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.

Effects of Feedstocks and Laser Remelting on Microstructural Characteristics of ZrO2-7wt.%Y2O3 Thermal Barrier Coatings Prepared by Plasma Spraying

2020 ◽  
Vol 984 ◽  
pp. 23-30
Author(s):  
Dong Sheng Wang
Keyword(s):  
Plasma Spraying ◽  
Thermal Barrier Coatings ◽  
Ceramic Coating ◽  
Nanostructured Coating ◽  
Thermal Barrier ◽  
Laser Remelting ◽  
Barrier Coatings ◽  
Melted Region ◽  
Plasma Sprayed ◽  
Conventional Coating

Conventional and nanometer aggregate ZrO2-7wt.%Y2O3 ceramic powders taken as raw materials, plasma spraying and plasma spraying-laser remelting compound technology was used to prepare conventional and nanostructured thermal barrier coatings on the TiAl alloy surface. Effects of powder structure (feedstock) and laser remelting on organizational structure and phase of the coatings were analyzed using scanning electron microscope (SEM) and X-ray diffractometer (XRD). Results indicate that: conventional plasma sprayed ceramic coating presents typical lamellar stacking features; plasma sprayed nanostructured coating consists of fully melted region and partially melted region, presenting a two-phase structure. Under the comprehensive impacts of laser power, energy density, temperature field distribution in the laser action region, ceramic heat conductivity coefficient and coating thickness and other factors, the coating presents obvious lamellar structural features after laser remelting; the upper part is compact columnar crystal remelting region and the lower part is residual plasma spraying region. Due to toughening effect of residual nanoparticles in the remelting region of laser remelted nanostructured coating, grain-boundary strength is high and there are a considerable number of transgranular fractures, but the fractures in the remelting region of laser remelted conventional coating are basically intergranular fractures. Conventional plasma sprayed ceramic coating is mainly of tetragonal phase together with a small quantity of monoclinic phases, but nanometer plasma sprayed ceramic coating only has non-equilibrium tetragonal phases. After laser remelting, both conventional coating and nanometer coating mainly have non-equilibrium tetragonal phases with a small quantity of cubic phases.

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.

Nano-SiC Modified Plasma Sprayed Ceramic Coatings Prepared by Laser Sintering

2008 ◽  
Vol 375-376 ◽  
pp. 348-352 ◽  
Author(s):  
Zong Jun Tian ◽  
Li Da Shen ◽  
Yin Hui Huang ◽  
Guo Ran Hua
Keyword(s):  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Laser Sintering ◽  
Laser Remelting ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Coating ◽  
Plasma Sprayed ◽  
Steel Substrates ◽  
Electronic Microscope

This paper describes an investigation of nano-SiC reinforced ceramic coating, which has included NiCrAl and Al2O3+13wt%TiO2 coatings pre-produced by atmosphere plasma spraying, implemented by laser sintering. Commercial NiCrAl powders were plasma sprayed onto 45 steel substrates to produce a bond coating with thickness of ~100μm. The Al2O3-TiO2 based coating with ~500μm thickness was then plasma sprayed on top of the NiCrAl bond coating. With CO2 laser, nano-SiC powders were laser sintered on Al2O3-TiO2 based coatings. The microstructure and chemical composition of the modified based coatings were analyzed by such detection devices as scanning electronic microscope (SEM) and x-ray diffraction (XRD). The results show that the size of SiC grains has no obvious growth. In addition, due to the nanostructured SiC phase and laser remelting, the modified coatings exhibited better abrasion resistance than those unmodified samples.

Characterization of thermal barrier coatings formed by electon-beam physical vapor deposition (EB-PVD)

1989 ◽  
Vol 47 ◽  
pp. 426-427
Author(s):  
Ozer Unal
Keyword(s):  
Thermal Barrier Coatings ◽  
Physical Vapor Deposition ◽  
Ceramic Coating ◽  
High Vacuum ◽  
Ceramic Coatings ◽  
High Energy ◽  
Thermal Barrier ◽  
Protective Oxide ◽  
Barrier Coatings ◽  
Energy Beam

Interest in ceramics as thermal barrier coatings for hot components of turbine engines has increased rapidly over the last decade. The primary reason for this is the significant reduction in heat load and increased chemical inertness against corrosive species with the ceramic coating materials. Among other candidates, partially-stabilized zirconia is the focus of attention mainly because ot its low thermal conductivity and high thermal expansion coefficient.The coatings were made by Garrett Turbine Engine Company. Ni-base super-alloy was used as the substrate and later a bond-coating with high Al activity was formed over it. The ceramic coatings, with a thickness of about 50 μm, were formed by EB-PVD in a high-vacuum chamber by heating the target material (ZrO2-20 w/0 Y2O3) above its evaporation temperaturef >3500 °C) with a high-energy beam and condensing the resulting vapor onto a rotating heated substrate. A heat treatment in an oxidizing environment was performed later on to form a protective oxide layer to improve the adhesion between the ceramic coating and substrate. Bulk samples were studied by utilizing a Scintag diffractometer and a JEOL JXA-840 SEM; examinations of cross-sectional thin-films of the interface region were performed in a Philips CM 30 TEM operating at 300 kV and for chemical analysis a KEVEX X-ray spectrometer (EDS) was used.

scholarly journals Ceramic Thermal Barrier Coatings for Turbine Engine Components

1982 ◽  
Author(s):  
D. S. Duvall ◽  
D. L. Ruckle
Keyword(s):  
Thermal Barrier Coatings ◽  
Ceramic Coatings ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Turbine Engine ◽  
Thermal Environments ◽  
Strain Tolerance ◽  
Endurance Testing ◽  
Plasma Sprayed ◽  
Cooling Air

The durability of plasma sprayed ceramic thermal barrier coatings subjected to cyclic thermal environments has been improved substantially by improving the strain tolerance of the ceramic structure and also by controlling the substrate temperature during the application of the coating. Improved strain tolerance was achieved by using ceramic structures with increased porosity, microcracking or segmentation. Plasma spraying on a controlled-temperature substrate also has been shown to improve durability by reducing harmful residual stresses. The most promising of the strain tolerant ceramic coatings have survived up to 6000 cycles of engine endurance testing with no coating or vane platform damage. In side-by-side engine tests, thermal barrier coatings have shown that they greatly reduce platform distress compared to conventionally coated vanes in addition to permitting reductions in cooling air and attendant increases in engine efficiency.

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.

Simulation of Thermal Barrier Plasma-Sprayed Coatings

1990 ◽  
Vol 190 ◽  
Author(s):  
Mauro Ferrari ◽  
John H. Harding ◽  
Maurizio Marchese
Keyword(s):  
Thermal Barrier ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Sprayed Coatings

scholarly journals A Comparison between CoNiCrAlY Bond Coat and Zirconia Plasma Sprayed Coatings on Creep Tests

2008 ◽  
Vol 591-593 ◽  
pp. 30-35
Author(s):  
Danieli A.P. Reis ◽  
Carlos de Moura Neto ◽  
Antônio Augusto Couto ◽  
Cosme Roberto Moreira Silva ◽  
Francisco Piorino Neto ◽  
...  
Keyword(s):  
Bond Coat ◽  
Ceramic Coating ◽  
Constant Load ◽  
Creep Tests ◽  
Engineering Ceramic ◽  
Wide Range ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Engine Components ◽  
Sprayed Coatings

Thermomechanical and electrical properties of zirconia-based ceramics have led to a wide range of advanced and engineering ceramic applications like solid electrolyte in oxygen sensors, fuel cells and furnace elements and its low thermal conductivity has allowed its use for thermal barrier coatings for aerospace engine components. A comparison between CoNiCrAlY bond coat and zirconia plasma sprayed coatings on creep tests of the Ti-6Al-4V alloy was studied. The material used was commercial Ti-6Al-4V alloy. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. Constant load creep tests were conducted on a standard creep machine in air on coated samples, at stress levels of 520 MPa at 500°C to evaluate the oxidation protection on creep of the Ti-6Al-4V alloy. Results indicate that the creep resistance of the ceramic coating was greater than metallic coating.

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.

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