Time-Dependent Behavior and Fracture of Functionally Graded Thermal Barrier Coatings under Thermal Shock

2005 ◽  
Vol 492-493 ◽  
pp. 379-384 ◽  
Author(s):  
Klod Kokini ◽  
Sudarshan V. Rangaraj
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Functionally Graded ◽  
Yttria Stabilized Zirconia ◽  
Time Dependent ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Dependent Behavior ◽  
Bond Coat Alloy

The thermal fracture and its dependence on time-dependent behavior in functionally graded yttria stabilized zirconia - NiCoCrAlY bond coat alloy thermal barrier coatings was studied. The response of three coating architectures of similar thermal resistance to laser thermal shock tests was considered, experimentally and computationally.

Improving Thermal Shock Resistance of Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings by Laser Remelting

2012 ◽  
Vol 472-475 ◽  
pp. 2502-2507
Author(s):  
Zong Yin Duan ◽  
Dong Sheng Wang
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Thermal Shock Resistance ◽  
Yttria Stabilized Zirconia ◽  
Thermal Barrier ◽  
Laser Remelting ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Shock Resistance ◽  
Plasma Sprayed

This paper deals with the microstructure and thermal shock behavior of laser remelting of yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) deposited by plasma spraying. The microstructures of the coatings were analyzed by scanning electron microscopy (SEM). It was found that the as-sprayed ceramic coating had laminated structure with high porosity. However, the coating exhibited a dense lamellar-like layer with segment cracks on the remained plasma-sprayed porous layer. Thermal shock experiments for the two kinds of TBCs were performed by water quenching method. Testing result showed that the laser-remelted TBC had better thermal shock resistance than the as-sprayed one. The damage mode of the as-sprayed TBC was great-size whole spalling. In contract, the failure mechanism of the laser-remelted one was mainly local pelling. Segmented cracks of the top ceramic coatings caused by laser remelting improved the stress accommodation and were mainly attributed to the enhancement for thermal shock life of TBC.

scholarly journals Thermal Shock and Oxidation Stability Tests to Grade Plasma Sprayed Functionally Gradient Thermal Barrier Coatings

2019 ◽  
Vol 1 (1) ◽  
pp. 1-11
Author(s):  
Pasupuleti Kirti Teja ◽  
Parvati Ramaswamy ◽  
Narayana Murthy S.V.S.
Keyword(s):  
Thermal Barrier Coatings ◽  
Inconel 718 ◽  
Oxidation Stability ◽  
Ceramic Coatings ◽  
Functionally Graded ◽  
Yttria Stabilized Zirconia ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Plasma Sprayed

Functionally graded layers in thermal barrier coatings reduce the stress gradient between the overlaid ceramic coatings and the underlying metallic component. Introduced to alleviate early onset of spallation of the coating due to thermal expansion mismatch, this facilitates improvement in the life of the component. Conventional thermal barrier coatings typically comprise of duplex layers of plasma sprayed 8% yttria stabilized zirconia (ceramic) coatings on bond coated (NiCrAlY) components/substrates (Inconel 718 for example). This work highlights the superiority of plasma sprayed coatings synthesized from blends of the intermetallic bond coat and ceramic plasma spray powders on Inconel 718 substrates in three-layer configuration over the duplex layered configuration. Assessed through (a) thermal shock cyclic tests (at 1200oC and 1400oC) in laboratory scale basic burner rig test facility and (b) oxidation stability test in high temperature furnace (at 800oC and 1000oC) the functionally graded coatings of certain configurations exhibited more than double the life of the conventional 8% yttria stabilized zirconia duplex (double layer) coatings. Micro- and crystal structure analysis support the findings and results are detailed and discussed.

scholarly journals Combined effect of thermal shock and hot corrosion on the failure of yttria stabilized zirconia thermal barrier coatings

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Changhai Zhou ◽  
X. W. Li ◽  
R.Y. Pan
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Hot Corrosion ◽  
Yttria Stabilized Zirconia ◽  
Combined Effect ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Air Plasma Spraying ◽  
Stabilized Zirconia ◽  
Barrier Coatings

The thermal barrier coatings (TBCs) of 8wt.% yttria stabilized zirconia (8YSZ) on a GH2132 alloy were deposited by air plasma spraying. The combined effect of thermal shock and hot corrosion on the failure of TBCs was highlighted investigated. The results showed that the combined effect of hot corrosion and thermal shock was prone to induce the failure of TBCs. The main failure of TBCs under the combined effect was in the form of penetrating crack to the bondcoat/substrate interface and oxidation at the penetrating crack front. 

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