Phase and fracture toughness evolution during isothermal annealing of spark plasma sintered zirconia co-doped with Yb, Gd and Nd oxides

Ponnuchamy, Mohan B.; Gandhi, Ashutosh

doi:10.1016/j.jeurceramsoc.2014.12.027

Cited by 20 publications

(7 citation statements)

References 34 publications

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“…The fracture toughness of sintered YSZ with 8 mol%YO 1.5 decreased drastically upon short thermal exposure at 1150 and 1250 C but recovered during prolonged aging up to 192 h [28]. Similar observations were made on t 0 zirconia stabilized with YbO 1.5 or GdO 1.5 , as well as co-doped zirconia [31][32][33][34]. Changes in fracture toughness of YSZ coatings upon aging have also been reported [35,36].…”

Section: Phase Transformationssupporting

confidence: 67%

“…In view of these considerations, it is believed that tetragonal phases with higher c/a ratio would possess high fracture toughness. Based on this consideration, a few compositions with tetragonal structure have been studied [33,34,46,[69][70][71][72][73]. It should be noted, however, that the c/a ratio is not the dominant parameter influencing ferroelastic toughening.…”

Section: Enhancing the Fracture Toughness Of Tbcsmentioning

confidence: 99%

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Materials Aspects of Thermal Barrier Coatings

Gandhi¹

2020

Handbook of Advanced Ceramics and Composites

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Thermal barrier coatings (TBCs) are being used for the past few decades for providing thermal insulation to metallic components of hot parts of gas turbine engines. The low thermal conductivity ceramic coatings contribute toward maintaining a large temperature difference between the hot gases in the gas turbine and the superalloy components. High engine efficiency as well as prolonged component lifetime can be achieved by integrating TBCs with gas turbine components at the design stage itself. While yttria-stabilized zirconia emerged as the work-horse TBC material, a few other advanced compositions are also being used by some of the engine manufacturers. Prominent among these are zirconiabased compositions with rare-earth oxide additions, either with tetragonal or pyrochlore structure. A lot of research activity has focused on durability issues relevant to the TBC technology, for enhancing reliability as well as performance.

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Section: Phase Transformationssupporting

confidence: 67%

Section: Enhancing the Fracture Toughness Of Tbcsmentioning

confidence: 99%

Materials Aspects of Thermal Barrier Coatings

Gandhi¹

2020

Handbook of Advanced Ceramics and Composites

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“…One crucial aspect in this is issue of the phase decomposition and phase transformation [1,15,16]. As is known to all, YSZ TBCs are usually prepared either by electron beam physical vapor deposition (EB-PVD) [17,18] or by air plasma spraying (APS) [19][20][21]. Additionally, they exhibit a non-transformable metastable tetragonal (t') phase, which is desirable for thermal insulation yet.…”

Section: Introductionmentioning

confidence: 99%

Phase Composition and Stability, Sintering and Thermal Conductivity of Gd2O3 and Yb2O3 Co-Doped YSZ

Tian

Wei

2022

Coatings

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Y2O3-stabilized ZrO2 (YSZ) has been the material of choice for thermal barrier coatings (TBCs) in the past decades, yet its phase decomposition limits its application above 1200 °C. In this study, Gd2O3 and Yb2O3 co-doped YSZ powders were produced, in which some amounts of monoclinic (m) phase were introduced into the cubic (c) phase matrix. XRD results showed that the fabricated powders obtained by a solid phase synthesis were composed of m and c phases, and hat the m phase content decreased in a sequence of 4Gd-2Yb-4Y, 2Gd-2Yb-6Y and 2Gd-4Yb-4Y powders. This indicated that Yb3+ is an excellent stabilizer in the ZrO2-based lattice, which could largely suppress the formation of the m phase. The m phase content in the powders was almost kept unchanged with heating at 1300 °C, which could provide a toughening effect to the ceramic. All the powders exhibited no obvious sintering at 1300 °C for 150 h. As compared to YSZ, the three fabricated ceramics had lower thermal conductivities, and they increased in a sequence of 4Gd-2Yb-4Y, 2Gd-4Yb-4Y and 2Gd-2Yb-6Y.

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“…Changes in the phase composition and microstructure of the material may reduce its strength, e.g. decrease its fracture toughness [15,16].…”

Section: Introductionmentioning

confidence: 99%

“…Yttria-stabilized zirconia-based materials have been studied the most widely so far. However, there are quite a few works dealing with the effect of heat treatment on the structure and properties of zirconiabased materials stabilized with other oxides [15,16,22]. On the other hand, gadolinia-stabilized materials that can be used for the fabrication of thermal barrier coatings due to their low heat conductivity have been increasingly studied.…”

Section: Introductionmentioning

confidence: 99%

Effect of heat treatment on the structure and mechanical properties of partially gadolinia-stabilized zirconia crystals

Borik

Chislov

Kulebyakin

et al. 2021

Journal of Asian Ceramic Societies

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ZrO 2 ) 1-x (Gd 2 O 3 ) x (x= 0.028-0.04) is heat-treated at 1600°C in air or in vacuum. Partially gadolinia-stabilized zirconia crystals are grown by the skull melting technique. The effect of annealing on the phase compositions, structures, and mechanical properties of the crystals is studied using X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and indentation. A comparison with previously obtained data on the structure and properties of crystals after growth shows that annealing the crystals leads to the redistribution of gadolinia between the tetragonal phases: the t phase is depleted of gadolinia while the t' phase becomes enriched. The gadolinia-enriched t' phase undergoes multistage twinning. Thus, the sizes of the twins in the t' phase are far smaller than those in the t phase. Annealing the crystals increases their fracture toughness, and this increase is larger for all crystals after air annealing. The increase in the fracture toughness of the crystals is caused by a decrease in the gadolinia concentration in the transformable t phase, which enhances the effect of the transformation hardening mechanism. The fracture toughness of the crystals is further increased by the ferroelastic hardening mechanism, the effect of which is enhanced with an increase in the quantity of the t' phase in the crystals.

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Phase and fracture toughness evolution during isothermal annealing of spark plasma sintered zirconia co-doped with Yb, Gd and Nd oxides

Cited by 20 publications

References 34 publications

Materials Aspects of Thermal Barrier Coatings

Materials Aspects of Thermal Barrier Coatings

Phase Composition and Stability, Sintering and Thermal Conductivity of Gd2O3 and Yb2O3 Co-Doped YSZ

Effect of heat treatment on the structure and mechanical properties of partially gadolinia-stabilized zirconia crystals

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