Journal ArticleDOI
Upper Temperature Limit of Environmental Barrier Coatings Based on Mullite and BSAS
Kang N. Lee,Dennis S. Fox,Jeffrey I. Eldridge,Dongming Zhu,Raymond C. Robinson,Narottam P. Bansal,Robert A. Miller +6 more
TLDR
The state-of-the-art environmental barrier coatings (EBCs) for Si-based ceramics consist of three layers: a silicon bond coat, an intermediate mullite (3Al2O3-2SiO2), and a BSAS top coat as discussed by the authors.Abstract:
Current state-of-the-art environmental barrier coatings (EBCs) for Si-based ceramics consist of three layers: a silicon bond coat, an intermediate mullite (3Al2O3-2SiO2) or mullite + BSAS (1-xBaO-xSrO-Al2O3-2SiO2) layer, and a BSAS top coat. Areas of concern for long-term durability are environmental durability, chemical compatibility, silica volatility, phase stability, and thermal conductivity. Variants of this family of EBCs were applied to monolithic SiC and melt infiltrated SiC/SiC composites. Reaction between BSAS and silica results in low melting (approx. 1300 C) glasses at T > 1400 C, which can cause the spallation of the EBC. At temperatures greater than 1400 C, the BSAS top coat also degrades by formation of a porous structure, and it suffers significant recession via silica volatilization in water vapor-containing atmospheres. All of these degradation mechanisms can be EBC life-limiting factors. BSAS undergoes a very sluggish phase transformation (hexagonal celsian to monoclinic celsian), the implications of which are not fully understood at this point. There was evidence of rapid sintering at temperatures as low as 1300 C, as inferred from the sharp increase in thermal conductivity.read more
Citations
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Rare earth silicate environmental barrier coatings for SiC/SiC composites and Si3N4 ceramics
TL;DR: In this paper, rare earth silicates have been investigated to evaluate their potential as an advanced environmental barrier coating (EBC) having higher temperature capability than current EBCs in high steam environments.
Journal ArticleDOI
Silicon Nitride for High‐Temperature Applications
TL;DR: In this article, a summary of the development of high-temperature silicon nitride (T>1200°C) is provided, where the influence of various sintering additive systems is evaluated with focus on the high temperature potential of the resulting materials.
Journal ArticleDOI
Doped Oxides for High-Temperature Luminescence and Lifetime Thermometry
M.D. Chambers,David R. Clarke +1 more
TL;DR: The measurement of high temperatures in oxides and oxide-based structures in practical applications often presents challenges including steep thermal gradients, the presence of flames or chemically aggressive environments, and transparency or translucency of most oxides as mentioned in this paper.
Journal ArticleDOI
Advances in Thermal Spray Coatings for Gas Turbines and Energy Generation: A Review
Canan U. Hardwicke,Yuk-Chiu Lau +1 more
TL;DR: In this article, the current status of materials, equipment, processing, and properties aspects for key coatings in the energy industry, especially the developments in large-scale gas turbines, are reviewed.
References
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Journal ArticleDOI
Corrosion of Silicon-Based Ceramics in Combustion Environments
TL;DR: In this paper, the processes of passive oxidation, deposit-induced corrosion, active oxidation, scale/substance interactions, and scale volatility are studied in the case of high-purity SiC and Si3N4 in pure oxygen, giving attention to such secondary elements in the ceramics as water and CO2 oxidants, combustion environment impurities, and thermal cycling.
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Paralinear Oxidation of CVD SiC in Water Vapor
TL;DR: In this article, the long-term degradation rate of CVD SiC is determined by the volatility of the silica scale, which is observed as the water vapor oxidized the SiC and simultaneously volatilized the scale.
Journal ArticleDOI
Current status of environmental barrier coatings for Si-Based ceramics
TL;DR: In this paper, a brief history and the current status of external environmental barrier coatings for Si-based ceramics with the main focus on water vapor protection is discussed. But the focus of the development research has been shifted towards the protection from water vapor attack.
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SiC Recession Caused by SiO2 Scale Volatility under Combustion Conditions: I, Experimental Results and Empirical Model
TL;DR: In this article, a high-pressure burner rig was developed to evaluate the response of chemical-vapor-deposited SiC material during exposure to simulated gas turbine combustor conditions.
Journal ArticleDOI
New generation of plasma-sprayed mullite coatings on silicon carbide
TL;DR: In this paper, the authors proposed a new coating for silicon-based ceramics, which exhibits excellent adherence and crack resistance under thermal cycling between room temperature and 1000 to 1400 C. The coating showed good resistance to Na2CO3-induced hot corrosion.