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IUPUI School of Engineering and Technology

IUPUI School of Engineering and Technology

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Novel Thermal Barrier Coatings

1. Design, Fabrication and Characterization of Lanthanum Zirconate Based Thermal Barrier Coatings

TBC

Lanthanum zirconate (La2Zr2O7) coatings are newly proposed thermal barrier coating 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% yttria stabilized zirconia (8YSZ) single-layer and double-layer thermal barrier coating (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 -1172 K (24 -899 oC), which was approximately 25% lower than that of porous 8YSZ (0.84 - 0.87 W/m/K) in the same temperature range. The coefficients of thermal expansion values of La2Zr2O7 were approximately 9 - 10×10-6/K from 400 K (127 oC) to 1600 K (1327 oC), which were about 10% lower than those of porous 8YSZ. The double-layer coating system consisting of the porous 8YSZ and La2Zr2O7layers had better thermal shock resistance and thermal cycling performance than those of single-layer La2Zr2O7coating and double-layer coating with dense 8YSZ andLa2Zr2O7 coatings. This study suggests that porous 8YSZ coating can be employed as a buffer layerinLa2Zr2O7based TBC systems to improve the overall coating durability during service.

Publications:

1. Jing Zhang, Xingye Guo, Yeon-Gil Jung, Li Li, James Knapp, Lanthanum Zirconate Based Thermal Barrier Coatings: A Review, Surface and Coatings Technology, (DOI: 10.1016/j.surfcoat.2016.10.019), 2016

2. Sung-Hoon Jung, Zhe Lu, Yeon-Gil Jung, Dowon Song, Ungyu Paik, Baig-Gyu Choi, In-Soo Kim, Xingye Guo, Jing Zhang,Thermal durability and fracture behavior of layered Yb-Gd-Y-based thermal barrier coatings in thermal cyclic exposure, Surface and Coatings Technology, (http://dx.doi.org/10.1016/j.surfcoat.2016.09.032), 2016

3. Dowon Song, Ungyu Paik, Xingye Guo, Jing Zhang, Ta-Kwan Woo, Zhe Lu, Sung-Hoon Jung, Je-Hyun Lee, Yeon-Gil Jung, Microstructure design for blended feedstock and its thermal durability in lanthanum zirconate based thermal barrier coatings, Surface and Coatings Technology , (http://dx.doi.org/10.1016/j.surfcoat.2016.07.112), 2016

4. Xingye Guo, Zhe Lu, Yeongil Jung, Li Li, James Knapp, and Jing Zhang, Thermal properties, thermal shock and thermal cycling behavior of lanthanum zirconate based thermal barrier coatings, Metallurgical and Materials Transactions E , Vol. 3, pp. 64-70, 2016

5. Xingye Guo, Bin Hu, Changdong Wei, Jiangang Sun, Yeon-Gil Jung, Li Li, James Knapp, Jing Zhang, Image-Based Multi-Scale Simulation and Experimental Validation of Thermal Conductivity of Lanthanum Zirconate, International Journal of Heat and Mass Transfer , Vol. 100, pp. 34-38, 2016

6. Jing Zhang, Yeon-Gil Jung (eds.) "Advanced Ceramic and Metallic Coating and Thin Film Materials for Energy and Environmental Applications" Springer International Publishing (ISBN 978-3-319-59906-9), 2017

2. Modeling of Ceramic-Metal (C-M) Interfaces in Thermal Barrier Coatings

C-M Interface in TBC

The ideal mechanical strengths of ZrO2 (111)/Ni (111) ceramic-metal (C-M) interface are calculated using the first principles calculations, with the periodic slab density functional theory within the generalized gradient approximation. The projector augmented wave pseudopotentials were used in the calculations to specify the electron interactions. The structures of ZrO2 (111) / Ni (111) interfaces with one- and three- Ni layer thicknesses were optimized and the mechanical properties were examined. The calculated tensile strengths of one- Ni layer are , respectively, and three-layer . We find that the interface with a thinner Ni layer has higher tensile and shear strengths, and the toughness of interface with a thinner Ni film is higher than that of the thicker film model. Bader charge transfer and the electron distribution analyses show that charge transfers between the Ni and O atoms are larger in 1-layer Ni models than that in 3-layer models.

Publications:

1. Xingye Guo, Yi Zhang, Yeon-Gil Jung, Li Li, James Knapp, Jing Zhang, Ideal Tensile Strength and Shear Strength of ZrO2(111)/Ni(111) Ceramic - Metal Interface: A First Principle Study, Materials & Design , 112, pp. 254-262, 2016