Study on Thermal Insulation Performance and CMAS Hot Corrosion Resistance of Gd-Sc(Yb)-YSZ Ceramic Coatings AITranslate

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Chinese Library Classification Number:TG174.4[金属学及工艺—金属表面处理]

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A two-step hydrothermal method was used to prepare two kinds of ceramic powders containing semi-hollow spheres with chemical composition ofZr_0.87Y_0.07Gd_0.02Sc_0.04O_1.94(Gd-Sc-YSZ)and Zr_0.87Y_0.08Gd_0.03Yb_0.02O_1.94(Gd-Yb-YSZ),respectively.The above ceramic powders were granulated and coated by atmospheric plasma spraying on the surface of the Al-permeated coating,to prepare two kinds of ceramic layers and form ceramic layer/Al-permeated layer/NiCrAlY/DZ40M thermal barrier coatings.The thermal insulation temperature at the heat source temperatures of 1050℃and 1400℃and CMAS hot corrosion resistance at 1250℃of the two kinds of thermal barrier coatings and the traditional YSZ coating were tested.The results demonstrates that both the Gd-Yb-YSZ and Gd-Sc-YSZ coatings remain intact and do not peel off after thermal insulation at 1400℃for 6 h.The two coatings are primarily composed of a metastable tetragonal phase(t'-ZrO₂),which indicates that both the Gd-Yb-YSZ and Gd-Sc-YSZ coatings are expected to serve at 1400℃for a long term.At the high temperature,the Al-permeated layer plays a crucial role in maintaining the bonding stability of the ceramic layer on the surface of NiCrAlY alloy.The thermal insulation temperature of Gd-Yb-YSZ and Gd-Sc-YSZ coatings is higher than that of YSZ coating at the heat source temperatures of 1050℃and 1400℃.Furthermore,their thermal conductivities are only 0.35~0.5 times that of YSZ coating.It can be concluded that doping with Gd,Yb and Sc significantly en-hances the thermal insulation effect of the YSZ coating.Following exposure to hot corrosion of CMAS at 1250℃for 1 h,the edges of the YSZ coating exhibits peeling,whereas the centre of the Gd-Yb-YSZ coa-ting only becomes rough and the Gd-Sc-YSZ coating remains intact after 6 h.The CMAS hot corrosion re-sistance of the Gd-Sc-YSZ and Gd-Yb-YSZ coatings is much better than that of the YSZ coating,particular-ly for the former.