A rare earth silicate environmental barrier coating against crack propagation and preparation method thereof

Abstract

The invention relates to an anti-crack propagation rare earth silicate environmental barrier coating and a preparation method thereof. The rare earth silicate environmental barrier coating sequentially comprises a substrate, a bonding layer on the surface of the substrate, a surface layer, and a coating layer on the surface of the substrate. The intermediate layer between the bonding layer and the surface layer; the bonding layer is a Si layer, and the intermediate layer is Yb 2 Si 2 o 7 layer, the surface layer is rare earth monosilicate Re 2 SiO 5 . The coating designed by the present invention adopts Yb 2 Si 2 o 7 The structure of the middle layer and the surface layer of rare earth silicate has remarkable resistance to crack expansion and excellent thermal shock resistance.

Description

technical field [0001] The invention relates to a crack propagation-resistant rare earth silicate environmental barrier coating and a preparation method, belonging to the coating field. Background technique [0002] A high thrust-to-weight ratio is a hallmark of a high-performance aeroengine. Increasing the gas inlet temperature and reducing the structural mass are the key to realize the development of aero-engine towards high thrust-to-weight ratio and high efficiency. Silicon-based ceramic materials, including SiC, Si 3 N 4 , C / SiC and SiC / SiC, etc., are gradually replacing superalloys, and are applied to the hot end parts of high thrust-to-weight ratio aero-engines. However, during the long-term service of aero-engines, silicon-based ceramic materials will be threatened by water vapor and corrosive impurities from the gas environment, resulting in a sharp decline in material performance. At present, the most feasible and effective solution is to deposit environmental ...

AI Technical Summary

Problems solved by technology

However, some studies have shown that due to the large difference in thermal expansion coefficient, the Si / rare earth silicate coating material system will produce cracks through the rare earth silicate coating during the thermal cycle, and the Si bonding layer will be oxidized by the corrosive medium. Make the coating invalid【1K.N.Lee, D.S.Fox, N.P.Bansal, Rare earth silicate environmental barrier coatings for SiC / SiC composites and Si 3 N 4 ceramics, J.Eur.Ceram.Soc.2005,25(10):1705-1715.3B.T.Richards,K.A.Young,F.D.Francqueville,S.Sehr,M.R.Begley,H.N.G.Wadley,Response of ytterbiumdisilicate-silicon environmental barrier coatings cling to in water vapor,Acta Mater.,2016,106:1-14.]; and for the Si / mullite / rare earth silicate coating material system, during the thermal cycle, it was found that the crack penetrated the surface layer and the mullite Layer 【4B.T.Richards, S.Sehr, F.deFranqueville, M.R.Begley, H.N.G.Wadley, Fracture mechanisms of ytterbium monosilicate environmental barrier coatings during cyclic thermal exposure, Acta Materialia, vol.103, pp.448-460, 2016.5. ,M.R.Begley,and H.N.G.Wadley,Mechanisms of ytterbium monosilicate / mullite / silicon coating failure during thermal cycling in water vapor,J.Am.Ceram.Soc.,2015,98(12):4066-4075.】

[0004] At the same time, the mullite coating prepared by plasma spraying technology has the following disadvantages: (1) the plasma sprayed mullite coating contains more amorphous phases, and the high temperature environment of service will make the amorphous phase in the coating crystallize. (crystallization temperature is about 1000°C), resulting in a large volume change, resulting in cracks inside the mullite coating, resulting in a decrease in the stability of the coating system; (2) Mullite decomposes during the spraying process , producing Al 2 o 3 phase, while Al 2 o 3 There is a difference in thermal expansion coefficient with mullite (mullite: 5-6×10 -6 K -1 , Al 2 o 3 : 7.2×10 -6 K -1 ), the internal stress concentration of the coating during the thermal cycle, the corrosive substances may penetrate into the coating through cracks, causing damage to the coating system and also affecting the stability of the coating system [2B.T.Richards, H.N.G.Wadley, Plasma spray deposition of tri-layer environmental barrier coatings.J.Eur.Ceram.Soc.,2014,34(12):3069-3083.5B.T.Richards,M.R.Begley,and H.N.G.Wadley,Mechanisms of ytterbium monosilicate / mullite / silicon coating thermal failure duration cycling in water vapor, J.Am.Ceram.Soc.,2015,98(12):4066-4075.6K.N.Lee,R.A.Miller,and N.S.Jabocson,New generation of plasma-sprayed mullite coatings on silicon-carbide,J. Am.Ceram.Soc.,1995,78(3):705-710]

Images