Thermal Shock Analysis of Surface Al-modified 7YSZ Nano-thermal Barrier Coatin

doi:10.15541/jim20160661

Abstract

Abstract:

In order to improve the thermal shock resistance of 7YSZ nano-thermal barrier coating (TBC), bond coating NiCoCrAlYTa was prepared on simulated turbine blade by HVOF (high velocity oxygen flame). Subsequently, 7YSZ nano-ceramic coating was produced on bond coating as top coating. Al film was deposited on the surface of TBC samples. Then the Al-deposited TBCs were carried out by heat-treatment at different pressures (200, 250, 300 Pa). After that, the thermal shock tests of as-sprayed and Al-modified 7YSZ nano-TBC were taken from 1050 ℃ to atmospheric water with holding time of 10 and 5 min, respectively. Micrograph and microstructure evolution of the TBC sample were characterized before and after thermal shock. The results show that a loose top layer with Al nano-grains is formed on the TBC surface due to evaporation and condensation of Al film at vacuum pressure. Besides, with increase of heat-treatment pressure, the density of loose layer is increased. A dense Al₂O₃ layer was in-situ synthesized under the loose layer due to the reaction of Al and ZrO₂. The Al-modified 7YSZ nano-TBCs heat-treated at different pressures has less spallation area than the as-sprayed TBCs after withstood 73 thermal shocks, showing better thermal shock resistance.

Key words: thermal barrier coating, 7YSZ, thermal cycle, Al-modification

CLC Number:

TQ174

ZHANG Xiao-Feng, ZHOU Ke-Song, LIU Min, DENG Chun-Ming, DENG Chang-Guang, CHEN Huan-Tao. Thermal Shock Analysis of Surface Al-modified 7YSZ Nano-thermal Barrier Coatin[J]. Journal of Inorganic Materials, 2017, 32(9): 973-979.

Figures/Tables 8

Fig. 1 Turbine blade simulated sample

Fig. 2 7YSZ nano-TBC microgrsphy before and after Al-modification (a-c) As-sprayed TBC: surface, un-polished cross-section, polished cross-section; (d-f) Al-modified TBC at 200 Pa: surface, un-polished cross-section, polished cross-section

Fig. 3 XRD patterns of (a) as-sprayed 7YSZ nano-coating and (b) Al-modified 7YSZ nano-coating

Fig. 4 Schematic diagram of surface Al-modification process in TBC

Fig. 5 Images of Al grains on the glass at different heat-treatment pressures

Fig. 6 Schematic diagram of Al-modified 7YSZ nano-TBC (a) Before Al-modification; (b) After Al-modification

Fig. 7 Macrographs of as-sprayed and Al-modified 7YSZ nano-TBC after 73 thermal shocks (a) Front ; (b) Behind

Fig. 8 Micrographs of 7YSZ nano-TBC after 73 thermal shocks (a) As-sprayed TBC; (b) Al-modified TBC

References 21

[1]	SANCHEZ M, MORENO M N, SEGRERA S,et al.Method and process development of advanced atmospheric plasma spraying for thermal barrier coating. J. Therm. Spray Technol., 2012, 21(3): 400-408.
[2]	GUO H B, GONG S K, XU H B.Progress in thermal barrier coatings for advanced aeroengine.Materials China, 2009, 28(Z2): 18-26.
[3]	ZHANG Y J, SUN X F, JIN T,et al. Microstructure of air plasma sprayed YSZ nanostructured thermal barrier coatin. Acta Metallurgica Sinica, 2003, 39(4): 395-398.
[4]	ZHAI M L, LI D C, ZHAO Y X,et al.Comparative study on thermal shock behavior of thick thermal barrier coatings fabricated with nano-based YSZ suspension and agglomerated particle. Ceram. Int., 2016, 42(10): 12172-12179.
[5]	ZHANG C X, ZHOU C G, PENG H,et al.Influence of thermal shock on insulation effect of nano-multilayer thermal barrier coating. Surf. Coat. Technol., 2007, 201(14): 6340-6344.
[6]	WANG Y, BAI Y, LIU K,et al.Microstructural evolution of plasma sprayed submicron-/nano-zirconia-based thermal barrier coating. Applied Surf. Sci., 2016, 363(15): 101-112.
[7]	ZHANG X F, ZHOU K S, XU W,et al.In situ synthesis of α-alumina layer at top yttrium-stabilized zirconia thermal barrier coatings for oxygen barrie. Ceram. Int., 2014, 40: 12703-12708.
[8]	ZHANG X F, ZHOU K S, XU W,et al.In situ synthesis of α-alumina layer on thermal barrier coating for protection against CMAS (CaO-MgO-Al2O3-SiO2) corrosio. Surf. Coat. Technol., 2015, 261: 54-59.
[9]	ZHANG X F, ZHOU K S, LIU M,et al. Enhanced properties of Al-modified EB-PVD 7YSZ thermal barrier coating. Ceram. Int., 2016, 42: 13969-13975.
[10]	KAVEENDRAN B, WANG G S, HUANG L J,et al.In situ ( Al3Zr-Al2O3) metal matrix composite with novel reinforcement distributions fabricated by reaction hot pressin. J. Alloys Compd., 2013, 581: 16-22.
[11]	DREXLER J M, GLEDHILL A D, SHINODA K,et al. Jet engine coatings for resisting volcanic ash damag. Adv. Mater., 2011, 23: 2419-2424.
[12]	DIAZ P, RALPHA B, EDIRISINGHE M J.Transmission electron microscope characterization of a plasma-sprayed ZrO2-Y2O3-TiO2 thermal barrier coatin.Mater. Characterization, 1998, 41(2/3): 55-67.
[13]	POERSCHKE D L, LEVI C G.Effects of cation substitution and temperature on the interaction between thermal barrier oxides and molten CMA.J. Eur. Ceram. Soc., 2015, 35: 681-691.
[14]	LIU H F, LI S L, LI Q L,et al.Preparation and phase stability of La2O3, Y2O3 co-doped ZrO2 ceramic powder application for thermal barrier coatin. Journal of Inorganic Materials, 2009, 24(6): 1226-1230.
[15]	NEJATI M, RAHIMIPOUR M R, MPBASHERPOUR I,et al.Microstructural analysis and thermal shock behavior of plasma sprayed ceria-stabilized zirconia thermal barrier coatings with micro and nano Al2O3 as a third layer. Surf. Coat. Technol., 2015, 282: 129-138.
[16]	DOKUR M M, GOLLER G.Processing and characterization of CYSZ/Al2O3 and CYSZ/Al2O3+YSZ multilayered thermal barrier coating.Surf. Coat. Technol., 2014, 258: 804-813.
[17]	LIN F, YU Y G, JIANG X L, et al. Microstructures and properties of nanostrutured TBCs fabricated by plasma spraying. The Chinese Journal of Nonferrous Metals, 2006, 16(3): 482-487.
[18]	张立德, 牟季美. 纳米材料学. 辽宁科学技术出版社, 1994: 67-69.
[19]	孟红梅. 蒸镀、磁控溅射铝和铝合金薄膜的组织与性. 天津: 天津大学, 2007.
[20]	ZHANG X F, ZHOU K S, XU W,et al.Reaction mechanism and thermal insulation property of Al-deposited 7YSZ thermal barrier coatin. J. Mater. Sci. Technol., 2015, 31: 1006-1010.
[21]	HE M Y, EVANS A G, HUTCHINSON J W.The ratcheting of com-pressed thermally grown thin films on ductile substrate.Acta Mater., 2000, 48: 2593-2601.