scholarly journals LC/8YSZ TBCs Thermal Cycling Life and Failure Mechanism under Extreme Temperature Gradients

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1051
Author(s):  
Kun Liu ◽  
Xi Chen ◽  
Kangping Du ◽  
Yu Wang ◽  
Jinguang Du ◽  
...  
Keyword(s):  
High Temperature ◽  
Surface Temperature ◽  
Thermal Cycling ◽  
Thermal Shock ◽  
Failure Mechanism ◽  
Extreme Temperature ◽  
Temperature Gradients ◽  
Accelerated Life Test ◽  
Ceramic Layer ◽  
Cycling Life

The purpose of this paper is to study the thermal shock resistance and failure mechanism of La2Ce2O7/8YSZ double-ceramic-layer thermal barrier coatings (LC/8YSZ DCL TBCs) under extreme temperature gradients. At high surface temperatures, thermal shock and infrared temperature measuring modules were used to determine the thermal cycling life and insulation temperature of LC/8YSZ DCL TBCs under extreme temperature gradients by an oxygen–acetylene gas flame testing machine. A viscoelastic model was used to obtain the stress and strain law of solid phase sintering of a coating system using the finite element method. Results and Conclusion: (1) Thermal cycling life was affected by the surface temperature of LC/8YSZ DCL TBCs and decreased sharply with the increase of surface temperature. (2) The LC ceramic surface of the failure coating was sintered, and the higher the temperature, the faster the sintering process. (3) Accelerated life test results showed that high temperature thermal cycling life is not only related to thermal fatigue of ceramic layer, but is also related to the sintering degree of the coating. (4) Although the high temperature thermal stress had great influence on the coating, great sintering stress was produced with sintering of the LC ceramic layer, which is the main cause of LC/8YSZ DCL TBC failure. The above results indicate that for new TBC ceramic materials, especially those for engines above class F, their sinterability should be fully considered. Sintering affects the thermal shock properties at high temperature. Our research results can provide reference for material selection and high temperature performance research.

High temperature Au-based solder reliability in electronic packages for harsh environments

2011 ◽  
Vol 2011 (1) ◽  
pp. 000438-000445
Author(s):  
M.F. Sousa ◽  
S. Riches ◽  
C. Johnston ◽  
P.S. Grant
Keyword(s):  
High Temperature ◽  
Thermal Cycling ◽  
Thermal Shock ◽  
Microstructural Analysis ◽  
Temperature Stability ◽  
Acoustic Microscopy ◽  
Harsh Environments ◽  
Electronic Packages ◽  
High Temperature Stability ◽  
Die Attach

The operation of electronic packages in high temperature environments is a significant challenge for the microelectronics industry, and poses a challenge to the traditional temperature limit of 125°C for high electronic systems, such as those used in down-hole, well-logging and aero-engine applications. The present work aims to develop understanding of how and why attach materials for Si dies degrade/fail under harsh environments by investigating high temperature Au based solders. Au-2wt%Si eutectic melts at < 400°C and offers high temperature stability but high temperature processing and complex manufacturing steps are the major drawbacks. Changes in the die attach material were investigated by isothermal ageing at 350°C, thermal shock and thermal cycling treatments. Die attach reliability investigated by thermal shock and thermal cycling showed that the bonded area degraded. Nevertheless, most of the samples tested had high bonded area ranging from 92.5 to 97.5%. The failure behaviour of the die attach materials included cracking of die and/or attach material, delamination and voiding. Scanning acoustic microscopy images provided a rapid assessment of delamination and other defects and their location within the package. Microstructural analysis and die shear testing were also carried out, along with the high temperature endurance of a SOI test chip for signal conditioning and processing applications at 250°C. All functions evaluated have shown stable performance at 250°C for up to 9000 hours.

Failure Analysis of Thermally Shocked NiCr Films on Mn-Ni-Co Spinel Oxide Substrates

2005 ◽  
Vol 875 ◽  
Author(s):  
Min-Seok Jeon ◽  
Jun-Kwang Song ◽  
Eui-Jong Lee ◽  
Yong-Nam Kim ◽  
Hyun-Gyu Shin ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Thermal Cycling ◽  
Thermal Shock ◽  
Failure Mechanism ◽  
Thick Film ◽  
Sheet Resistance ◽  
Spinel Oxide ◽  
Initial Value ◽  
Shock Chamber ◽  
Oxide Substrates

AbstractNiCr films were thermally evaporated on the Mn-Ni-Co-O thick-film substrates. The NiCr/Mn-Ni-Co-O bi-layer systems were tested in a thermal shock chamber with three temperature differences of 150, 175 and 200°C. The systems were considered to have failed when the sheet resistance of NiCr films changed by 30% relative to an initial value. As the cyclic repetition of thermal shock increased, the sheet resistance of NiCr coatings increased. The Coffin-Manson equation was applied to the failure mechanism of cracking of NiCr coatings and the SEM observation of cracks and delamination in NiCr coatings due to thermal cycling agreed well with the failure mechanism.

Reliability during Thermal Shock Testing of NiCr Films on Mn-Ni-Co Oxide Substrates

2006 ◽  
Vol 317-318 ◽  
pp. 553-556 ◽  
Author(s):  
Min Seok Jeon ◽  
Jun Kwang Song ◽  
Eui Jong Lee ◽  
Hee Soo Lee ◽  
Tae Hyung No ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Thermal Cycling ◽  
Thermal Shock ◽  
Failure Mechanism ◽  
Sheet Resistance ◽  
Temperature Cycling ◽  
Accelerated Testing ◽  
Initial Value ◽  
Shock Testing ◽  
Oxide Substrates

There is an increasing reliability concern of thermal stress-induced failures in multilevel coatings in recent years. This work reports investigations of cracking of NiCr coatings due to thermal cycling. The temperature cycling in accelerated testing was performed in three temperature range of 150, 175 and 200°C. The NiCr coatings were considered to have failed when the sheet resistance changed by 30% relative to an initial value. As the cyclic repetition of thermal shock increased, the sheet resistance of NiCr coatings increased. The Coffin-Manson equation was applied to the failure mechanism of cracking of NiCr coatings and the SEM observation of cracks and delamination in NiCr coatings due to thermal cycling agreed well with the failure mechanism.

Effect of Yb2SiO5 Ceramic Layer Thickness on the Thermal Cycling Life of Yb2SiO5⁄LaMgAl11O19 Coating Deposited on C⁄SiC Composites

2013 ◽  
Vol 537 ◽  
pp. 36-41 ◽  
Author(s):  
Ying Wang ◽  
Bing Lin Zou ◽  
Xi Zhi Fan ◽  
Xue Qiang Cao
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Cycling ◽  
Layer Thickness ◽  
Chemical Stability ◽  
Influencing Mechanism ◽  
Expansion Behavior ◽  
Sic Composites ◽  
Plasma Sprayed ◽  
Cycling Life

C⁄SiC composites were plasma sprayed with Yb2SiO5⁄LaMgAl11O19 (LMA) coatings with varying Yb2SiO5 layer thickness. The effect of Yb2SiO5 layer thickness on the thermal cycling life of the Yb2SiO5LMA coatings was investigated. The results showed that the thermal cycling life is significantly dependent on the Yb2SiO5 layer thickness. It decreased from 130 cycles to 35 cycles as Yb2SiO5 layer thickness increased from 50 µm to 100 µm. Further increasing Yb2SiO5 layer thickness to 200 µm made it decrease to 2 cycles. The influencing mechanism of Yb2SiO5 layer thickness for the thermal cycling life was clarified based on the thermal expansion behavior, the chemical stability at high temperature and the microstructure analysis.

Effect of Thermal Cycling on Lifetime and Failure Mechanism of EB-PVD TBC with NiCoCrAlYZr Bondcoats

2013 ◽  
Vol 652-654 ◽  
pp. 1826-1829
Author(s):  
Peng Song ◽  
Jian Sheng Lu
Keyword(s):  
High Temperature ◽  
Crack Propagation ◽  
Thermal Cycling ◽  
Failure Mechanism ◽  
High Frequency ◽  
Cyclic Oxidation ◽  
Rapid Propagation ◽  
Small Cracks ◽  
Cracks Propagation ◽  
Tbc Systems

EB-PVD TBC with conventional MCrAlY bondcoats was widely used within the high temperature environments. The effect of oxidation frequency on the lifetime of TBC with NiCoCrAlYZr and the failure mechanism was investigated in this paper. The TBC systems with Zr-doped MCrAlY bondocats presented a longer lifetime after discontinuous oxidation than cyclic oxidation. Formation of thick TGO in the TBC-system with Zr-containing bondcoat did not result in an immediate failure. The crack propagation in the case of the Zr-doped NiCoCrAlY bondcoat at the TGO/bondcoat interface was hindered due to the inhomogeneous TGO morphology. The inner oxidation and pores hindered the above small cracks propagation and then result a longer lifetime. However, the lifetime of TBC-system with NiCoCrAlY+Zr bondcoat is significantly shorter in the cyclic than in the discontinuous test due to the rapid propagation of cracks under high frequency thermal cycling conditions.

KUBOTA ALLOY KHR12C

Alloy Digest ◽  
1999 ◽  
Vol 48 (3) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Thermal Cycling ◽  
Tensile Properties ◽  
Casting Alloy ◽  
Type Ii ◽  
Temperature Performance

Abstract Kubota alloy KHR12C is an austenitic Fe-Cr-Ni-Nb casting alloy developed from the well known HH type II grade. This alloy is superior to other grades in components that are subjected to frequent thermal cycling and shock. The alloy is available in both centrifugal and static castings. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on high temperature performance as well as casting and joining. Filing Code: SS-738. Producer or source: Kubota Metal Corporation.

Thermal shock resistance of Ti3SiC2 ceramic under extremely rapid thermal cycling

2021 ◽  
Vol 866 ◽  
pp. 158985
Author(s):  
Xiaojia Su ◽  
Yiwang Bao ◽  
Detian Wan ◽  
Haibin Zhang ◽  
Ludi Xu ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Shock Resistance ◽  
Rapid Thermal Cycling
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