Journal ArticleDOI
Degradation of Thermal-Barrier Coatings at Very High Temperatures
F.H. Stott,D.J. de Wet,R. Taylor +2 more
TLDR
A ceramic thermal-barrier coating needs to be refractory and chemically inert, and it also needs to possess a high thermal expansion coefficient of ~11 × 10−6 K−1, to match the nickel-base superalloy substrate as discussed by the authors.Abstract:
Thermal-barrier coatings are finding increasing use in engineering applications, particularly in gas turbines. Such coatings, consisting of ceramic insulating layers bonded to the superalloy substrate by oxidation-resistant alloy coatings, are deposited onto components to reduce heat flow through the cooled substrate and to limit operating temperature. They have been used effectively on static components such as combustor cans, flare heads, hot gas seal segments, fuel evaporators, and deflector plates, giving considerable improvements in component life. They have been used successfully on vane platforms. In recent years, the emphasis has shifted toward the development of coatings for high-risk areas, such as turbine blades.A ceramic thermal-barrier coating needs to be refractory and chemically inert, and to have low thermal conductivity. However, it also needs to possess a high thermal expansion coefficient of ~11 × 10−6 K−1, to match the nickel-base superalloy substrate. The latter specification has focused attention on ZrO2. However, ZrO2 is polymorphic and undergoes two phase changes, cubic to tetragonal at 2350°C and tetragonal to monoclinic at 1170°C. The latter transformation is accompanied by a 5% volume increase which means that ZrO2 has to be alloyed to stabilize one of the high-temperature phases. Early systems in the 1970s consisted of ZrO2 stabilized with MgO, but this has been shown to be a metastable system. Present-day commercial thermal-barrier coatings consist of a plasma-sprayed yttria- or magnesiastabilized zirconia layer on top of an M-Cr-Al-Y bond coat. The latter plays a very important role by helping to key the ceramic to the alloy substrate and to accommodate the mechanical strains arising because of differences in thermal expansion coefficients and elastic moduli between the ceramic and the substrate.read more
Citations
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Journal ArticleDOI
Thermal-barrier coatings for more efficient gas-turbine engines
TL;DR: In this article, an introduction to TBCs is presented, where complex, multi-layer evolving systems touch on several known phenomena in materials science and engineering, and the major challenges to improved coating development and the rich opportunities for materials research are discussed.
Journal ArticleDOI
Thermochemical Interaction of Thermal Barrier Coatings with Molten CaO–MgO–Al2O3–SiO2 (CMAS) Deposits
TL;DR: In this paper, the authors investigated the thermochemical aspects of the degradation phenomena using a model CMAS composition and ZrO2-7.6%YO1.5 (7YSZ) grown by vapor deposition on alumina substrates.
Journal ArticleDOI
Environmental degradation of thermal- barrier coatings by molten deposits
TL;DR: In this article, the thermomechanical and thermochemical aspects of the calcium-magnesium alumino-silicates (CMAS) interactions with thermal-barrier coatings, as well as the current status of mitigating strategies are discussed.
Journal ArticleDOI
Novel thermal barrier coatings that are resistant to high-temperature attack by glassy deposits
TL;DR: In this paper, a solution-precursor plasma spray (SPPS) process is used to mitigate CMAS attack on thermal barrier coatings (TBCs) in gas-turbine engines, where up to 20mol.% Al2O3 and 5.5m.% TiO2 in the form of a solid solution is incorporated into Y 2O3-stabilized ZrO2 (YSZ) TBCs.
Journal ArticleDOI
Electroless copper deposition for ULSI
TL;DR: In this article, the electroless copper deposition process as a metallization method for integrated circuit applications is discussed and two basic approaches are presented, planar and non-planar.
References
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Journal ArticleDOI
Microstructure, composition and property relationships of plasma-sprayed thermal barrier coatings☆
TL;DR: In this paper, the benefits deriving from the use of thermal barrier coatings are discussed and reasons for the selection of ZrO2-based alloys highlighted, and the relationship between microstructure and properties of plasma coatings is reviewed.
Journal ArticleDOI
Thermal barrier coatings for turbine applications in aero engines
T. N. Rhys-Jones,F. C. Toriz +1 more
TL;DR: In this article, the current status of thermal barrier coatings (TBGs) with reference to gas turbine applications is evaluated with respect to the performance of TBG systems in engine trials.
Journal ArticleDOI
Flight service evaluation of thermal barrier coatings by physical vapor deposition at 5200 H
TL;DR: In this article, the service condition of vanes with thermal barrier coatings applied by physical vapor deposition was evaluated in a flight service evaluation of TBCs applied on turbine vane airfoils and rotating blades.