Thermal properties, thermal shock, and thermal cycling behavior of lanthanum zirconate-based thermal barrier coatings
- Journal
- Metallurgical and Materials Transactions E
- Vol
- 3
- Page
- 64-70
- Year
- 2016
- File
- Thermal properties, thermal shock, and thermal cycling behavior of lanthanum zirconate-based thermal barrier coatings.pdf (1.9M) 34회 다운로드 DATE : 2021-08-23 17:40:01
systems which exhibit lower thermal conductivity and potentially higher thermal stability
compared to other traditional thermal barrier systems. In this work, La2Zr2O7 and 8 wt pct
yttria stabilized zirconia (8YSZ) single-layer and double-layer TBC systems were deposited
using the air plasma spray technique. Thermal properties of the coatings were measured.
Furnace heat treatment and jet engine thermal shock tests were implemented to evaluate coating
performance during thermal cycling. The measured average thermal conductivity of porous
La2Zr2O7 coating ranged from 0.59 to 0.68 W/m/K in the temperature range of 297 K to
1172 K (24 _C to 899 _C), which was approximately 25 pct lower than that of porous 8YSZ
(0.84 to 0.87 W/m/K) in the same temperature range. The coefficients of thermal expansion
values of La2Zr2O7 were approximately 9 to 10 9 10_6/K from 400 K to 1600 K (127 _C to
1327 _C), which were about 10 pct lower than those of porous 8YSZ. The double-layer coating
system consisting of the porous 8YSZ and La2Zr2O7 layers had better thermal shock resistance
and thermal cycling performance than those of single-layer La2Zr2O7 coating and double-layer
coating with dense 8YSZ and La2Zr2O7 coatings. This study suggests that porous 8YSZ coating
can be employed as a buffer layer in La2Zr2O7-based TBC systems to improve the overall
coating durability during service.