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- Matysiak, Hubert, et al.
(author)
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Microstructure of Haynes® 282® Superalloy after Vacuum Induction Melting and Investment Casting of Thin-Walled Components
- 2013
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In: Materials. - : MDPI AG. - 1996-1944. ; 6:11, s. 5016-5037
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Journal article (peer-reviewed)abstract
- The aim of this work was to characterize the microstructure of the as-cast Haynes® 282® alloy. Observations and analyses were carried out using techniques such as X-ray diffraction (XRD), light microscopy (LM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray spectroscopy (EDS), wave length dispersive X-ray spectroscopy (WDS), auger electron spectroscopy (AES) and electron energy-loss spectrometry (EELS). The phases identified in the as-cast alloy include: γ (gamma matrix), γʹ (matrix strengthening phase), (TiMoCr)C (primary carbide), TiN (primary nitride), σ (sigma-TCP phase), (TiMo)2SC (carbosulphide) and a lamellar constituent consisting of molybdenum and chromium rich secondary carbide phase together with γ phase. Within the dendrites the γʹ appears mostly in the form of spherical, nanometric precipitates (74 nm), while coarser (113 nm) cubic γʹ precipitates are present in the interdendritic areas. Volume fraction content of the γʹ precipitates in the dendrites and interdendritic areas are 9.6% and 8.5%, respectively. Primary nitrides metallic nitrides (MN), are homogeneously dispersed in the as-cast microstructure, while primary carbides metallic carbides (MC), preferentially precipitate in interdendritic areas. Such preference is also observed in the case of globular σ phase. Lamellar constituents characterized as secondary carbides/γ phases were together with (TiMo)2SC phase always observed adjacent to σ phase precipitates. Crystallographic relations were established in-between the MC, σ, secondary carbides and γ/γʹ matrix.
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| 2. |
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| 3. |
- Gizinski, Damian, et al.
(author)
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On-the-fly Catalyst Accretion and Screening in Chemoselective Flow Hydrogenation
- 2018
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In: ChemCatChem. - : WILEY-V C H VERLAG GMBH. - 1867-3880 .- 1867-3899. ; 10:17, s. 3641-3646
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Journal article (peer-reviewed)abstract
- Herein, it is reported an on-the-fly accretion/reaction protocol to evaluate the structure-performance relationship in the chemoselective flow citral hydrogenation over Ni-based catalysts. Based on the methodology one was able to determine Ni nanoparticles ideal average size (ca. 9nm), in a rapid and facile manner. The methodology offers a simple workflow, cost-effective and adaptable strategy for process intensification and optimization.
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| 5. |
- Zienkiewicz-Machnik, Malgorzata, et al.
(author)
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Tuning Nano-Nickel Catalyst Hydrogenation Aptitude by On-the-Fly Zirconium Doping
- 2020
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In: ChemCatChem. - : Wiley. - 1867-3880 .- 1867-3899. ; 12:11, s. 3132-3138
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Journal article (peer-reviewed)abstract
- The effect of nano‐Ni catalyst post‐synthetic Zr‐modification on hydrogenation reaction of 6‐methyl‐5‐hepten‐2‐one was investigated in a fixed bed continuous‐flow micro‐reactor to produce fine chemicals. The catalytic performance revealed that Zr‐doping achieved by surface organometallic chemistry approach modifies the natural aptitude of nickel to hydrogenate C=C bond, since the addition of small quantities of zirconium significantly increased the amount of unsaturated and saturated alcohols formed in 6‐methyl‐5‐hepten‐2‐one hydrogenation. Quantum chemical calculations revealed a stronger interaction between Zr←O=C that promotes the formation of C=C semihydrogenation product and enhances the probability of complete hydrogenation. The on‐the‐fly strategy presented herein enables for rapid optimization and understanding of catalytic processes.
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| 6. |
- Zienkiewicz-Machnik, Malgorzata, et al.
(author)
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Tuning nano-nickel selectivity with tin in flow hydrogenation of 6-methyl-5-hepten-2-one by surface organometallic chemistry modification
- 2018
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In: Catalysis Today. - : ELSEVIER SCIENCE BV. - 0920-5861 .- 1873-4308. ; 308, s. 38-44
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Journal article (peer-reviewed)abstract
- Chemoselective flow hydrogenation of 6-methyl-5-hepten-2-one was performed over nano-nickel catalysts. The parent catalyst composed solely of nickel nanoparticles grafted on the polymeric resin exhibited high activity and selectivity towards C=C bond saturation but its modification with small quantities of tin significantly increased its ability to perform C=O bond hydrogenation. The post-synthetic modification of the parent catalyst was achieved by surface organometallic chemistry approach and performed in the same flow micro-reactor, which was used for the catalytic studies, providing a methodology for online modification of parent catalysts.
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