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Thermal shock
About: Thermal shock is a research topic. Over the lifetime, 5012 publications have been published within this topic receiving 58954 citations.
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TL;DR: In this article, the authors analyzed thermal stresses and the stress intensity factor in an edge-cracked strip of a functionally graded material (FGM) subjected to sudden cooling at the cracked surface.
Abstract: We analyze thermal stresses and the stress intensity factor in an edge-cracked strip of a functionally graded material (FGM) subjected to sudden cooling at the cracked surface. It is assumed that the shear modulus of the material decreases hyperbolically with the higher value at the surface exposed to the thermal shock and that the thermal conductivity varies exponentially. Volume fractions of the constituents in a ceramic-metal FGM are then determined with the assumed shear modulus gradient using a three-phase model of conventional composites. The differences between the other assumed material properties and those predicted by the three-phase model are delineated and the applicability of the assumed FGM is discussed. It is shown that the maximum tensile thermal stress in the strip without cracks is substantially reduced by the assumed thermal conductivity gradient and that the magnitude of the compressive stress is increased. A strong compressive zone just away from the thermally shocked surface is devel...
176 citations
TL;DR: In this article, a finite element model was used to estimate the temperatures and stresses in both ceramics during quench testing, and the model predicted that maximum thermal stresses during the experimental quench test exceeded the strength of ZrB2 (568 MPa) but not Zb2-30 vol.% SiC (863 MPa).
172 citations
TL;DR: In this paper, the authors used fused and crushed yttria stabilized zirconia (YSZ) to improve the strain tolerance of atmospheric plasma sprayed (APS) TBCs.
Abstract: Thermal barrier coatings (TBCs) with high strain tolerance are favorable for application in hot gas sections of aircraft turbines. To improve the strain tolerance of atmospheric plasma sprayed (APS) TBCs, 400 μm–500 μm thick coatings with very high segmentation crack densities produced with fused and crushed yttria stabilized zirconia (YSZ) were developed. Using a Triplex II plasma gun and an optimized spraying process, coatings with segmentation crack densities up to 8.9 cracks mm − 1 , and porosity values lower than 6% were obtained. The density of branching cracks was quite low which is inevitable for a good inter-lamellar bonding. Thermal cycling tests yielded promising strain tolerance behavior for the manufactured coatings. Samples with high segmentation crack densities revealed promising lifetime in burner rig tests at rather high surface (1350 °C) and bondcoat temperatures (up to 1085 °C), while coatings with lower crack densities had a reduced performance. Microstructural investigations on cross-sections and fracture surfaces showed that the segmentation crack network was stable during thermal shock testing for different crack densities. The main failure mechanism was delamination and horizontal cracking within the TBC near the thermal grown oxide layer (TGOs) and the TBC.
170 citations
TL;DR: In this paper, the authors investigated the thermal shock behavior of three as-sprayed TBCs at 1000°C and 1200°C with NiCrAlY as the bond coat, and the results indicated that the thermal cycling lifetime of the double-ceramic-layer (DCL) TBC is longer than that of SCL 8YSZ TBC due to the fact that the DCL LZ/8YSZ further enhance the thermal insulation effect, improve the sintering resistance ability and relieve the thermal mismatch between the ceramic layer and the metallic layer at
166 citations
TL;DR: In this paper, nanostructured and conventional zirconia coatings are deposited by atmospheric plasma spraying and the thermal shock resistances of as-sprayed coatings were investigated by the water quenching method.
Abstract: Nanostructured and conventional zirconia coatings were deposited by atmospheric plasma spraying and the thermal shock resistances of as-sprayed coatings were investigated by the water quenching method. The results showed that the nanostructured as-sprayed coating possessed better thermal shock resistance than the conventional coating. This phenomenon is explained in terms of the difference in microstructure and microstructural changes occurring during thermal shock cycling.
161 citations