scholarly journals Microstructure modification of Y2O3 stabilized ZrO2 thermal barrier coatings by laser glazing and the effects on the hot corrosion resistance

2020 ◽  
Vol 9 (2) ◽  
pp. 232-242 ◽  
Author(s):  
Lei Guo ◽  
Hui Xin ◽  
Zhao Zhang ◽  
Xinmu Zhang ◽  
Fuxing Ye
Keyword(s):  
Corrosion Resistance ◽  
Thermal Barrier Coatings ◽  
Hot Corrosion ◽  
Thermal Barrier ◽  
Laser Glazing ◽  
Barrier Coatings ◽  
Microstructure Modification

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.

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