The Experts below are selected from a list of 12219 Experts worldwide ranked by ideXlab platform
Satya Prakash - One of the best experts on this subject based on the ideXlab platform.
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high temperature corrosion behaviour of Superalloys under actual waste incinerator environment
Engineering Failure Analysis, 2016Co-Authors: Lalit Ahuja, Deepa Mudgal, Divya Bhatia, Surendra Singh, Satya PrakashAbstract:Abstract In the present study, three Superalloys viz. Superni 718, Superni 600 and Superco 605 were hung inside the secondary chamber of actual medical waste incinerator where the temperature is more than 1050 °C. Burning of medical waste produces very corrosive environment at high temperature which can degrade the components of construction. Hence the three Superalloys were kept for 1000 h inside the chamber. Corrosion rate has been calculated in mpy. Corrosion products so produced were characterized using SEM/EDS and XRD technique. It was observed that both the Nickel based Superalloys showed better corrosion resistance than the cobalt based superalloy under the given environment.
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high temperature oxidation studies of detonation gun sprayed cr3c2 nicr coating on fe and ni based Superalloys in air under cyclic condition at 900 c
Journal of Alloys and Compounds, 2009Co-Authors: Subhash Kamal, R Jayaganthan, Satya PrakashAbstract:Abstract The cyclic oxidation behavior of detonation-gun-sprayed Cr3C2–NiCr coating on three different Superalloys namely Superni 75, Superni 718 and Superfer 800H at 900 °C for 100 cycles in air under cyclic heating and cooling conditions has been investigated in the present work. The kinetics of oxidation of coated and bare Superalloys was analysed, using thermogravimetric technique. It was observed that all the coated and bare Superalloys obey a parabolic rate law of oxidation. X-ray diffraction, FE-SEM/EDAX and X-ray mapping techniques were used to analyse the oxidation products of coated and bare Superalloys. The results on the Cr3C2–NiCr-coated Superalloys showed better oxidation resistance due to the formation of a compact and adhesive thin Cr2O3 scale on the surface of the coating during oxidation. The scale remained intact and adherent to the partially oxidised coating during cyclic oxidation due to its good compatibility and similar thermal expansion coefficient between Cr3C2–NiCr coating and the superalloy substrates. In all the coated Superalloys, the chromium, iron, silicon and titanium were oxidised in the inter-splat region, whereas splats which consisted mainly of Ni remained unoxidised. The parabolic rate constants of Cr3C2–NiCr-coated alloys were lower than that of the bare Superalloys as observed in the present work.
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hot corrosion behavior of detonation gun sprayed cr3c2 nicr coatings on ni and fe based Superalloys in na2so4 60 v2o5 environment at 900 c
Journal of Alloys and Compounds, 2008Co-Authors: Subhash Kamal, R Jayaganthan, Satya Prakash, Sanjay KumarAbstract:Abstract The present work investigates the hot corrosion resistance of detonation gun sprayed (D-gun) Cr3C2–NiCr coatings on Superni 75, Superni 718 and Superfer 800 H Superalloys. The deposited coatings on these superalloy substrates exhibit nearly uniform, adherent and dense microstructure with porosity less than 0.8%. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of bare and Cr3C2–NiCr coated Superalloys in molten salt environment (Na2SO4–60% V2O5) at high temperature 900 °C for 100 cycles. The corrosion products of the detonation gun sprayed Cr3C2–NiCr coatings on Superalloys are analyzed by using XRD, SEM, and FE-SEM/EDAX to reveal their microstructural and compositional features for elucidating the corrosion mechanisms. It is shown that the Cr3C2–NiCr coatings on Ni- and Fe-based superalloy substrates are found to be very effective in decreasing the corrosion rate in the given molten salt environment at 900 °C. Particularly, the coating deposited on Superfer 800 H showed a better hot corrosion protection as compared to Superni 75 and Superni 718. The coatings serve as an effective diffusion barrier to preclude the diffusion of oxygen from the environment into the substrate Superalloys. It is concluded that the hot corrosion resistance of the D-gun sprayed Cr3C2–NiCr coating is due to the formation of desirable microstructural features such as very low porosity, uniform fine grains, and the flat splat structures in the coating.
Subhash Kamal - One of the best experts on this subject based on the ideXlab platform.
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high temperature oxidation studies of detonation gun sprayed cr3c2 nicr coating on fe and ni based Superalloys in air under cyclic condition at 900 c
Journal of Alloys and Compounds, 2009Co-Authors: Subhash Kamal, R Jayaganthan, Satya PrakashAbstract:Abstract The cyclic oxidation behavior of detonation-gun-sprayed Cr3C2–NiCr coating on three different Superalloys namely Superni 75, Superni 718 and Superfer 800H at 900 °C for 100 cycles in air under cyclic heating and cooling conditions has been investigated in the present work. The kinetics of oxidation of coated and bare Superalloys was analysed, using thermogravimetric technique. It was observed that all the coated and bare Superalloys obey a parabolic rate law of oxidation. X-ray diffraction, FE-SEM/EDAX and X-ray mapping techniques were used to analyse the oxidation products of coated and bare Superalloys. The results on the Cr3C2–NiCr-coated Superalloys showed better oxidation resistance due to the formation of a compact and adhesive thin Cr2O3 scale on the surface of the coating during oxidation. The scale remained intact and adherent to the partially oxidised coating during cyclic oxidation due to its good compatibility and similar thermal expansion coefficient between Cr3C2–NiCr coating and the superalloy substrates. In all the coated Superalloys, the chromium, iron, silicon and titanium were oxidised in the inter-splat region, whereas splats which consisted mainly of Ni remained unoxidised. The parabolic rate constants of Cr3C2–NiCr-coated alloys were lower than that of the bare Superalloys as observed in the present work.
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hot corrosion behavior of detonation gun sprayed cr3c2 nicr coatings on ni and fe based Superalloys in na2so4 60 v2o5 environment at 900 c
Journal of Alloys and Compounds, 2008Co-Authors: Subhash Kamal, R Jayaganthan, Satya Prakash, Sanjay KumarAbstract:Abstract The present work investigates the hot corrosion resistance of detonation gun sprayed (D-gun) Cr3C2–NiCr coatings on Superni 75, Superni 718 and Superfer 800 H Superalloys. The deposited coatings on these superalloy substrates exhibit nearly uniform, adherent and dense microstructure with porosity less than 0.8%. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of bare and Cr3C2–NiCr coated Superalloys in molten salt environment (Na2SO4–60% V2O5) at high temperature 900 °C for 100 cycles. The corrosion products of the detonation gun sprayed Cr3C2–NiCr coatings on Superalloys are analyzed by using XRD, SEM, and FE-SEM/EDAX to reveal their microstructural and compositional features for elucidating the corrosion mechanisms. It is shown that the Cr3C2–NiCr coatings on Ni- and Fe-based superalloy substrates are found to be very effective in decreasing the corrosion rate in the given molten salt environment at 900 °C. Particularly, the coating deposited on Superfer 800 H showed a better hot corrosion protection as compared to Superni 75 and Superni 718. The coatings serve as an effective diffusion barrier to preclude the diffusion of oxygen from the environment into the substrate Superalloys. It is concluded that the hot corrosion resistance of the D-gun sprayed Cr3C2–NiCr coating is due to the formation of desirable microstructural features such as very low porosity, uniform fine grains, and the flat splat structures in the coating.
Baptiste Gault - One of the best experts on this subject based on the ideXlab platform.
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on the rhenium segregation at the low angle grain boundary in a single crystal ni base superalloy
Scripta Materialia, 2020Co-Authors: Felicitas Scholz, Baptiste Gault, O M Horst, Pascal Thome, Jan Frenzel, Gunther EggelerAbstract:Abstract Industrial scale single crystal (SX) Ni-base Superalloys contain numerous low angle grain boundaries inherited from the solidification process. Here, we demonstrate that low angle grain boundaries in a fully heat-treated SX model Ni-base superalloy are strongly segregated with up to 12 at% Re. Some Re-rich dislocations forming this grain boundary are found located inside γ, others close to a γ/γ′ interface. Although these segregated Re atoms lose their solid-solution strengthening effect, they may enhance the creep resistance by pinning the low angle grain boundaries and slowing down dislocation reactions.
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atomistic phase field chemomechanical modeling of dislocation solute precipitate interaction in ni al co
Acta Materialia, 2019Co-Authors: Jonathan Cormier, Paraskevas Kontis, Baptiste Gault, Jaber Rezaei Mianroodi, Pratheek Shanthraj, Bob SvendsenAbstract:Abstract Dislocation-precipitate interaction and solute segregation play important roles in controlling the mechanical behavior of Ni-based Superalloys at high temperature. In particular, the increased mobility of solutes at high temperature leads to increased dislocation-solute interaction. For example, atom probe tomography (APT) results [ 1 ] for single crystal MC2 superalloy indicate significant segregation of solute elements such as Co and Cr to dislocations and stacking faults in γ′ precipitates. To gain further insight into solute segregation, dislocation-solute interaction, and its effect on the mechanical behavior in such Ni-Superalloys, finite-deformation phase field chemomechanics [ 2 ] is applied in this work to develop a model for dislocation-solute-precipitate interaction in the two-phase γ-γ′ Ni-based superalloy model system Ni–Al–Co. Identification and quantification of this model is based in particular on the corresponding Ni–Al–Co embedded atom method (EAM) potential [ 3 ]. Simulation results imply both Cottrell- and Suzuki-type segregation of Co in γ and γ'. Significant segregation of Co to dislocation cores and faults in γ′ is also predicted, in agreement with APT results. Predicted as well is the drag of Co by γ dislocations entering and shearing γ'. Since solute elements such as Co generally prefer the γ phase, Co depletion in γ′ could be reversed by such dislocation drag. The resulting change in precipitate chemistry may in turn affect its stability and play a role in precipitate coarsening and rafting.
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microstructural degradation of polycrystalline Superalloys from oxidized carbides and implications on crack initiation
Scripta Materialia, 2018Co-Authors: Paraskevas Kontis, R C Reed, Dierk Raabe, David M Collins, Angus J Wilkinson, Baptiste GaultAbstract:Abstract Surface connected carbides in a polycrystalline superalloy oxidized at 750 °C in air were studied as potential crack initiation sites. Lattice rotations measured in the γ/γ′ grains using high-resolution electron backscatter diffraction enabled investigation of the plastic deformation induced solely by the oxidation of carbides. Dislocations were found to enhance γ′ precipitate dissolution kinetics, resulting in soft recrystallized regions in the vicinity of the oxidized carbide with substantial compositional variation compared to the original γ/γ′ microstructure. Ramifications of such deleterious oxidized carbides alongside soft recrystallized regions on the crack initiation life in Superalloys are discussed.
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correlative microscopy novel methods and their applications to explore 3d chemistry and structure of nanoscale lattice defects a case study in Superalloys
JOM, 2018Co-Authors: Surendra Kumar Makineni, Steffen Neumeier, Malte Lenz, Paraskevas Kontis, Ankit Kumar, Peter Felfer, Michael Herbig, Erdmann Spiecker, Dierk Raabe, Baptiste GaultAbstract:Nanoscale solute segregation to or near lattice defects is a coupled diffusion and trapping phenomenon that occurs in Superalloys at high temperatures during service. Understanding the mechanisms underpinning this crucial process will open pathways to tuning the alloy composition for improving the high-temperature performance and lifetime. Here, we introduce an approach combining atom probe tomography with high-end scanning electron microscopy techniques, in transmission and backscattering modes, to enable direct investigation of solute segregation to defects generated during high-temperature deformation such as dislocations in a heat-treated Ni-based superalloy and planar faults in a CoNi-based superalloy. Three protocols were elaborated to capture the complete structural and compositional nature of the targeted defect in the alloy.
R Jayaganthan - One of the best experts on this subject based on the ideXlab platform.
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high temperature oxidation studies of detonation gun sprayed cr3c2 nicr coating on fe and ni based Superalloys in air under cyclic condition at 900 c
Journal of Alloys and Compounds, 2009Co-Authors: Subhash Kamal, R Jayaganthan, Satya PrakashAbstract:Abstract The cyclic oxidation behavior of detonation-gun-sprayed Cr3C2–NiCr coating on three different Superalloys namely Superni 75, Superni 718 and Superfer 800H at 900 °C for 100 cycles in air under cyclic heating and cooling conditions has been investigated in the present work. The kinetics of oxidation of coated and bare Superalloys was analysed, using thermogravimetric technique. It was observed that all the coated and bare Superalloys obey a parabolic rate law of oxidation. X-ray diffraction, FE-SEM/EDAX and X-ray mapping techniques were used to analyse the oxidation products of coated and bare Superalloys. The results on the Cr3C2–NiCr-coated Superalloys showed better oxidation resistance due to the formation of a compact and adhesive thin Cr2O3 scale on the surface of the coating during oxidation. The scale remained intact and adherent to the partially oxidised coating during cyclic oxidation due to its good compatibility and similar thermal expansion coefficient between Cr3C2–NiCr coating and the superalloy substrates. In all the coated Superalloys, the chromium, iron, silicon and titanium were oxidised in the inter-splat region, whereas splats which consisted mainly of Ni remained unoxidised. The parabolic rate constants of Cr3C2–NiCr-coated alloys were lower than that of the bare Superalloys as observed in the present work.
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hot corrosion behavior of detonation gun sprayed cr3c2 nicr coatings on ni and fe based Superalloys in na2so4 60 v2o5 environment at 900 c
Journal of Alloys and Compounds, 2008Co-Authors: Subhash Kamal, R Jayaganthan, Satya Prakash, Sanjay KumarAbstract:Abstract The present work investigates the hot corrosion resistance of detonation gun sprayed (D-gun) Cr3C2–NiCr coatings on Superni 75, Superni 718 and Superfer 800 H Superalloys. The deposited coatings on these superalloy substrates exhibit nearly uniform, adherent and dense microstructure with porosity less than 0.8%. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of bare and Cr3C2–NiCr coated Superalloys in molten salt environment (Na2SO4–60% V2O5) at high temperature 900 °C for 100 cycles. The corrosion products of the detonation gun sprayed Cr3C2–NiCr coatings on Superalloys are analyzed by using XRD, SEM, and FE-SEM/EDAX to reveal their microstructural and compositional features for elucidating the corrosion mechanisms. It is shown that the Cr3C2–NiCr coatings on Ni- and Fe-based superalloy substrates are found to be very effective in decreasing the corrosion rate in the given molten salt environment at 900 °C. Particularly, the coating deposited on Superfer 800 H showed a better hot corrosion protection as compared to Superni 75 and Superni 718. The coatings serve as an effective diffusion barrier to preclude the diffusion of oxygen from the environment into the substrate Superalloys. It is concluded that the hot corrosion resistance of the D-gun sprayed Cr3C2–NiCr coating is due to the formation of desirable microstructural features such as very low porosity, uniform fine grains, and the flat splat structures in the coating.
Sanjay Kumar - One of the best experts on this subject based on the ideXlab platform.
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hot corrosion behavior of detonation gun sprayed cr3c2 nicr coatings on ni and fe based Superalloys in na2so4 60 v2o5 environment at 900 c
Journal of Alloys and Compounds, 2008Co-Authors: Subhash Kamal, R Jayaganthan, Satya Prakash, Sanjay KumarAbstract:Abstract The present work investigates the hot corrosion resistance of detonation gun sprayed (D-gun) Cr3C2–NiCr coatings on Superni 75, Superni 718 and Superfer 800 H Superalloys. The deposited coatings on these superalloy substrates exhibit nearly uniform, adherent and dense microstructure with porosity less than 0.8%. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of bare and Cr3C2–NiCr coated Superalloys in molten salt environment (Na2SO4–60% V2O5) at high temperature 900 °C for 100 cycles. The corrosion products of the detonation gun sprayed Cr3C2–NiCr coatings on Superalloys are analyzed by using XRD, SEM, and FE-SEM/EDAX to reveal their microstructural and compositional features for elucidating the corrosion mechanisms. It is shown that the Cr3C2–NiCr coatings on Ni- and Fe-based superalloy substrates are found to be very effective in decreasing the corrosion rate in the given molten salt environment at 900 °C. Particularly, the coating deposited on Superfer 800 H showed a better hot corrosion protection as compared to Superni 75 and Superni 718. The coatings serve as an effective diffusion barrier to preclude the diffusion of oxygen from the environment into the substrate Superalloys. It is concluded that the hot corrosion resistance of the D-gun sprayed Cr3C2–NiCr coating is due to the formation of desirable microstructural features such as very low porosity, uniform fine grains, and the flat splat structures in the coating.
