Evolution of high temperature corrosion behavior of La₂(Zr_0.7Ce_0.3)₂O₇ with the addition of Y₂O₃ thermal barrier coatings in contacts with vanadate-sulfate salts

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• 作者：Zhenhua Xu ; Limin He ; Zhihui Tang ; Rende Mu ; Xueqiang Cao
• 关键词：Thermal barrier coatings ; EB-PVD ; Hot corrosion ; 3Y-LZ7C3 ; NaVO3
• 刊名：Journal of Alloys and Compounds
• 出版年：2012
• 出版时间：25 September, 2012
• 年：2012
• 卷：536
• 期：Complete
• 页码：106-112
• 全文大小：1063 K

文摘

Thermal barrier coatings (TBCs) of La₂(Zr_0.7Ce_0.3)₂O₇ with the addition of 3 wt. % Y₂O₃ (3Y-LZ7C3) were deposited by electron beam-physical vapor deposition (EB-PVD). The phase structure, surface and cross-sectional morphologies, hot corrosion behavior of the 3Y-LZ7C3 coatings were studied in detail. The present study investigates the hot corrosion performance of 3Y-LZ7C3 coating in the presence of molten mixture of Na₂SO₄ + V₂O₅ at 1173 K for 100 h. X-ray diffraction (XRD) indicates that the chemical reaction between NaVO₃ and 3Y-LZ7C3 produces LaVO₄, YVO₄, m-ZrO₂ and CeO₂, leaching La₂O₃ and Y₂O₃ from 3Y-LZ7C3 and causing the progressive destabilization transformation from t¡ä to m-ZrO₂. The excess La₂O₃ in the as-deposited 3Y-LZ7C3 coating can largely aggravate the degradation of 3Y-LZ7C3 coating by both NaVO₃ and Na₂SO₄ (Usually formation of the mixtures of LaVO₃, (Y_kLa_1?k)₂O₂SO₄ and few of (Y_kLa_1?k)₂(SO₄)₃ (k = i or j) phases), resulting in very rapid disintegration of the coating. Phase transformation and chemical interaction are the primarily corrosive mechanisms for deterioration of 3Y-LZ7C3 coating.