Composite Ceramics for Thermal-Barrier Coatings Produced from Zirconia Doped with Rare Earth Oxides

• Published in: Powder metallurgy and metal ceramics Vol. 61; no. 7-8; pp. 441 - 450
• Main Authors: Dudnik, O. V., Lakiza, S. M., Grechanyuk, M. I., Red’ko, V. P., Marek, I. O., Makudera, A. O., Shmibelsky, V. B., Ruban, O. K.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-11-2022; Springer; Springer Nature B.V
• Subjects: Aluminum oxide; Ceramic coatings; Ceramic materials; Ceramics; Cerium oxides; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coatings; Composites; Electron beams; Electron-beam physical vapor deposition; Erbium oxide; Europium compounds; Fatigue; Fatigue life; Fatigue testing machines; Furnaces; Gadolinium oxides; Gas turbine engines; Glass; Lanthanum oxides; Lutetium oxide; Materials; Materials Science; Metallic Materials; Microstructure; Muffle furnaces; Natural Materials; Physical vapor deposition; Praseodymium oxide; Rare earth metals; Rare earth oxides; Refractory and Ceramic Materials; Silicon dioxide; Solid solutions; Subgroups; Thermal barrier coatings; Thermal cycling; Thermal fatigue; Turbines; Yttria-stabilized zirconia; Zirconium oxide; complex composite oxide ceramics; thermal fatigue life; complex doping; zirconia; rare earth oxides; thermal-barrier coating; zirconia solid solution
• ISSN: 1068-1302; 1573-9066
• DOI: 10.1007/s11106-023-00331-2

The thermal fatigue life of zirconia-based complex composite ceramics doped with a mixture of rare earth oxides was studied. Two concentrates of rare earth oxides were chosen (wt.%): 1) cerium- subgroup concentrate of composition 62.4 CeO
2
, 13.5 La
2
O
3
, 10.9 Nd
2
O
3
, 3.9 Pr
6
O
11
, 0.92 Sm
2
O
3
, 1.2 Gd
2
O
3
, 0.24 Eu
2
O
3
, 2.66 ZrO
2
, 1.2 Al
2
O
3
, 1.7 SiO
2
, and 1.38 other oxides (light concentrate (LC)) and 2) yttrium-subgroup concentrate of composition 13.3 Y
2
O
3
, 1.22 Tb
4
O
7
, 33.2 Dy
2
O
3
, 8.9 Ho
2
O
3
, 21.8 Er
2
O
3
, 1.86 Tm
2
O
3
, 12.5 Yb
2
O
3
, 0.57 Lu
2
O
3
, and 6.65 other oxides (heavy concentrate (HC)). Two-layer metal/ceramic thermal-barrier coatings (TBCs) were deposited on gas turbine engine blades by electron-beam physical vapor deposition (EB-PVD) in one process cycle. The properties of ZrO
2
–LC and ZrO
2
–HC TBC ceramic top coats were compared to those of a standard yttria-stabilized zirconia layer (ZrO
2
–Y
2
O
3
). The thermal fatigue experiment was performed by heating the samples to 1100°C in a muffle furnace for 5 min, holding them at this temperature for 50 min, and cooling in water for 5 min. The standard ZrO
2
–Y
2
O
3
layer withstood 138 thermal cycles, while the ZrO
2
–LC and ZrO
2
–HC layers withstood 161 thermal cycles. The porous microstructure of the ceramic layers developed during thermal cycling was found to depend on laminar microstructures acquired by the layers in the EB-PVD process. The number of spherical pores in the ZrO
2
–LC and ZrO
2
–HC layers was much higher than in the ZrO
2
–Y
2
O
3
layer. This increased their thermal fatigue life by 16% compared to the standard coating. An integrated approach to the choice of the ceramic top coat composition based on ZrO
2
solid solutions doped with natural rare earth oxide concentrates and of the technique for their deposition, as well as improvement in the coating architecture, will promote cost-effective TBCs with the properties required.