Oxidation behavior of ytterbium silicide in air and steam

Miyazaki, Toshihisa; Usami, Syo; Arai, Yutaro; Tsunoura, Toru; Inoue, Ryo; Aoki, Toru; Tamura, Ryuji; Kogo, Yasuo

doi:10.1016/j.intermet.2020.106992

Cited by 7 publications

(7 citation statements)

References 22 publications

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“…In addition to transition metal silicides, rare-earth silicides have also been studied as coating materials in aero gas turbine engines [12][13][14][15]. Such use is due to the oxidation of a conventional coating material (Si) in a combustion environment (T<1300 °C, 10−30 atm [16]), forming cristobalite, which is a polymorphous type of SiO 2 , thereby causing the delamination of the coating.…”

Section: Introductionmentioning

confidence: 99%

Degradation of Yb–Gd–Ti-Si middle entropy silicides in oxidizing atmosphere

Arai¹,

Inoüe²

2022

Mater. Res. Express

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Using arc melting, a novel rare-earth silicide, middle entropy Yb-Gd-Ti-Si, was fabricated for high-temperature material applications. The oxidation behavior of the Yb-Gd-Ti-Si was evaluated through oxidation tests conducted at 1200 °C for 1, 2, 4, and 8 h in air. The oxidation rate at 1200 °C was almost the same, regardless of the addition of Ti. The oxidation rate of Yb-Gd-Ti-Si at lower temperatures (600 °C to 900 °C) was lower than that of Yb-Gd-Si. In addition, detailed microstructural observations indicate that the formation of TiO2 and other oxides in the Yb-Ti-O (Yb-Ti-Si-O) phase suppresses the formation of Yb2O3, causing a drastic oxidation at intermediate temperatures (600 °C to 900 °C). These results indicate that the addition of Ti to Yb-Gd-Si is effective at preventing the preferential oxidation of the grain boundaries at 600 °C to 900 °C, which is commonly observed in metal silicides

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Section: Introductionmentioning

confidence: 99%

Degradation of Yb–Gd–Ti-Si middle entropy silicides in oxidizing atmosphere

Arai¹,

Inoüe²

2022

Mater. Res. Express

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“…Local thermal stresses were induced in the Si BC around cristobalite, thereby facilitating the propagation of cracks in the Si BC layer. A novel bond coat material is explored and some candidates have been evaluated, however, attractive candidates are not found so far 9–12 …”

Section: Introductionmentioning

confidence: 99%

“…A novel bond coat material is explored and some candidates have been evaluated, however, attractive candidates are not found so far. [9][10][11][12] After the heat exposure of the EBC system, the coefficient of thermal expansion (CTE) of silicate TC (~4-8 × 10 −6 /°C) was higher than those of the Si BC (~4 × 10 −6 /°C) and SiC/SiC substrates (~4-5 × 10 −6 /°C), thereby indicating that the thermal stresses were evolved in each layer. 2,13 It was assumed that the thermal compressive stress was primarily applied in the Si BC layer because the CTE for Si BC was lower than those of the TC and substrate.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic crack propagation behavior for the silicon‐bond coat layer in a multilayer coated system

Arai

Inoue

Kakisawa

2021

Int J Applied Ceramic Tech

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This study sought to examine the relationship between the degradation mechanism, thermal stress, and crack propagation behavior in environmental barrier coating (EBC) systems. An EBC system composed of a mullite topcoat (TC), Si‐bond coat (BC), and SiC substrate was prepared by atmospheric plasma spraying. Heat exposure tests were conducted to evaluate the microstructure of the EBC system at 1300°C for 1, 10, 50, and 100 h. The fracture resistance of the Si BC for the in‐plane (direction parallel to each layer, 0.4–0.6 MPnormalam) and through‐thickness directions (direction from the TC to substrate, 1.7–2.1 MPnormalam) differed because a thermal compressive stress was induced for the in‐plane direction owing to the mismatch of the thermal expansion coefficients for each layer, which acted as a barrier for crack propagation. However, cracks tended to propagate in the in‐plane direction because they were not affected by the in‐plane compressive stress. These results clearly showed that Si BC exhibited in‐plane anisotropy and crack propagation after heat exposure, which were the major sources of delamination of the EBC system.

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“…Recently, some researchers have evaluated the degradation behavior of rare-earth silicides for their application as advanced bond coat materials [17][18][19][20]. They investigated the degradation behaviors of Yb3Si5 and Yb5Si3 at temperatures up to 1200 °C in air, steam, and mixed environments because their melting point is higher than that of Si [19,20]. The studies revealed that these silicides oxidize, and Yb2O3, Yb2SiO5, and Yb2Si2O7 form ultimately.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, rare-earth silicates and silicides are considered as potential candidates for environmental barrier coatings (EBCs) for aero-gas turbine engines [13][14][15][16][17][18][19][20]. EBCs are mainly composed of two layers of coating: a topcoat and a bond coat.…”

Section: Introductionmentioning

confidence: 99%

Improvement of the Oxidation Behavior of Yb-Gd-Si Ternary Alloys at Low Temperatures via Ti Addition

Arai

Morigayama

Aoki

et al. 2021

Preprint

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To improve the oxidation behavior of Yb-Gd-Si, 0.5 and 1 at% of Ti-containing Yb-Gd-Si (denoted as YGTS-0.5 and YGTS-1, respectively) were fabricated by arc melting. The oxidation behaviors of both YGTS specimens were evaluated by oxidation tests performed in a temperature range of 600–1200 °C for 1, 2, 4, and 8 h in air. Additionally, thermogravimetric analysis (TGA) was conducted at the abovementioned temperature range in air and steam. Oxidation tests at 1200 °C revealed no significant changes in the oxidation rate. Moreover, the oxidation tests revealed that Yb-Gd-Si and YGTS-0.5 became powdery after oxidation, whereas YGTS-1 maintained its form. Detailed microstructural observations indicated that the formation of TiO2 and other oxides in the Yb-Ti-O phase and oxide-containing Yb, Gd, Ti, and Si suppressed the formation of Yb2O3, which caused drastic oxidation at intermediate temperatures (600–900 °C). These results indicated that the addition of 1 at% of Ti to Yb-Gd-Si was effective in improving its oxidation behavior.

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Oxidation behavior of ytterbium silicide in air and steam

Cited by 7 publications

References 22 publications

Degradation of Yb–Gd–Ti-Si middle entropy silicides in oxidizing atmosphere

Degradation of Yb–Gd–Ti-Si middle entropy silicides in oxidizing atmosphere

Anisotropic crack propagation behavior for the silicon‐bond coat layer in a multilayer coated system

Improvement of the Oxidation Behavior of Yb-Gd-Si Ternary Alloys at Low Temperatures via Ti Addition

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Oxidation behavior of ytterbium silicide in air and steam

Cited by 7 publications

References 22 publications

Degradation of Yb–Gd–Ti-Si middle entropy silicides in oxidizing atmosphere

Degradation of Yb–Gd–Ti-Si middle entropy silicides in oxidizing atmosphere

Anisotropic crack propagation behavior for the silicon‐bond coat layer in a multilayer coated system

Improvement of the Oxidation Behavior of Yb-Gd-Si&nbsp;Ternary Alloys at Low Temperatures via Ti Addition

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Improvement of the Oxidation Behavior of Yb-Gd-Si Ternary Alloys at Low Temperatures via Ti Addition