scholarly journals Influence of SiC Addition on Mechanical Behavior of Thermal Barriers with the Aid of Acoustic Emission

2021 ◽  
Vol 5 (1) ◽  
pp. 16
Author(s):  
David Jeronimo Busquets ◽  
Carlos Bloem ◽  
Amparo Borrell ◽  
Maria Dolores Salvador
Keyword(s):  
Acoustic Emission ◽  
Mechanical Behavior ◽  
Thermal Barrier Coatings ◽  
Wavelet Transforms ◽  
Coefficient Of Thermal Expansion ◽  
Microstructural Analysis ◽  
Thermal Barrier ◽  
Transfer Coefficients ◽  
Barrier Coatings ◽  
Thermal Barriers

The improvement of high temperature materials with lower heat transfer coefficients lead to the development of thermal barrier coatings (TBCs). One of the most widely used materials for thermal barrier coatings is Y2O3 stabilized ZrO2 (Y-TZP) because of its excellent shock resistance, low thermal conductivity, and relatively high coefficient of thermal expansion. The aim of this work is to study the TBCs mechanical behavior with the addition of SiC into the suspension of Y-TZP/Al2O3 by acoustic emission (AE). Additionally, a microstructural analysis and a finite elements model were carried out in order to compare results. The coatings were made by suspension plasma spray (SPS) on metal plates of 70 × 12 × 2 mm3. An intermetallic was deposited as a bond coating, followed by a coating of Y-TZP/Al2O3 with and without 15 wt.% SiC, with thicknesses between 87 and 161 μm. The AE becomes a fundamental tool in the study of the mechanical behavior of thermal barriers. The use of wavelet transforms streamlines the study and analysis of recorded sound spectra. The crack generation arises at very low stress levels.

Finite Element Analysis of Thermal-Mechanical Behavior in the Thermal Barrier Coatings With Cooling Hole Structure

2017 ◽  
Author(s):  
Jishen Jiang ◽  
Zhenwei Cai ◽  
Weizhe Wang ◽  
Yingzheng Liu
Keyword(s):  
Mechanical Behavior ◽  
Thermal Barrier Coatings ◽  
Film Cooling ◽  
Operating Conditions ◽  
Thermal Barrier ◽  
Transfer Coefficients ◽  
Adiabatic Wall ◽  
Element Analysis ◽  
Barrier Coatings ◽  
Cooling Hole

The present work aims to investigate the thermal-mechanical behavior in thermal barrier coatings (TBCs) with a round film cooling hole under gas turbine operating conditions. The adiabatic wall temperatures and surface heat transfer coefficients are firstly calculated for thermal boundary conditions. Subsequently, stress analyses during both thermal exposure and cooling down period are presented. The results show that: although the cooling hole has lower temperature, large stress concentration still appears because of the geometry of cooling holes and thermal mismatch between TBCs and substrate. The huge thermal stress may lead to pre-mature failure of TBCs, which should be carefully considered in the design of film cooling-TBC system.

Life approximation of thermal barrier coatings via quantitative microstructural analysis

2012 ◽  
Vol 549 ◽  
pp. 76-81 ◽  
Author(s):  
C. Bargraser ◽  
P. Mohan ◽  
K. Lee ◽  
B. Yang ◽  
J. Suk ◽  
...  
Keyword(s):  
Thermal Barrier Coatings ◽  
Microstructural Analysis ◽  
Thermal Barrier ◽  
Barrier Coatings

Evaluation of CeSZ Thermal Barrier Coatings for Diesels

2000 ◽  
Author(s):  
P.J. Huang ◽  
J.J. Swab ◽  
P.J. Patel ◽  
W.S. Chu
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Thermal Barrier Coatings ◽  
Coefficient Of Thermal Expansion ◽  
Fuel Efficiency ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Mechanical And Thermal Properties ◽  
Barrier Coatings ◽  
Spray Process

Abstract The development of thermal barrier coatings (TBCs) for diesel engines has been driven by the potential improvements in engine power and fuel efficiency that TBCs represent. TBCs have been employed for many years to reduce corrosion of valves and pistons because of their high temperature durability and thermal insulative properties. There are research programs to improve TBCs wear resistance to allow for its use in tribologically intensive areas of the engine. This paper will present results from tribological tests of ceria stabilized zirconia (CeSZ). The CeSZ was applied by atmospheric plasma spray process. Various mechanical and thermal properties were measured including wear, coefficient of thermal expansion, thermal conductivity, and microhardness. The results show the potential use of CeSZ in wear sensitive applications in diesel applications. Keywords: Thermal Barrier Coating, Diesel Engine, Wear, Thermal Conductivity, and Thermal Expansion

Modeling Effects of Material Properties and Three-Dimensional Surface Roughness on Thermal Barrier Coatings

2000 ◽  
Vol 645 ◽  
Author(s):  
Michael L. Glynn ◽  
K.T. Ramesh ◽  
P.K. Wright ◽  
K.J. Hemker
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Thermal Barrier Coatings ◽  
Material Properties ◽  
Bond Coat ◽  
Coefficient Of Thermal Expansion ◽  
Three Dimensional ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Dimensional Surface

ABSTRACTThermal barrier coatings (TBCs) are known to spall as a result of the residual stresses that develop during thermal cycling. TBC's are multi-layered coatings comprised of a metallic bond coat, thermally grown oxide and the ceramic top coat, all on top of a Ni-base superalloy substrate. The development of residual stresses is related to the generation of thermal, elastic and plastic strains in each of the layers. The focus of the current study is the development of a finite element analysis (FEA) that will model the development of residual stresses in these layers. Both interfacial roughness and material parameters (e.g., modulus of elasticity, coefficient of thermal expansion and stress relaxation of the bond coat) play a significant role in the development of residual stresses. The FEA developed in this work incorporates both of these effects and will be used to study the consequence of interface roughness, as measured in SEM micrographs, and material properties, that are being measured in a parallel project, on the development of these stresses. In this paper, the effect of an idealized three-dimensional surface roughness is compared to residual stresses resulting from a grooved surface formed by revolving a sinusoidal wave about an axis of symmetry. It is shown that cylindrical and flat button models give similar results, while the 3-D model results in stresses that are significantly larger than the stresses predicted in 2-D.

Quantitative Microstructural Analysis of Thermal Barrier Coatings Deposited on Inconel 625

2013 ◽  
Vol 197 ◽  
pp. 70-76 ◽  
Author(s):  
Grzegorz Galant ◽  
Jan Dulęba ◽  
Sebastian Toczek ◽  
Beata Dubiel ◽  
Aleksandra Czyrska-Filemonowicz
Keyword(s):  
Quantitative Analysis ◽  
Thermal Barrier Coatings ◽  
Microstructural Analysis ◽  
Deposition Process ◽  
Inconel 625 ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Microstructural Parameters ◽  
Macroscopic Observation

The aim of the present work was to determine the influence of air plasma spraying (APS) parameters on the microstructure of thermal barrier coatings (TBC) consisting on NiCoCrAlY bond coat and yttria - stabilized zirconia (YSZ) top coat. The scope of the investigation involved macroscopic observation and microstructural analysis by means of light microscopy (LM) and scanning electron microscopy (SEM). For the varied parameters of deposition process quantitative analysis of coatings thickness, porosity, oxide inclusions, metallic inclusions, globular inclusions and cracks were performed. The results of quantitative analysis allowed to establish which APS conditions influence the particular microstructural parameters of TBC coatings.

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