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• 作者：Krishna Praveen Jonnalagadda ; Satyapal Mahade…
• 关键词：gadolinium zirconate ; hot corrosion ; multi ; layer thermal barrier coatings ; suspension plasma spraying ; vanadium pentoxide + sodium sulfate
• 刊名：Journal of Thermal Spray Technology
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：26
• 期：1-2
• 页码：140-149
• 全文大小：4112KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Surfaces and Interfaces, Thin Films; Tribology, Corrosion and Coatings; Characterization and Evaluation of Materials; Operating Procedures, Materials Treatment; Analytical Chemistry;
• 出版者：Springer US
• ISSN：1544-1016
• 卷排序：26

文摘

This study investigates the corrosion resistance of two-layer Gd₂Zr₂O₇/YSZ, three-layer dense Gd₂Zr₂O₇/ Gd₂Zr₂O₇/YSZ, and a reference single-layer YSZ coating with a similar overall top coat thickness of 300-320 µm. All the coatings were manufactured by suspension plasma spraying resulting in a columnar structure except for the dense layer. Corrosion tests were conducted at 900 °C for 8 h using V₂O₅ and Na₂SO₄ as corrosive salts at a concentration of approximately 4 mg/cm2. SEM investigations after the corrosion tests show that Gd₂Zr₂O₇-based coatings exhibited lower reactivity with the corrosive salts and the formation of gadolinium vanadate (GdVO₄), accompanied by the phase transformation of zirconia was observed. It is believed that the GdVO₄ formation between the columns reduced the strain tolerance of the coating and also due to the fact that Gd₂Zr₂O₇ has a lower fracture toughness value made it more susceptible to corrosion-induced damage. Furthermore, the presence of a relatively dense layer of Gd₂Zr₂O₇ on the top did not improve in reducing the corrosion-induced damage. For the reference YSZ coating, the observed corrosion-induced damage was lower probably due to combination of more limited salt penetration, the SPS microstructure and superior fracture toughness of YSZ.