Special Issue: Environmental Barrier Coatings

Abstract

The global increase in air travel will require commercial vehicles to be more efficient than ever before. Advanced turbine hot section materials are a key technology required to keep fuel consumption and emission to a minimum. Ceramic matrix composites (CMCs) are the most promising material to revolutionize turbine hot section materials because of their excellent high-temperature properties. Rapid surface recession due to volatilization by water vapor is the Achilles heel of CMCs. Environmental barrier coatings (EBCs), which protect CMCs from water vapor, is an enabling technology for CMCs. The first CMC component entered into service in 2016 in a commercial engine, and more CMC components are scheduled to follow within the next few years. One of the most difficult challenges to CMC components is EBC durability because failure of EBC leads to a rapid reduction in CMC component life. Novel EBC chemistries, creative EBC designs, and robust processes are required to meet EBC durability challenges. Engine-relevant testing, characterization, and lifting methods need to be developed to improve EBC reliability. The aim of this Special Issue is to present recent advances in EBC technology to address current EBC challenges.

Nanoscratch Testing of 3Al2O3·2SiO2 EBCs: Assessment of Induced Damage and Estimation of Adhesion Strength

“…As a consequence of more than two decades of focused research and development, it has been demonstrated that EBCs are effective tools to protect Si-based substratesespecially SiC/SiC Ceramic Matrix Composites (CMCs)-from the severe pitting corrosion and recession typical of gas turbine applications [2][3][4][5][6][7][8][9][10]. Today, EBC-coated SiC/SiC CMCs are used in high pressure shrouds in 7F gas turbines as well as hot components of the LEAP aircraft engine [7,8].…”

“…As a consequence of more than two decades of focused research and development, it has been demonstrated that EBCs are effective tools to protect Si-based substratesespecially SiC/SiC Ceramic Matrix Composites (CMCs)-from the severe pitting corrosion and recession typical of gas turbine applications [2][3][4][5][6][7][8][9][10]. Today, EBC-coated SiC/SiC CMCs are used in high pressure shrouds in 7F gas turbines as well as hot components of the LEAP aircraft engine [7,8]. One of the most critical challenges to tackle is reliability and durability, since failure of EBCs reduces the lifespan of CMC components, with thermal and thermomechanical strains shown to be one of the key contributors to EBC degradation [8,[11][12][13].…”

Pressure infiltration of molten aluminum for densification of environmental barrier coatings

“…To prevent the deleterious environmental attack of SiC components, environmental barrier coatings (EBCs) were developed to cover the SiC surface. Candidate materials for EBCs should meet a set of requirements [4,[12][13][14], such as hightemperature phase stability, similar thermal expansion coefficient (CTE) to the matrix, chemical compatibility, steam stability, and CMAS corrosion resistance.…”

Pressure Infiltration of Molten Aluminum for Densification of Environmental Barrier Coatings

“…To prevent the deleterious environmental attack of SiC components, environmental barrier coatings (EBCs) were developed to cover the SiC surface. The candidate materials for EBC are expected to fulfill a set of requirements [4,[12][13][14], such as high-temperature phase stability, similar thermal expansion coefficient (CTE) to the matrix, chemical compatibility, steam stability, and CMAS corrosion resistance.…”