element is defined based on energy dissipation and the element is considered to have failed when it dissipates 95% of its total fracture energy.…”

Section: Resultsmentioning

confidence: 99%

Numerical Investigation into the Effect of Splats and Pores on the Thermal Fracture of Air Plasma-Sprayed Thermal Barrier Coatings

et al. 2019

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The effect of splat interfaces on the fracture behavior of air plasma-sprayed thermal barrier coatings (APS-TBC) is analyzed using finite element modeling involving cohesive elements. A multiscale approach is adopted in which the explicitly resolved top coat microstructural features are embedded in a larger domain. Within the computational cell, splat interfaces are modeled as being located on a sinusoidal interface in combination with a random distribution of pores. Parametric studies are conducted for different splat interface waviness, spacing, pore volume fraction and fracture properties of the splat interface. The results are quantified in terms of crack nucleation temperature and total microcrack length. It is found that the amount of cracking in TBCs actually decreases with increased porosity up to a critical volume fraction. In contrast, the presence of splats is always detrimental to the TBC performance. This detrimental effect is reduced for the splat interfaces with high waviness and spacing compared to those with low waviness and spacing. The crack initiation temperature was found to be linearly dependent on the normal fracture properties of the splat interface. Insights derived from the numerical results aid in engineering the microstructure of practical TBC systems for improved resistance against thermal fracture.

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Modelling the fracture behaviour of thermal barrier coatings containing healing particles

Cited by 17 publications

References 47 publications

Numerical Simulation of Failure of Composite Coatings due to Thermal and Hygroscopic Stresses

Numerical Simulation of Failure of Composite Coatings due to Thermal and Hygroscopic Stresses

Damage evolution in a self‐healing air plasma sprayed thermal barrier coating containing self‐shielding MoSi₂ particles

Numerical Investigation into the Effect of Splats and Pores on the Thermal Fracture of Air Plasma-Sprayed Thermal Barrier Coatings

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Modelling the fracture behaviour of thermal barrier coatings containing healing particles

Cited by 17 publications

References 47 publications

Numerical Simulation of Failure of Composite Coatings due to Thermal and Hygroscopic Stresses

Numerical Simulation of Failure of Composite Coatings due to Thermal and Hygroscopic Stresses

Damage evolution in a self‐healing air plasma sprayed thermal barrier coating containing self‐shielding MoSi2 particles

Numerical Investigation into the Effect of Splats and Pores on the Thermal Fracture of Air Plasma-Sprayed Thermal Barrier Coatings

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Damage evolution in a self‐healing air plasma sprayed thermal barrier coating containing self‐shielding MoSi₂ particles