Development and Optimization of Tailored Composite TBC Design Architectures for Improved Erosion Durability

Schmitt, Michael P.; Schreiber, Jeremy M.; Amarendra, K.; Eden, Timothy J.; Wolfe, Douglas E.

doi:10.1007/s11666-017-0561-6

Cited by 13 publications

(11 citation statements)

References 39 publications

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“…The sole paper exploring GAP indicates a value of approximately 3.2 W/m·K at elevated temperatures . However, in previous studies it was found that the thermal conductivity of the toughening phase had a minor effect on the thermal conductivity of GZO‐based composite coatings . This response has been observed for bulk ceramic composites of other materials such as Al 2 O 3 and mullite in YSZ, indicating series‐like behavior.…”

Section: Resultsmentioning

confidence: 92%

“…Unfortunately, the changes are not well understood and still result in toughness values significantly lower than that of 7YSZ, ultimately limiting their applicability. Conversely, extrinsically modifying the apparent toughness by incorporating secondary toughening phases has been previously shown by the authors to produce significant improvements in the erosion durability for two design architectures (multilayer and composite) . It was shown that by incorporating a secondary phase with higher toughness, the overall durability of the coating system was improved.…”

Section: Introductionmentioning

confidence: 99%

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Durable aluminate toughened zirconate composite thermal barrier coating (TBC) materials for high temperature operation

et al. 2019

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Research on advanced thermal barrier coating (TBC) materials capable of operating beyond 1200°C has primarily focused on the rare earth zirconate pyrochlores, particularly gadolinium zirconate (Gd 2 Zr 2 O 7 -GZO). The drawback of this material is a significant reduction in durability due to a low fracture toughness. This study investigates utilization of a thermodynamically compatible gadolinia alumina perovskite (GdAlO 3 -GAP) toughening phase to improve the durability of GZO. Dense pellets were fabricated to assess the material properties with minimal microstructural influence. Thermal stability, elastic modulus, hardness, indentation fracture resistance and erosion durability were evaluated for GZO, GAP, and composite pellets containing 10, 30, and 50 wt.% GAP. It was demonstrated that GAP and GZO are thermodynamically compatible through 1600°C and thus capable of operating well beyond the limits of traditional 7 wt.% yttria stabilized zirconia (YSZ). Grain sizes are maintained due to a lack of diffusion, and thus microstructural stability is enhanced. The GAP fracture toughness was shown to be over 2X that of GZO while exhibiting a lower elastic modulus and similar hardness. The 50:50 GZO-GAP composite exhibited a 63% reduction in the absolute erosion rate, demonstrating the immense toughening capabilities of this system. The implications for composite TBCs utilizing this system are discussed, along with future work. K E Y W O R D Saluminates, composites, durability, gadolinium zirconate, thermal barrier coatings

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Section: Resultsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Durable aluminate toughened zirconate composite thermal barrier coating (TBC) materials for high temperature operation

et al. 2019

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“…The pores and cracks in the coating may provide the starting sources for the peeling of the coating, and thus the erosion resistance of the coating decreases with increasing porosity [28,29]. In addition, according to Schmitt's research, smaller splat size provides a lower surface roughness, which has been shown to reduce erosion rate by yielding smaller failure regions [30,31]. In this study, the porosity of F-TBC is lower than that of C-TBC, and the splat size of F-TBC is smaller than that of C-TBC due to the fine feedstock.…”

Section: Particle Erosion Resistancementioning

confidence: 99%

Influence of Lamellar Interface Morphology on Cracking Resistance of Plasma-Sprayed YSZ Coatings

et al. 2018

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Splat morphology is an important factor that influences the mechanical properties and durability of thermal barrier coatings (TBCs). In this study, yttria-stabilized zirconia (YSZ) coatings with different lamellar interface morphologies were deposited by atmospheric plasma spraying (APS) using feedstocks with different particle sizes. The influence of lamellar interface roughness on the cracking resistance of the coatings was investigated. Furthermore, the thermal shock and erosion resistance of coatings deposited by two different powders was evaluated. It was found that the particle size of the feedstock powder affects the stacking morphology of the splat that forms the coating. Coatings fabricated from coarse YSZ powders (45-60 µm) show a relatively rough inter-lamellar surface, with a roughness about 3 times greater than those faricated from fine powders (15-25 µm). Coatings prepared with fine powders tend to form large cracks parallel to the substrate direction under indentation, while no cracking phenomena were found in coatings prepared with coarse powders. Due to the higher cracking resistance, coatings prepared with coarse powders show better thermal shock and erosion resistances than those with fine powders. The results of this study provide a reference for the design and optimization of the microstructure of TBCs.

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“…8,9 To combat the low toughness of zirconates, the authors have explored utilizing multiphase composites consisting of GZO modified with a secondary toughening phase in the form of multilayers 10,11 and composites. [12][13][14][15] It was demonstrated that minor additions of a toughening phase can have substantial improvement on the erosion durability of coatings while having minimal debit on thermal conductivity for both electron beam-physical vapor deposition and air plasma spray-derived coatings. In fact, it was determined that the thermal conductivity of the secondary phase has only a minor contribution to the conductivity of the system, particularly when in the relatively small amounts needed to enhance erosion.…”

Section: Introductionmentioning

confidence: 99%

Enhanced calcium–magnesium–aluminosilicate (CMAS) resistance of GdAlO₃ (GAP) for composite thermal barrier coatings

et al. 2022

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The impact of calcium-magnesium-alumino-silicate (CMAS) degradation is a critical factor for development of new thermal and environmental barrier coatings. Several methods of preventing damage have been explored in the literature, with formation of an infiltration inhibiting reaction layer generally given the most attention. Gd 2 Zr 2 O 7 (GZO) exemplifies this reaction with the rapid precipitation of apatite when in contact with CMAS. The present study compares the CMAS behavior of GZO to an alternative thermal barrier coating (TBC) material, GdAlO 3 (GAP), which possesses high temperature phase stability through its melting point as well as a significantly higher toughness compared with GZO.The UCSB laboratory CMAS (35CaO-10MgO-7Al 2 O 3 -48SiO 2 ) was utilized to explore equilibrium behavior with 50:50 mol% TBC:CMAS ratios at 1200, 1300, and 1400 • C for various times. In addition, 8 and 35 mg/cm 2 CMAS surface exposures were performed at 1425 • C on dense pellets of each material to evaluate the infiltration and reaction in a more dynamic test. In the equilibrium tests, it was found that GAP appears to dissolve slower than GZO while producing an equivalent or higher amount of pore blocking apatite. In addition, GAP induces the intrinsic crystallization of the CMAS into a gehlenite phase, due in part to the participation of the Al 2 O 3 from GAP. In surface exposures, GAP experienced a substantially thinner reaction zone compared with GZO after 10 h (87 ± 10 vs. 138 ± 4 μm) and a lack of strong sensitivity to CMAS loading when tested at 35 mg/cm 2 after 10 h (85 ± 13 versus 246 ± 10 μm). The smaller reaction zone, loading agnostic behavior, and intrinsic crystallization of the glass suggest this material warrants further evaluation as a potential CMAS barrier and inclusion into composite TBCs. K E Y W O R D Scomposites, environmental barrier coatings (EBC), rare earths, thermal barrier coatings (TBC), zirconate, calcium-magnesium-alumino-silicate (CMAS)

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Development and Optimization of Tailored Composite TBC Design Architectures for Improved Erosion Durability

Cited by 13 publications

References 39 publications

Durable aluminate toughened zirconate composite thermal barrier coating (TBC) materials for high temperature operation

Durable aluminate toughened zirconate composite thermal barrier coating (TBC) materials for high temperature operation

Influence of Lamellar Interface Morphology on Cracking Resistance of Plasma-Sprayed YSZ Coatings

Enhanced calcium–magnesium–aluminosilicate (CMAS) resistance of GdAlO₃ (GAP) for composite thermal barrier coatings

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Development and Optimization of Tailored Composite TBC Design Architectures for Improved Erosion Durability

Cited by 13 publications

References 39 publications

Durable aluminate toughened zirconate composite thermal barrier coating (TBC) materials for high temperature operation

Durable aluminate toughened zirconate composite thermal barrier coating (TBC) materials for high temperature operation

Influence of Lamellar Interface Morphology on Cracking Resistance of Plasma-Sprayed YSZ Coatings

Enhanced calcium–magnesium–aluminosilicate (CMAS) resistance of GdAlO3 (GAP) for composite thermal barrier coatings

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Enhanced calcium–magnesium–aluminosilicate (CMAS) resistance of GdAlO₃ (GAP) for composite thermal barrier coatings