Influence of Processing on Microstructure and Performance of EB-PVD Thermal Barrier Coatings

2000 ◽  
Author(s):  
U. Schulz ◽  
K. Fritscher ◽  
C. Leyens ◽  
M. Peters
Keyword(s):  
Processing Parameters ◽  
Columnar Structure ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Processing Conditions ◽  
Cyclic Life ◽  
Barrier Coatings ◽  
Equiaxed Zone ◽  
And Performance ◽  
Microstructure And Performance

The paper addresses the effect of processing parameters on microstructure and lifetime of EB-PVD PYSZ coatings deposited onto NiCoCrAlY-coated Ni-base superalloys. In particular, the formation of a thermally grown oxide layer, an equiaxed zone, and various columnar arrangements of the highly textured PYSZ layers are discussed with respect to processing conditions. Three different microstructures were cyclically tested at 1100°C. The intermediate columnar structure was superior with respect to cyclic life times to a fine and to a coarse columnar structure which was mainly attributed to differences in the elastic properties. The effect of PYSZ microstructure on hot corrosion behavior of the TBC system at 950°C is briefly discussed.

Influence of Processing on Microstructure and Performance of Electron Beam Physical Vapor Deposition (EB-PVD) Thermal Barrier Coatings

2002 ◽  
Vol 124 (2) ◽  
pp. 229-234 ◽  
Author(s):  
U. Schulz ◽  
K. Fritscher ◽  
C. Leyens ◽  
M. Peters
Keyword(s):  
Electron Beam ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Processing Parameters ◽  
Columnar Structure ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
And Performance ◽  
Microstructure And Performance

The paper addresses the effect of processing parameters on microstructure and lifetime of electron beam physical vapor deposition, partially yttria-stabilized zirconia (EB-PVD PYSZ) coatings deposited onto NiCoCrAlY-coated Ni-base superalloys. In particular, the formation of a thermally grown oxide layer, an equi-axed zone, and various columnar arrangements of the highly textured PYSZ layers are discussed with respect to processing conditions. Three different microstructures were cyclically tested at 1100°C. The intermediate columnar structure was superior with respect to cyclic life times to a fine and to a coarse columnar structure which was mainly attributed to differences in the elastic properties. The effect of PYSZ microstructure on hot corrosion behavior of the thermal barrier coating (TBC) system at 950°C is briefly discussed.

NONDESTRUCTIVE IMPEDANCE SPECTROSCOPY EVALUATION OF THE BOND COAT OXIDATION IN THERMAL BARRIER COATINGS

2007 ◽  
Vol 14 (05) ◽  
pp. 935-943 ◽  
Author(s):  
L. YANG ◽  
Y. C. ZHOU ◽  
W. G. MAO ◽  
Q. X. LIU
Keyword(s):  
Impedance Spectroscopy ◽  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Equivalent Circuit Model ◽  
Isothermal Oxidation ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Plasma Sprayed

In this paper, the impedance spectroscopy technique was employed to examine nondestructively the isothermal oxidation of air plasma sprayed (APS) thermal barrier coatings (TBCs) in air at 800°C. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were also used to characterize the microstructure evolution of TBCs. After oxidation, the thermally grown oxide (TGO), which was mainly composed of alumina as confirmed by EDX, formed at the upper ceramic coat/bond coat interface, the lower bond coat/substrate interface, and the bond coat. Impedance diagrams obtained from impedance measurements at room temperature were analyzed according to the equivalent circuit model proposed for the TBCs. Various observed electrical responses relating to the growth of oxides and the sintering of YSZ were explained by simulating the impedance spectra of the TBCs.

Determination of the Structure and Chemistry of Thermally Grown Oxides in Thermal Barrier Coatings

1999 ◽  
Vol 5 (S2) ◽  
pp. 854-855
Author(s):  
M.R. Brickey ◽  
J.L. Lee
Keyword(s):  
Thermal Barrier Coatings ◽  
Nickel Aluminide ◽  
Physical Vapor Deposition ◽  
Thermal Exposure ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Engine Operation ◽  
Barrier Coatings ◽  
Combustion Gas ◽  
Thermally Grown

Thermal barrier coatings (TBCs) insulate gas turbine hot section components from the hot (∽1200 - 1450°C) combustion gas exhaust stream. An airline company can save millions of dollars per year by using TBCs to protect vital engine components and to improve fuel efficiency. TBCs typically consist of an 8 wt.% yttria-partially-stabilized zirconia (YPSZ) ceramic topcoat deposited on a platinum-nickel-aluminide (Pt-Ni-Al) bondcoat covering a nickel-based superalloy substrate. Thermal exposure during YPSZ electron beam-physical vapor deposition (EB-PVD) and engine operation promotes the formation of a thermally grown oxide (TGO) between the Pt-Ni-Al and the YPSZ layers. Stresses can develop at the Pt-Ni-Al/TGO and TGO/YPSZ interfaces due to TGO growth and thermal expansion coefficient mismatch. These stresses eventually cause spallation of the YPSZ, leaving the metallic substrate vulnerable to high temperature degradation since exhaust temperatures are often higher than the melting temperature of most nickel-based superalloys (∽1200 - 1450°C).

Characterization of Plasma Sprayed and Electron Beam-Physical Vapor Deposited Thermal Barrier Coatings

1997 ◽  
Author(s):  
Z. Mutasim ◽  
C. Rimlinger ◽  
W. Brentnall
Keyword(s):  
Electron Beam ◽  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
And Performance ◽  
Plasma Sprayed ◽  
Industrial Gas Turbine ◽  
Tbc Systems

Laboratory testing was conducted on air plasma sprayed (APS) and electron beam-physical vapor deposited (EB-PVD) thermal barrier coatings (TBCs) applied onto nickel alloy specimens. As-coated chemistry, microstructure, and bond strength of the TBC systems were evaluated. Cyclic oxidation tests that simulated industrial gas turbine environments were also conducted on the various thermal barrier coatings. This study evaluated the effects of ceramic and metallic coating compositions and application processes on coatings microstructure and performance. The relative cyclic performance of the TBC systems was determined from the laboratory tests.

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