Effect of Hollow Spherical Powder Size Distribution on Porosity and Segmentation Cracks in Thermal Barrier Coatings

2006 ◽  
Vol 89 (12) ◽  
pp. 3797-3804 ◽  
Author(s):  
H. B. Guo ◽  
H. Murakami ◽  
S. Kuroda
Keyword(s):  
Size Distribution ◽  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Powder Size ◽  
Spherical Powder ◽  
Barrier Coatings ◽  
Powder Size Distribution ◽  
Segmentation Cracks

Highly Porous Thick Thermal Barrier Coatings Produced by Air Plasma Spraying of a Plastic-Ceramic Mixed Powder

1997 ◽  
Author(s):  
G. Gualco ◽  
S. Corcoruto ◽  
A. Campora ◽  
R. Taylor ◽  
D. Schwingel ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Plasma Spraying ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Thermal Barrier ◽  
High Porosity ◽  
Air Plasma ◽  
Air Plasma Spraying ◽  
Barrier Coatings ◽  
Segmentation Cracks

Abstract In order to increase the efficiency of heavy duty gas turbines for power generation and to reduce their emissions, higher combustion chamber temperature is required; a considerable improvement of the insulation properties of the thermal barrier coatings is therefore required. 1.5 mm thick thermal barrier coatings have been deposited by air plasma spraying a mixed polyester-zirconia powder; by this process high porosity, up to 22%, has been achieved together with a good deposition efficiency (about 50%); the coating microstructure has been thoroughly examined by quantitative image analysis, determining the pores size distribution and the vertical segmentation cracks density. Thermal shock tests showed a life improvement with respect to the state-of-art by a factor > 100; relationships among thermal shock life, deposition rate, segmentation cracks density and porosity were determined. Thermal expansion and thermal diffusivity were measured up to 1200 °C; failure strength, failure strain and Young's modulus were determined by a four-point bending technique.

Thermal Cycling and Hot-Corrosion Behavior of Plasma Sprayed Segmented Thermal Barrier Coatings

2007 ◽  
Vol 546-549 ◽  
pp. 1713-1716 ◽  
Author(s):  
Hong Bo Guo ◽  
Hideyuki Murakami ◽  
Seiji Kuroda
Keyword(s):  
High Temperature ◽  
Thermal Cycling ◽  
Thermal Barrier Coatings ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Crystalline Substrate ◽  
Plasma Sprayed ◽  
Segmentation Cracks

Modified zirconia thermal barrier coatings (TBCs) with segmentation cracks were sprayed onto a TMS 82+ single crystalline substrate. The thermal cycling lifetime of the modified TBC was improved by 10 times compared to that of the traditional non-segmented TBC. Also, the modified coating showed much better resistance to high temperature cyclic hot-corrosion.

Characterization of thermal barrier coatings formed by electon-beam physical vapor deposition (EB-PVD)

1989 ◽  
Vol 47 ◽  
pp. 426-427
Author(s):  
Ozer Unal
Keyword(s):  
Thermal Barrier Coatings ◽  
Physical Vapor Deposition ◽  
Ceramic Coating ◽  
High Vacuum ◽  
Ceramic Coatings ◽  
High Energy ◽  
Thermal Barrier ◽  
Protective Oxide ◽  
Barrier Coatings ◽  
Energy Beam

Interest in ceramics as thermal barrier coatings for hot components of turbine engines has increased rapidly over the last decade. The primary reason for this is the significant reduction in heat load and increased chemical inertness against corrosive species with the ceramic coating materials. Among other candidates, partially-stabilized zirconia is the focus of attention mainly because ot its low thermal conductivity and high thermal expansion coefficient.The coatings were made by Garrett Turbine Engine Company. Ni-base super-alloy was used as the substrate and later a bond-coating with high Al activity was formed over it. The ceramic coatings, with a thickness of about 50 μm, were formed by EB-PVD in a high-vacuum chamber by heating the target material (ZrO2-20 w/0 Y2O3) above its evaporation temperaturef >3500 °C) with a high-energy beam and condensing the resulting vapor onto a rotating heated substrate. A heat treatment in an oxidizing environment was performed later on to form a protective oxide layer to improve the adhesion between the ceramic coating and substrate. Bulk samples were studied by utilizing a Scintag diffractometer and a JEOL JXA-840 SEM; examinations of cross-sectional thin-films of the interface region were performed in a Philips CM 30 TEM operating at 300 kV and for chemical analysis a KEVEX X-ray spectrometer (EDS) was used.

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