scholarly journals Damage evolution in a self‐healing air plasma sprayed thermal barrier coating containing self‐shielding MoSi 2 particles

2019 ◽  
Vol 102 (8) ◽  
pp. 4899-4910 ◽  
Author(s):  
Ying Chen ◽  
Xun Zhang ◽  
Sybrand van der Zwaag ◽  
Willem G. Sloof ◽  
Ping Xiao
Keyword(s):  
Thermal Barrier Coating ◽  
Damage Evolution ◽  
Thermal Barrier ◽  
Self Healing ◽  
Air Plasma ◽  
Barrier Coating ◽  
Plasma Sprayed

A Statistical Assessment of the Damage State in Plasma-Sprayed Thermal Barrier Coating

2003 ◽  
Author(s):  
X. J. Wu ◽  
P. C. Patnaik ◽  
M. Liao ◽  
W. R. Chen
Keyword(s):  
Thermal Barrier Coating ◽  
Bond Coat ◽  
Damage Evolution ◽  
Protective Coatings ◽  
Mechanistic Model ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Damage State ◽  
Barrier Coating ◽  
Plasma Sprayed

Thermal barrier coatings (TBC), which consist of yttria-partially-stabilized zirconia top coat and metallic bond coat deposited onto superalloy substrate, are favorably used as protective coatings of the hot section parts in advanced gas turbine engines to withstand increased inlet temperatures and thus improve engine performance. However, understanding and modeling the damage evolution in TBC under service exposed conditions still remain to be a challenge. This is due to the failure by the coupled effects of the external load-environment, the thermal expansion mismatch between the bond coat and TBC, microstructure of the coating, and degradation of the bond coat. In this study, the damage state in an air-plasma-sprayed APS) thermal barrier coating system was assessed using metallurgical and statistical methods. The damage evolution in the TBC can thus be described with a high degree of confidence. A mechanistic model, representing the micro-cracking mechanism, is presented and its prediction is also assessed on a statistical basis.

HOT CORROSION OF CERIA-YTTRIA STABILIZED ZIRCONIA PLASMA SPRAYED THERMAL BARRIER COATING BY EUTECTIC VANDIUM PENTAOXIDE-SODIUM SULFATE

2018 ◽  
Vol 18 (1) ◽  
pp. 182-192 ◽  
Author(s):  
Mohammed J Kadhim ◽  
Mohammed H Hafiz ◽  
Maryam A Ali Bash
Keyword(s):  
Thermal Barrier Coating ◽  
Hot Corrosion ◽  
Monoclinic Phase ◽  
Volume Fraction ◽  
High Volume ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Plan View ◽  
Barrier Coating ◽  
Plasma Sprayed

The high temperature corrosion behavior of thermal barrier coating (TBC) systemconsisting of IN-738 LC superalloy substrate, air plasma sprayed Ni24.5Cr6Al0.4Y (wt%)bond coat and air plasma sprayed ZrO2-20 wt% ceria-3.6 wt% yttria (CYSZ) ceramic coatwere characterized. The upper surfaces of CYSZ covered with 30 mg/cm2 , mixed 45 wt%Na2SO4-55 wt% V2O5 salt were exposed at different temperatures from 800 to 1000 oC andinteraction times from 1 up to 8 h. The upper surface plan view of the coatings wereidentified for topography, roughness, chemical composition, phases and reaction productsusing scanning electron microscopy, energy dispersive spectroscopy, talysurf, and X-raydiffraction. XRD analyses of the plasma sprayed coatings after hot corrosion confirmed thephase transformation of nontransformable tetragonal (t') into monoclinic phase, presence ofYVO4 and CeVO4 products. Analysis of the hot corrosion CYSZ coating confirmed theformation of high volume fraction of YVO4, with low volume fractions of CeOV4 and CeO2.The formation of these compounds were combined with formation of monoclinic phase (m)from transformation of nontransformable tetragonal phase (t').

scholarly journals The Effect of Environment on Thermal Barrier Coating Lifetime

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Bruce A. Pint ◽  
Kinga A. Unocic ◽  
J. Allen Haynes
Keyword(s):  
Water Vapor ◽  
Thermal Barrier Coating ◽  
Carbon Capture ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Combustion Gas ◽  
Bond Coatings ◽  
Barrier Coating ◽  
Negative Effect ◽  
Plasma Sprayed

While the water vapor content of the combustion gas in natural gas-fired land-based turbines is ∼10%, it can be 20–85% with coal-derived (syngas or H2) fuels or innovative turbine concepts for more efficient carbon capture. Additional concepts envisage working fluids with high CO2 contents to facilitate carbon capture and sequestration. To investigate the effects of changes in the gas composition on thermal barrier coating (TBC) lifetime, furnace cycling tests (1-h and 100-h cycles) were performed in air with 10, 50, and 90 vol. % water vapor and CO2-10% H2O and compared to prior results in dry air or O2. Two types of TBCs were investigated: (1) diffusion bond coatings (Pt-diffusion or Pt-modified aluminide) with commercial electron-beam physical vapor-deposited yttria-stabilized zirconia (YSZ) top coatings on second-generation superalloy N5 and N515 substrates and (2) high-velocity oxygen fuel (HVOF) sprayed MCrAlYHfSi bond coatings with air plasma-sprayed YSZ top coatings on superalloys X4, 1483, or 247 substrates. For both types of coatings exposed in 1-h cycles, the addition of water vapor resulted in a decrease in coating lifetime, except for Pt-diffusion coatings which were unaffected by the environment. In 100-h cycles, environment was less critical, perhaps because coating failure was chemical (i.e., due to interdiffusion) rather than mechanical. In both 1-h and 100-h cycles, CO2 did not appear to have any negative effect on coating lifetime.

Sign in / Sign up

Export Citation Format

Share Document