Autor: Halimi, A. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Grain refinement, microhardness distribution, strain hardening behaviour and mechanical proprieties of RD-ECAPed AA 1050
Autorzy:: Halimi, A.
Hemmouche, L.
Chettah, I. E.
Louchene, Z. A.
Tematy:: aluminium alloys
Rotary Die Equal Channel Angular Pressing
microstructure
longitudinal microhardness
compression test; Pokaż więcej
Wydawca:: Instytut Podstawowych Problemów Techniki PAN
Powiązania:: https://bibliotekanauki.pl/articles/38697115.pdf Link otwiera się w nowym oknie
Opis:: This study aims to investigate the evolution of mechanical and microstructural characteristics of the 1050 aluminium alloy processed by Rotary Die Equal Channel Angular Pressing (RD-ECAP). The RD-ECAPed specimens were analysed after each pass using optical microscopy, quasi-static compression test and microhardness measurements. The results revealed a reduction in grain size from 29 _m before the RD-ECAP process to a minimum value of 2 _m at the second pass, corresponding to the maximum value of compressive yield strength, reaching 184MPa. Furthermore, there was an increase in hardness from 30 Hv to 63 Hv with a homogeneous distribution along the longitudinal surface, especially in the initial four RD-ECAP passes. Additionally, the appearance of a 45_ shear plane was observed at the last fifth pass, coinciding with the region of maximum microhardness.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Quasi-static and dynamic characterization of ultrafine-grained 2017A-T4 aluminium alloy processed by accumulative roll bonding PDF
Autorzy:: Halimi, A.
Boudiaf, A.
Hemmouche, L.
Medjahed, A.
Tria, D. E.
Henniche, A.
Djeghlal, M. E. A.
Baudin, T.
Tematy:: accumulative roll bonding (ARB)
2017A-T4 aluminium alloy
quasi-static loading
dynamic loading
grain refinement; Pokaż więcej
Wydawca:: Instytut Podstawowych Problemów Techniki PAN
Powiązania:: https://bibliotekanauki.pl/articles/38627443.pdf Link otwiera się w nowym oknie
Opis:: In this study, novel composite strips based on 2017A-T4 aluminium alloy (Al-Cu-Mg) produced by accumulative roll bonding (ARB) were developed. The microstructure and mechanical properties of the ultrafine-grained sheets under quasistatic and dynamic loadings were investigated. The initial microstructure characterization with an Optical Microscope and a Scanning Electron Microscope indicated that the ARBed sheets formed a compact material with the homogeneous and identical thickness for the individual bonded layers. Besides, the presence of precipitates was identified in all the processed strips with diverse sizes, quantities and distribution. Moreover, from Electron Back Scatter Diffraction, the microstructure was noticeably refined with increasing theARBcycles to reach 1.7 mof the grain size at the fifth cycle. The microhardness measurement and the tensile test were carried out for both natural ageing and ARBed specimens. Accordingly, the tensile stress acts on the individual layers rather than the entire sample that conduct to a reduction in the overall properties for the ARBed strips. Furthermore, a stabilization in the mechanical properties for the three first ARB cycles was noted, whereas, the domination of the dynamic recrystallization was responsible for a significant drop after the fourth cycle which is considered as the transition state. The characteristics of the compression deformation were examined under dynamic and quasi-static loadings conditions by using the Split–Hopkinson Pressure Bar system and the universal testing machine, respectively. The strain hardening behaviour was investigated using the Hollomon analysis. It was found that the thermal softening played a crucial role when compared to the strain hardening for all the studied strips. Moreover, the strain rate under the dynamic loading has a minor effect on the stress flow of the ARBed sheets compared to the as-received material.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Maintenance actions planning in industrial centrifugal compressor based on failure analysis
Planowanie czynności konserwacyjnych dla przemysłowej sprężarki odśrodkowej w oparciu o analizę uszkodzeń
Autorzy:: Halimi, D.
Hafaifa, A.
Bouali, E.
Tematy:: planowanie obsługi
niezawodność
gotowość
układ sprężania gazu
sprężarka odśrodkowa
optymalizacja
analiza uszkodzeń
maintenance planning
reliability
availability
gas compression system
centrifugal compressor
optimization
failure analysis; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Powiązania:: https://bibliotekanauki.pl/articles/302203.pdf Link otwiera się w nowym oknie
Opis:: Obsługa urządzeń przemysłowych wymaga analizy zachowań układów i ich części składowych. W niniejszej pracy zoptymalizowano czynności konserwacyjne tak, aby wyeliminować występowanie uszkodzeń w kontrolowanym procesie przemysłowym. Celem prezentowanej pracy było poprawienie niezawodności elementów układu sprężania gazu poprzez zaplanowanie czynności konserwacyjnych w oparciu o analizę uszkodzeń z wykorzystaniem optymalizacji interwencji w przemysłowej sprężarce odśrodkowej. O skuteczności proponowanego podejścia świadczy poprawa parametrów niezawodności oraz gotowość omawianej instalacji olejowej.
The industrial maintenance implementation requires to the behaviour system analysis and their components. In this work, we optimize the maintenance actions to eliminate failures in the inspected industrial process. Our purpose in this work is to improve the components reliability in gas compression system, by the planning of the maintenance actions based on failure analysis using the intervention optimization in industrial centrifugal compressor plant. The finality of this proposed approach is proved by the improvement of the reliability performances and by the availability of this oil installation.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Structural and Optical Properties of ZnO and Co Doped ZnO Thin Films Prepared by Sol-Gel
Autorzy:: Khantoul, A.
Sebais, M.
Rahal, B.
Boudine, B.
Halimi, O.
Tematy:: Co doped ZnO
XRD
nanometric size
photoluminescence; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1030548.pdf Link otwiera się w nowym oknie
Opis:: We report on ZnO films doped with different Co concentrations (0, 0.5, and 1 wt%) prepared by sol-gel technique in association with dip-coating onto glass substrates. Zinc acetate dehydrate, cobalt acetate, mono ethanolamine were used as starting materials, as well as solvent and stabilizer, respectively. Nanostructured polycrystalline ZnO thin films with different concentrations of Co doping (0, 0.5, and 1 wt%) are prepared for the first time by the sol-gel method and annealed at 500°C for 1 h. The surface morphologies of the ZnO thin films deposited on glass substrate with different concentrations were evaluated by atomic force microscopy. The optical absorption of the films showed a blue shift of the band gap. The photoluminescence signal of the thin films of undoped and Co-doped ZnO presents different bands in the visible region. The electrical conductivity of the sample with 0.5%Co was found to be 4.62 (ΩCm)¯¹.
Dostawca treści:: Biblioteka Nauki

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