Microstructure and hot corrosion resistance of Si-Al-Y coated TiAl alloy

Li, Yongquan; Xie, Fei; Yang, Shaolin

doi:10.1007/s11771-020-4478-8

Cited by 8 publications

(5 citation statements)

References 31 publications

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“…At a temperature of 1000 • C, the coating is primarily composed of TiSi 2 , TiSi, and Ti 5 Si 3 phases, with a small amount of Al 2 O 3 present on the surface. This is due to the outward growth of the coating, which results in part of the Al 2 O 3 used as a filler being bonded to the surface of the coating [4,27]. The flaky Al 2 O 3 that adheres to the sample surface at 1050 • C is formed through the reaction of aluminum atoms diffusing outward within the substrate with the remaining oxygen in the crucible.…”

Section: Effect Of Temperatures On Ti-si Coatingsmentioning

confidence: 99%

“…The chemical potential gradient for reaction diffusion can be derived from the change in chemical potential ∆µ versus distance d 0 : ∇µ = ∂∆µ ∂d 0 (27) where d 0 represents the average distance over which the atoms diffuse in a 1 mol reaction. The volume of the phase change due to reaction diffusion is denoted by V, the thickness of the phase change induced is denoted by h, and the surface area of the sample is denoted by S. Then, the following applies:…”

Section: Modelingmentioning

confidence: 99%

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Formation Mechanism of Ti–Si Multi-Layer Coatings on the Surface of Ti–6Al–4V Alloy

Zhao,

Liang,

Zhang

et al. 2024

Coatings

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Titanium alloys are widely used in aerospace applications due to their high specific strength and exceptional corrosion resistance. In this study, a silicide coating with a multi-layer structure was designed and prepared via a pack cementation process to improve the high-temperature oxidation resistance of titanium alloy. A new theory based on the Le Chatelier’s principle is proposed to explain the generation mechanism of active Si atoms. Taking the chemical potential as a bridge, a functional model of the relationship between the diffusion driving force and the change in the Gibbs free energy of reaction diffusion is established. Experimental results indicate that the depth of the silicide coating increases with the siliconization temperature (1000–1100 °C) and time (0–5 h). The multi-layer coating prepared at 1075 °C for 3 h exhibits a thick and dense structure with a thickness of 23.52 μm. This coating consists of an outer layer of TiSi2 (9.40 μm), a middle layer of TiSi (3.36 μm), and an inner layer of Ti5Si3 (10.76 μm). Under this preparation parameter, increasing the temperature or prolonging the holding time will cause the outward diffusion flux of atoms in the substrate to be much larger than the diffusion flux of silicon atoms to the substrate, thus forming pores in the coating. The calculated value of the diffusion driving force FTiSi = 2.012S is significantly smaller than that of FTiSi2 = 13.120S and FTi5Si3 = 14.552S, which perfectly reveals the relationship between the thickness of each layer in the Ti–Si multi-layer coating.

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Section: Effect Of Temperatures On Ti-si Coatingsmentioning

confidence: 99%

Section: Modelingmentioning

confidence: 99%

Formation Mechanism of Ti–Si Multi-Layer Coatings on the Surface of Ti–6Al–4V Alloy

Zhao,

Liang,

Zhang

et al. 2024

Coatings

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“…Fabrication of Si-Al, Al-Y, and Si-Al-Y layers on TiAl alloys have been shown to produce a series of different intermetallic layers (e.g., aluminide and silicide) and oxide layers, increasing the oxidation resistance of the coated alloys [227][228][229][230][231][232]. In particular, J. Xiang et al [232] Platinum aluminide coatings seem to protect the titanium alloys from oxidation as well as from hot corrosion, preventing the formation of the alpha phase.…”

Section: Aluminide and Chromizing Metallic Coatingsmentioning

confidence: 99%

“…They observed an excellent oxidation resistance of the Ti alloys up to 800 • C, thanks to Pt, which effectively promotes continuous alumina scale formation during high temperature exposure. Fabrication of Si-Al, Al-Y, and Si-Al-Y layers on TiAl alloys have been shown to produce a series of different intermetallic layers (e.g., aluminide and silicide) and oxide layers, increasing the oxidation resistance of the coated alloys [227][228][229][230][231][232]. In particular, J. Xiang et al [232] coated a Ti alloy by means of Si-Y co-deposition and aluminization, which, due to inward diffusion of Al atoms and outward diffusion of Ti and Nb atoms, gave rise to the formation of different mixed intermetallic layers and promoted the preferential development of Al2O3 on the surface in spite of the less resistant TiO2 oxide.…”

Section: Aluminide and Chromizing Metallic Coatingsmentioning

confidence: 99%

Critical Raw Materials Saving by Protective Coatings under Extreme Conditions: A Review of Last Trends in Alloys and Coatings for Aerospace Engine Applications

et al. 2021

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Several applications where extreme conditions occur require the use of alloys often containing many critical elements. Due to the ever increasing prices of critical raw materials (CRMs) linked to their high supply risk, and because of their fundamental and large utilization in high tech products and applications, it is extremely important to find viable solutions to save CRMs usage. Apart from increasing processes’ efficiency, substitution, and recycling, one of the alternatives to preserve an alloy and increase its operating lifetime, thus saving the CRMs needed for its manufacturing, is to protect it by a suitable coating or a surface treatment. This review presents the most recent trends in coatings for application in high temperature alloys for aerospace engines. CRMs’ current and future saving scenarios in the alloys and coatings for the aerospace engine are also discussed. The overarching aim of this paper is to raise awareness on the CRMs issue related to the alloys and coating for aerospace, suggesting some mitigation measures without having the ambition nor to give a complete overview of the topic nor a turnkey solution.

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“…The gradient coating achieved through this combination of methods was promising for corrosion protection, but it was also beneficial for internal stress reduction. The pack cementation method was used to successfully deposit a Si-Al-Y coating on a Ti-48Al-2Cr-2Nb (at%) alloy; however, it had limited-time protective properties in a 25wt% K 2 SO 4 + 75wt% Na 2 SO 4 corrosive environment at 900 • C [40]. Silicide diffusion coatings were also used for Ti-46Al-8Ta (at%) alloy protection against hot corrosion caused by NaCl or/and Na 2 SO 4 salt deposits [41].…”

Section: Introductionmentioning

confidence: 99%

Influence of Silicon and Chromium on the Na2SO4-Induced Hot Corrosion Behavior of Titanium Alloys

Mitoraj-Królikowska

2023

Crystals

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Titanium alloys are widely used as construction materials in the aerospace and automotive industries. They have many advantages but also have limitations related to their susceptibility to high-temperature oxidation and hot corrosion. Many efforts to increase the lifetime of components made of titanium alloys have been reported in the literature; the most promising ones involve the deposition of coatings. The present paper is focused on the development of coatings containing chromium and silicon, and their further evaluation in hot corrosion tests. It was proved that the Cr-Si coatings were more effective than Si coatings alone in protecting the titanium alloys against Na2SO4-induced hot corrosion at 800 °C. The enhanced corrosion resistance was attributed to the preferential formation of a thick and continuous SiO2 layer on the surface and—in the case of titanium aluminide alloy—the growth of an Al2O3-rich inner layer of the scale, promoted by chromium.

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Microstructure and hot corrosion resistance of Si-Al-Y coated TiAl alloy

Cited by 8 publications

References 31 publications

Formation Mechanism of Ti–Si Multi-Layer Coatings on the Surface of Ti–6Al–4V Alloy

Formation Mechanism of Ti–Si Multi-Layer Coatings on the Surface of Ti–6Al–4V Alloy

Critical Raw Materials Saving by Protective Coatings under Extreme Conditions: A Review of Last Trends in Alloys and Coatings for Aerospace Engine Applications

Influence of Silicon and Chromium on the Na2SO4-Induced Hot Corrosion Behavior of Titanium Alloys

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