4 résultat(s) recherche sur le tag 'copper'    

Effets du courant electrique sur le mecanisme de croissance de la couche d’oxyde a l’interface des contacts electrodynamiques cuivre-graphite et graphite-graphite / Youcef Mouadji    

Public ISBD Titre : Effets du courant electrique sur le mecanisme de croissance de la couche d’oxyde a l’interface des contacts electrodynamiques cuivre-graphite et graphite-graphite Type de document : texte imprimé Auteurs : Youcef Mouadji, Auteur ; Ali Bouchoucha, Directeur de thèse Editeur : constantine [Algérie] : Université Constantine 1 Année de publication : 2013 Importance : 132 f. Format : 30 cm Note générale : 2 copies imprimées disponibles Langues : Français (fre) Tags : ????????  ??????  ???????  ?????? ????????? ???????  ?????????????? friction  wear  temperature  stresses  contact dynamic  electric current  oxide  bronze  graphite  copper  frottement  usure  température  contrainte  contact dynamique  courant électrique  oxyde  cuivre Index. décimale : 620 Génie Mécanique Résumé : Our study concerns the tribological behavior of bronze-graphite, copper-graphite and graphite-graphite couples in a dry sliding contact with and without electrical current. We conducted experimental trials to determine the coefficient of friction, wear and temperature in the vicinity of the contact as a function of mechanical and electrical parameters. Starting from the Bowden and Tabor, we have calculated friction coefficient and using the Archard’s e have determined the wear rate of the pin. Measurements of the temperature change in the pins instrumented of thermocouple lead to estimate the heat flow in the pin. The distribution of the temperature field in the pin-disk geometrical area is obtained with a numerical method based on finite volume elements. It is important to know the type and magnitude of mechanical stresses imposed at the contact dynamics. To do this, a modeling based on quasi-analytical solutions was developed by a Matlab program. The discussion of results is based on observations and analyzes of worn surfaces of the contact elements. These analyzes show that the electric current has a significant influence on the nature, composition and the growth rate of the oxide layer. The mechanism of formation and rupture of the film govern the tribological behavior, especially in the presence of electrical current. The analysis of the electrical contact resistance shows the cyclical growth and rupture of this film. This study also optimizes operating conditions tribocontacts, with and without electrical current, to increase the life of these couples and make a wise choice for best couple. Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/MOU6400.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9417 Effets du courant electrique sur le mecanisme de croissance de la couche d’oxyde a l’interface des contacts electrodynamiques cuivre-graphite et graphite-graphite [texte imprimé] / Youcef Mouadji, Auteur ; Ali Bouchoucha, Directeur de thèse . - constantine (Route ain el bey, Algérie) : Université Constantine 1, 2013 . - 132 f. ; 30 cm. 2 copies imprimées disponibles Langues : Français (fre) Tags : ????????  ??????  ???????  ?????? ????????? ???????  ?????????????? friction  wear  temperature  stresses  contact dynamic  electric current  oxide  bronze  graphite  copper  frottement  usure  température  contrainte  contact dynamique  courant électrique  oxyde  cuivre Index. décimale : 620 Génie Mécanique Résumé : Our study concerns the tribological behavior of bronze-graphite, copper-graphite and graphite-graphite couples in a dry sliding contact with and without electrical current. We conducted experimental trials to determine the coefficient of friction, wear and temperature in the vicinity of the contact as a function of mechanical and electrical parameters. Starting from the Bowden and Tabor, we have calculated friction coefficient and using the Archard’s e have determined the wear rate of the pin. Measurements of the temperature change in the pins instrumented of thermocouple lead to estimate the heat flow in the pin. The distribution of the temperature field in the pin-disk geometrical area is obtained with a numerical method based on finite volume elements. It is important to know the type and magnitude of mechanical stresses imposed at the contact dynamics. To do this, a modeling based on quasi-analytical solutions was developed by a Matlab program. The discussion of results is based on observations and analyzes of worn surfaces of the contact elements. These analyzes show that the electric current has a significant influence on the nature, composition and the growth rate of the oxide layer. The mechanism of formation and rupture of the film govern the tribological behavior, especially in the presence of electrical current. The analysis of the electrical contact resistance shows the cyclical growth and rupture of this film. This study also optimizes operating conditions tribocontacts, with and without electrical current, to increase the life of these couples and make a wise choice for best couple. Diplôme : Doctorat en sciences En ligne : ../theses/gmecanique/MOU6400.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9417

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Les formations évaporitiques triasiques des hautes plaines Sétifiennes (NE Algérien) / Aboutaleb Mezerzi  

Public ISBD Titre : Les formations évaporitiques triasiques des hautes plaines Sétifiennes (NE Algérien) : Répartition et caractrisation des substances minirales associées Type de document : texte imprimé Auteurs : Aboutaleb Mezerzi, Auteur ; Abdeslam Demdoum, Directeur de thèse ; Ramdane Marmi, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2015 Importance : 178 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Tags : Hautes plaines sétifiènnes  koudiat El Bassour  diapir  sel gemme  gypse  cuivre  fer  Draa El Djebbas  exploitation  répartition  guelle  triasique  caractérisation  évaporites  Setifian high plains  triassic  rock salt  gypsum  copper  iron  guellal  characterization  evaporites  ?????? ?????? ?????????  ?????????  ??????  ?????  ????  ????? ??????  ???? ???????  ???? ?????? Index. décimale : 550 Sciences de la terre Résumé : tract The main purpose of this work was the characterization of minerals associated with evaporite Triassic formations of the Setifian High Plains. In the north eastern of Algeria and between the two barriers of mountains, Hodna in South and Babors in North, situated a vast plains, commonly known as the Setifian High Plains. This zone occupies the central part of the wilaya of Setif, and it's a part of the externe areas of the Alps, eastern Algeria, between the Tellian slicks in the North and the forward land autochton in the South. It is considered a closed continental basin, filled by Neogene and Quaternary deposits. The genesis of evaporite deposits caused by the lagoon system that prevailed in the Triassic era with an arid climate and a high degree of evaporation which led to the precipitation of ions, Ca ++ So3--, Na +, Cl-, giving salt deposits and gypsum. The spatial distribution, and the surface movement of the Triassic evaporite formations in the Setifian High Plains would probably caused by the phenomenon of overlapping slicks of alloctons to the south. We find five (5) evaporite formations dating from the Triassic; Guellal, Koudiat el Bassour, Methgoub Ras, Draa El Djebbas and Jebel el Garsa. The principal minerals related to Triassic outcrops are represented essentially by evaporite deposits (gypsum and rock salt) .The particularity is marked by the presence of metallic minerals (iron and copper) in the blocks associated with evaporites Koudiat El Bassour. The iron mineralization associated with copper, is hosted mainly in carbonate rocks, considered by the ancient writers as an infraliasiques formation. The morphology of the mineralized bodies is characterized essentially by a vein shape and stockworks type. The mineralogical characterization by XRD and metallographic microscopic observation shows that the mineralization is usually oxidized brown-black (hematite, goethite, limonite) developed on iron carbonate (siderite, ankerite) associated with a few sulphides (chalcopyrite covellite, pyrite) and copper carbonate (malachite). Gypsum deposits are widespread in all the Triassic outcrops of the region; it comes in four (4) forms (fibrous, crystalline, microcrystalline and grainy). The Gîtologics characters, the mineralogical characterization by XRD and chemical analysis by fluorescence X show that the gypsum is characterized by a variation of quality and quantity in an outcrops to another. As such, the economic importance gypsum deposit is observed in the Triassic of Guellal. Contrary to gypsum, rock salt (halite) is prevalent only in the depth of the Triassic outcrop in Guellal, and is forming a deposit of a great economic importance. Geological, gîtologic and chemical characteristics of the rock salt deposits are the source of economic interest. Geophysical, mining and hydrogeological works of research in the diapir, which resulted an exploitation of salts for human consumption and industrial purposes. The exploitation is more methodical, it is provided by the ENASel. Diplôme : Magistère En ligne : ../theses/sc-terre/MEZ6885.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10208 Les formations évaporitiques triasiques des hautes plaines Sétifiennes (NE Algérien) : Répartition et caractrisation des substances minirales associées [texte imprimé] / Aboutaleb Mezerzi, Auteur ; Abdeslam Demdoum, Directeur de thèse ; Ramdane Marmi, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2015 . - 178 f. ; 30 cm. 2 copies imprimées disponibles Langues : Français (fre) Tags : Hautes plaines sétifiènnes  koudiat El Bassour  diapir  sel gemme  gypse  cuivre  fer  Draa El Djebbas  exploitation  répartition  guelle  triasique  caractérisation  évaporites  Setifian high plains  triassic  rock salt  gypsum  copper  iron  guellal  characterization  evaporites  ?????? ?????? ?????????  ?????????  ??????  ?????  ????  ????? ??????  ???? ???????  ???? ?????? Index. décimale : 550 Sciences de la terre Résumé : tract The main purpose of this work was the characterization of minerals associated with evaporite Triassic formations of the Setifian High Plains. In the north eastern of Algeria and between the two barriers of mountains, Hodna in South and Babors in North, situated a vast plains, commonly known as the Setifian High Plains. This zone occupies the central part of the wilaya of Setif, and it's a part of the externe areas of the Alps, eastern Algeria, between the Tellian slicks in the North and the forward land autochton in the South. It is considered a closed continental basin, filled by Neogene and Quaternary deposits. The genesis of evaporite deposits caused by the lagoon system that prevailed in the Triassic era with an arid climate and a high degree of evaporation which led to the precipitation of ions, Ca ++ So3--, Na +, Cl-, giving salt deposits and gypsum. The spatial distribution, and the surface movement of the Triassic evaporite formations in the Setifian High Plains would probably caused by the phenomenon of overlapping slicks of alloctons to the south. We find five (5) evaporite formations dating from the Triassic; Guellal, Koudiat el Bassour, Methgoub Ras, Draa El Djebbas and Jebel el Garsa. The principal minerals related to Triassic outcrops are represented essentially by evaporite deposits (gypsum and rock salt) .The particularity is marked by the presence of metallic minerals (iron and copper) in the blocks associated with evaporites Koudiat El Bassour. The iron mineralization associated with copper, is hosted mainly in carbonate rocks, considered by the ancient writers as an infraliasiques formation. The morphology of the mineralized bodies is characterized essentially by a vein shape and stockworks type. The mineralogical characterization by XRD and metallographic microscopic observation shows that the mineralization is usually oxidized brown-black (hematite, goethite, limonite) developed on iron carbonate (siderite, ankerite) associated with a few sulphides (chalcopyrite covellite, pyrite) and copper carbonate (malachite). Gypsum deposits are widespread in all the Triassic outcrops of the region; it comes in four (4) forms (fibrous, crystalline, microcrystalline and grainy). The Gîtologics characters, the mineralogical characterization by XRD and chemical analysis by fluorescence X show that the gypsum is characterized by a variation of quality and quantity in an outcrops to another. As such, the economic importance gypsum deposit is observed in the Triassic of Guellal. Contrary to gypsum, rock salt (halite) is prevalent only in the depth of the Triassic outcrop in Guellal, and is forming a deposit of a great economic importance. Geological, gîtologic and chemical characteristics of the rock salt deposits are the source of economic interest. Geophysical, mining and hydrogeological works of research in the diapir, which resulted an exploitation of salts for human consumption and industrial purposes. The exploitation is more methodical, it is provided by the ENASel. Diplôme : Magistère En ligne : ../theses/sc-terre/MEZ6885.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10208

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Study of the order disorder transitions and the mechanical properties in the metallic alloys (AuCu and AuCuAg). / Imene Lamiri  

Public ISBD Titre : Study of the order disorder transitions and the mechanical properties in the metallic alloys (AuCu and AuCuAg). Type de document : texte imprimé Auteurs : Imene Lamiri, Auteur ; Djamel Hamana, Directeur de thèse Editeur : جامعة الإخوة منتوري قسنطينة Année de publication : 2018 Importance : 133 f. Note générale : 2 copies imprimées disponibles Langues : Anglais (eng) Tags : 12 and 18-carat  gold  silver  copper  thermal analyses  precipitation  dendrite  mechanical spectroscopy  anelasticity  internal dissipation  Zener relaxation  twin boundary relaxation  grainboundaries sliding relaxation  12 et 18 carats  or  argent  cuivre  analyses thermiques  précipitation  spectroscopie mécanique  anélasticité  dissipation interne  relaxation de Zener  relaxation des joints de macles  joints de grains  21? 18 ?????  ????  ???  ???????? ????????  ???????  ???? ????  ??????? ???????????  ??? ???  ??????? ???????  ??????? ????  ???? ??????? ?????????  ??????? ?????? ?????? Index. décimale : 530 Physique Résumé : This work is motivated by a scientific interest in gaining a better understanding of the phase transformations that govern the mechanical properties of gold alloys due to their huge industrial importance such as their common use in jewelry applications, luxury watch making, catalyses, electronic industries ...etc... The selected alloys fall in one of two categories of yellow gold, based on the binary system of GoldCopper and the ternary system Gold–Copper–Silver In this thesis, selected alloys from the two categories are studied, using two principal compositions of 12 and 18-carat. The study starts primarily by the thermal identification of the possible anomalies that could happen during the heating from the room temperature up to 973K (temperature near to the industrial use -1023K). Un expectable anomaly at low temperature has been noticed by the thermal analyses while the primary state before the heating process was the disorder. The fact that has orientate the study to the use of surface techniques in order to determine the relationship of the thermally detected anomalies with the surface aspect of the alloys. The study has lead to highlight new kind of metastable phase transition that precede the ordering reaction in gold alloys at low temperature presented in dendrite shape of precipitated phase on the surface. The participation of the silver in the alloy composition leads to accelerate the ordering reaction. 18-carat binary composition, has been treated in the thorough way in terms of structural study. Using the in-situ temperature XRD measurement with data acquisition frequency of 1 pattern/1.1min. Phase transition sequences and temperatures have been determined over the fitting of the obtained patterns and through the following of the behavior evolution of the intensities of the typical peak of every phase as well as the atomic volume occupancy. The analysis and interpretation of the experimental data stemming from the mechanical spectroscopy reveal three important anelastic relaxations (internal dissipation processes), which dominate the mechanical loss spectrum of the binary 18-carat alloy above room temperature. A Zener relaxation, due to directional ordering of atoms in the substitutional solid solution, occurs nearby the phase transition AuCuI - AuCuII upon heating and the classic Zener relaxation peak accompanies the phase transition A1 - AuCuI + AuCuII upon cooling. An antiphase boundaries relaxation peak has been highlighted as typical peak of the AuCuII. Grain boundaries sliding relaxation peak has been attributed to the pure disordered phase Diplôme : Doctorat En ligne : ../theses/physique/LAM7381.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=11031 Study of the order disorder transitions and the mechanical properties in the metallic alloys (AuCu and AuCuAg). [texte imprimé] / Imene Lamiri, Auteur ; Djamel Hamana, Directeur de thèse . - [S.l.] : جامعة الإخوة منتوري قسنطينة, 2018 . - 133 f. 2 copies imprimées disponibles Langues : Anglais (eng) Tags : 12 and 18-carat  gold  silver  copper  thermal analyses  precipitation  dendrite  mechanical spectroscopy  anelasticity  internal dissipation  Zener relaxation  twin boundary relaxation  grainboundaries sliding relaxation  12 et 18 carats  or  argent  cuivre  analyses thermiques  précipitation  spectroscopie mécanique  anélasticité  dissipation interne  relaxation de Zener  relaxation des joints de macles  joints de grains  21? 18 ?????  ????  ???  ???????? ????????  ???????  ???? ????  ??????? ???????????  ??? ???  ??????? ???????  ??????? ????  ???? ??????? ?????????  ??????? ?????? ?????? Index. décimale : 530 Physique Résumé : This work is motivated by a scientific interest in gaining a better understanding of the phase transformations that govern the mechanical properties of gold alloys due to their huge industrial importance such as their common use in jewelry applications, luxury watch making, catalyses, electronic industries ...etc... The selected alloys fall in one of two categories of yellow gold, based on the binary system of GoldCopper and the ternary system Gold–Copper–Silver In this thesis, selected alloys from the two categories are studied, using two principal compositions of 12 and 18-carat. The study starts primarily by the thermal identification of the possible anomalies that could happen during the heating from the room temperature up to 973K (temperature near to the industrial use -1023K). Un expectable anomaly at low temperature has been noticed by the thermal analyses while the primary state before the heating process was the disorder. The fact that has orientate the study to the use of surface techniques in order to determine the relationship of the thermally detected anomalies with the surface aspect of the alloys. The study has lead to highlight new kind of metastable phase transition that precede the ordering reaction in gold alloys at low temperature presented in dendrite shape of precipitated phase on the surface. The participation of the silver in the alloy composition leads to accelerate the ordering reaction. 18-carat binary composition, has been treated in the thorough way in terms of structural study. Using the in-situ temperature XRD measurement with data acquisition frequency of 1 pattern/1.1min. Phase transition sequences and temperatures have been determined over the fitting of the obtained patterns and through the following of the behavior evolution of the intensities of the typical peak of every phase as well as the atomic volume occupancy. The analysis and interpretation of the experimental data stemming from the mechanical spectroscopy reveal three important anelastic relaxations (internal dissipation processes), which dominate the mechanical loss spectrum of the binary 18-carat alloy above room temperature. A Zener relaxation, due to directional ordering of atoms in the substitutional solid solution, occurs nearby the phase transition AuCuI - AuCuII upon heating and the classic Zener relaxation peak accompanies the phase transition A1 - AuCuI + AuCuII upon cooling. An antiphase boundaries relaxation peak has been highlighted as typical peak of the AuCuII. Grain boundaries sliding relaxation peak has been attributed to the pure disordered phase Diplôme : Doctorat En ligne : ../theses/physique/LAM7381.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=11031

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Etude , exploration et identification des processus de rétention des métaux lourds par certains sous produits agricoles / Sihem Arris

Public ISBD Titre : Etude , exploration et identification des processus de rétention des métaux lourds par certains sous produits agricoles Type de document : texte imprimé Auteurs : Sihem Arris ; Univ.Mentouri, Editeur scientifique ; Mossaab Bencheikh Lehocine, Directeur de thèse Année de publication : 1999 Importance : 75 f. Note générale : 1 Disponible à la salle de recherche 2 Disponibles au magasin de la bibliothèque centrale Langues : Français (fre) Tags : Zinc  Cadmium  Adsorption  By-products, Heavy metals  Removal  Water  Waste water  Copper Index. décimale : 661 Chimie Industrielle Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=4568 Etude , exploration et identification des processus de rétention des métaux lourds par certains sous produits agricoles [texte imprimé] / Sihem Arris ; Univ.Mentouri, Editeur scientifique ; Mossaab Bencheikh Lehocine, Directeur de thèse . - 1999 . - 75 f. 1 Disponible à la salle de recherche 2 Disponibles au magasin de la bibliothèque centrale Langues : Français (fre) Tags : Zinc  Cadmium  Adsorption  By-products, Heavy metals  Removal  Water  Waste water  Copper Index. décimale : 661 Chimie Industrielle Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=4568

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