3D microstructure model and thermal shock failure mechanism of a Si3N4-bonded SiC ceramic refractory with SiC high volume ratio particles

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.

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Evaluations of cooling rate and initial temperature on thermal shock behavior of ZrB2-SiC ceramic

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2018.01.173 ◽

2018 ◽

Vol 741 ◽

pp. 509-513 ◽

Cited By ~ 6

Author(s):

Anzhe Wang ◽

Ping Hu ◽

Cheng Fang ◽

Dongyang Zhang ◽

Xinghong Zhang

Keyword(s):

Thermal Shock ◽

Cooling Rate ◽

Initial Temperature ◽

Sic Ceramic ◽

Thermal Shock Behavior

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Failure Modes of a Laminated Composite With Complaint Interlayers

Journal of Applied Mechanics ◽

10.1115/1.4049078 ◽

2020 ◽

Vol 88 (3) ◽

Author(s):

M. R. O’Masta ◽

V. S. Deshpande

Keyword(s):

Failure Mechanism ◽

Failure Mode ◽

Failure Modes ◽

Volume Fraction ◽

Flexural Rigidity ◽

Laminated Composite ◽

High Volume ◽

Tensile Fracture ◽

Reduced Order ◽

Fe Simulations

Abstract Composites comprising a high-volume fraction of stiff reinforcements within a compliant matrix are commonly found in natural materials. The disparate properties of the constituent materials endow resilience to the composite, and here we report an investigation into some of the mechanisms at play. We report experiments and simulations of a prototype laminated composite system comprising silicon layers separated by polymer interlayers, where the only failure mechanism is the tensile fracture of the brittle silicon. Two failure modes are observed for such composites loaded in three-point bending: failure under the central roller in (i) the top ply (in contact with the roller) or (ii) the bottom ply (free surface). The former mode is benign with the beam retaining load carrying capacity, whereas the latter leads to catastrophic beam failure. Finite element (FE) simulations confirm this transition in failure mode and inform the development of a reduced order model. Good agreement is shown between measurements, FE simulations, and reduced order predictions, capturing the effects of material and geometric properties on the flexural rigidity, first ply failure mode, and failure load. A failure mechanism map for this system is reported that can be used to inform the design of such laminated composites.

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Analysis and Design of Multistage Electrostatically-Actuated Micro Vacuum Pumps

Microelectromechanical Systems ◽

10.1115/imece2002-39308 ◽

2002 ◽

Cited By ~ 5

Author(s):

Aaron Astle ◽

Anthony Paige ◽

Luis P. Bernal ◽

Jennifer Munfakh ◽

Hanseup Kim ◽

...

Keyword(s):

Thermodynamic Model ◽

Volume Ratio ◽

High Volume ◽

Fixed Number ◽

Vacuum Pump ◽

Pump Performance ◽

Analysis And Design ◽

Electrostatically Actuated ◽

Flow Through ◽

Low Volume

A new concept for a MEMS-fabricated micro vacuum pump is proposed. The pump is designed to operate in air and can be easily integrated into MEMS-fabricated micro fluidic systems. The pump consists of a series of pumping cavities with electrostatically actuated membranes interconnected by electrostatically actuated microvalves. A thermodynamic model of the micropump has been developed and used to determine the pump performance. It is shown that volume ratio plays an important role in the operation of the pump. For a fixed number of stages, at high volume ratio, pumping action is uniformly distributed among the stages. In contrast, at low volume ratio most of the pumping takes place in the latter stages of the pump. Detailed calculations of the flow through key components of the micropump are also reported. In particular the flow through a checkerboard microvalve and electrode perforations is discussed, and new correlations for the pressure loss in these components are proposed.

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Sic Based Ceramic Foams Reinforced by In Situ Mullite Whisker

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.79-82.1983 ◽

2009 ◽

Vol 79-82 ◽

pp. 1983-1986 ◽

Cited By ~ 1

Author(s):

Xiao Li Ji ◽

Fei Xu ◽

Hai Ya Chen

Keyword(s):

Compressive Strength ◽

Thermal Shock ◽

Thermal Shock Resistance ◽

Ceramic Foams ◽

Sic Ceramic ◽

Influence Of Temperature On ◽

Shock Resistance ◽

Mullite Whiskers ◽

Maximum Compressive Strength

Prepared silicon carbide(SiC) ceramic foams combined with mullite whiskers which synthesized by in-situ reaction. Studied on the influence of temperature on the synthesis of mullite whisker, and the influence of mullite content on the compressive strength, thermal shock resistance of SiC ceramic foams. The results indicate that the performance of mullite whiskers synthesized at 1400°Cwere best, when mullite content was 25%, SiC ceramic foams could reach the maximum compressive strength for 1.75MP, the most thermal shock resistance for14 times.

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