Advanced Environmental Barrier Coatings (EBC’s)

2007 ◽  
Vol 333 ◽  
pp. 59-70 ◽  
Author(s):  
T. Kulkarni ◽  
S.N. Basu ◽  
V.K. Sarin
Keyword(s):  
Crystal Structure ◽  
Growth Rate ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Vapor Deposition ◽  
Surface Composition ◽  
Narrow Range ◽  
Chemical Vapor ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings

Dense, uniform and crack-free mullite (3Al2O3·2SiO2) coatings were deposited on Sibased substrates by chemical vapor deposition using the AlCl3–SiCl4–H2–CO2 system. The coatings were compositionally graded, with the Al/Si ratio increasing towards the outer surface of the coatings for improved corrosion resistance. Mullite grains nucleated when the surface composition of the growing coating was in a narrow range close to that of stoichiometric mullite. The growth rate and crystal structure of mullite were dependent upon temperature, pressure, reactant concentration, and reactant ratios. The phase transformations occurring in these coatings during high-temperature anneals in the range 1100–1400 °C were studied.

Effect of Deposition Parameters on the Microstructure and Growth Rate of CVD Mullite Environmental Barrier Coatings

2005 ◽  
Vol 890 ◽  
Author(s):  
Soumendra Basu ◽  
Tushar Kulkarni ◽  
Vinod Sarin
Keyword(s):  
Vapor Deposition ◽  
Chemical Vapor ◽  
Metal Chloride ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Deposition Parameters ◽  
Mullite Coatings ◽  
Coating Microstructure ◽  
Reactor Pressure

ABSTRACTSi-based ceramics such as SiC require environmental barrier coatings to protect against hot-corrosion and recession in gas turbine applications. Dense, crystalline mullite coatings of uniform thickness have been deposited by hot-wall chemical vapor deposition (CVD) on SiC substrates, using the AlCl3-SiCl4-CO2-H2 system. The effects of the CVD deposition parameters such as temperature, total reactor pressure, and metal-chloride partial pressure on the coating microstructure and growth kinetics have been investigated, and are discussed in this paper.

Polymer Derived SiAlCN for Environmental Barrier Coatings

2005 ◽  
Author(s):  
Yiguang Wang ◽  
Linan An
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Elevated Temperatures ◽  
Chemical Vapor ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Environmental Barrier ◽  
Alkali Salt ◽  
Near Term ◽  
Silicon Based

Silicon-based ceramics and composites are one of the most promising candidates for high temperature structural components in next generation gas turbines due to their excellent thermo-mechanical properties. However, these materials severely degraded when used in high temperature oxidizing environments, particularly, in the presence of corrosive species such as alkali elements or water vapor. Currently, the most promising approach with near-term benefits is to employ environmental barrier coatings (EBCs) that prevent direct contact between silicon-based materials and aggressive environments exist in turbine engines. Previous work on EBCs has primarily focused on using oxide coatings because oxides are in general more resistant to corrosive environments than Silicon-based ceramics. In this study, we propose to develop polymer-derived SiAlCN amorphous ceramics for EBC applications. Our research revealed that the oxidation rate of the SiAlCN ceramics is about 10 times lower than the lowest values observed on chemical vapor deposition (CVD) silicon carbide/nitride. Furthermore, the SiAlCN also exhibited good corrosion resistance to alkali salt at elevated temperatures.

Influence of Ca0.6Mg0.4Zr4(PO4)6 Coating on Alkali Corrosion Resistance of SiC Ceramic

2010 ◽  
Vol 105-106 ◽  
pp. 386-389 ◽  
Author(s):  
Jian Er Zhou ◽  
Xiao Zhen Zhang ◽  
Shi Jiang Peng
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Flexural Strength ◽  
Sol Gel ◽  
Microstructural Analysis ◽  
Mass Change ◽  
High Quality ◽  
Barrier Coatings ◽  
Environmental Barrier Coatings ◽  
Sic Ceramic

Ca0.6Mg0.4Zr4(PO4)6 coating was used as environmental barrier coatings (EBC) to improve the alkali corrosion resistance of SiC ceramic at high temperature. A new sol-gel based process has been developed for preparing high quality and thick C0.6M0.4ZP coating on SiC ceramic with once deposition. The prepared C0.6M0.4ZP coating on SiC ceramic is homogeneous and dense, and shows a thickness of about 200 μm when sintered at 1400 °C for 3h. The effectiveness of C0.6M0.4ZP coating in improving the alkali corrosion resistance of SiC ceramic was evaluated based on the SEM microstructural analysis, mass change and flexural strength measurements after being subjected to alkali Na-salt attack at 1000 °C for 96 h. Significantly improved alkali corrosion resistance was confirmed for SiC ceramic using C0.6M0.4ZP coating as EBC.

scholarly journals Unusual Dependence of the Diamond Growth Rate on the Methane Concentration in the Hot Filament Chemical Vapor Deposition Process

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 426
Author(s):  
Byeong-Kwan Song ◽  
Hwan-Young Kim ◽  
Kun-Su Kim ◽  
Jeong-Woo Yang ◽  
Nong-Moon Hwang
Keyword(s):  
Growth Rate ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Methane Concentration ◽  
Chemical Vapor ◽  
Diamond Growth ◽  
Lower Growth ◽  
Filament Temperature ◽  
Diamond Phase ◽  
Hot Filament

Although the growth rate of diamond increased with increasing methane concentration at the filament temperature of 2100 °C during a hot filament chemical vapor deposition (HFCVD), it decreased with increasing methane concentration from 1% CH4 –99% H2 to 3% CH4 –97% H2 at 1900 °C. We investigated this unusual dependence of the growth rate on the methane concentration, which might give insight into the growth mechanism of a diamond. One possibility would be that the high methane concentration increases the non-diamond phase, which is then etched faster by atomic hydrogen, resulting in a decrease in the growth rate with increasing methane concentration. At 3% CH4 –97% H2, the graphite was coated on the hot filament both at 1900 °C and 2100 °C. The graphite coating on the filament decreased the number of electrons emitted from the hot filament. The electron emission at 3% CH4 –97% H2 was 13 times less than that at 1% CH4 –99% H2 at the filament temperature of 1900 °C. The lower number of electrons at 3% CH4 –97% H2 was attributed to the formation of the non-diamond phase, which etched faster than diamond, resulting in a lower growth rate.

Deposition and Crystallisation Behaviour of Amorphous Silicon Thin Films Obtained by Pyrolysis of Disilane Gas at Very Low Pressure

1994 ◽  
Vol 345 ◽  
Author(s):  
T. Kretz ◽  
D. Pribat ◽  
P. Legagneux ◽  
F. Plais ◽  
O. Huet ◽  
...  
Keyword(s):  
Activation Energy ◽  
Growth Rate ◽  
Amorphous Silicon ◽  
Vapor Deposition ◽  
Electrical Conductance ◽  
Chemical Vapor ◽  
Crystalline Fraction ◽  
Silicon Thin Films ◽  
Crystallisation Behaviour

AbstractHigh purity amorphous silicon layers were obtained by ultrahigh vacuum (millitorr range) chemical vapor deposition (UHVCVD) from disilane gas. The crystalline fraction of the films was monitored by in situ electrical conductance measurements performed during isothermal annealings. The experimental conductance curves were fitted with an analytical expression, from which the characteristic crystallisation time, tc, was extracted. Using the activation energy for the growth rate extracted from our previous work, we were able to determine the activation energy for the nucleation rate for the analysed-films. For the films including small crystallites we have obtained En ∼ 2.8 eV, compared to En ∼ 3.7 eV for the completely amorphous ones.

Effect of Argon during Diamond Deposition by Hot Filament Chemical Vapor Deposition

2016 ◽  
Vol 869 ◽  
pp. 721-726 ◽  
Author(s):  
Divani C. Barbosa ◽  
Ursula Andréia Mengui ◽  
Mauricio R. Baldan ◽  
Vladimir J. Trava-Airoldi ◽  
Evaldo José Corat
Keyword(s):  
Growth Rate ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Diamond Growth ◽  
Gas Mixture ◽  
X Ray Diffraction ◽  
Hot Filament ◽  
Argon Content

The effect of argon content upon the growth rate and the properties of diamond thin films grown with different grains sizes are explored. An argon-free and argon-rich gas mixture of methane and hydrogen is used in a hot filament chemical vapor deposition reactor. Characterization of the films is accomplished by scanning electron microscopy, Raman spectroscopy and high-resolution x-ray diffraction. An extensive comparison of the growth rate values and films morphologies obtained in this study with those found in the literature suggests that there are distinct common trends for microcrystalline and nanocrystalline diamond growth, despite a large variation in the gas mixture composition. Included is a discussion of the possible reasons for these observations.

Adhesion and Corrosion Resistance Properties of TiC/Ti(CN)/TiN Multilayer CVD Coatings on 42CrMo Steels

2009 ◽  
Vol 79-82 ◽  
pp. 1009-1012
Author(s):  
Jin Zhang ◽  
Qi Xue ◽  
Xiao Wei Cheng ◽  
Chun Mei Zhang ◽  
Song Xia Li
Keyword(s):  
Corrosion Resistance ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Fracture Morphology ◽  
Immersion Test ◽  
Multilayer Films ◽  
Multilayer Coatings ◽  
Cvd Method ◽  
42Crmo Steel ◽  
Immersion Corrosion

The TiC/Ti(CN)/TiN multilayer coatings were deposited on 42CrMo steel by chemical vapor deposition (CVD) method. The fracture morphology,structure,microhardness and adhesion of the coatings were analyzed. The immersion test in simulant solution with H2S,CO2 at 100°C and electrochemistry test in 20wt% H2SO4 at room temperture were applied to investigate the corrosion resistance of the multilayer films.The results reveal that the multilayer coatings can offer 42CrMo steel higher corrosion resistance,especially the immersion corrosion test.The corrosion rate of the samples coated with CVD multilayer films is reduced more 70 times than that of the uncoated and samples by quenching-polishing-quenching (QPQ) treat.

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