Environmental durability of slurry based mullite–gadolinium silicate EBCs on silicon carbide

Yb2Si2O7 Environmental barrier coatings with reduced bond coat oxidation rates via chemical modifications for long life

“…Most of the current EBCs are variants of the second‐generation EBCs. Various aspects of current EBCs, including processing, volatility in water vapor, silica activity in Y 2 O 3 ‐SiO 2 and Yb 2 O 3 ‐SiO 2 systems, interactions with CMAS, stress analysis, fracture mechanism, impact damage, and oxidation, have been reported.…”

“…Since permeability = diffusivity x solubility, the permeability of H 2 O in SiO 2 is ~10 times larger than that of O 2 . In Si/Yb 2 Si 2 O 7 EBC water vapor permeates through Yb 2 Si 2 O 7 and reacts with the Si bond coat, forming a layer of SiO 2 scale, known as thermally grown oxide (TGO), at the Si/Yb 2 Si 2 O 7 interface . One of the most frequently observed EBC failure modes, identified in laboratory tests and confirmed in rig and engine tests, is spallation due to oxidation by water vapor (steam oxidation) .…”

Slurry-based protective coatings for Oxide/Oxide ceramic matrix composites

“…For example, mullite/Gd 2 SiO 5 composite coatings could be deposited on ¡-SiC by dip-coating and sintering at 1430°C. 8) Another example was the dip-coating of C/C composites with Y2SiO5 and sintering in Ar at 1560°C. 9) The situation is much more difficult for porous Ox-CMCs which are typically much more susceptible to thermal overload, resulting not only in matrix densification but also in fiber grain growth and fiber/matrix reactions.…”

Advances in the control of electrophoretic process parameters to tune the ytterbium disilicate coatings microstructure

“…The properties of EBCs vary with the different preparation processes. There are several methods to produce ceramic coatings, such as chemical vapor deposition, physical vapor deposition, ion implantation, thermal‐spray, soft chemistry including sol‐gel routes and newly developed electrophoretic deposition (EPD) 8‐12 …”

“…There are several methods to produce ceramic coatings, such as chemical vapor deposition, physical vapor deposition, ion implantation, thermal-spray, soft chemistry including sol-gel routes and newly developed electrophoretic deposition (EPD). [8][9][10][11][12] Electrophoretic deposition is a suspension processing technique, and is increasingly gaining applications in manufacturing of thin and thick films, laminates, advanced functional coatings, porous materials, ceramics with complex geometric shape, or thermal barrier coatings. [13][14][15] Once the EPD processing and suspension parameters well were determined, this process is robust, rapid, low-cost and versatile.…”