Publications Internationales

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Author: search.filters.author.Si-Chaib, Mohamed Ouali

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    Analysis of a Directionally Solidified (DS) GTD-111 Turbine Blade Failure
    (Springer, 2020) Sabri, Khier; Gaceb, Mohamed; Si-Chaib, Mohamed Ouali
    The purpose of this paper is to clarify the impact of pitting corrosion and erosion on the directionally solidified (DS) GTD-111 turbine blade behavior. Moreover, the pitting corrosion and oxidation phenomena engendered inside cooling channels of the turbine blade are utterly highlighted. Other features such as the η (Ni3, Ti) platelets nucleation, needle σ-phase precipitation at the interface NiPtAl/(DS) GTD-111 substrate are exhibited as well. Finally, the different microstructural changes in (NiPtAl) coating strata against hot corrosion, oxidation and interaction with (DS) GTD-111 substrate are revealed and argued.
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    Assessment of the degraded high-pressure blades in a land-based gas turbine
    (Springer, 2021) Sabri, Khier; Si-Chaib, Mohamed Ouali; Gaceb, Mohamed
    The purpose of this paper is to evaluate high-pressure turbine blades after a long-term thermal exposure in a land-based gas turbine. Emphasis is placed upon structure and composition of the various layers evolving, on the one hand, due to hot oxidation/corrosion attacks and, on the other hand, because of interdiffusion phenomena between the substrates and their protective coatings. This work therefore discusses the influence of γ′-Ni3 (Al, Ti) precipitates coarsening, needle σ-phase nucleation, and M23C6-Carbides formation on the hardness properties of blades. In addition, this assessment attempts to evaluate the influence of γ′-Ni3 (Al, Ti) orientation changes and crystallites size growth on the intrinsic degradation of GTD-111 and IN738LC substrates
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    Effect of Rejuvenation Heat Treatment on the Degraded Turbine Blades
    (Springer, 2020) Sabri, Khier; Si-Chaib, Mohamed Ouali; Gaceb, Mohamed
    This paper presents a novel approach to estimate the extended lifetime of first-stage turbine blades made of directionally solidified GTD-111 nickel-based superalloys. These turbine blades were removed from land-based industrial gas turbines for power generation. In addition, this new way to evaluate the lifetime extension of degraded turbine blades after rejuvenation heat treatment is based on knowledge of newly introduced degradation index (Di) evolution. The rejuvenation heat treatment (RHT) process offers an extension of 36% in blades lifetime. Effect of the RHT on the aged γ-γ’ microstructures is presented and discussed.