Copper Pieces Research Articles

Corrosion Inhibitors in the Development of Hybrid-Smart-Nanostructured Coatings

Results of the corrosion behavior of inhibitors contained inside of ceramic nanoparticles as part of the development of a hybrid smart coating used to protect pieces of copper used in the manufacture of historical pieces belonging to the cultural heritage . The kaolin is a waste product from the ceramic industry with porous properties that facilitate the process of absorption of chemicals inhibitors of the corrosion process as benzotriazole (BTA) and copper sulfate pentahydrate (CuSO4.5H2O). The optimal efficiency of the inhibitors was determined using gravimetric methods and using potentiodynamic polarization . The adsorption of the inhibitors is reached preparing several mixtures of acetone and distilled water saturated with inhibitor through a process of stirring for 24 hours . Copper samples were coated with a commercial brush No. 10 using epoxy resin mixed with 2.5 %, 5% and 10 % of kaolin nanoparticles doped with inhibitor. The system was characterized using electrochemical techniques like electrochemical impedance spectroscopy (EIS), potentiodynamic polarization methods and electrochemical noise spectroscopy (EN) to determine the efficiency of the new structured kaolin particles into the coating. The electrolytic solution for the application of electrochemical techniques was a mixture of NaCl. and (NH4)2SO4, used to study atmospheric corrosion; simulating contaminated atmospheres with chlorides and sulfates in urban environments. The techniques used for materials characterization were scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) like a great complement to the complete study of the system.

Low-level γ-ray spectrometry at the underground laboratory Garching

Two low-background setups for material screening based on HPGe detectors were built in the Garching Underground Laboratory with an overburden of ~10m.w.e. They include several layers of passive shielding as well as an active muon veto. The first setup (GEM) comprises a 150% efficiency HPGe detector which can optionally be surrounded by a NaI(Tl) scintillation detector that serves as anti-Compton veto. The second setup (LoAx) consists of two smaller HPGe detectors which are arranged face-to-face to cover a larger solid angle around the sample and to allow coincidence measurements.For a 5.6kg piece of copper after 11 days of measurement we have reached a sensitivity for 226Ra and 228Ra/228Th of ~5mBqkg−1 with the GEM setup. In the LoAx setup we have achieved limits of less than 100mBqkg−1 for 234Th and 210Pb with a 156g sample of PPO wavelength shifter after 18 days of measurement.

Characterization and Reliability of Sintered Nanosilver Joints by a Rapid Current-Assisted Method for Power Electronics Packaging

A rapid current-assisted sintering technology (CAST) was used to bond electronic devices with nanosilver paste, which is a promising alternative compared with traditional solders. Instead of using an external heating source, the specimen and bonding material of nanosilver paste were heated by the alternating current whose current direction is not constant. Die-shear testing and hardness measurement were used to evaluate the bonding strength. The bonding strength and hardness increase with increasing the current and/or current-on time. CAST was able to sinter nanosilver in a very short time, i.e., less than 1 s. Scanning electron microscopy was used to characterize the microstructures of sintered silver joints. The reliability of the sintered joints by CAST was also evaluated by cyclic shearing tests. The joint by CAST could survive much longer time than that by the conventional hot pressing way. The CAST was recommended to bond two pieces of bare copper with nanosilver paste in power electronic applications without any protective gas atmosphere, e.g., bus bar connection.

Studies on enzymatic biomachining of copper by glucose oxidase

Biomachining is one of the recent machining methods in which chemolithotrophic bacteria such as Acidithiobacillus ferrooxidans are used for the controlled material removal from the surfaces. In the present research, as a novel method, machining of copper was investigated by H2O2 produced in medium of biological oxidation of glucose which is catalyzed by glucose oxidase (GOx). It was shown that 0.01g/h material removal is carried out using 100mL solution containing FeSO4·7H2O 0.5g, β-d-(+)-glucose 1g and GOx 100U that incubated in the shaker-incubator for 10h. The results of this work revealed changes of the surface morphology were negligible compared with chemical and bacterial machining and no significant disintegrity or increases of roughness was observed on the surface. Material removal rate (MRR) was about 15 times less than that of microbial material removal which indicates more controllability of the enzymatic biomachining, in the same conditions of time, copper pieces dimension, temperature and other parameters.

17th century Huron village life: insights from the copper-based metals of the Ball site, southern Ontario, Canada

Copper-based metal artifacts from the Ball site, a late 16th – early 17th century Huron (Wendat) village in southern Ontario that doubled in size during its estimated 20-year existence, were analysed by INAA. The goal was to assess the number of kettles that had reached the village, explore the chronology of their arrival and examine patterns in their discard within the site. Our results suggest that about two to three dozen European copper, red brass, and yellow brass kettles may have reached the village during its occupation; that copper kettles may have been traded to the inhabitants of the village before brass kettles; that the new inhabitants may have brought some kettles with them; and that differences in the discarding of copper and brass pieces inside and outside longhouses indicate that yellow brass was possibly of lower value than red copper.

Nd:YAG 레이저를 이용한 금속유물에 코팅된 아크릴수지의 제거 및 표면 특성 연구

Laser cleaning have been found to be a useful cleaning tool to remove contaminants without inducing damage to the substrate and making secondary pollutant. In this study, the effect of Nd:YAG laser cleaning system, emitting at 1064 nm and 532 nm, on acrylic resin applied onto copper coupons and pieces of bronze was investigated. The samples after laser cleaning tests were examined using microscopy, FT-IR, SEM-EDS. As a result, the acrylic resin could be removed from most of the samples at low laser energy density. Laser wavelength 532 nm was more effective than 1064 nm because of using lower laser energy density, which could reduce heat damage to substrates. Although the acrylic resin was easily removed, it revealed melted surfaces and removed bronze patina which must remain. The problems should be solved by future studies using different laser system or laser wavelengths.

Female Genital Mutilation: Design and Fabrication of a Wall Plaque for Awareness Creation

This research designs and fabricates a metal mosaic wall plaque which is aesthetically pleasing and durable to complement other means of awareness creation of Female Genital Mutilation (FGM). Metal Scraps such as milk tins, canned mineral tins, pieces of aluminium, copper and brass sheets etc. were used for the plaque depending on the colour to be depicted in the scene using Metal Mosaic Technique. The Experimental and Descriptive research methods based on quantitative and qualitative approaches were employed in the study. The plaque as was hypothesized thus, from the designing stage, fabrication stage and the finishing stage proved to be what it was intended for with respect to helping to educate people, especially rural folks who are custodians and champions of customs and opinion leaders of the heinous practice of Female Genital Mutilation (FGM). Materials for the project were locally available but the technique was painstaking, time consuming and tedious. It is recommended that other cooperate bodies such us WHO and others who preach total annihilation of this form of practice must bring on board metal artists to produce aesthetically pleasing and intriguing scenes in the form of wall plaques to complement the campaign.

Morphology and magnetic properties of CeCo5 submicron flakes prepared by surfactant-assisted high-energy ball milling

CeCo5 permanent magnetic alloy has been processed by surfactant assisted high energy ball milling. Heptane and oleic acid were used as the solvent and surfactant, respectively. The amount of surfactant used was 50% by weight of the starting powder. The produced particles were deposited on a piece of copper (4mm in length and width) under a magnetic field of 27kOe applied along the copper surface and immobilized by ethyl α-cyanoacrylate. Scanning electron microscope pictures show that the particles are flakes, several μm in length and width and tens of nm in thickness. X-ray diffraction patterns and magnetic measurements prove that the flakes are crystalline with c-axes magnetic anisotropy. The easy magnetization axis is oriented perpendicular to the surface of the flake. A maximum coercivity of 3.3kOe was obtained for the sample milled for 40min.

Electro-thermal FEM simulations of the 13 kA LHC joints

The interconnections between the superconducting main dipole and main quadrupole magnets are made of soldered joints of two superconducting Nb–Ti cables embedded in a copper busbar stabilizer. The primary cause of the September 2008 incident in the LHC was a defect in an interconnection between two dipole magnets. Analyses of the incident show that possibly more defects might be present in the 13kA circuits, which can lead to unprotected resistive transitions. To avoid the reoccurrence of such an event, thorough experimental and numerical investigations have taken place to determine the safe operating conditions of the LHC. However to show measured curves is beyond the scope of this article. Furthermore, improvements in the design have been proposed in the form of additional parallel copper pieces, or shunts, which bridge the possible voids in the soldering and offer a bypass for the current in case of a quench.The purpose of this work is to support the design choices and to indicate the sensitivity to some of the free parameters in the design. Electro-thermal Finite Element Method (FEM) simulations are performed, making use of COMSOL Multiphysics. The use of FEM allows for a profound three-dimensional analysis and some interesting features of the shunted busbar can only be revealed this way. Especially current redistribution in the shunted area of the interconnect gives important insights in the problem. The results obtained using the model are very sensitive to the exact geometrical properties as well as to the material properties, which drive the Joule heating inside the interconnection. Differences as compared to a one-dimensional model, QP3, are presented. QP3 is also used for simulations of non-shunted busbar joints as well as shunted busbars. Furthermore, margins are given for the soldering process and the quality control of the shunted interconnections, since the contact area between the stabilizer pieces and the shunt is an important quality aspect during the manufacturing of a safe interconnection.

THz-waves channeling in a monolithic saddle-coil for Dynamic Nuclear Polarization enhanced NMR

A saddle coil manufactured by electric discharge machining (EDM) from a solid piece of copper has recently been realized at EPFL for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance experiments (DNP-NMR) at 9.4 T. The corresponding electromagnetic behavior of radio-frequency (400 MHz) and THz (263 GHz) waves were studied by numerical simulation in various measurement configurations. Moreover, we present an experimental method by which the results of the THz-wave numerical modeling are validated. On the basis of the good agreement between numerical and experimental results, we conducted by numerical simulation a systematic analysis on the influence of the coil geometry and of the sample properties on the THz-wave field, which is crucial in view of the optimization of DNP-NMR in solids.

Status of CIEMAT work on PETS

The goal of the present CLIC Test Facility (CTF3) is to demonstrate the technical feasibility of the CLIC scheme, where the RF power extracted from the drive beam is used to accelerate the main beam. Several prototypes of the RF power extractor so-called PETS (Power Extraction and Transfer Structure) have been developed at CIEMAT for this facility. The first device was embedded in a steel vacuum tank and installed at the Test Beam Line (TBL), whose aim is to prove the beam stability during deceleration and power extraction. Presently, CERN and CIEMAT share the responsibility to build eight additional PETS for TBL. Finally, in the framework of EuCARD (European Coordination for Accelerator Research and Development) collaboration, a new PETS configuration is presently under engineering design at CIEMAT. It is based on a compact concept developed at CERN. This device will be installed in the Test Module at CTF3, in a similar configuration to that of the final two-beam scheme acceleration of CLIC. This paper describes the PETS prototype fabrication techniques used at CIEMAT, with particular attention to the production of the long copper rods which induce the RF generation and the welding and assembly procedures. The characterization of the devices with low RF power and the first tests with beam are also described. ► Correct PETS performance is essential to show CLIC technical feasibility. ► Assembly and production of OFE copper pieces with extreme precision is proved. ► PETS design is evolving towards a compact structure with integrated vacuum tank.

Eddy currents in MRI gradient coils configured as rings and patches

The current distribution in a set of parallel rings and patches, called islands, positioned at the surface of a cylinder, is investigated. The current is driven by an externally applied source current. The islands are rectangular pieces of copper (patches) placed in parallel between the rings. The eddy currents in the islands induce currents in the rings that vary in the tangential direction. From the quasi-static Maxwell equations, an integral equation for the current distribution in the strips is derived. The Galerkin method, using global basis functions, is applied to solve this integral equation. It shows fast convergence. The global basis functions are Legendre polynomials in the axial direction and 2π-periodic trigonometric functions in the tangential direction. The Legendre polynomials efficiently cope with the singularity of the kernel function of the integral equation. Explicit numerical results are shown for three configurations. Apart from the current distributions, the resistance and self-inductance of the three systems of rings and islands are computed. The resulting tool can be used to qualitatively understand eddy currents in z-gradient coils, and as such enable the incorporation of eddy currents in the optimization of gradient-coil design.

Metallurgical analysis of copper artifacts from Cahokia

Copper artifacts from Cahokia Mounds, Illinois were analyzed from a materials science perspective to shed light on techniques used by Mississippian copper workers to deform nuggets of native copper into thin sheets. Eight small copper pieces from a copper-working site at Cahokia’s Mound 34 were subjected to metallographic examination. Replication experiments thereafter recreated features of the artifacts under controlled conditions. It is concluded that copper sheets were thinned through repeated cycles of hammering and annealing performed at temperatures achievable in an open wood fire. The welding of sheets to create multilayered objects was not observed in any artifacts and could not be accomplished experimentally. Additionally, a possible cutting method used on some artifacts was identified.

Experimental and numerical study on the orthogonal and oblique impact on water filled pipes

A 300 mm long piece of copper (ASTM B280) pipe with an outer diameter of 35 mm and 0.7 mm wall thickness was subjected to a rigid steel pipe impact under a drop weight loading configuration where the pipe was simply supported at its ends. Differences in deformation features for a pipe filled with water and an empty pipe were investigated for two configurations namely orthogonal and oblique impact. Compared to orthogonal pipe impact the oblique pipe impact has not been reported in the literature. It is hoped that current work would serve as a first step in this direction. Finite Element Method coupled with Smooth Particle Hydrodynamics (SPH) available in LS-DYNA was used to simulate the empty and water filled pipe impacts under orthogonal and oblique configurations respectively. Fluid structure interaction (FSI) during the water filled pipe impact was successfully modeled using SPH which is a simple method for predicting the short duration FSI events. Experimental results of the effect of varying D/T ratio on the empty and water filled pipes have been reported.

Symmetric miniaturized heating system for active microelectronic devices

To qualify interconnect technologies such as microelectronic fine wire bonds for mass production of integrated circuit (IC) packages, it is necessary to perform accelerated aging tests, e.g., to age a device at an elevated temperature or to subject the device to thermal cycling and measure the decrease of interconnect quality. There are downsides to using conventional ovens for this as they are relatively large and have relatively slow temperature change rates, and if electrical connections are required between monitoring equipment and the device being heated, they must be located inside the oven and may be aged by the high temperatures. Addressing these downsides, a miniaturized heating system (minioven) is presented, which can heat individual IC packages containing the interconnects to be tested. The core of this system is a piece of copper cut from a square shaped tube with high resistance heating wire looped around it. Ceramic dual in-line packages are clamped against either open end of the core. One package contains a Pt100 temperature sensor and the other package contains the device to be aged placed in symmetry to the temperature sensor. According to the temperature detected by the Pt100, a proportional-integral-derivative controller adjusts the power supplied to the heating wire. The system maintains a dynamic temperature balance with the core hot and the two symmetric sides with electrical connections to the device under test at a cooler temperature. Only the face of the package containing the device is heated, while the socket holding it remains below 75 degrees C when the oven operates at 200 degrees C. The minioven can heat packages from room temperature up to 200 degrees C in less than 5 min and maintain this temperature at 28 W power. During long term aging, a temperature of 200 degrees C was maintained for 1120 h with negligible resistance change of the heating wires after 900 h (heating wire resistance increased 0.2% over the final 220 h). The device is also subjected to 5700 thermal cycles between 55 and 195 degrees C, demonstrating reliability under thermal cycling.

MapCHECK used for rotational IMRT measurements: Step‐and‐shoot, Tomotherapy, RapidArc

To measure patient-specific-QA dose distributions with a 2D array of diodes, the MapCHECK, for the dose delivered, with step-and-shoot and rotational IMRT. Two MapCHECKs were used that had different styles of diode connection. These MapCHECKs were used in their original manufactured configuration and in a modified configuration. The modification made in the clinic consists of filling air gaps with sheets of Lucite that had custom-machined slots for the diodes and by adding pieces of copper to offset the intrinsic asymmetry of the diodes. The MapCHECKs were housed in a tight-fitting phantom fabricated from solid water. Measurements were made on IMRT treatment plans delivered with Varian linear accelerators with step-and-shoot and RapidArc methods, and a TomoTherapy machine with helical delivery. Patient plans and QA plans were developed with the XiO, Eclipse, and TomoTherapy planning systems. All MapCHECK data were analyzed with its commercially available software. Kilovoltage CT imaging of the MapCHECK in its phantom has streak artifacts from high atomic number components. These artifacts must be corrected in order to obtain accurate calculation of dose. The original MapCHECK is found to have an angular dependence of +/- 20%. A modification of the MapCHECK has been made that reduces the angular dependence to +/- 2%. Proper compensation for attenuation by the treatment couch is also necessary for accurate results. The modified MapCHECK has been successfully used for doing patient-specific QA for IMRT treatments delivered with step-and-shoot, TomoTherapy, and RapidArc methods. Treatment plans that require large amounts of fluence from the 90 degrees and 270 degrees directions have significantly better QA measurements when made with modified MapCHECKs. When properly modified, the MapCHECK response becomes isotropic. It can then be used for patient-specific QA measurements for IMRT treatments delivered with step-and-shoot and rotational techniques such as helical Tomotherapy and RapidArc.

Possible role of hydrogen sulphide gas in self-heating of pyrrhotite-rich materials

Self-heating of sulphides poses safety, environmental and economic concerns to the mining and metallurgical industries, especially when sulphide ores or concentrates have to be stored or transported. The first target of this investigation is the self-heating of pyrrhotite (Po), the most commonly suspected mineral to trigger the phenomenon because of its fast oxidation in moist air. Following a standard experimental protocol, self-heating was assessed on samples of Po mixed with sand as an inert material. With increasing Po content, self-heating rates progressively increased but the samples visually appeared less and less oxidized. A high Po content, it was hypothesized, may give a more reducing environment favouring formation of hydrogen sulphide (H 2S). The presence of this gas could be significant for self-heating for several reasons which are discussed. The hypothesis was tested by including copper pieces to detect the gas by forming copper sulphide, and adding copper sulphate in excess which suppressed self-heating, apparently by reacting with and removing the gas.

Does Four-dimensionalism explain coincidence?*

For those who think the statue and the piece of copper that compose it are distinct objects that coincide, there is a burden of explanation. After all, common sense says that different ordinary objects cannot occupy the same space at the same time. A common argument in favour of four-dimensionalism (or ‘perdurantism’ or ‘temporal parts theory’) is that it provides the resources for a superior explanation of this coincidence. This, however, is mistaken. Any explanatory work done by the four-dimensionalist notion of absolute parthood rests ultimately on notions equally available to the three-dimensionalist. Thus, a neutral explanation of coincidence is at least as good while avoiding commitment to temporal parts. *Many thanks to David Christensen, Louis deRosset, Matti Eklund, and two anonymous referees for helpful comments.

Rapid detection of genetically modified organisms on a continuous-flow polymerase chain reaction microfluidics

The ability to perform DNA amplification on a microfluidic device is very appealing. In this study, a compact continuous-flow polymerase chain reaction (PCR) microfluidics was developed for rapid analysis of genetically modified organisms (GMOs) in genetically modified soybeans. The device consists of three pieces of copper and a transparent polytetrafluoroethylene capillary tube embedded in the spiral channel fabricated on the copper. On this device, the P35S and Tnos sequences were successfully amplified within 9 min, and the limit of detection of the DNA sample was estimated to be 0.005 ng μl −1. Furthermore, a duplex continuous-flow PCR was also reported for the detection of the P35S and Tnos sequences in GMOs simultaneously. This method was coupled with the intercalating dye SYBR Green I and the melting curve analysis of the amplified products. Using this method, temperature differences were identified by the specific melting temperature values of two sequences, and the limit of detection of the DNA sample was assessed to be 0.01 ng μl −1. Therefore, our results demonstrated that the continuous-flow PCR assay could discriminate the GMOs in a cost-saving and less time-consuming way.

Differential-outputB-dot andD-dot monitors for current and voltage measurements on a 20-MA, 3-MV pulsed-power accelerator

We have developed a system of differential-output monitors that diagnose current and voltage in the vacuum section of a 20-MA 3-MV pulsed-power accelerator. The system includes 62 gauges: 3 current and 6 voltage monitors that are fielded on each of the accelerator's 4 vacuum-insulator stacks, 6 current monitors on each of the accelerator's 4 outer magnetically insulated transmission lines (MITLs), and 2 current monitors on the accelerator's inner MITL. The inner-MITL monitors are located 6 cm from the axis of the load. Each of the stack and outer-MITL current monitors comprises two separate $B$-dot sensors, each of which consists of four 3-mm-diameter wire loops wound in series. The two sensors are separately located within adjacent cavities machined out of a single piece of copper. The high electrical conductivity of copper minimizes penetration of magnetic flux into the cavity walls, which minimizes changes in the sensitivity of the sensors on the 100-ns time scale of the accelerator's power pulse. A model of flux penetration has been developed and is used to correct (to first order) the $B$-dot signals for the penetration that does occur. The two sensors are designed to produce signals with opposite polarities; hence, each current monitor may be regarded as a single detector with differential outputs. Common-mode-noise rejection is achieved by combining these signals in a $50\mathrm{\text{\ensuremath{-}}}\ensuremath{\Omega}$ balun. The signal cables that connect the $B$-dot monitors to the balun are chosen to provide reasonable bandwidth and acceptable levels of Compton drive in the bremsstrahlung field of the accelerator. A single $50\mathrm{\text{\ensuremath{-}}}\ensuremath{\Omega}$ cable transmits the output signal of each balun to a double-wall screen room, where the signals are attenuated, digitized ($0.5\mathrm{\text{\ensuremath{-}}}\mathrm{ns}/\mathrm{sample}$), numerically compensated for cable losses, and numerically integrated. By contrast, each inner-MITL current monitor contains only a single $B$-dot sensor. These monitors are fielded in opposite-polarity pairs. The two signals from a pair are not combined in a balun; they are instead numerically processed for common-mode-noise rejection after digitization. All the current monitors are calibrated on a 76-cm-diameter axisymmetric radial transmission line that is driven by a 10-kA current pulse. The reference current is measured by a current-viewing resistor (CVR). The stack voltage monitors are also differential-output gauges, consisting of one 1.8-cm-diameter $D$-dot sensor and one null sensor. Hence, each voltage monitor is also a differential detector with two output signals, processed as described above. The voltage monitors are calibrated in situ at 1.5 MV on dedicated accelerator shots with a short-circuit load. Faraday's law of induction is used to generate the reference voltage: currents are obtained from calibrated outer-MITL $B$-dot monitors, and inductances from the system geometry. In this way, both current and voltage measurements are traceable to a single CVR. Dependable and consistent measurements are thus obtained with this system of calibrated diagnostics. On accelerator shots that deliver 22 MA to a low-impedance $z$-pinch load, the peak lineal current densities at the stack, outer-MITL, and inner-MITL monitor locations are 0.5, 1, and $58\text{ }\text{ }\mathrm{MA}/\mathrm{m}$, respectively. On such shots the peak currents measured at these three locations agree to within 1%.