Ceramic Oxide-Coated Silicon Carbide for High Temperature Corrosive Environments

Mullite is promising as a protective coating for silicon‐based ceramics in aggressive high‐temperature environments. Conventionally plasma‐sprayed mullite on SiC tends to crack and debond on thermal cycling. It is shown that this behavior is due to the presence of amorphous mullite in the conventionally sprayed mullite. Heating the SiC substrate during the plasma spraying eliminated the amorphous phase and produced coatings with dramatically improved properties. The new coating exhibits excellent adherence and crack resistance under thermal cycling between room temperature and 1000–1400°C. Preliminary tests showed good resistance to Na2CO3‐induced hot corrosion.

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“…5 - 6 In this section, key fundamental properties of plasmasprayed mullite are critically evaluated to identify the cracking mechanism.…”

Section: Resultsmentioning

confidence: 99%

New Generation of Plasma‐Sprayed Mullite Coatings on Silicon Carbide

Lee¹,

Miller²,

Jacobson³

1995

Journal of the American Ceramic Society

238

135

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“…[55] The first EBC attempt was a mullite layer because fulfilled two of the requirements: small TEC mistmach and chemical compatibility with SiC or Si 3 N 4 substrates. [56] However, even an optimized fully crystalline mullite coating, [57] with a good thermal shock resistance and durability, presented volatilization of silica in water vapour, [58] leading to surface recession in high velocity combustion environments. [60] The proposed solution included the development of multilayered coatings to fulfil all the requirements.…”

Section: Environmental Barrier Coatings (Ebcs)mentioning

confidence: 99%

Advanced Ceramic Materials for High Temperature Applications

Belmonte

2006

Adv Eng Mater

197

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The increasing interest in ecological aspects related to the reduction of harmful emissions to the atmosphere and, at the same time, the need to achieve higher efficiencies of energy production are the driving forces that justify the current development of advanced ceramic materials for high temperature applications, namely those associated to energy and transportation industries. Ceramic matrix composites (CMCs), thermal barrier coatings (TBCs), environmental barrier coatings (EBCs) and solid oxide fuel cells (SOFCs) are increasingly used to work under the new demanding conditions. In this review, the recent progress and trends in the research and development of CMCs, TBCs, EBCs and SOFCs based on ceramic materials for high temperature applications are highlighted.

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“…3 Mullite attracted the most interest as a protective coating for SiC or Si 3 N 4 ceramics in the early days of coating development due to its low coefficient of thermal expansion (CTE), chemical compatibility with Si-based ceramics, and good adherence. [3][4][5][6][7] One key issue with plasma-sprayed mullite coatings is the phase stability. 7 Mullite processed with conventional plasma spraying contains a significant amount of metastable amorphous phase due to the rapid cooling of molten mullite during its solidification on a cold substrate.…”

Section: Introductionmentioning

confidence: 99%