Copper Melt Research Articles

High-fidelity modelling of selective laser melting copper alloy: Laser reflection behavior and thermal-fluid dynamics

Despite of the promising capabilities of selective laser melting (SLM), the poor formability of copper and its alloys is a critical challenge for industrial applications, which is widely-believed attributed to the high reflectivity of copper. Due to the difficulty of observing laser reflections, current understanding on the laser reflection mechanisms is still vague and unclear. This work constructs a high-fidelity CFD model coupled with a ray-tracing method to visualize the flow kinetics and reflection behavior during SLM Cu-Cr-Zr alloy. Considering the material specificity of copper, a temperature-dependent absorption rule is introduced to overcome the simulation deviation caused by the widely-used Fresnel absorption, showing good agreement with experiments in terms of track width and depth. The in-situ absorptivity measurement experiments are further conducted to compare with simulations with the error less than 2%. Additionally, different reflection mechanisms for continuous and distorted tracks are revealed. At relatively high linear energy density (LED), the global absorptivity undergoes a rise and a decrease in the initial stage, and finally gets stable. At low LED level, the surface tension drives the melt pool to form isolated balls and exposed plat surface, which is responsible for the intense absorptivity oscillation as the balling effect occurs.

Partial-cluster model of viscosity of copper-aluminum melt

The adequacy of the developed partial-cluster viscosity model with respect to melts of metal alloys was verified using the well-studied copper-aluminum system, for which the state diagram and viscosity isotherms are known in a wide range of compositions. Based on the literature on the thermodynamics of mixing copper and aluminum melts, it was found that this shift is accompanied by heat generation due to the formation of intermetallic compounds in the melt. The destruction of these compounds requires appropriate heat consumption, therefore, it should be taken into account in the partial-cluster viscosity model as an additional thermal barrier to randomization. On this basis, a refined and more generalized form of the partial-cluster model with the expression of the randomization energy of the melt in the form of the algebraic sum of the randomization heat along the liquidus line and the heat of destruction of any intermetallic formations is proposed ΔHch = RTliq – ΔHmix. Application of the generalized partial-cluster model to copper-aluminum melts ensured the repetition of the extreme form of empirical isotherms, even with the appearance of excess viscosity in the calculated dependence. A more detailed analysis of the heat of mixing according to its covalent and metal components showed that the second of them is already randomized and only the covalent component should be taken into account, which should be randomized and should be included in the total randomization barrier in the form ΔHch = RTliq – ΔcovH. Taking this component into account allowed us to obtain a more adequate calculated dependence of the viscosity of the Cu – Al alloy at a temperature of 1100 оC with a correlation coefficient of 0.986, which can be considered as a priority result in the description of viscosity isotherms according to state diagrams. This result is due to the analytical determination of the fraction of clusters in the melt based on the distribution of clusters proposed by the authors according to the number of particles included in the framework of the concept of randomized particles developed by the authors, which is directly related to the Boltzmann’s distribution.

Predicted Heat Flux Performance of Actively Cooled Tungsten-Armored Graphitic Foam Monoblocks

Tungsten (W)–armored graphitic foam monoblocks were developed for applications requiring high-Z plasma-facing material in long-pulse fusion experiments and ultimately deuterium-tritium fusion reactors. The monoblocks are an integrated material system combining the advantages of a chemical vapor deposited (CVD) W coating with a high-conductivity graphitic foam. The W is a high-melting-point, high-Z material with low tritium retention. The graphitic foam coupled to a swirl tube serves as a high-thermal-conductivity heat sink that cannot melt, although it can sublime at much higher temperatures than copper melts. Together, they comprise a robust plasma-facing component (PFC) weighing roughly 5% of an all-W component or 17% of a traditional W-coated copper heat sink. A single-channel mock-up consisting of four graphitic foam monoblocks equipped with a water-cooled swirl tube was fabricated for eventual testing in the 60-kW, EB-60, rastered electron beam at the Applied Research Laboratory of The Pennsylvania State University. Two monoblocks have a thin 50-μm-thick coating of pure W chemically vapor deposited over NbC and pure Nb interlayers. Two others have a 2-mm-thick pure W coating CVD on graphitic monoblocks using the same interlayers. The mock-up will be cooled with available 10 m/s, 0.7 MPa water with a 22°C inlet temperature and subjected to varying uniform heat loads up to 20 MW/m2. It is equipped with type-K thermocouples at various depths, and calibrated infrared thermography and spot pyrometry will be used to characterize the heated surface. Real-time water calorimetry will be used to ascertain the absorbed steady-state power and infer the heat flux during testing. Since testing cannot be done under prototypic divertor flow conditions, it is necessary to predict the thermal response of this novel PFC system and investigate the power sharing between radiation and convection at divertor heat flux levels and its inherent ability to avoid critical heat flux. Results are reported for predictions obtained from computational fluid dynamics models up to 30 MW/m2 of steady-state uniform heat flux. Leading-edge heat loads of 30 MW/m2 on a 2-mm-wide side strip were also investigated to ascertain if coating delamination is likely.

Investigation of dissimilar laser welding of stainless steel 304 and copper using the artificial neural network model

In this study, to accurately predict the temperature and melting ratio at low time and cost, the process of dissimilar laser welding of stainless steel 304 and copper was simulated based on artificial neural network (ANN). Among various ANN models, the Bayesian regulation backpropagation training method was utilized to model the current problem. This method was used considering the two temperatures of copper and steel and the two melting ratios of steel and copper as the four outputs, and the four parameters, pulse width, pulse frequency, welding speed, and focal length, as the inputs. According to the results, regression values had a good accuracy in all cases and the histogram diagrams indicated that the error distribution was mainly concentrated at the center; in other words, the major errors of the network were not very large. It was also observed that the error concerning the trained neural networks was acceptable in the experiment phase. Finally, this neural network could be used as a numerical model to estimate the four outputs of steel temperature, copper temperature, steel melting ratio, and copper melting ratio for all input values of pulse width, pulse frequency, welding speed, and focal length in the studied range, without any need to rerun the experiment.

Structure forming of Cu–W pseudoalloys prepared in different routes

The microstructures of alloys formed during the sintering of tungsten powder mixtures (PV2, 3.8–6.0 μm average particle size) and copper (PMS-11, 45–60 μm fraction) prepared by various methods were compared. The methods included simple metal powder mixing, mechanical activation (MA) of metal powders, copper precipitation from the solution of its sulfate (CuSO4·5H2O) on tungsten powder with simultaneous mechanical activation. The molar ratio of metals in mixtures Cu/W = 1. An aqueous solution for copper deposition included diethylene glycol (up to 30 %), glycerin (up to 8 %), hydrofluoric acid (up to 0.1 %), wetting agent OP-10 (up to 0.8 %). Mechanical activation was carried out in an AGO-2 planetary mill with 200 g of steel balls charged into the drums rotating at 2220 rpm for 5 min. Reduced copper in the solution and in the air rapidly oxidizes to the Cu2O oxide, so the composite powders obtained were washed, dried, and stored in an argon atmosphere. Samples pressed from the powders obtained (tablets 3 mm in diameter, 1.5–2.0 mm in height with a density of 7.7–8.0 g/cm3) were sintered in argon at atmospheric pressure and temperatures from 1000 to 1500 °C. During the sintering of Cu–W composite particles, several areas of the process can be distinguished. «Solid phase» sintering occurs at the contact points of composite particles at temperatures lower than the copper melting point. When samples are heated from the melting point to 1200 °C, samples are sintered by the liquid-phase mechanism from the conventional mixture of metal powders to form a low-porous cake. When composite powders obtained by MA during the copper deposition and MA of metal powder mixtures are sintered, samples are delaminated with the formation of large pores elongated perpendicular to the pressing axis and partially filled with copper melt. When samples obtained by powder MA are heated above 1400 °C, phase separation occurs and almost all copper is displaced from the sample to the surface.

Separating the reaction and spark plasma sintering effects during the formation of TiC–Cu composites from mechanically milled Ti–C–3Cu mixtures

The goal of this work was to separate the reaction and spark plasma sintering (SPS) effects during the in-situ synthesis of TiC in mechanically milled Ti–C–3Cu powder mixtures. The powders were milled for 3–10 min in a high-energy planetary ball mill. Structural changes occurring in the reaction mixtures during thermal explosion (TE) in a furnace and SPS in a graphite die were compared. Although the maximum temperature of TE reached the melting point of copper in some samples, no evidence of extensive melting was observed in the microstructure of the products of TE. The ignition and maximum temperatures of TE were found to decrease with increasing milling time of the mixture. In the mixture milled for 10 min, the maximum temperature of TE was only 820 °C. Melting of copper at the inter-particle contacts during SPS was observed in samples milled for 5–10 min (SPS at 900–980 °C) and caused the formation of TiC-depleted regions in the microstructure. Those regions were the re-solidified melt partially filling the pores between the agglomerates. Based on the analysis of the TE parameters in the mixtures and microstructures of the products of TE and SPS, melting during SPS was attributed to the effect of electric current (a high electric current density at the inter-particle contacts) and not to the heat of reaction. The hardness, compressive strength and Young's modulus of the sintered composites are reported. A TiC–Cu composite (milling time 5 min, SPS at 980 °C, relative density 93%) shows a compressive yield strength of 890 MPa and an ultimate compressive strength of 920 MPa.

Interfacial reactions between titanium–copper melt and crucible oxides

Interfacial reactions of various cold isostatic pressed oxide crucibles (calcia, yttria-stabilized zirconia, and yttria) with Ti–5wt% Cu alloy at 1680 °C for 15 min melting in an argon environment have been investigated to estimate the corrosion resistance. Predicting thermodynamic analysis results indicate that oxide refractories based on calcia, zirconia, and yttria, can be used for melting titanium–copper alloy. However, significant differences between experimental results and those thermodynamic analysis results in the ZrO2–12 wt% Y2O3 and CaO systems were identified. The surface observations and element distribution made on cross-sections perpendicular to the interface using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) show that obvious interfacial reactions between alloy melt and ceramics in ZrO2–12 wt% Y2O3, and CaO systems occur at experimental temperature, while yttria shows the most superior stability with the most desirable features of interface properties of metal and crucible, and the product of dissolved Y2O3 was still found in the metal. Meanwhile, the interaction between the ZrO2 oxide and the Ti–5 wt% Cu melt can be effectively reduced by the addition of Y2O3. The high apparent porosity of the crucible results in low resistance to erosion caused by Ti–5Cu melt. Moreover, the reduction of calcia causes the boiling of the melt. These results would provide the basis for designing a new refractory for the melting of titanium–copper alloy.

The mechanism of hydrogen-accelerated melting of polycrystalline copper

We investigate the melting process of polycrystalline copper doped with hydrogen atoms by using the newly developed Cu/H ReaxFF force field. Hydrogen atoms are found to effectively promote the melting of copper, and even make it happen at temperatures below the equilibrium melting temperature of copper during rapid heating. The enhanced melting is closely relevant to the interaction of hydrogen atoms with the grain boundary. We find that host Cu atoms perform cooperative vibration around the grain boundaries as the precursor of premelting. The doping of hydrogen atoms is shown to drive the vibration more violent so that the grain boundary becomes broader and the premelting is prematurely triggered. Meanwhile, hydrogen atoms segregated in grain boundaries massively diffuse into the bulk region with increasing temperature, resulting in intensification of lattice distortion of the bulk phase. This facilitates the rapid advancement of the liquid-solid interface during melting in contrast to the slow and discontinuous interface advancement in hydrogen-free polycrystalline copper. Our results suggest that even a small amount of hydrogen atoms is expected to significantly affect the thermodynamic properties of metals with the existence of structural defects.

Взаимодействие карбидов WС и Cr3С2 при термообработке сплавов WС – Cr3С2 – Сu

Composite alloys WC – Cr3C2 – Cu were obtained by infiltration of copper melt into uncompacted powders WC and Cr3C2 (reference alloys) and their mixtures with a weight ratio WC: Cr3C2 = 1:1. Impregnation of uncompacted carbide powders with copper melt was carried out at low frequency (~ 80 Hz) vertical vibration (LFV) of the crucible with alloy components for 10 min in a resistance furnace in an atmosphere of flowing argon. The effect of heat treatment of the obtained model composites on the interaction of carbides WC and Cr3C2 under isothermal and dynamic action of temperature, as well as during high-speed cyclic heating of the alloy surface by an electric arc (120 A, 45 V, 2 Hz, 10000 arc interruption cycles) has been studied. The evolution of the structure of alloys has been investigated by means of electron microscopy, X-ray spectral microanalysis, X-ray phase and differential thermal analysis. It is shown that the action on the sample surface of the temperature field created by an electric arc leads to an intense interaction of carbides. In this case, matrix copper, periodically transforming into a melt, plays the role of a transfer medium (diffusion medium). As a result of such heat treatment in the upper layers of the alloys, finely dispersed compositions of complex carbide phases with sizes of ≤ 1 – 2 μm were formed, i.e. 1 – 2 orders of magnitude smaller than the size of the initial carbides.

Wear-Resistant TiCN-Based Ceramic Materials for High-Load Friction Units

The tribological properties of matrix and skeletal titanium carbonitride composites were studied in dry friction conditions in air. Experiments on wetting of the TiCN–Cr3C2 composite by nickel–chromium alloys and copper using the sessile drop method were performed to choose matrix composition and ascertain whether the samples could be produced by impregnation of the porous skeleton. The sessile drop experiments showed that nickel and its alloys formed a low contact angle on the TiCN–Cr3C2 composite (θ ≈ 8°). In particular, Ni3Al intermetallic had θ < 5°, allowing it to be used as a metal matrix. The same situation was observed for copper. A technique was developed for producing TiN–Cr3C2 composites by impregnation of the porous skeleton with Ni3Al and copper melts, and the tribological behavior of the cermets was tested in dry friction conditions. When the starting composite was impregnated with Ni3Al intermetallic, the friction coefficient decreased (μ = = 0.25). Structural studies were conducted with a MIM-10 metallographic microscope and X-ray diffraction with a DRON-2 diffractometer. The hardness and contact area thickness were measured employing a Falcon 9 hardness tester (manufactured in the Netherlands). Thin cross sections were made to examine the structure and phase composition of the contact area. The structure was analyzed using X-ray diffraction and scanning electron microscopy. The effect exerted by hardness of the counterface (steel 45, 40Kh, ShKh15) on the tribological properties of the TiCN–Cr3C2 composite was established. When steel hardness was 60 HRC, the friction coefficient increased with friction distance. These results were, however, obtained at low speeds and loads. Friction losses decreased with loading increasing from 2 to 6 MPa at 12 m/sec: friction coefficient reduced to 0.23. The TiCN–20% Cr3C2 cermets impregnated with Ni3Al may be recommended as antifriction materials for use in high-speed and high-load friction units.

Effect of process parameters on tensile strength of Friction stir welded butt joints of thick AA1350 aluminum plates using Taguchi experimental design

Abstract The requirement for defect free welding for critical applications has resulted in continuous development of advanced material joining processes. Friction stir welding (FSW), a solid state welding process has been accepted for joining of a diversity of materials viz aluminium, copper and other low melting point alloys. This mechanical way of joining is also a proven technique that is being used for joining of dissimilar materials efficiently. In this paper, the FSW has been utilizing for joining of thick aluminium plates to widen the industrial application of FSW. The spindle rotational speed, travel speed of tool and tilt angle of the tool were taken to study their effect on the tensile strength of FSW weld joint. The AA1350 grade aluminium plates having 12.7 mm thickness was taken as the work material for joining. Experimentation was carried out according the Taguchi’s L9 orthogonal array. The lowest level of spindle rotation, and highest level of travel speed and tilt angle of tool were obtained as optimal input variables for desired tensile strength of the joint. The confirmation experiments were also done to validate the optimal settings.

High‐Temperature Environmental Protection Metal Material 3D Printing Equipment Development and Process Research

At present, 3D printing technology is becoming more and more popular, but the traditional learning method has some limitations. The price of 3D printing equipment is expensive, and there are some security risks in the process of learning operation. This paper mainly introduces the development and process research of high‐temperature environmental protection metal 3D printing equipment and realizes the design of 3D printing equipment combined with virtual reality technology. In this paper, the whole system of 3D printing equipment is designed and built. The function of motion platform and substrate in mechanical system is analyzed, and the detailed structure design is carried out; the control principle of control system including motion control system and temperature control system is introduced in detail, and the corresponding design and construction work is carried out. In this paper, the pure tin wire with low melting point was used as the experimental material, and the mechanical properties and microstructure of the metal tin forming parts were analyzed. On the basis of tin formation experiment, metal deposition experiment and metal forming error experiment were carried out with H65 high melting copper wire as the raw material. The experimental results show that when the printing speed is 35/mm, the dimensional accuracy of the products is high; the microhardness of the printed tin is close to that of the original material, the surface hardness is 12.50HV0.05, and that of the copper alloy is 14.31HV0.05; the tensile strength of tin wire after melt deposition is slightly reduced after tensile test for the machined tin parts, the ultimate tensile strength of the first group of specimens is reduced by 1.58%, and that of the second group is reduced by 0.74%. This paper combines virtual reality technology with 3D printing technology and develops 3D printing equipment for high‐temperature environmental protection metal using virtual reality technology. The forming and printing performance of the device is analyzed theoretically and experimentally. The experimental results verify the feasibility of the system and the practicability of the device.

Interaction of a Low-Power Laser Radiation with Nanoparticles Formed over the Copper Melt in Rarefied Argon Atmosphere

Two effects have been recently observed by the authors for the copper sample melted in a rarefied argon atmosphere. The first of these effects is a strong decrease in the normal reflectance of a copper sample with time just after the beginning of melting. A partially regular crystal structure was also formed on the surface of the solid sample after the experiment. Both effects were explained by generation of a cloud of levitating nanoparticles. Additional experiments reported in the present paper show that the rate of decrease in reflectance increases with pressure of argon atmosphere and the surface pattern on the solid sample after the experiment depends on the probe laser radiation. It is theoretically shown for the first time that the dependent scattering effects in the cloud of copper nanoparticles are responsible for the abnormal decrease in normal reflectance and also for the observed significant role of light pressure in deposition of nanoparticles on the sample surface. The predicted minimum of normal reflectance is in good agreement with the experimental value.

Combustion in Ni–Al system with Cu additive (powder or rod) Experiment and mathematical model

Experimental studies were carried out with theoretical calculations of wave synthesis in the Ni–Al–Cu system were performed using the mathematical model developed. Approximate analytical formulas were obtained for synthesis performance evaluation. The inverse problem method was used to get kinetic constants that determine process dynamics based on the experimental data and analytical relationships. It is shown that the combustion front propagation velocity increases monotonically with an increase in the reaction sample relative density in the range of relative density values of 0.4 to 0.6. The depth of copper melt penetration from the center of the sample into the nickel-aluminum matrix depends on the relative density of the sample and copper wire diameter: higher densities and larger diameters lead to an increase in the liquid-phase impregnation area. The rate of nickel and aluminum powder frame wetting with copper melt is limited by the synthesis wave speed. Based on the experimental data and analytical ratios, we estimated the effective kinetic constants describing the high-temperature synthesis of the Ni + Al reaction mixture in the presence of copper additives. The thermal effect of the NiAl intermetallic formation reaction and the preexponential factor in the chemical transformation equation are calculated, the exponent value in the ratio for the mixture thermal conductivity is established; a constant determining the process of nickel-aluminum matrix impregnation with copper melt is found. The macroscopic approach used to analyze the NiAl intermetallic synthesis makes it possible to determine all the desired physicochemical characteristics and model parameters. The mathematical model is suitable for predictive estimates and experimental data analysis in the macroscopic approximation. Approximate analytical formulas are obtained for calculating the NiAl intermetallic synthesis characteristics. They allow for calculating the through channel characteristics and can be used in the design of NiAl products.

Microstructure and properties of dual-scale particulate reinforced copper matrix composites with superior comprehensive properties

In this work, Cu–Cr–Zr–ZrB2 composites were prepared via in situ melt reaction, casting and aging treatment. The reinforcement involved both micro ZrB2 particulate, primary Cr particles and nano precipitates, formed by in-situ reactions in copper melt and specific aging, respectively. The effect of the two reinforcements on the mechanical properties, thermal stability and tribological behavior of the Cu–Cr–Zr–ZrB2 composites were investigated. The ultimate tensile strength, electrical conductivity and the softening temperature of Cu-1wt%Cr-0.3 wt%Zr-1wt%ZrB2 composite were 592 MPa,79.0% IACS and 923 K. Additionally, the dual-scale particulates facilitated substantial improvements in the wear resistance. Microstructural observation revealed that the wear mechanisms was mostly abrasive with the presence of both Cr phase and ceramic particulates. Formation of Cr3O was noted, which also contributed to the decrease in the friction coefficient.

Effect of B on improving wetting and imbibition of sintered porous Ta by Cu melt

The present study focuses on the interaction between copper melts and porous tantalum plates (purity, 99.99 wt% Ta). The samples were prepared by sintering tantalum powder with different grain size and were characterized by 65% porosity. A procedure to perform direct observations of the interaction between the melt and plates was developed. Equipment for high-speed recording of dipping of the samples into the melt was designed. The frame rate was up to 5000 fps. A high-vacuum furnace with a graphite heater was used. Wetting experiments were performed in the temperature range of 1100–1400 °C.As expected, at temperatures near 1150 °C the tantalum cake coated with an oxide layer is not wetted by pure copper and does not imbibe it. Rising temperature slightly improves wetting. Doping the copper melt with 2 at.% B at 1150 and 1275 °C reduced the contact angle to 60° it dropped below 25° at 1400 °C. The reason for the observed phenomenon was that doping with boron results in reactive wetting and formation of tantalum boride. Wetting of the porous samples was compared to wetting of cast tantalum plates.The kinetics of imbibition with Cu(B) melt were recorded. The imbibition dependence changed from power-law to linear one as temperature increased from 1275 to 1400 °C. This behavior is associated with degradation of the tantalum boride layer.

Low-Temperature Decomposition of the (Nb,W)C Carbide Solid Solutions in NbC–WC–Cu Composite Alloys

Abstract—NbC–WC–Cu composite alloys are fabricated at 1300°C by impregnating mixtures of compacted and noncompacted carbide powders with the copper melt under low-frequency (80 Hz) vibration. Under these conditions, carbides are shown to interact with the formation of core (NbC)–shell ((W,Nb)C) solid solution) structures in the copper melt. The formation of a (W,Nb)C solid solution on the surface of NbC particles promotes the wetting of the carbide with copper. The thermal stability of the carbide solid solutions is investigated during isothermal holding at 500 and 1000°C for 60 min and during slow (10 K/min) heating to 1300°C. A reversible decomposition is detected, and the boundaries of low-temperature latent decomposition of the (Nb,W)C solid solutions are determined by the mass ratio of monocarbides NbC : WC in their alloy with copper. The higher the ratio, the lower the (Nb,W)C decomposition temperature.

Kinetic and mechanistic study of CO oxidation over nanocomposite Cu−Fe−Al oxide catalysts

AbstractThe oxidation of CO has been studied over Fe−Al and Cu−Fe−Al oxide nanocomposite catalysts prepared by melting of copper, iron, and aluminum nitrates. It was shown that the addition of copper significantly increases the catalytic activity of the Fe−Al nanocomposites. The catalysts were characterized by low‐temperature nitrogen adsorption, X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS). It was found that the catalysts contain Fe2O3 with the hematite structure modified by aluminum. Copper in the three‐component catalyst is in the Cu2+ state, forming CuO and CuFeOx clusters on the catalyst surface. An increase in the copper content leads to the formation of a CuxAlyFe3‐x‐yO4 spinel phase. In situ XPS study showed that a treatment of the catalysts in a CO flow leads to the reduction of both copper and iron cations into the metallic state. In contrast, a treatment in a CO/O2 flow leads only to partial reduction of Cu2+ to Cu1+, while Fe3+ are not reduced. The tests of catalytic activity performed in a flow fixed bed reactor using a CO pulse technique showed that the light‐off temperature in the oxidation of CO over the Cu−Fe−Al nanocomposite catalysts depends on the copper content. The minimal light‐off temperature was achieved over the catalyst containing 5 wt% CuO. In addition, we performed kinetic measurements in a differential reactor and obtained the activation energy and the reaction orders with respect to the reactants. The reaction mechanism of the catalytic oxidation of CO and the origin of active species are discussed.

Traditions and innovations: versatility of copper and tin bronze making recipes in Iron Age Emporion (L\u2019Escala, Spain)

Established around 575 BC, Emporion was a Greek colonial enclave in north-east Iberia and hence constitutes a good context to study Mediterranean innovations and their adaptation with indigenous technologies. Here, we present an analytical study of the archaeometallurgical assemblage from a workshop context dated to the first occupational moment of Emporion’s Neapolis (second half of the sixth century BC), including slag and technical ceramics. We aimed at reverse engineering the copper and tin bronze metallurgical technologies at the site. The results allow the identification of copper smelting and melting, and a variety of bronze alloying techniques, together with iron smelting and forging. The use of Fe-rich copper ores with BaO, ZnO and PbO impurities is consistent with the exploitation of local sources, preceding the diversification of raw materials documented for later phases. The co-occurrence of co-smelting, cementation and co-melting as bronze making technologies is discussed with reference to parameters of efficiency and cost-effectiveness and contextualised in the broader colonial interaction, providing pointers for future comparative work and discussion. The early use of metallic tin for bronze production at the site supports a Mediterranean origin for this innovation in Iberia.

Laser Cutting Characteristics on Uncompressed Anode for Lithium-Ion Batteries

Lithium-ion batteries are actively used for many applications due to many advantages. Although electrodes are important during laser cutting, most laser cutting studies use commercially available electrodes. Thus, effects of electrodes characteristics on laser cutting have not been effectively studied. Since the electrodes’ characteristics can be manipulated in the laboratory, this study uses an uncompressed anode on laser cutting for the first time. Using the lab-made anode, this study identifies laser cutting characteristics of the uncompressed anode. First, the absorption coefficients of graphite and copper in the ultraviolet, visible, and infrared range are measured. The measured absorptivity of the graphite and copper at the wavelength of 1070 nm is 88.25% and 1.92%, respectively. In addition, cutting phenomena can be categorized in five regions: excessive cutting, proper cutting, defective cutting, excessive ablation, and proper ablation. The five regions are composed of a combination of multi-physical phenomena, such as ablation of graphite, melting of copper, evaporation of copper, and explosive boiling of copper. In addition, the top width varies in the order of 10 μm and 1 μm when applying high and low volume energy, respectively. The logarithmic relationship between the melting width and the volume laser energy was found.