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 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.

Composition optimization, high-temperature stability, and thermal cycling performance of Sc-doped Gd2Zr2O7 thermal barrier coatings: Theoretical and experimental studies

“…When x O-48f = 0.3125, it is an ideal pyrochlore structure, while when x O-48f = 0.375, the system exhibits a disordered fluorite structure, that is, a larger value of x O-48f means a more disordered lattice structure [39]. After completing structural relaxation, the results of a 0 , x O-48f , and density of the Gd 2 Zr 2 O 7 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 hightemperature protective coating used for aero turbine engine blades, prolonging blade working lifetime and 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.…”

Pressure infiltration of molten aluminum for densification of environmental barrier coatings

“…One is concerning the optimization of suitable deposition techniques and deposition parameters. A lot of studies have tried various preparing techniques, such as sol-gel [25], slurry [26][27][28], chemical vapor deposition (CVD) [29], thermal spray techniques including air plasma spray (APS) [6,[30][31][32], electron-beam physical vapor deposition (EB-PVD) [33], and plasma spray physical vapor deposition (PS-PVD) [34][35][36][37]. Among them, thermal spray technique is primarily used, which has a high deposition temperature and can completely melt the powder materials and form a dense coating.…”

Reaction products of Sm2Zr2O7 with calcium-magnesium-aluminum-silicate (CMAS) and their evolution

“…that may be ingested by an engine [3,4]. These molten silicates, commonly referred to as calcium-magnesium-aluminum-silicate (CMAS), cause severe degradation of TBCs and premature delamination, exposing the metallic components to dangerous hot gases [5][6][7].…”