Interaction of a Crack in the Plasma-Sprayed Ceramic Coating with the Metal Substrate

2005 ◽  
Vol 482 ◽  
pp. 223-226
Author(s):  
Luboš Náhlík ◽  
Zdeněk Knésl ◽  
F. Kroupa
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Surface Crack ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Metal Substrate ◽  
High Density ◽  
Initial Surface ◽  
Young’S Moduli ◽  
Plasma Sprayed

Plasma-sprayed ceramic coatings contain a high density of intrasplat microcracks which are responsible for small Young’s moduli and low fracture toughness. The extension of an initial surface crack in the direction to the interface, where the crack is repelled by the metal substrate with higher Young’s modulus, is studied using the methods of fracture mechanics. It is shown that high tensile stresses induced by the crack in the interface can lead to a local decohesion along the interface so that the crack can deviate into the interface.

Fracture toughness measurement of plasma sprayed ceramic coatings

1989 ◽  
Vol 181 (1-2) ◽  
pp. 407-415 ◽  
Author(s):  
F Beltzung ◽  
G Zambelli ◽  
E Lopez ◽  
A.R Nicoll
Keyword(s):  
Fracture Toughness ◽  
Ceramic Coatings ◽  
Fracture Toughness Measurement ◽  
Plasma Sprayed ◽  
Toughness Measurement

Influence of Surface Microstructure of Ceramic Coatings on the Initiation and Development of Scuffing Phenomena

1998 ◽  
Author(s):  
B. Antoszewski ◽  
W. Zorawski
Keyword(s):  
Friction Force ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Surface Microstructure ◽  
Frictional Pair ◽  
Plasma Sprayed ◽  
Thermally Sprayed

Abstract This paper deals with findings of experiments concerning the scuffing phenomenon in case the frictional pair is embodying an element with a thermally sprayed ceramic coating. The progress of building up of seizure is related and evaluated for a set of ceramic coatings embodying a diversity of granulations of Al2O3TiO2 and Cr2O3 plasma sprayed on steel, the IHI8N9T steel and carbon-graphite when tested on a roller-block machine. The greatest antiscuffing resistance was recorded for Cr2O3/carbon-graphite pair. An analysis of regression approximating friction force was carried through.

Thermal Barrier Effects Comparison of Plasma-Sprayed and Laser-Remelted Al2O3-13 % TiO2 Ceramic Coatings

2014 ◽  
Vol 978 ◽  
pp. 40-43
Author(s):  
Dong Sheng Wang ◽  
Guang Qu ◽  
Jin Lan Su
Keyword(s):  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Nanostructured Coating ◽  
Thermal Barrier ◽  
Heat Current ◽  
Barrier Effect ◽  
Laser Remelting ◽  
Plasma Sprayed ◽  
Sprayed Coatings ◽  
Conventional Coating

Conventional and nanosturctured Al2O3–13 wt% TiO2ceramic coatings were deposited by plasma spraying on TiAl alloy surface. Laser remelting experiment on as-sprayed coatings was carried out and the influences of laser remelting on microstructure and thermal barrier effect of the coating were researched. The results show that the as-sprayed conventional coating has a typical plasma-sprayed lamellar-like structure, while the nanostructured coating consisted of both fully melted regions and partially melted regions. The laser-remelted conventional coating exhibits column-like crystals which grew along the direction of the heat current, while the nanostructured coating composed of fine equiaxed grains with some remained nanoparticles. The nanostructured ceramic coating has higher thermal barrier effect than the conventional ceramic coating does. The thermal barrier effect of the as-sprayed coatings decreases after laser remelting.

The Weibull Distribution of Microhardness in Plasma Sprayed NiCrAl/AT13 Nanostructured Ceramic Coating

2013 ◽  
Vol 321-324 ◽  
pp. 318-323
Author(s):  
Gao Xu Tan ◽  
Tong Wang ◽  
En Bing Bi
Keyword(s):  
Weibull Distribution ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Tem Analysis ◽  
Average Value ◽  
Nanostructured Ceramic ◽  
Microhardness And Microstructure ◽  
Size Of Particles ◽  
Plasma Sprayed ◽  
The Relationship

Al2O3-13% TiO2 based nanostructured ceramic coatings were prepared on the surface of NiCrAl alloy by Plasma Spraying technology. Compared to the micron ceramic coating (MCC), the average value of hardness of nanostructured ceramic coating (NCC) was much higher than that of MCC, and the NCC presents typical bi-modal distribution. The Weibull distribution of both coatings exhibited apparently dispersible, but NCCs was quite well-distributed. The relationship between microhardness and microstructure were analyzed through SEM, XRD and TEM. The results indicate that the microcracks of NCC are fine and the size of particles is small. The structure of NCC coatings contained more α-Al2O3 and TiO2 and less γ-Al2O3 than that of MCC coatings. According to TEM analysis, it can be considered that the grain refinement, toughening of microcracks, and the dispersive refinement of Al2O3 nanoparticles on Al2O3-TiO2 matrix are main mechanisms to improve the mechanical properties of NCC.

scholarly journals Strain Isolated Ceramic Coatings

1983 ◽  
Author(s):  
R. P. Tolokan ◽  
J. B. Brady ◽  
G. P. Jarrabet
Keyword(s):  
Ceramic Coating ◽  
Combustion Engine ◽  
Ceramic Coatings ◽  
Thermal Barrier ◽  
Turbine Engine ◽  
Shock Testing ◽  
Low Modulus ◽  
Metal Strain ◽  
Fiber Metal ◽  
Plasma Sprayed

The durability of thermally shocked high tempererature ceramic coatings on metal substrates can be dramatically improved using a fiber metal strain isolator between ceramic and metal. The fiber metal strain isolator is a compliant, porous and low modulus material which yields to control the stress on the ceramic coating during thermal cycling. Plasma sprayed strain isolated ceramic coatings .060” (1.5 mm) thick have shown excellent durability in thermal shock testing. The strain isolated ceramic coating is an excellent thermal barrier since both the ceramic and fiber metal are good insulators. Applications include ceramic thermal barrier coatings for gas turbine engine seals and turbine components, combustors, MHD electrodes, and internal combustion engine insulation.

Study on Life Extension of Aged RPV Material Based on Probabilistic Fracture Mechanics: Japanese Round Robin

1995 ◽  
Vol 117 (1) ◽  
pp. 7-13 ◽  
Author(s):  
G. Yagawa ◽  
S. Yoshimura ◽  
N. Handa ◽  
T. Uno ◽  
K. Watashi ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Surface Crack ◽  
Round Robin ◽  
Life Extension ◽  
Loading Conditions ◽  
Pressurized Water ◽  
Unique Problem ◽  
Probabilistic Fracture Mechanics ◽  
Failure Probabilities

This paper is concerned with round-robin analyses of probabilistic fracture mechanics (PFM) problems of aged RPV material. Analyzed here is a plate with a semi-elliptical surface crack subjected to various cyclic tensile and bending stresses. A depth and an aspect ratio of the surface crack are assumed to be probabilistic variables. Failure probabilities are calculated using the Monte Carlo methods with the importance sampling or the stratified sampling techniques. Material properties are chosen from the Marshall report, the ASME Code Section XI, and the experiments on a Japanese RPV material carried out by the Life Evaluation (LE) subcommittee of the Japan Welding Engineering Society (JWES), while loads are determined referring to design loading conditions of pressurized water reactors (PWR). Seven organizations participate in this study. At first, the procedures for obtaining reliable PFM solutions with low failure probabilities are examined by solving a unique problem with seven computer programs. The seven solutions agree very well with one another, i.e., by a factor of 2 to 5 in failure probabilities. Next, sensitivity analyses are performed by varying fracture toughness values, loading conditions, and pre and in-service inspections. Finally, life extension simulations based on the PFM analyses are performed. It is clearly demonstrated from these analyses that failure probabilities are so sensitive to the change of fracture toughness values that the degree of neutron irradiation significantly influences the judgment of plant life extension.

Finite Element Analysis of Ceramic Coating Systems Under Spherical Indentation With Metallic Interlayer: Part II — Ring Crack Analysis

2005 ◽  
Author(s):  
Minh-Quy Le ◽  
Jin-Woo Yi ◽  
Seock-Sam Kim
Keyword(s):  
Fracture Mechanics ◽  
Fracture Resistance ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Spherical Indentation ◽  
J Integral ◽  
Element Analysis ◽  
Linear Fracture ◽  
Low Elastic Modulus ◽  
Ductile Substrate

Spherical indentation problems of ceramic coatings/metallic inter-layer/ductile substrate were investigated numerically by axisymmetric FEA for two typical ceramic coatings with relatively high and low elastic modulus deposited on aluminum alloy and carbon steel. The fracture mechanics of the ceramic coatings due to occurrence of surface ring cracks extending traverse coating thickness under spherical indenter were considered under the framework of linear fracture mechanics. The J-integral associated to such cracks was computed. The evolution of J-integral versus crack length and indentation depth was studied. The results show that metallic inter-layers can improve the fracture resistance of the ceramic layer under the same indentation conditions.

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