The degradation of thermal barrier coatings by molten deposits: introducing the concept of basicity

Ndamka, N.L.; Wellman, R.G.; Nicholls, John

doi:10.1179/1878641315y.0000000017

Cited by 13 publications

(7 citation statements)

References 14 publications

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“…Air pressures up to approximately 30 bar are possible [2]. Gas turbines operate globally and as such experience a wide range of contaminants including salt, calcium magnesium alumina silicate (CMAS) and all atmospheric pollutants [3]. Operating stresses are such that the cyclic yield strength of the material is commonly exceeded in stress concentration features (particularly for discs), and for aerofoils high cycle fatigue (HCF) loading may dictate component design.…”

Section: Industrial Application (A) Applications Load Regimes and Opmentioning

confidence: 99%

“…Hydrides form in a δ-ZrH(111) || α-Zr(0002), [1][2][3][4][5][6][7][8][9][10] || [11][12][13][14][15][16][17][18][19][20] orientation relationship, where the habit plane is the basal (0002) plane; hydrides in Ti have the same behaviour. In zirconium, Carpenter rationalized the appearance of the macro-hydride packets at 14-17°from the (0002) plane as being a consequence of the arrangement of nano-hydride platelets in such as manner as to autocatalytically accommodate each other's strain fields [77].…”

Section: (F) Hydrogen Effects On Deformation Behaviourmentioning

confidence: 99%

Section: Industrial Application (A) Applications Load Regimes and Operating Environmentmentioning

confidence: 99%

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Hydrogen in Ti and Zr alloys: industrial perspective, failure modes and mechanistic understanding

Chapman

Dye²,

Rugg

2017

Phil. Trans. R. Soc. A.

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Titanium is widely used in demanding applications, such as in aerospace. Its strength-to-weight ratio and corrosion resistance make it well suited to highly stressed rotating components. Zirconium has a no less critical application where its low neutron capture cross section and good corrosion resistance in hot water and steam make it well suited to reactor core use, including fuel cladding and structures. The similar metallurgical behaviour of these alloy systems makes it alluring to compare and contrast their behaviour. This is rarely undertaken, mostly because the industrial and academic communities studying these alloys have little overlap. The similarities with respect to hydrogen are remarkable, albeit potentially unsurprising, and so this paper aims to provide an overview of the role hydrogen has to play through the material life cycle. This includes the relationship between alloy design and manufacturing process windows, the role of hydrogen in degradation and failure mechanisms and some of the underpinning metallurgy. The potential role of some advanced experimental and modelling techniques will also be explored to give a tentative view of potential for advances in this field in the next decade or so.This article is part of the themed issue 'The challenges of hydrogen and metals'.

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Section: Industrial Application (A) Applications Load Regimes and Opmentioning

confidence: 99%

Section: (F) Hydrogen Effects On Deformation Behaviourmentioning

confidence: 99%

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Hydrogen in Ti and Zr alloys: industrial perspective, failure modes and mechanistic understanding

Chapman

Dye²,

Rugg

2017

Phil. Trans. R. Soc. A.

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“…It has a high melting point, typically around 1240 • C (Poerschke & Levi 2015) (although it can be significantly higher; see e.g. Wiesner, Vempati & Bansal (2016) and references therein), which allows it to exist in the molten state even at high temperatures encountered in modern aviation gas turbine engines (Clarke, Oechsner & Padture 2012;Ndamka, Wellman & Nicholls 2016). With high viscosity, high density and high surface tension, CMAS tends to form non-volatile droplets with θ eq / = 0 rather than completely wetting the surfaces (Grant et al 2007;Vidal-Setif et al 2012;Nieto et al 2021).…”

Section: Introductionmentioning

confidence: 99%

“…When it solidifies, it forms a glass-like material that can adhere to surfaces and resist erosion. The buildup of CMAS on turbine engine components can lead to clogging of the cooling passages and degradation of the protective coatings, resulting in engine performance issues and even damage or failure (Clarke et al 2012;Ndamka et al 2016;Song et al 2016;Wiesner et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Characterization of partial wetting by CMAS droplets using multiphase many-body dissipative particle dynamics and data-driven discovery based on PINNs

Kiyani,

Kooshkbaghi,

Shukla

et al. 2024

J. Fluid Mech.

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The molten sand that is a mixture of calcia, magnesia, alumina and silicate, known as CMAS, is characterized by its high viscosity, density and surface tension. The unique properties of CMAS make it a challenging material to deal with in high-temperature applications, requiring innovative solutions and materials to prevent its buildup and damage to critical equipment. Here, we use multiphase many-body dissipative particle dynamics simulations to study the wetting dynamics of highly viscous molten CMAS droplets. The simulations are performed in three dimensions, with varying initial droplet sizes and equilibrium contact angles. We propose a parametric ordinary differential equation (ODE) that captures the spreading radius behaviour of the CMAS droplets. The ODE parameters are then identified based on the physics-informed neural network (PINN) framework. Subsequently, the closed-form dependency of parameter values found by the PINN on the initial radii and contact angles are given using symbolic regression. Finally, we employ Bayesian PINNs (B-PINNs) to assess and quantify the uncertainty associated with the discovered parameters. In brief, this study provides insight into spreading dynamics of CMAS droplets by fusing simple parametric ODE modelling and state-of-the-art machine-learning techniques.

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Trends and Perspectives in Mitigating CMAS Infiltration in Thermal Barrier Coating

Gaudin,

Despres,

Dolmaire

et al. 2023

Engineering Materials

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The degradation of thermal barrier coatings by molten deposits: introducing the concept of basicity

Cited by 13 publications

References 14 publications

Hydrogen in Ti and Zr alloys: industrial perspective, failure modes and mechanistic understanding

Hydrogen in Ti and Zr alloys: industrial perspective, failure modes and mechanistic understanding

Characterization of partial wetting by CMAS droplets using multiphase many-body dissipative particle dynamics and data-driven discovery based on PINNs

Trends and Perspectives in Mitigating CMAS Infiltration in Thermal Barrier Coating

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