Interlamellar cracking of thermal barrier coatings with TGOs by non-standard four-point bending tests

2011 ◽  
Vol 528 (25-26) ◽  
pp. 7641-7647 ◽  
Author(s):  
P.F. Zhao ◽  
X.D. Li ◽  
F.L. Shang ◽  
C.J. Li
Keyword(s):  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Bending Tests ◽  
Four Point Bending

Mechanical Properties of Thermal Barrier Coatings at Room Temperature

2005 ◽  
Vol 290 ◽  
pp. 336-339 ◽  
Author(s):  
G. Guidoni ◽  
Y. Torres Hernández ◽  
Marc Anglada
Keyword(s):  
Mechanical Properties ◽  
Thermal Barrier Coatings ◽  
Room Temperature ◽  
Inconel 625 ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Bending Tests ◽  
Four Point Bending ◽  
Barrier Coating ◽  
Plasma Sprayed

Four point bending tests have been carried out on a thermal barrier coating (TBC) system, at room temperature. The TBC system consisted of a plasma sprayed Y-TZP top coat with 8 % in weight of Yttria, a bond coat of NiCrAlY and a Ni-based superalloy Inconel 625 as substrate. The TBC coating was deposited on both sides of the prismatic specimens. Efforts have been done in detecting the damage of the coating by means of Maltzbender et al [1] model.

Finite Element Modelling of TBC Failure Mechanisms by Using XFEM

2018 ◽  
Author(s):  
Safa Mesut Bostancı ◽  
Ercan Gürses ◽  
Demirkan Çöker
Keyword(s):  
Finite Element ◽  
Thermal Barrier Coatings ◽  
Failure Mechanisms ◽  
Crack Spacing ◽  
Experimental Results ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Finite Element Software ◽  
Four Point Bending ◽  
Average Crack

Thermal Barrier Coatings have been widely used in modern turbine engines to protect the nickel based metal substrate from the high temperature service conditions, 1600–1800 K. In this study, some of the failure mechanisms of typical Air Plasma Sprayed Thermal Barrier Coatings (TBC) used in after-burner structures composed of three major layers: Inconel 718 substrate, NiCrAlY based metallic bond coat (BC) and Yttria Stabilized Zirconia (YSZ) based ceramic top coat (TC) are investigated. Investigation of the cracking mechanism of TBC in terms of design and performance is very important because the behavior of TBCs on ductile metallic substrates is brittle. To this end, four-point bending experiments conducted in Kütükoğlu (2015) is analyzed by using the Extended Finite Element Method (XFEM). All the analyses are conducted with the commercial finite element software ABAQUS. Three different models with varying TC and BC thicknesses are studied under four-point bending. It is observed that multiple vertical cracks are initiated in the TC. Cracks initiate at the top of YSZ and propagate through the whole TC. It is observed that the average crack spacing increases with the increasing thickness of the TC. Numerical results are found to be consistent with the experimental results. In other words, the average crack spacing for three different models are similar with the experimental results.

Near-Interface Crack Initiation in Thermal Barrier Coatings

1999 ◽  
Vol 586 ◽  
Author(s):  
Z. Zhang ◽  
T. E. Bloomer ◽  
J. Kameda ◽  
S. Sakurai
Keyword(s):  
Tensile Stress ◽  
Thermal Barrier Coatings ◽  
Volume Effect ◽  
Thermal Barrier ◽  
Cracking Behavior ◽  
Barrier Coatings ◽  
Stressed Volume ◽  
Four Point Bending ◽  
Principal Tensile Stress ◽  
Similar Mode

ABSTRACTThe delamination behavior of thermal barrier coatings (TBC) in transition ducts of inservice used combusters has been characterized using a protruded four-point bending testing technique recently developed by the authors. A reinforced protruded TBC specimen allowed the formation of TBC cracks adjacent to the TBC/alumina interface in a similar mode to inservice TBC failure. Finite element stress analysis showed that a peak transverse stress appeared in a protruded TBC part away from the interface and a large principal tensile stress operated on planes inclined to the interface. It was found that the onset of near-interface TBC cracks in the protruded TBC specimen did not occur under the high transverse and principal tensile stresses. The critical local tensile stress for the onset of TBC cracks near the interface, estimated to be 127 MPa, was lower than that of the near-center TBC. The near-interface TBC cracking behavior in the protruded TBC tests is discussed in light of the residual stress distribution and stressed volume effect.

scholarly journals Characterization of the mechanical properties of thermal barrier coatings by 3 points bending tests and modified small punch tests

2017 ◽  
Vol 332 ◽  
pp. 40-46 ◽  
Author(s):  
Pierre Planques ◽  
Vanessa Vidal ◽  
Philippe Lours ◽  
Vincent Proton ◽  
Fabrice Crabos ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Bending Tests ◽  
Small Punch

scholarly journals Protruded Four-Point Bending Testing Method and Characterization of Near Interface Cracking in Thermal Barrier Coatings

1999 ◽  
Author(s):  
Zhehua Zhang ◽  
T. E. Bloomer ◽  
J. Kameda ◽  
S. Sakurai
Keyword(s):  
Stress Distribution ◽  
Thermal Barrier Coatings ◽  
Local Stress ◽  
Thermal Barrier ◽  
Element Analysis ◽  
Cracking Behavior ◽  
Barrier Coatings ◽  
Testing Method ◽  
Four Point Bending ◽  
Plasma Sprayed

A protruded four-point bending testing method has been developed to characterize the crack initiation of thermal barrier coatings (TBC) near the interface. Two types of protruded TBC specimens, with and without a reinforcement attached on the top of the protruded TBC, were prepared from in-service used transition ducts made of TBC (6% Y2O3 stabilized ZrO2) and bond coatings (NiCoCrAlY) plasma-sprayed over a superalloy substrate. In the unreinforced protruded TBC specimen tests, pre-existing TBC cracks extended in the transverse direction while near interface TBC cracking did not occur. The reinforced protruded TBC specimen hindered the transverse TBC cracking and allowed the formation of TBC cracks adjacent to the oxidized TBC/bond coating interface in a similar mode to in-service TBC spalling. The onset of TBC cracks was identified by a change in the loading rate in the elastic deformation regime. The local stress distribution at the edges of the reinforced protruded TBC was analyzed using finite element analysis. The critical local tensile stress for the initiation of TBC cracks near the interface was estimated for the in-service used transition duct. The near interface TBC cracking behavior in the protruded TBC tests is discussed in light of the applied and residual stress distribution.

scholarly journals Influence of substrate twisting on Young's modulus measured by four-point bending test for thermal barrier coatings

2017 ◽  
Vol 4 (5) ◽  
pp. 16-00714-16-00714
Author(s):  
Masahiko KATO ◽  
Yuuki MATSUO ◽  
Hiroyuki WAKI ◽  
Satoru TAKAHASHI ◽  
Hiroyuki AKEBONO ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Thermal Barrier Coatings ◽  
Young's Modulus ◽  
Bending Test ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Four Point Bending ◽  
Four Point Bending Test ◽  
Influence Of Substrate

Acoustic Emission Evaluation of Thermal Barrier Coatings Using the Three Point Bending Test

1991 ◽  
Author(s):  
A. T. J. Verbeek ◽  
J. M. Houben ◽  
J. A. Klostermann
Keyword(s):  
Acoustic Emission ◽  
Thermal Barrier Coatings ◽  
Light And Electron Microscopy ◽  
Wide Band ◽  
Bending Test ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Bending Tests ◽  
Three Point Bending ◽  
Resonance Sensor

Thermal Barrier coatings were tested in three point bending tests, combined with acoustic emission evaluation. The test specimens consist of a 2 mm substrate with a 0.1 mm FeCrAlY bondcoat and a 0.3 mm ZrO2/Y2O3 93/7.8 weight % topcoat. Both the topcoat and the bondcoat were air plasma sprayed under varying conditions of the substrate cooling and the length of the plasma flame. On investigating the microstructure of the coatings, using light and electron microscopy, differences could be observed, due to the various spraying techniques. The coated specimens were tested in a tensile testing machine equiped with a special tool for three point bending tests. During bending, acoustic emissions from the coating were measured, using a two channel acoustic emission apparatus. Two types of AE sensors were used, namely a 150 kHz resonance sensor and a 0.1 −1 MHz wide band sensor. The various coatings show different AE patterns, especially the bondcoats which showed differences according to the spraying techniques. The use of wide band sensors had some advantages, however they were less sensitive than resonance sensors, they take signals that were received by the resonance ones. After testing, the specimens were prepared and microscopically investigated. Herewith it was possible to establish a relationship between the measured AE signal and the type of coating and coating failure.

Fracture characteristics of thermal barrier coatings after tensile and bending tests

2002 ◽  
Vol 157 (2-3) ◽  
pp. 118-127 ◽  
Author(s):  
Y.C Zhou ◽  
T Tonomori ◽  
A Yoshida ◽  
L Liu ◽  
G Bignall ◽  
...  
Keyword(s):  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Fracture Characteristics ◽  
Bending Tests
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