CMAS degradation of EB-PVD TBCs: The effect of basicity

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

doi:10.1016/j.surfcoat.2015.03.009

Cited by 45 publications

(26 citation statements)

References 14 publications

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“…However, the study focused only on a fully-infiltrated coating using an excess of one composition of CMAS. Previous studies have demonstrated the importance of the CMAS composition on the characteristics and severity of the attack, due to the basicity of the oxide melt [16]. For instance, the presence of iron oxide Fe 2 O 3 led to a decrease of the melting point via the formation of eutectics [17], hence reducing the viscosity of the melt, which in turn induced a faster penetration of the CMAS [18].…”

Section: Kakuda Et Al Investigated the Effect Of Amorphous Cmas Infimentioning

confidence: 99%

Thermal insulation of CMAS (Calcium-Magnesium-Alumino-Silicates)- attacked plasma-sprayed thermal barrier coatings

Boissonnet

Chalk

Nicholls

et al. 2020

Journal of the European Ceramic Society

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The impact of the penetration of small quantities of calcium-magnesium-aluminosilicates (CMAS) glassy melt in the porous plasma-sprayed (PS) thermal barrier coatings (TBCs) is often neglected even though it might play a non-negligible role on the sintering and hence on the thermal insulation potential of TBCs. In this study, the sintering potential of small CMAS deposits (from 0.25 to 3 mg.cm-2) on freestanding yttria-stabilized zirconia (YSZ) PS TBCs annealed at 1250°C for 1 h was investigated. The results showed a gradual in-depth sintering with increasing CMAS deposits. This sintering was concomitant with local transformations of the tetragonal YSZ and resulted in an increase in the thermal diffusivity of the coatings that reached a maximum of 110 % for the fully penetrated coating.

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Section: Kakuda Et Al Investigated the Effect Of Amorphous Cmas Infimentioning

confidence: 99%

Thermal insulation of CMAS (Calcium-Magnesium-Alumino-Silicates)- attacked plasma-sprayed thermal barrier coatings

Boissonnet

Chalk

Nicholls

et al. 2020

Journal of the European Ceramic Society

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“…The relation between BI and the viscosity of CMAS is in good agreement with the theory proposed by Seok and Ndamaka. 15,16,18 The advantage of using the relation of BI to the viscosity of the melt is that viscosity measurements are not necessary each time and the BI should provide at least a qualitative prediction of viscosity trends. …”

Section: Discussionmentioning

confidence: 99%

The Accelerating Effect of CaSO₄ Within CMAS (CaO–MgO–Al₂O₃–SiO₂) and Its Effect on the Infiltration Behavior in EB‐PVD 7YSZ

et al. 2016

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Infiltration and deposition of CaSO 4 in thermal barrier coatings (TBC) in addition to the CMAS deposits was found in many occasions on real aviation engines. The source and role of CaSO 4 on the degradation of TBC is not well understood. CaSO 4 containing CMAS was synthesized and a systematic study of its role on the CMAS infiltration behavior in EB-PVD 7YSZ is presented in this work. Its influence on the melting and crystallization behavior of CMAS was studied with the help of differential scanning calorimetry. The decomposition of CaSO 4 into CaO and SO 3 was observed at 1050°C in laboratory air under the presence of CMAS using mass spectroscopy and in situ high-temperature XRD. The same amount of CaO is brought into the CMAS system by means of adding CaCO 3 , which will eventually decompose into CaO and CO 2 at 700°C. CMAS infiltration tests were carried out at different temperatures with and without CaSO 4 /CaCO 3 and the results demonstrate that the sulfur has no direct effect on the aggressiveness of the anhydrite containing CMAS with regard to its infiltration behavior in EB-PVD 7YSZ at high temperatures. The extra amount of calcia added to CMAS that is introduced by the evaporating species is responsible for enhanced infiltration of the deposits into the TBC.

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“…The attack from CMAS, including the impact damage caused by large siliceous debris and erosive wear or local spallation caused by small debris [15][16][17][18][19], will cause corrosion of TBC that deteriorates the performance and shorten the lifetime of TBCs. Researches showed that the siliceous particles can penetrate into TBCs due to conspicuous wetting ability when the temperature in TBCs is higher than the melting point of CMAS [15,20,21], deteriorating the thermal insulating performance and increasing the stiffness of TBCs. Moreover, YSZ is partially dissolved by CMAS, resulting in a microstructure degradation and phase transformation [22].…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation on the Thermal and Mechanical Behaviours of Thermal Barrier coatings Exposed to CMAS Corrosion

Li¹,

Jiang

Gao

et al. 2020

Preprint

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Calcium-magnesium-alumino-silicate (CMAS) corrosion is one of the most critical failure mechanisms of thermal barrier coating (TBC). CMAS attack significantly alters the temperature and stress fields in TBCs, resulting in their delamination or spallation. In this work, the dynamic evolution process of suspension plasma sprayed (SPS) TBC under CMAS attack is investigated. The CMAS corrosion leads to the formation of reaction layer and subsequent bending of TBC. Based on the observations, a corrosion model is proposed to describe the generation and evolution of the reaction layer and bending of TBC. Then, numerical simulations are performed to investigate the corrosion process of free-standing TBC and the complete TBC system under CMAS attack, respectively. Results show that the CMAS corrosion has a significant influence on the stress field, such as the peak stress, while it has little influence on the steady state temperature field. It should be noted that the peak of stress increases with holding time which increases the risk of the rupture of TBC. There is a parabolic relationship between the stress and reaction layer thickness in the holding stage. Furthermore, in the traditional failure zone, such as the interface of top coat and bond coat, the stress obviously change during CMAS corrosion.

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CMAS degradation of EB-PVD TBCs: The effect of basicity

Cited by 45 publications

References 14 publications

Thermal insulation of CMAS (Calcium-Magnesium-Alumino-Silicates)- attacked plasma-sprayed thermal barrier coatings

Thermal insulation of CMAS (Calcium-Magnesium-Alumino-Silicates)- attacked plasma-sprayed thermal barrier coatings

The Accelerating Effect of CaSO₄ Within CMAS (CaO–MgO–Al₂O₃–SiO₂) and Its Effect on the Infiltration Behavior in EB‐PVD 7YSZ

Experimental and Numerical Investigation on the Thermal and Mechanical Behaviours of Thermal Barrier coatings Exposed to CMAS Corrosion

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CMAS degradation of EB-PVD TBCs: The effect of basicity

Cited by 45 publications

References 14 publications

Thermal insulation of CMAS (Calcium-Magnesium-Alumino-Silicates)- attacked plasma-sprayed thermal barrier coatings

Thermal insulation of CMAS (Calcium-Magnesium-Alumino-Silicates)- attacked plasma-sprayed thermal barrier coatings

The Accelerating Effect of CaSO4 Within CMAS (CaO–MgO–Al2O3–SiO2) and Its Effect on the Infiltration Behavior in EB‐PVD 7YSZ

Experimental and Numerical Investigation on the Thermal and Mechanical Behaviours of Thermal Barrier coatings Exposed to CMAS Corrosion

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The Accelerating Effect of CaSO₄ Within CMAS (CaO–MgO–Al₂O₃–SiO₂) and Its Effect on the Infiltration Behavior in EB‐PVD 7YSZ