High-Temperature Cycling of Plasma Sprayed Multilayered NiCrAlY/YSZ/GZO/YAG Thermal Barrier Coatings Prepared from Liqui
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High-Temperature Cycling of Plasma Sprayed Multilayered NiCrAlY/YSZ/GZO/YAG Thermal Barrier Coatings Prepared from Liquid Feedstocks Radek Musalek1 Rogerio S. Lima3
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Tomas Tesar1,2 • Jan Medricky1 • Frantisek Lukac1
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Submitted: 7 July 2020 / in revised form: 5 October 2020 / Accepted: 5 October 2020 ASM International 2020
Abstract High-enthalpy hybrid water/argon-stabilized plasma (WSP-H) torch may be used for efficient deposition of coatings from dry powders, suspensions, and solutions. WSP-H torch was used to deposit two complete thermal barrier coatings (TBCs) with multilayered top-coat. NiCrAlY was used as bond-coat and deposited on nickelbased superalloy substrates. Top-coat consisted of up to three sublayers: (i) yttria-stabilized zirconia (ZrO28 wt.%Y2O3-YSZ) deposited from solution, (ii) gadolinium zirconate (Gd2Zr2O7-GZO) deposited from suspension, and (iii) optional yttrium aluminum garnet (Y3Al5O12-YAG) overlayer deposited from suspension. Each of the sublayers was intended to provide different functionalities, namely improved fracture toughness, low thermal conductivity, and high erosion resistance, respectively. High-temperature performance and thermal shock resistance of the deposited coatings were tested by thermal cycling fatigue ‘‘TCF’’ test (maximum temperature Production Notes: Credit Line: This article is an invited paper selected from abstracts submitted for the 2020 International Thermal Spray Conference, ITSC2020, that was to be held from June 10-12, 2020, in Vienna, Austria. The conference was cancelled due to the coronavirus (COVID-19) pandemic. The paper has been expanded from the planned presentation. & Radek Musalek [email protected] 1
Institute of Plasma Physics of the Czech Academy of Sciences, Department of Materials Engineering, Prague, Czechia
2
Faculty of Nuclear Sciences and Physical Engineering, Department of Materials, Czech Technical University in Prague, Prague, Czechia
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National Research Council of Canada, Boucherville, QC, Canada
1100 C, 1 h dwell per cycle) and ‘‘laser-rig’’ test (maximum temperature * 1530 C, 5 min dwell per cycle) exposing samples to isothermal and gradient thermal conditions, respectively. In both tests, coatings endured around 800 test cycles which shows great potential for further development of these layers and their application in demanding thermal conditions. Analysis of the samples after the test showed microstructural changes and identified reason of ultimate coating failure. Keywords hybrid plasma torch solution precursor spraying suspension spraying thermal barrier coatings (TBCs) thermal cycling water stabilized plasma yttria stabilized zirconia (YSZ)
Introduction Thermal barrier coatings typically protect components of gas turbines against harsh in-service conditions combining effect of heat, corrosion, erosion, etc. (Ref 1). Thermally sprayed TBCs usually consist of MCrAlY-based bond-coat (M being Ni, Co, or both) and YSZ (yttria-stabilized zirconia) top-coat and have been successfully used for m
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