TY - JOUR
T1 - EBC Development for Hot-Pressed Y2O3/Al2O3 Doped Silicon Nitride Ceramics
AU - Ramasamy, Sivakumar
AU - Lee, Kang N.
AU - Bhatt, Ramakrishna T.
AU - Fox, Dennis S.
N1 - Ramasamy, S., Tewari, S., Lee, K., Bhatt, R., , & Fox, D. (2010). EBC development for hot-pressed EBC development for hot-pressed Y2O3/Al2O3 doped silicon nitride ceramics doped silicon nitride ceramics. Materials Science & Engineering A, 527(21-22), 5492-5498. doi:10.1016/j.msea.2010.05.067
PY - 2010/8/20
Y1 - 2010/8/20
N2 - Multilayer EBCs of alcohol and sol-based slurries containing (a) 45% SiO 2 -34% Y 2 O 3 -%Al 2 O 3 , (b) mullite/Gd 2 SiO 5 (88/12wt.%) with and without B 2 O 3 addition, (c) mullite/rare-earth silicates (94/6wt.%, (Gd 2 SiO 5 , Lu 2 SiO 5 , Er 2 SiO 5 , and HfSiO 4 )), and (d) only mullite, were applied on hot pressed Y 2 O 3 /Al 2 O 3 doped Si 3 N 4 substrates. Of the four major EBC systems studied, only mullite/Gd 2 SiO 5 (88/12wt.%) EBCs sintered in air at 1400^oC for 3h showed good bonding with the substrate. In all other EBC systems studied, the Y 2 O 3 /Al 2 O 3 additives present in Si 3 N 4 reacted with silica and rare-earth silicates to form low melting point constituents during sintering causing bubble formation and/or de-bonding at the substrate/coating interface. Thermal cyclic resistance of silicon nitride coupons coated with mullite/Gd 2 SiO 5 (88/12wt.%) EBC was investigated in a moisture containing environment (90% H 2 O-10% O 2 ) for 100 cycles from 1350^oC to room temperature (1h hot and 15min cold). Moisture exposure resulted in accumulation of large pores in the coating, mostly aligned along the substrate/coating interface.
AB - Multilayer EBCs of alcohol and sol-based slurries containing (a) 45% SiO 2 -34% Y 2 O 3 -%Al 2 O 3 , (b) mullite/Gd 2 SiO 5 (88/12wt.%) with and without B 2 O 3 addition, (c) mullite/rare-earth silicates (94/6wt.%, (Gd 2 SiO 5 , Lu 2 SiO 5 , Er 2 SiO 5 , and HfSiO 4 )), and (d) only mullite, were applied on hot pressed Y 2 O 3 /Al 2 O 3 doped Si 3 N 4 substrates. Of the four major EBC systems studied, only mullite/Gd 2 SiO 5 (88/12wt.%) EBCs sintered in air at 1400^oC for 3h showed good bonding with the substrate. In all other EBC systems studied, the Y 2 O 3 /Al 2 O 3 additives present in Si 3 N 4 reacted with silica and rare-earth silicates to form low melting point constituents during sintering causing bubble formation and/or de-bonding at the substrate/coating interface. Thermal cyclic resistance of silicon nitride coupons coated with mullite/Gd 2 SiO 5 (88/12wt.%) EBC was investigated in a moisture containing environment (90% H 2 O-10% O 2 ) for 100 cycles from 1350^oC to room temperature (1h hot and 15min cold). Moisture exposure resulted in accumulation of large pores in the coating, mostly aligned along the substrate/coating interface.
KW - Electron microscopy
KW - Silicon nitride ceramics
KW - Coating
KW - Sintering
KW - Oxidation
KW - Thermal cycling
UR - https://engagedscholarship.csuohio.edu/encbe_facpub/61
U2 - 10.1016/j.msea.2010.05.067
DO - 10.1016/j.msea.2010.05.067
M3 - Article
VL - 527
JO - Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing
JF - Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing
ER -