Microstructure and Thermal Conductivity of Thermal Barrier Coatings Processed by Plasma Spray and Physical Vapor Deposition Techniques

1996 ◽  
Vol 434 ◽  
Author(s):  
K. S. Ravichandran ◽  
R. E. Dutton ◽  
S. L. Semiatin ◽  
K. An
Keyword(s):  
Thermal Conductivity ◽  
Plasma Spray ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Multilayer Coatings ◽  
Spray Technique ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Sprayed Coatings ◽  
Deposition Techniques

AbstractThe temperature dependence of the thermal conductivity of multilayer coatings made by a plasma spray technique as well as some coatings made by physical vapor deposition (PVD) was investigated. The multilayer coatings consisted of a varying number of layers of Al2O3 and ZrO2 stabilized by 8%Y2O3. Plasma sprayed coatings exhibited a large reduction in thermal conductivity at all temperatures when compared to the bulk monolithic materials. This reduction was found to be due to porosity as well as thermal resistance brought about by interfaces in the coatings. A comparable reduction in thermal conductivity was achieved in monolithic ZrO2 as well as in a composite coating deposited by the PVD technique. Microstructural factors that may be responsible for this reduction are discussed.

scholarly journals Porosity and Its Significance in Plasma-Sprayed Coatings

Coatings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 460 ◽  
Author(s):  
John Gerald Odhiambo ◽  
WenGe Li ◽  
YuanTao Zhao ◽  
ChengLong Li
Keyword(s):  
Working Environment ◽  
Atmospheric Plasma ◽  
Formation Mechanisms ◽  
Multilayer Coatings ◽  
Oxide Coatings ◽  
Spraying Parameters ◽  
Plasma Sprayed Coatings ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Sprayed Coatings

Porosity in plasma-sprayed coatings is vital for most engineering applications. Porosity has its merits and demerits depending on the functionality of the coating and the immediate working environment. Consequently, the formation mechanisms and development of porosity have been extensively explored to find out modes of controlling porosity in plasma-sprayed coatings. In this work, a comprehensive review of porosity on plasma-sprayed coatings is established. The formation and development of porosity on plasma-sprayed coatings are governed by set spraying parameters. Optimized set spraying parameters have been used to achieve the most favorable coatings with minimum defects. Even with the optimized set spraying parameters, defects like porosity still occur. Here, we discuss other ways that can be used to control porosity in plasma-sprayed coating with emphasis to atmospheric plasma-sprayed chromium oxide coatings. Techniques like multilayer coatings, nanostructured coatings, doping with rare earth elements, laser surface re-melting and a combination of the above methods have been suggested in adjusting porosity. The influences of porosity on microstructure, properties of plasma-sprayed coatings and the measurement methods of porosity have also been reviewed.

Thermal conductivity of plasma-sprayed coatings Ni-Cr-B-Si

1991 ◽  
Vol 30 (8) ◽  
pp. 641-642
Author(s):  
V. D. Podzorov ◽  
V. S. Kharchenkov ◽  
A. I. Kadin
Keyword(s):  
Thermal Conductivity ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Sprayed Coatings

scholarly journals Columnar Thermal Barrier Coatings Produced by Different Thermal Spray Processes

2021 ◽  
Author(s):  
Nitish Kumar ◽  
Mohit Gupta ◽  
Daniel E. Mack ◽  
Georg Mauer ◽  
Robert Vaßen
Keyword(s):  
Thermal Conductivity ◽  
Plasma Spraying ◽  
Thermal Spray ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Deposition Process ◽  
Cyclic Fatigue ◽  
Atmospheric Plasma ◽  
Plasma Sprayed ◽  
Thermal Spray Processes

AbstractSuspension plasma spraying (SPS) and plasma spray-physical vapor deposition (PS-PVD) are the only thermal spray technologies shown to be capable of producing TBCs with columnar microstructures similar to the electron beam-physical vapor deposition (EB-PVD) process but at higher deposition rates and relatively lower costs. The objective of this study was to achieve fundamental understanding of the effect of different columnar microstructures produced by these two thermal spray processes on their insulation and lifetime performance and propose an optimized columnar microstructure. Characterization of TBCs in terms of microstructure, thermal conductivity, thermal cyclic fatigue lifetime and burner rig lifetime was performed. The results were compared with TBCs produced by the standard thermal spray technique, atmospheric plasma spraying (APS). Bondcoats deposited by the emerging high-velocity air fuel (HVAF) spraying were compared to the standard vacuum plasma-sprayed (VPS) bondcoats to investigate the influence of the bondcoat deposition process as well as topcoat–bondcoat interface topography. The results showed that the dense PS-PVD-processed TBC had the highest lifetime, although at an expense of the highest thermal conductivity. The reason for this behavior was attributed to the dense intracolumnar structure, wide intercolumnar gaps and high column density, thus improving the strain tolerance and fracture toughness.

Solid Particle Erosion Behaviour of Plasma Sprayed Coatings on a Fe-Based Superalloy

2005 ◽  
Author(s):  
S. B. Mishra ◽  
S. Prakash ◽  
K. Chandra
Keyword(s):  
Plasma Spray ◽  
Impact Angle ◽  
Silica Sand ◽  
Spray Process ◽  
Air Jet ◽  
Microhardness And Microstructure ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
The Impact ◽  
Sprayed Coatings

In the present investigation plasma sprayed metallic coatings of NiCrAlY and Ni-20Cr were deposited on a Fe-based Superalloy (32Ni-21Cr-1.5Mn-1Si-0.3Ti-0.3Al-0.1C and Balance Fe) by shrouded plasma spray process. NiCrAlY was used as bond coat in both the cases. Erosion studies were conducted on uncoated as well as plasma spray coated superalloy specimens using an air-jet erosion test rig at a velocity of 40m/s and impingement angles of 30° and 90°. Silica sand particles of size ranging between 150 and 212 μm were used as erodent. The coatings have been characterised for porosity, microhardness and microstructure. Erosion behaviours of the superalloy and plasma spray coatings are discussed. Of the two plasma sprayed coatings, the NiCrAlY coating gave the lowest erosion rate regardless of the impact angle.

CHARACTERIZATION OF AS-SPRAYED AND LASER-TREATED ZIRCONIA-BASED PLASMA SPRAYED COATINGS

1990 ◽  
Vol 51 (C5) ◽  
pp. C5-393-C5-402
Author(s):  
A. FERRIERE ◽  
G. FLAMANT ◽  
J.-F. ROBERT ◽  
P. PEKSHEV ◽  
I. SMUROV ◽  
...  
Keyword(s):  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Sprayed Coatings
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