Search results for " Copper"

Dismantling and copper recovery from Waste Printed Circuit Boards (WPCBs) using an integrated hydro-electrometallurgical approach

A physical-based constitutive model for surface integrity prediction in machining of OFHC copper

2017

International audience; Due to the rising interest in predicting machined surface integrity and sustainability, various models for metal cutting simulation have been developed. However, their accuracy depends deeply on the physical description of the machining process. This study aims to develop an orthogonal cutting model for surface integrity prediction, which includes a physical-based constitutive model of Oxygen Free High Conductivity (OFHC) copper. This constitutive model incorporates the effects of the state of stress and microstructure on the work material behavior, as well as a dislocation density-based model for surface integrity prediction. The coefficients of the constitutive mod…

Influence of cutting process mechanics on surface integrity and electrochemical behavior of OFHC copper

2014

The authors gratefully acknowledge the support received from IC ARTS and CEA Valduc; International audience; Superfinishing machining has a particular impact on cutting mechanics, surface integrity and local electrochemical behavior. In fact, material removal during this process induces geometrical, mechanical and micro-structural modifications in the machined surface and sub-surface. However, a conventional 3D cutting process is still complex to study in terms of analytical/numerical modeling and experimental process monitoring. So, researchers are wondering if a less intricate configuration such as orthogonal cutting would be able to provide information about surface integrity as close as…

Orthogonal cutting simulation of OFHC copper using a new constitutive model considering the state of stress and the microstructure effects

2016

International audience; This work aims to develop an orthogonal cutting model for surface integrity prediction, which incorporates a new constitutive model of Oxygen Free High Conductivity (OFHC) copper. It accounts for the effects of the state of stress on the flow stress evolution up to fracture. Moreover, since surface integrity parameters are sensitive to the microstructure of the work material, this constitutive model highlights also the recrystallization effects on the flow stress. Orthogonal cutting model is validated using experimental designed cutting tests. More accurate predictions were obtained using this new constitutive model comparing to the classical Johnson-Cook model.

A Study Using X-ray Absorption and Emission Spectroscopy of Dioxygen-Binding Xerogels Incorporating Cyclam Units Complexed with Copper Salts.

2005

X-ray absorption spectroscopy was used to elucidate how hybrid xerogels complexed with CuCl2 could reversibly bind molecular dioxygen. Difference EXAFS analyses at the Cu K-edge suggest that dioxygen could bridge two Cu atoms in a μ-η1:η1 peroxo-like conformation with unequal Cu···O distances. Only the short distance (RCu–O1 = 1.86 ± 0.01 A) was unambiguously determined and looks typical of a CuII site. The Cu···Cu internuclear distances would be rather long: RCu–Cu ≈ 4.0 A (3.9 A) for the oxygenated (oxygen-free) xerogels. Cl K-edge EXAFS spectra revealed the pre-existence in the oxygen-free xerogels of CuI sites with short Cl–Cu bonds (2.11 ± 0.03 A). Pentacoordinate CuII sites with a lon…

Detoxification of Copper and Chromium via Dark Hydrogen Fermentation of Potato Waste by Clostridium butyricum Strain 92

2022

The accumulation of various types of waste containing both organic and inorganic metal-containing compounds is extremely hazardous for living organisms. The possibility of polymer degradation, biohydrogen synthesis, and metal detoxification via the dark fermentation of model potato waste was investigated. For this purpose, the strict anaerobic strain was isolated and identified as Clostridium butyricum. The high efficiency of dark hydrogen fermentation of potatoes with yield of hydrogen in 85.8 ± 15.3 L kg−1 VSpotato was observed. The copperand chromium salts solutions were added to the culture fluid to obtain the concentrations of 50, 100, and 200 mg L−1 Cu(II) and Cr(VI) in the active pha…

A novel scientific approach to the conservation of archaeological copper alloys artefacts

2007

A novel research approach focused on innovative materials and methods to assure the long-term stability of bronze archaeological artefacts during exhibition and storage is reported. The work deals with the application of advanced analytical techniques and the development, characterisation and testing of materials and procedures for the conservation, protection and restoration of ancient Cu-based alloy artefacts. Our first aim was the selection of Cu-based alloy artefacts from different archaeological sites in Southern Italy with respect of chemical composition, metallurgical features and corrosion products. This step allowed the identification of the ancient alloys, the study of natural pat…

Control of Bactrocera oleae and Ceratitis capitata in Organic Orchards: Use of Clays and Copper Products.

2010

Tests on the effect of clays (kaolin and bentonite) and copper products (hydroxide and oxychloride) in the control of olive fruit fly, Bactrocera oleae (Rossi), and Mediterranean fruit fly, Ceratitis capitata (Wiedemann), were carried out from 2003 to 2006 in olive groves and in organic citrus orchards (satsuma, clementine, ‘Navelina’ orange). Results demonstrate an efficacy of kaolin products in reducing attacks of B. oleae on olives and those of C. capitata on citrus fruits; in olive groves the clays gave similar or better results than copper hydroxide. Bentonite AG/8W showed a significant reduction in punctures by C. capitata. Bentonite products and BPLK kaolin are washed off by rainfall…

Synthesis of [5]Rotaxanes Containing Bi- and Tridentate Coordination Sites in the Axis

2010

A new example of a linear [5]rotaxane has been synthesized by using the traditional "gathering-and-threading" approach but based on an unusual axle incorporating a symmetrical bis(bidentate) chelating fragment built on a 4,7-phenanthroline core. The stoppering reaction is particularly noteworthy since, instead of using a trivial bulky stopper as precursor to the blocking group, two semistoppered copper-complexed [2]pseudorotaxanes (namely [2]semirotaxanes) are used, which leads to the desired [5]rotaxane in good yield. The efficiency of the method relies on the use of "click" chemistry, with its very mild conditions, and on the protection by a transition-metal (copper(I)) of the various coo…

NonclassicalPschorr andSandmeyer Reactions in Pyrazole Series

2005

The diazonium salt derived from 4-amino-N,1,3-trimethyl-N-(3-methyl-1-phenyl-1H-pyrazol-5-yl)-1H-pyrazole-5-carboxamide (14) was reacted with a mixture of CuSO4 and NaCl, with ascorbic acid as an initiator to afford the planar derivative 4,6-dihydro-1,4,6,8-tetramethyl-3-phenyldipyrazolo[3,4-b:4′,3′-d]pyridin-5(3H)-one (16) and its unexpected isomer 4,6-dihydro-3,4,6,8-tetramethyl-1-phenyldipyrazolo[4,3-b:4′,3′-d]pyridin-5(1H)-one (17), as well as the epimers (3S,4S)- (or (3S,4R)-) and (3S,4R)- (or (3S,4S)-) 4-chloro-2,4-dihydro-1′,3′,5,5′-tetramethyl-2-phenylspiro[pyrazole-3,4′(1′H)-pyrrolo[3,4-c]pyrazol]-6′(5′H)-one (18a and b, respectively). Epimers 18a and b were converted under basic c…