Investigation of the effect of V2O5 and Na2SO4 melted salts on thermal barrier coatings under cyclic conditions

2019 ◽  
Vol 66 (5) ◽  
pp. 644-650
Author(s):  
Yasin Ozgurluk ◽  
Kadir Mert Doleker ◽  
Abdullah Cahit Karaoglanli
Keyword(s):  
Thermal Barrier Coatings ◽  
Hot Corrosion ◽  
Gas Turbines ◽  
Zirconia Ceramic ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Content Type ◽  
X Ray ◽  
Spray Method ◽  
Metallic Bond

Purpose Thermal barrier coatings (TBCs), which are used in high temperature applications of gas turbines, are damaged due to fuels and airborne minerals under working conditions. Stable zirconia coatings, which are usually used as topcoat materials in TBCs, are damaged by interacting at high temperatures with elements such as vanadium and sulfur from low quality fuels. The purpose of this paper is to see the failure mechanism of TBC systems after hot corrosion damages. Design/methodology/approach CoNiCrAlY metallic bond coatings of TBC samples were produced by cold gas dynamic spray method which is a new trend production method and stabilized zirconia ceramic top coating was produced by atmospheric plasma spray method. In total, 50% by weight of V2O5 and 50% Na2SO4 salt mixtures were placed on TBC samples and subjected to hot corrosion test at 1000°C. Findings Hot corrosion behaviors of TBC samples were examined by scanning electron microscopy, elemental mapping analysis, energy dispersive X-ray spectrometry analysis and X-ray diffraction analysis. TBC samples were damaged at the end of 12-h cycles. Originality/value The paper provides to understand the mechanism of hot corrosion of TBCs with cold sprayed metallic bond coat.

Fundamental Coating Development Study to Improve the Isothermal Oxidation Resistance and Thermal Cycle Durability of Thermal Barrier Coatings

2006 ◽  
Vol 522-523 ◽  
pp. 247-254 ◽  
Author(s):  
Taiji Torigoe ◽  
Hidetaka Oguma ◽  
Ikuo Okada ◽  
Guo Chun Xu ◽  
Kazuhisa Fujita ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Atmospheric Plasma ◽  
Zirconia Ceramic ◽  
Thermal Barrier ◽  
Temperature Oxidation ◽  
Barrier Coatings ◽  
Oxidation Properties

Thermal barrier coatings(TBCs) are used in high temperature gas turbines to reduce the surface temperature of cooled metal parts such as turbine blades[1]. TBC consist of a bondcoat (e.g. MCrAlY where M is Co, Ni, CoNi, etc.) and a partially stabilized zirconia ceramic topcoat. Usually, the MCrAlY bondcoat is applied by LPPS (low pressure plasma spray) or HVOF(high velocity oxi-fuel spray). The topcoat is applied by APS (atmospheric plasma splay) or EB-PVD (electron beam-physical vapor deposition). High temperature oxidation properties, thermal barrier properties and durability of TBC are very important to increase the reliability in high temperature service. In this study, new TBC has been investigated. The new TBC consists of a two-layered bondcoat (LPPS-MCrAlY plus dense PVD overlay MCrAlY) and the EB-PVD type YSZ columnar structure topcoat. As a result of evaluation tests, it was confirmed that the new TBC had better oxidation properties and durability than a conventional TBC system.

Effect of Aluminum Phosphate Sealing Treatment on Properties of Thick Thermal Barrier Coatings

2000 ◽  
Author(s):  
S. Ahmaniemi ◽  
E. Rajamäki ◽  
P. Vuoristo ◽  
T. Mäntylä
Keyword(s):  
Corrosion Resistance ◽  
Diesel Engine ◽  
Thermal Barrier Coatings ◽  
Hot Corrosion ◽  
Aluminum Phosphate ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
X Ray ◽  
Sealing Treatment

Abstract Partially stabilized zirconia (8Y2O3-ZrO2) coatings were studied as thick thermal barrier coatings (TTBCs) for diesel engine applications. To improve the hot corrosion resistance of TTBCs the 1 mm thick yttria stabilized zirconia coating was densified with aluminum phosphate based sealant. Combined with better hot corrosion resistance other benefits obtained with sealing treatment are improved adhesion as well as increased mechanical properties of the ceramic layer. Three aluminum phosphate based sealants were investigated with varying viscosity level. Different sealant viscosities were used to optimize the level of sealant penetration into the coating. Sealant penetration and the violence of the reaction were determined by XRD, SEM/EDS and optical microscopy. The hardness profile from bond coat to the surface of the top layer was determined. Coating microstructure and phase structure were characterized by optical microscopy and by X-ray diffraction. Microhardness and porosity were determined. Residual stress states were measured by X-ray based stress analyzer. Bond strength of the coatings was determined with tensile test equipment. To simulate the diesel engine combustion conditions, hot corrosion tests were performed for the sealed TTBCs. Hot corrosion resistance of the coating was tested in isothermal exposure of 60Na2SO4 - 40V2O5 melt for 48 hours at 600 °C.

An Investigation on Hot Corrosion Resistance of Plasma Sprayed Composite YSZ-Gd2Zr2O7 and Gd2Zr2O7 Thermal Barrier Coatings in Simulated Turbine Environment at 1050°C

2012 ◽  
Author(s):  
M. H. Habibi ◽  
Li Wang ◽  
Shengmin Guo
Keyword(s):  
Corrosion Resistance ◽  
Composite Coating ◽  
Thermal Barrier Coatings ◽  
Hot Corrosion ◽  
Gas Turbines ◽  
Chemical Interaction ◽  
Thermal Barrier ◽  
X Ray Diffraction ◽  
Barrier Coatings ◽  
Plasma Sprayed

Thermal barrier coatings (TBCs) are frequently used on hot section components in gas turbines. Rare-earth zirconate ceramics used as thermal barrier coatings have attracted increasing interest in recent years due to their distinctly lower thermal conductivity than common TBC material; Yttria stabilized zirconia (YSZ). This paper investigates the hot corrosion resistance of composite YSZ+Gd2Zr2O7 and Gd2Zr2O7 coating, in Na2SO4+V2O5 at 1050°C. Chemical interaction is found to be the major corrosive mechanism for the deterioration of these coatings. Characterizations using X-ray diffraction (XRD) and scanning electron microscope (SEM) indicate that the reaction between NaVO3 and Y2O3 in YSZ produces YVO4 and leads to the transformation of tetragonal ZrO2 to monoclinic ZrO2. Then For the Gd2Zr2O7+YSZ composite coating, by the formation of GdVO4, the amount of YVO4 formed on the YSZ+Gd2Zr2O7 composite coating is significantly reduced, thus the amount of monoclinic phase in the TBC coating is substantially reduced. Comparing to YSZ, under a high temperature of 1050°C, Gd2Zr2O7 is more stable, both thermally and chemically, So Gd2Zr2O7 exhibits a better hot corrosion resistance than YSZ+Gd2Zr2O7 composite coating.

Hot corrosion of Gd2Zr2O7, Gd2Zr2O7/YbSZ, YSZ + Gd2Zr2O7/YbSZ, and YSZ thermal barrier coatings exposed to Na2SO4 + V2O5

2020 ◽  
pp. 126718
Author(s):  
Mohadese Tabeshfar ◽  
Mehdi Salehi ◽  
Ghasem Dini ◽  
Paul Inge Dahl ◽  
Mari-Ann Einarsrud ◽  
...  
Keyword(s):  
Thermal Barrier Coatings ◽  
Hot Corrosion ◽  
Thermal Barrier ◽  
Barrier Coatings

Hot Corrosion Behavior of YSZ and CaZrO3/YSZ Composite Thermal Barrier Coatings in Contact with 50V2O5 + 50Na2SO4 Salts

2017 ◽  
Vol 26 (5) ◽  
pp. 913-928 ◽  
Author(s):  
Noveed Ejaz ◽  
Liaqat Ali ◽  
Furqan Ahmed ◽  
Khalid Mahmood Ghauri ◽  
A. Nusair Khan
Keyword(s):  
Thermal Barrier Coatings ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Thermal Barrier ◽  
Barrier Coatings

scholarly journals Analytical and Experimental Study of Residual Stresses in Thermal Barrier Coatings Deposited on Gas Turbine Blades in Laboratory Dimensions by APS and HVOF Methods to Calculate the Optimal Thickness

2021 ◽  
Vol 3 (1) ◽  
pp. 63-67
Author(s):  
Esmaeil Poursaeidi ◽  
◽  
Farzam Montakhabi ◽  
Javad Rahimi ◽  
◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Analytical Model ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Optimal Thickness ◽  
Barrier Coatings

The constant need to use gas turbines has led to the need to increase turbines' inlet temperature. When the temperature reaches a level higher than the material's tolerance, phenomena such as creep, changes in mechanical properties, oxidation, and corrosion occur at high speeds, which affects the life of the metal material. Nowadays, operation at high temperatures is made possible by proceedings such as cooling and thermal insulation by thermal barrier coatings (TBCs). The method of applying thermal barrier coatings on the turbine blade creates residual stresses. In this study, residual stresses in thermal barrier coatings applied by APS and HVOF methods are compared by Tsui–Clyne analytical model and XRD test. The analytical model results are in good agreement with the experimental results (between 2 and 8% error), and the HVOF spray method creates less residual stress than APS. In the end, an optimal thickness for the coating is calculated to minimize residual stress at the interface between the bond coat and top coat layers.

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