Publications Internationales

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    Oxidation and property evolution of AISI T5 steel under varying heat treatments
    (2025) Dadou, Abdenour; Dilmi, Hamid; Bezzazi, Boudjema; Aribi, Chouaib; Daoud, Ismail
    This study evaluates the effect of heat treatment on the mechanical, tribological, and oxidation behavior of AISI T5 steel. The chemical composition was first characterized using spectroscopy and SEM. A two-year oxidation test conducted in humid and relatively dry atmospheres showed strong environmental sensitivity: in humid air, the oxidation rate reached 11.27×10-2 P/P0 per month with a sharp increase after 25 days, whereas in dry air it remained below1.35×10-2 P/P0 per month, following a linear and nearly flat trend indicative of a protective oxide scale. Heat treatment significantly increased hardness from 34.15 ± 0.59 HRC (untreated) to 62.70 ± 0.66 and 60.80 ± 0.48 HRC for water and oil quenched steels, respectively. Impact strength decreased accordingly, with oil quenching offering the best hardness-toughness balance (60.8 HRC, 2.08 Kcv). Instrumented indentation confirmed substantial surface strengthening, with HIT rising to 17.39 ± 0.29 uced by 81.3% (Q. Water) and 62.5% (Q. Oil), with faster run-in in the water-quenched condition. XRD revealed tempered martensite with Fe3W3C/Cr7C3 (Q. Water) and Co3W3C (Q. Oil), consistent with thermal conditions. This study provides new experimental data on the effects of 15-minute austenitization followed by oil or water quenching on the properties of AISI T5 steel, highlighting its potential for process optimization.
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    1,4-Dimethoxybutadienediyl-Bridged diiron compounds in three oxidation states : evaluation of delocalization effects
    (American Chemical Society, 2019) Sahnoune, Hiba; Mahias, Virginie; Halet, Jean-François; Lapinte, Claude
    The binuclear iron complexes [Cp∗(PMe3)(CO)Fe-C(OCH3)=CH-CH=C(OCH3)-Fe(PMe3)(CO)Cp∗] (1meso and 1dl) were prepared by double deprotonation of their known parents [Cp∗(PMe3)(CO)Fe=C(OCH3)CH2-CH2-C(OCH3)=Fe(PMe3)(CO)Cp∗](PF6)2 (5meso and 5dl) and were isolated in good yield (90%). These complexes were characterized by ESI-mass spectrometry, IR and multinuclear NMR spectroscopy, and cyclic voltammetry. The singly and doubly oxidized forms 1meso(PF6)n and 1dl(PF6)n (n = 1, 2) were prepared by oxidation of the parent neutral complexes with 1 and 2 equiv of ferrocenium salt (93-100% yield). The related complex [Cp∗(dppe)Fe-C(OCH3)=CH-CH=C(OCH3)-Fe(dppe)Cp∗](PF6) (2(PF6)) was obtained by reduction of the known dicationic derivative [Cp∗(dppe)Fe-C(OCH3)=CH-CH=C(OCH3)-Fe(dppe)Cp∗](PF6) (2(PF6)2) with 1 equiv of cobaltocene (100% yield). Multinuclear NMR spectroscopy allowed us to establish the diiron(II) conjugated μ-bis(carbene) structure for 1meso(PF6)2 and 1dl(PF6)2. In the case of the meso derivative, 1H NMR revealed the presence of E and Z isomers in a 4:1 ratio, confirming the presence of a C=C double bond in the middle of the bridge. The three radicals 1meso(PF6), 1dl(PF6), and 2(PF6), which are thermally stable, were analyzed by IR, Mössbauer, ESR, UV-vis, and NIR spectroscopy. Experimental data, discussed with the support of quantum chemistry calculations performed at the DFT level of theory, indicate that these radical cations exhibit characteristics of oxidation on the butadienediyl bridge rather than on the metal centers
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    Characterization and transformation of the Opuntia ficus indica fruits
    (Springer US, 2018) Idir, Lamia; Zouhir, Cherrared; Amir, Youcef
    Opuntia ficus indica fruits have been associated with health effects, due to their protective actions against oxidation. Nevertheless, few studies about processing of Opuntia fruits are available’; therefore, we studied the pulp characteristics and processing of a local variety, for producing beverage nectars. The pulp had an average pH of 5.64, 13.47 °Brix, with total sugars (106 g L−1), K (1180 mg L−1), 503.3 µg L−1 of β carotene, 120 mg L−1 of total phenolic compounds, 4.9 mg and 46.9 mg L−1 respectively for betacyanins and betaxanthins and 243.4 mg L−1 of vitamin C. The formulated nectars with 35% of pulp (N35) and 45% of pulp (N45) had respectively 14 and 15 °Brix. Minor components represent 1109 and 1112 mg L−1 of K for N35 and N45 respectively, β carotene (318.6 µg and 362.8 µg L−1), and vitamin C 227 and 231 mg L−1. We confirmed the stability and acceptability of these beverages after a month of storage, after stability and panel tests. Therefore, we suggest that the pulp processing can be used as a new form of agro industrial utilization of this underutilized fruit