Experimental and numerical investigation on the thermal and mechanical behaviours of thermal barrier coatings exposed to CMAS corrosion

Abstract

Calcium-magnesium-alumino-silicate (CMAS) corrosion is a critical factor which causes the failure of thermal barrier coating (TBC). CMAS attack significantly alters the temperature and stress fields in TBC, resulting in their delamination or spallation. In this work, the evolution process of TBC prepared by suspension plasma spraying (SPS) under CMAS attack is investigated. The CMAS corrosion leads to the formation of the 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. The corrosion model constructs a bridge for connecting two numerical models. The results show that the CMAS corrosion has a significant influence on the stress field, such as the peak stress, whereas it has little influence on the steady-state temperature field. The peak of stress increases with holding time, which increases the risk of the rupture of TBC. The Mises stress increases nonlinearly along the thick direction of the reaction layer. Furthermore, in the traditional failure zone, such as the interface of the top coat and bond coat, the stress obviously changes during CMAS corrosion.

Composition Optimization, High-temperature Stability and Thermal Cycling Performance of Sc-doped Gd2Zr2O7 Thermal Barrier Coatings: Theoretical and Experimental Studies

“…When x=0.3125, it is an ideal pyrochlore structure, while when x=0.375, the system exhibits a disordered fluorite structure, that is, a larger value of xO-48f means a more disordered lattice structure [39]. After completing structural relaxation, the results of a0, xO-48f and density of the Gd2Zr2O7 model are obtained as shown in Table 3, which are 10.600 Å, 0.3386 and 6.79 g/cm 3 , respectively, showing agreement with the published values [40][41][42][43]. The above part demonstrates the reliability of our calculation results.…”

“…Thermal barrier coating (TBC) is a kind of high temperature protective coating used for aero turbine engine blades, prolonging blade working lifetime, improving thrust to weight ratio and thermal efficiency [1][2][3]. TBCs are generally composed of a ceramic topcoat, thermally grown oxide (TGO), bond coat and superalloy substrate.…”

Thermal Analysis of Turbine Blades with Thermal Barrier Coatings Using燰irtual Wall Thickness Method

“…A variety of technologies are used to increase the service temperature, such as single crystal substrates, film cooling technology and thermal barrier coatings (TBCs). TBCs can increase the service temperature of turbine blades by increasing the thermal resistance of the substrate surface and reducing the heat flux, providing hightemperature protection and oxidation protection for the blade [1][2][3][4][5]. A typical TBCs is composed of a load carrying substrate (SUB), a ceramic top-coat (TC), a metallic bond-coat (BC), and the thermally grown oxide (TGO) that forms between TC and BC.…”

Tailoring Periodic Vertical Cracks in Thermal Barrier Coatings Enabling High Strain Tolerance

“…However, the failure of top-coat (TC) is still an issue for current TBCs, especially for the atmospheric plasma sprayed top-coat (APS-TC). Generally, the TC is deposited either by electron beam physical vapor deposition (EB-PVD) or atmospheric plasma spraying (APS) [13][14][15][16][17]. In industrial applications, APS is regularly used to deposit the TC due to its operational simplicity, low maintenance cost, and probability to deposit thick TC up to 2 mm [18].…”