An environmental barrier coating(EBC) consisting of a silicon bond coat and an Yb2-SiO5 top-coat was sprayed on a carbon fibers reinforced SiC ceramic matrix composite(CMC) by atmospheric plasma spray(APS). The micros...An environmental barrier coating(EBC) consisting of a silicon bond coat and an Yb2-SiO5 top-coat was sprayed on a carbon fibers reinforced SiC ceramic matrix composite(CMC) by atmospheric plasma spray(APS). The microstructure of the coating annealed at 1300 ℃ and its high-temperature oxidation behavior at 1350 ℃ were investigated. The significant mass loss of silica during the plasma spray process led to the formation of Yb2SiO5 and Yb2O3 binary phases in the top-coat. Eutectics of Yb2SiO5 and Yb2O3 were precipitated in the top-coat, and channel cracks were formed in the top-coat after 20 h annealing because of the mismatch between the coefficients of thermal expansion(CTEs) of Yb2SiO5 and the SiC substrate. The EBC effectively improved the oxidation resistance of the CMC substrate. The channel cracks in the Yb2SiO5 top-coat provided inward diffusion channels for oxygen and led to the formation of oxidation delamination cracks in the bond coat, finally resulting in spallation failure of the coating after 80 h oxidation.展开更多
A novel Re modifiedβ-(Ni,Pt)Al coating was prepared on a Mo-rich Ni_3 Al-based single crystal(SC)superalloy by electro-deposition of Re/Pt dual films and low-activity aluminizing.The isothermal oxidation behavior of ...A novel Re modifiedβ-(Ni,Pt)Al coating was prepared on a Mo-rich Ni_3 Al-based single crystal(SC)superalloy by electro-deposition of Re/Pt dual films and low-activity aluminizing.The isothermal oxidation behavior of the Re modifiedβ-(Ni,Pt)Al coating and traditionalβ-(Ni,Pt)Al coating was comparatively studied at 1100℃.Apparent spallation of oxide scale was found on the surface of traditionalβ-(Ni,Pt)Al coating after 300 h isothermal exposure,which mainly resulted from the evaporation of Mo-containing oxides.It is further found that the outward diffusion of Mo from the SC substrate was effectively inhibited in the Re modifiedβ-(Ni,Pt)Al coating by forming theσ-MoRe phase both at the coating/superalloy interface and grain boundaries.It is also revealed that the addition of Re can stabilise Mo to form theσ-MoRe phase,allowing the improved oxidation resistance of the Re modifiedβ-(Ni,Pt)Al coating.展开更多
基金sponsored by the National Natural Science Foundation of China (NSFC) under grant Nos. 51590894, 51425102, and 51231001
文摘An environmental barrier coating(EBC) consisting of a silicon bond coat and an Yb2-SiO5 top-coat was sprayed on a carbon fibers reinforced SiC ceramic matrix composite(CMC) by atmospheric plasma spray(APS). The microstructure of the coating annealed at 1300 ℃ and its high-temperature oxidation behavior at 1350 ℃ were investigated. The significant mass loss of silica during the plasma spray process led to the formation of Yb2SiO5 and Yb2O3 binary phases in the top-coat. Eutectics of Yb2SiO5 and Yb2O3 were precipitated in the top-coat, and channel cracks were formed in the top-coat after 20 h annealing because of the mismatch between the coefficients of thermal expansion(CTEs) of Yb2SiO5 and the SiC substrate. The EBC effectively improved the oxidation resistance of the CMC substrate. The channel cracks in the Yb2SiO5 top-coat provided inward diffusion channels for oxygen and led to the formation of oxidation delamination cracks in the bond coat, finally resulting in spallation failure of the coating after 80 h oxidation.
基金financially supported by the National Science and Technology Major Project(Nos.2017-VI-0010-0081 and 2017-VI-0002-0072)the National Natural Science Foundation of China(Nos.51590894 and 51901107)+1 种基金the Beijing Natural Science Foundation(No.2194078)the“111 Project”(No.B17002)。
文摘A novel Re modifiedβ-(Ni,Pt)Al coating was prepared on a Mo-rich Ni_3 Al-based single crystal(SC)superalloy by electro-deposition of Re/Pt dual films and low-activity aluminizing.The isothermal oxidation behavior of the Re modifiedβ-(Ni,Pt)Al coating and traditionalβ-(Ni,Pt)Al coating was comparatively studied at 1100℃.Apparent spallation of oxide scale was found on the surface of traditionalβ-(Ni,Pt)Al coating after 300 h isothermal exposure,which mainly resulted from the evaporation of Mo-containing oxides.It is further found that the outward diffusion of Mo from the SC substrate was effectively inhibited in the Re modifiedβ-(Ni,Pt)Al coating by forming theσ-MoRe phase both at the coating/superalloy interface and grain boundaries.It is also revealed that the addition of Re can stabilise Mo to form theσ-MoRe phase,allowing the improved oxidation resistance of the Re modifiedβ-(Ni,Pt)Al coating.
