Fatigue behavior of a freestanding Pt-aluminide (PtAl) bond coat at ambient temperature

2021 ◽  
pp. 127787
Author(s):  
Mahesh K. Kumawat ◽  
Rajdeep Sarkar ◽  
Vikram Jayaram ◽  
Zafir Alam
Keyword(s):  
Ambient Temperature ◽  
Bond Coat ◽  
Fatigue Behavior

scholarly journals Experimental and Modeling Studies of Bond Coat Species Effect on Microstructure Evolution in EB-PVD Thermal Barrier Coatings in Cyclic Thermal Environments

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 626 ◽  
Author(s):  
Zhe Lu ◽  
Guanlin Lyu ◽  
Abhilash Gulhane ◽  
Hyeon-Myeong Park ◽  
Jun Seong Kim ◽  
...  
Keyword(s):  
Thermal Fatigue ◽  
Bond Coat ◽  
Physical Vapor Deposition ◽  
Fatigue Behavior ◽  
Equivalent Stress ◽  
Thermal Barrier ◽  
Fe Model ◽  
Air Plasma ◽  
Thermal Environments ◽  
Species Effect

In this work, the effects of bond coat species on the thermal barrier coating (TBC) microstructure are investigated under thermal cyclic conditions. The TBC samples are prepared by electron beam-physical vapor deposition with two species of bond coats prepared by either air-plasma spray (APS) or high-velocity oxygen fuel (HVOF) methods. The TBC samples are evaluated in a variety of thermal cyclic conditions, including flame thermal fatigue (FTF), cyclic furnace thermal fatigue (CFTF), and thermal shock (TS) tests. In FTF test, the interface microstructures of TBC samples show a sound condition without any delamination or cracking. In CFTF and TS tests, the TBCs with the HVOF bond coat demonstrate better thermal durability than that by APS. In parallel with the experiments, a finite element (FE) model is developed. Using a transient thermal analysis, the high-temperature creep-fatigue behavior of the TBC samples is simulated similar to the conditions used in CFTF test. The FE simulation predicts a lower equivalent stress at the interface between the top coat and bond coat in bond coat prepared using HVOF compared with APS, suggesting a longer cyclic life of the coating with the HVOF bond coat, which is consistent with the experimental observation.

Tensile and Fatigue Behavior of an Austenitic Stainless CrNi-Steel at 10 MPa Hydrogen Gas Atmosphere

2017 ◽  
Author(s):  
Martina Schwarz ◽  
Erich Sattler ◽  
Stefan Zickler ◽  
Stefan Weihe
Keyword(s):  
Hydrogen Embrittlement ◽  
Ambient Temperature ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Nickel Content ◽  
Hydrogen Gas ◽  
Material Behavior ◽  
Relative Reduction ◽  
Nominal Composition ◽  
Gas Atmosphere

To understand the role of nickel in austenitic stainless steels, six heats were produced from one nominal composition differing in the nickel content between 9 % and 13 %. To characterize the material behavior in hydrogen gas atmosphere at 10 MPa, tensile and fatigue testing was conducted at ambient temperature and at 223 K. The susceptibility to hydrogen embrittlement clearly decreases with increasing nickel content both at ambient temperature and at 223 K. But at low temperature the relative reduction of area is less and thus hydrogen embrittlement is intensified. Fatigue tests confirmed these results as the reduction of the fatigue life is strongly dependent on the nickel content and the temperature. The influence of the test frequency was investigated at 4 different frequency levels. A low frequency slightly increases the susceptibility to hydrogen embrittlement. To gain a better understanding of hydrogen embrittlement and its influences the crack growth behavior was analyzed in detail.

Mechanical Properties and Damage Durability of Thermal Barrier Coatings with Thermal Fatigue

2006 ◽  
Vol 317-318 ◽  
pp. 525-528
Author(s):  
Hyung Jun Jang ◽  
Dong Beak Kim ◽  
Yeon Gil Jung ◽  
Jung Chel Chang ◽  
Sung Churl Choi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Barrier Coatings ◽  
Thermal Fatigue ◽  
Bond Coat ◽  
Fatigue Behavior ◽  
Cyclic Fatigue ◽  
Thermal Barrier ◽  
Contact Damage ◽  
Barrier Coatings ◽  
Different Thickness

The effects of thermal fatigue conditions on the mechanical and contact damage behavior in thermal barrier coatings (TBCs) are investigated as functions of the bond coat thickness and the preparation method. Three kinds of TBCs with different thickness in the bond coat are prepared by two different methods of APS and HVOF. The static and cyclic thermal fatigues for the TBCs are conducted at temperatures of 950 and 1100 with different dwell times of 10 and 100 hr and 10 cycles at each temperature. Mechanical properties, hardness H and modulus E, in each condition and component are measured by nano-indentation. The contact damage behaviors are investigated by Hertzian indentation, including the cyclic fatigue behavior on the surface of the TBCs. The TGO formation is dependent on both temperature tested and time exposed, showing a similar effect with the cyclic thermal fatigues. The mechanical properties of the TBCs are increased due to the re-sintering of the top coating and the composition change of the bond coat during the thermal fatigues. The contact damage behaviors are affected by the thermal fatigue conditions and the fabrication method, independent of the bond coat thickness.

scholarly journals Thermal Fatigue Behavior of Air-Plasma Sprayed Thermal Barrier Coating with Bond Coat Species in Cyclic Thermal Exposure

Materials ◽  
2013 ◽  
Vol 6 (8) ◽  
pp. 3387-3403 ◽  
Author(s):  
Zhe Lu ◽  
Sang-Won Myoung ◽  
Yeon-Gil Jung ◽  
Govindasamy Balakrishnan ◽  
Jeongseung Lee ◽  
...  
Keyword(s):  
Thermal Barrier Coating ◽  
Thermal Fatigue ◽  
Bond Coat ◽  
Fatigue Behavior ◽  
Thermal Exposure ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coating ◽  
Thermal Fatigue Behavior ◽  
Plasma Sprayed

SEM of non-coated hepatocellular cytoskeleton of perfused livers

1984 ◽  
Vol 42 ◽  
pp. 306-307
Author(s):  
S.W. French ◽  
N.C. Benson ◽  
C. Davis-Scibienski
Keyword(s):  
Ambient Temperature ◽  
Critical Point ◽  
Protease Inhibitors ◽  
Metal Deposition ◽  
Heat Damage ◽  
Detergent Extraction ◽  
Cytoskeletal Elements ◽  
Triton X ◽  
Excised Tissue

Previous SEM studies of liver cytoskeletal elements have encountered technical difficulties such as variable metal coating and heat damage which occurs during metal deposition. The majority of studies involving evaluation of the cell cytoskeleton have been limited to cells which could be isolated, maintained in culture as a monolayer and thus easily extracted. Detergent extraction of excised tissue by immersion has often been unsatisfactory beyond the depth of several cells. These disadvantages have been avoided in the present study. Whole C3H mouse livers were perfused in situ with 0.5% Triton X-100 in a modified Jahn's buffer including protease inhibitors. Perfusion was continued for 1 to 2 hours at ambient temperature. The liver was then perfused with a 2% buffered gluteraldehyde solution. Liver samples including spontaneous tumors were then maintained in buffered gluteraldehyde for 2 hours. Samples were processed for SEM and TEM using the modified thicarbohydrazide procedure of Malich and Wilson, cryofractured, and critical point dried (CPD). Some samples were mechanically fractured after CPD.

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