Copper Insert Research Articles

Research of Three-High Screw Rolling of Aluminum Billets with Copper Inserts at Different Rolls Feed Angles

Three-high screw-rolling of aluminum alloy ingots was carried out at 12- and 20-degrees rolls feed angles. The ingots had two copper, cylindrical inserts oriented along the ingot axis: the center of one insert coincided with the ingot’s center, and the center of the other insert coincided with the ingot’s half-radius. The effect of the rolls feed angle value on the aluminum and copper microstructure as well as the hardness formation was established. X-ray study and three-dimensional modeling allowed the copper insert twisting angle to be estimated along the rolled billet axis. It also allowed detection of the number of breaks of the insert located in the ingot’s center and the insert located in the ingot’s half-radius depending on the rolls feed angle value.

Infiltration of aluminum in 3D‐printed metallic inserts

AbstractAluminum structural composites through the infiltration process can be performed by vacuum, centrifugal, or squeeze casting, involving the infiltration of molten Al into fibers, particles, foams, or even porous preforms. This methodology creates hybrid structures of two distinct metal alloys that can be used to locally strengthen components or even to improve the properties of bulk materials, such as ultimate tensile strength and thermal conductivity. New approaches involve the infiltration of liquid Al into a three‐dimensional (3D)‐printed structure of the more rigid metal, such as steel, that the Al matrix. In the current study, stainless steel and copper inserts were produced by fused filament fabrication techniques with various geometries. Moreover, some 3D inserts were electrochemically coated with pure copper to enhance the wettability of the steel insert by Al. Then, the infiltration of these inserts was evaluated by gravity casting, centrifugal casting, and low‐pressure sand casting (LPSC). Evaluations involved microstructural characterization using optical microscopy and SEM for interface analysis. It is revealed that centrifugal casting is highly reliable to infiltrate the inserts with Al, filling detailed cavities in depth. The copper coating aided in the creation of intimate interfaces. The infiltration at the insert's surfaces, curved‐like topography, is obtained through LPSC though it is affected by the direction in respect of material flow.

Surface Modification of Metallic Inserts for Enhancing Adhesion at the Metal-Polymer Interface.

A combination of mechanical and chemical treatments was utilized to modify the surface textures of copper and duralumin inserts in order to enhance the adhesion at the metal–polymer interface and provide an adhesive joint with a high loadbearing capacity. Pretreatment of the surfaces with sandblasting was followed by etching with various chemical mixtures. The resulting surface textures were evaluated with a scanning electron microscope (SEM) and an optical confocal microscope. Surface geometry parameters (Sa, Sz, and Sdr) were measured and their relationships to the adhesion joint strength were studied. It was found that the virgin and purely mechanically treated inserts resulted in joints with poor loadbearing capacity, while a hundredfold (duralumin) and ninetyfold (copper) increase in the force to break was observed for some combinations of mechanical and chemical treatments. It was determined that the critical factor is overcoming a certain surface roughness threshold with the mechanical pretreatment to maximize the potential of the mechanical/chemical approach for the particular combination of material and etchant.

A novel and simple method to improve thermal imbalance and sink mark of gate region in injection molding

Among the appearance defects of injection molded products, sink mark near the gate accounts for a large proportion, especially for the precision products that require a high appearance quality. The traditional method to relieve gate sink mark is to increase packing pressure and packing time. Even so, the problem cannot be completely solved. In current study, a three-dimensional numerical simulation method was employed to analyze the formation mechanism of gate sink mark. The analyses point out that high shear in the filling stage, melt refilling in packing stage and high mold temperature lead to the imbalance of shear heat generation and cooling between the gate and other regions, and finally result in the relatively high temperature and the sink mark defect in the gate region. Based on these results, a novel and simple method for improving gate sink mark by adding beryllium copper insert in the runner was proposed and implemented. Further simulation shows that the method is effective in eliminating the gate “hot spot” and improving the temperature uniformity of the entire product. The experiment results also prove that the heat sink mark in the gate area can be effectively avoided by using the mold with insert for both amorphous ABS and semi-crystalline PP products. The proposed method can not only solve the sink mark problem effectively, but also has the advantage of being simple and easy to achieve because the slide type side gate design is adopted.

Antimicrobial activity of poultry hatch baskets containing copper inserts

Commercial poultry hatcheries provide ideal conditions for the multiplication and spread of microorganisms. Formaldehyde is widely used as a disinfectant; however, it is harmful to human health and can cause abnormal morphology in chicks. An alternative microbiological control is the use of copper, a metallic antimicrobial agent for contact surfaces. The antimicrobial efficacy of copper surfaces has been established in healthcare environments. However, its use in the poultry chain is still limited. This study aimed to compare the antimicrobial activity of common polypropylene hatch baskets with hatch baskets composed of copper (polypropylene hatch baskets covered by copper hatch baskets; polypropylene hatch baskets with solid copper plates on the bottom; polypropylene hatch baskets covered by copper hatch baskets and with solid copper plates on the bottom). To simulate a hatching environment with high contamination, the eggs and hatching cabinet were not fumigated. Microbiological analysis of the hatching cabinet environmental, surface of hatch basket, and fluff were performed. The results indicated that the absence of bottom holes resulted in a higher volume of organic matter that interfered with the copper's antimicrobial activity. The presence of copper in the hatch baskets did not decrease microbial contamination under the conditions evaluated, confirming that the metal should only be used as a complement to standard hygiene and not as a substitute for surface disinfectants. Further analysis will evaluate the antimicrobial activity of hatch baskets composed only of copper and the ability of nanoparticles to remove the biofilms formed by bacteria isolated from the poultry environment.

Achieving high-strength metallurgical bonding between A356 aluminum and copper through compound casting

Due to stable surface oxides on the solid copper surface and the ease of forming Al 2 O 3 films at the aluminum melt surface, it is difficult to achieve high-strength metallurgical bonding between the two materials through compound casting. In this research, a novel surface coating method for the copper inserts, namely hot-dip Sn-coating, has been applied. Through this method, a high-quality bond between a cast aluminum alloy A356 and commercially pure copper was achieved through a gravity compound casting process. Tensile tests showed that a maximum ultimate tensile strength (UTS) of 90.8 MPa could be obtained for the bimetal interface. Microstructures formed in the aluminum/copper interface were studied by optical- and scanning electron microscopy, while a sessile drop wetting test was used to study the wettability between the aluminum melt and Sn-coated copper substrates. The effects of Sn-coating on the wettability and the formation of interfacial microstructure were discussed. • Continuous metallurgical bond was achieved in aluminum/copper compound castings. • Sn-coating of copper significantly improved wetting between aluminum and copper. • Ultimate tensile strength of 90.8 MPa was measured for the Al/Cu castings. • Effect of the Sn coating layer was discussed.

Rupture by impact-induced fatigue of a copper foil strip embedded in a multifunctional composite material

Multifunctional composite materials are highly sought-after by the aerospace and aeronautical industry but their performance depends on their ability to sustain various forms of damages, in particular damages due to repeated impacts. In this work we studied the mechanical behavior of a layered glass-epoxy composite with copper inserts subjected to fatigue under repeated impacts with different energy levels. Damage evolution as a function of impact energy was carefully monitored in order to determine the effect of the copper inserts on mechanical characteristics of the multifunctional composite, such as endurance and life. Results of repeated impact tests show that electric current interruption in the copper inserts occurs prior to the total perforation of the composite material, and after about 75% of the total number of impacts to failure. This is the case for the three energy levels considered in this study, [Formula: see text] = 2, 3 and 4 Joules. The epoxy resin was dissolved chemically in order to preserve the mechanical structure of the damaged copper inserts and the composite fibers for further inspection and analysis. Scanning electron microscopy (SEM) of the fractured copper inserts revealed interesting information on the nature of the damage, including information on plastic deformation, strain hardening, cracking mode, temperature increase during the impacts, and most importantly the glass fibers and their roles during the impact-fatigue tests.

Mathematical modeling and experimental study of damping behavior of a cantilever carbon fiber–reinforced polymer composite hollow member with metal inserts

Metal inserts are widely used particularly in bolted connections for joining composite members. In this work, a theoretical basis is provided for analyzing the damping behavior of a cantilever composite square hollow member embedded with metal inserts along its length. Analytic stress solutions around the boundaries of the insert and the member are introduced while deriving the expression of modal damping ratio. Kelvin–Voigt and amplitude-dependent damping models are considered for the formulation. Experiments are performed on the perforated composite tube reinforced with brass, copper, and steel annular inserts subjected to transverse base motion of varying amplitudes. The acceleration responses recorded from the tests are analyzed to evaluate the damping ratio of the fundamental mode. It is observed that the damping ratio evaluated from the experiments matches well with the proposed value. Furthermore, it is found that the damping ratio increases when the holes are reinforced with the inserts. The reason for the increase in damping stems from (i) frictional effect at the boundaries of the insert and the tube and (ii) material damping of the inserts. For example, the damping amplification of the tube with five steel inserts is noted to be around 3.0 and 2.1 times with respect to the unperforated and perforated (with holes) cases, respectively.

Effect of Using a Copper Insert on Stability and Energy Balance in an Aluminum Production Cell

Roughly half of the electrical energy input to a modern Hall–Heroult cell for the aluminum (Al) production is lost as heat. Naturally, significant efforts are currently directed toward increasing the thermal efficiency of the cell by a variety of means. In this work, a slice thermoelectric model of a Hall–Heroult cell was developed for a conventional base model (insert-free collector bar) as well as for a copper (Cu) insert model (cylindrical copper inserts in the steel collector bar). Finite element method-based simulations were carried out to determine the components of voltage drops, steady-state ledge profile, cell stability and the overall heat balance. Comparison of the specific energy consumption (SEC) and the cell current in all cases highlighted the advantages of copper insert collector bar assembly over the insert-free, base case. The use of a Cu insert can increase the plant productivity by over 5% at the same SEC as in the base case. Moreover, with the introduction of an insert, an increase in productivity with a concomitant decrease in the SEC could be achieved.

Digital Reconfiguration of a Single Arm 3-D Bowtie Antenna

This communication proposes the reconfiguration of a coplanar-fed single arm bowtie antenna structure by relying on the integration of a digital tunable capacitor (DTC). The coplanar-fed single arm bowtie antenna is presented in two configurations. The first configuration is a 2-D topology with a modified ground plane arrangement. The second configuration employs vertical folding for the ground plane as well as the radiating arm. In addition, vertical copper inserts are embedded within the bowtie single arm to further enhance the compactness of the structure and transform it into a 3-D topology. Both antennas are initially designed to operate at 868 MHz for Internet of Things (IoT) applications, with a digitally reconfigurable frequency operation for wireless communication. The 2-D antenna structure exhibits a 77% size reduction at the IoT operational frequency of 868 MHz in comparison with a similar rectangular patch antenna operating at the same frequency. On the other hand, the 3-D antenna structure reaches 84% of size reduction at the same frequency. A figure of merit (FOM) is derived to prove the superior performance of the presented antenna structure.

Selected Issues of Increasing the Fire Effectiveness of Combat Vehicles

Abstract The research paper reviews selected issues associated with the current state of the armoured (tanks) and infantry fighting vehicle technology, with particular emphasis on the operating effectiveness of elongated sub-calibre projectiles fired from tank guns, which enable full perforation of ca. 500 mm thick armour steel plates. Their efficiency is comparable with the impact of shaped heads with armour steel penetration capabilities, and amounts from 6 to 8 calibres – warhead diameters. Furthermore, the paper discusses a numerical analysis, which shows the velocities of elongated projectiles (of tungsten matrix sinters) required to achieve a determined armour steel penetration depth. In addition, it also presents the performance characteristics of two 100 mm calibre shaped warheads, with copper inserts and apex angles of 51º and 60º.

Numerical simulation of cathodic voltage drop in Hall-Héroult cell

Numerical simulations are widely used to predict cathode voltage drop in Hall-Héroult cells and to determine the qualifications needed for voltage savings. The aim of this study is to investigate the effect of change in the properties of cathode assembly materials with temperature, the effect of the copper insert in collector bar and effect of change in cathode design on the cathodic voltage drop, horizontal current density and potlife. Thermal and electrical measurements were performed on twenty cells to validate the model results. The results proved that resistivity of both collector bar and cathode block is considered the main property that controls the cathodic voltage drop in the cells. While the copper insert has a much higher potential for providing a lower cathode voltage, great effect on the horizontal current density in the cell and increases the expected potlife. However, the choice of cathode assembly materials must be compatible between cathodic voltage drop and horizontal current density. Therefore, these items have been examined for different cases to reach optimal conditions. The results show that select anthracitic with 30% graphite cathode blocks and adjust the resistivity of steel collector bars and cast iron, as well as insert copper in the steel collector bar, are effective in bringing down the cathodic voltage drop, lower the electro-erosion of the cathode block and the expected potlife will be increased.

Use of pure vanadium and niobium/copper inserts for laser welding of titanium to stainless steel

Niobium and vanadium have high metallurgical compatibility with titanium and therefore can be used as inserts to avoid the accumulation of brittle intermetallic phases such as Fe2Ti during the fusion welding of titanium alloys with steels. In the present study, the continuous double pass welding of 1 mm thick Ti-6Al-4V alloy and 316 L stainless steel plates through several mm wide pure vanadium or niobium insert was studied. In case of a vanadium insert, a beam offset on the vanadium was found to produce cold crack formation in vanadium/316 L melted zones containing more than 40 wt.% V despite the absence of σ phase. Whereas a centered beam position and offset on the steel side produced crack-free melted zones still composed of (Fe, V) solid solutions, and exhibiting a ductile fracture in the unmelted vanadium insert at UTS of 493 ± 25 MPa. The niobium insert produced brittle niobium/316 L melted zones with UTS of 160 ± 10 MPa, because of the formation of Fe2Nb and Fe7Nb6 layers at the niobium/316 L interface. The addition of a copper insert between niobium and steel allowed avoiding the development of Fe-Nb brittle intermetallics thanks to the absence of brittle phases in Cu-Nb system. For optimal welding conditions, a ductile fracture occurred in the copper interlayer at maximal UTS of 255 ± 10 MPa.

EBSD analysis of the structure of a weld joining a chromium-nickel steel sheet and a titanium alloy sheet through a copper insert

The structure of the different zones of a C02 laser welded joint between a chromium-nickel steel sheet and a titanium alloy sheet, with a copper insert between them, is studied by EBSD analysis. The phase compositions of all the zones have been determined. The weld material has been found to consist of a Cu-based solid solution and unevenly distributed intermetallic particles of different stoichiometric compositions. The heat-affected zones consist of supersaturated iron- and titanium-based solid solutions. After laser welding, the microdeformations of the phase lattices are distributed unevenly over the cross section of the welded joint; namely, the maximum microdeformations and the resulting microstresses are concentrated in the heat-affected zone at the boundary between the weld and the titanium alloy.

Crystallization of dissimilar Ti/Cu/steel laser welds

Laser welding of dissimilar materials is characterized by high radiation power density, penetration locality, melt convection in the weld pool, and high cooling rates. Therefore, it attracts the attention of developers of high-speed vehicles, who aim at utmost reducing the weight of structures via dissimilar materials welding. The crystallization mechanisms of the weld material govern the structure and strength of welded joints and require a detailed study. This study shows that laser radiation power and welding speed influence crystal forms of welds joining a titanium alloy and a chromium-nickel steel through a copper insert, their structure and tensile strength. At a power of 1.0 kW and a welding speed of 0.3 m/min, the largest amount of each of the alloys is melted in the weld pool and a wide weld is formed, the solidification being accompanied by dendrite formation. The increase in radiation power to 2.4 kW decreases the amount of the molten alloys in the weld pool thus forming welds narrower than 1.8 mm. The increase in the welding speed to 1 m/min inhibits formation of dendrites; in this case, (Fe,Cr)2Ti and Cu3Ti intermetallic particles are the first to solidify and the polyhedral crystals of the supersaturated copper-based solid solution, where nanodispersed (Fe,Cr)2Ti and Cu4Ti particles precipitate during cooling, are the next. This type of weld structure ensures the tensile strength of the joint comparable to the titanium alloy.

Microstructure of a Laser-Welded Joint between a Chromium–Nickel Steel and a Titanium Alloy with a Copper Insert

Microstructure of a Laser-Welded Joint between a Chromium–Nickel Steel and a Titanium Alloy with a Copper Insert

The microstructure of Nb3Sn superconductors differing in the number of copper inserts at various stages of heat treatment

Superconducting materials with a high critical current density in magnetic fields up to 16 T at a temperature of 4.2 K are required to create magnetic systems of high-energy physics devices. We have studied the change of the microstructure of model samples of various designs with an internal tin source, differing in the number of copper separators (three, six and without them) at different stages of heat treatment. The formation of the following intermediate phases was studied: Cu3Sn, Cu6Sn5 and triple Cu-Sn-Nb phase after annealing at 370°C/100 h, by the use of scanning and transmission electron microscopy. The formation of the Nb6Sn5 phase on Nb filaments located close to the tin source and copper separators was studied after heat treatment at a temperature of 665°C from 10 minutes to 25 hours. The results of the analysis led us to understand the kinetics of the Nb3Sn and Nb6Sn5 formation in internal tin superconductors with an increased current-carrying capacity and a low level of hysteresis losses.

Optimization of high heat flux components for DIII-D neutral beam upgrades

Upgrade of the DIII-D neutral beams leads to enhanced heat loads on many components, such as calorimeter, collimator, and pole shields which protect neutral beam magnets. Power increase from 2.6 MW to 3.2 MW per source leads to a normal heat flux loads of up to 55 MW/m2 for the calorimeter. The Princeton Plasma Physics Laboratory is responsible for the design and manufacturing of the upgrades of these components.Heat flux distribution on neutral beam components is very uneven and leads to significant thermal stresses. High heat flux density impact requires surface optimization to reduce surface heat flux projection, and avoid localized melting. Several new design features were introduced to accommodate increased heat loads, such as molybdenum inserts for the pole shields, two-dimensional shaping for the calorimeter, and three-dimensional shape optimization and replaceable copper inserts for the collimator. Additionally, all three components include an optimized cooling system design featuring peripheral cooling of copper components.The optimization process included applying analytical relations for the transient temperature distributions on the high heat flux components. These relations were confirmed by previous DIII-D experimental results. To validate the designs, numerical simulations were performed. Results of the design optimization and numerical simulations will be presented.

Thermal Properties of Intermetallic Phases at the Interface of Aluminum–Copper Compound Castings

High‐pressure die compound casting relies on high bond quality, and high thermal contact conductance at the interface is a key issue in the context of cast advanced cooling components, such as lightweight heat sinks for desktop and portable computers. The current study aims at enhancing the thermal contact between a copper insert piece and an AlSi9Cu3(Fe) cast alloy by developing suitable Zn‐based coatings, which are used to establish a firm metallurgical bond between the solid insert and the cast alloy during high‐pressure die‐casting. It is demonstrated by microstructural analyses that various phases form at the interfaces in the casting process. As the thermal conductivities of these phases have not been available, these are determined individually using a thermoflash device. The SEM investigations indicate that mainly ternary phases of the type AlxCuyZnz emerge in the bonding zone, as the high casting temperatures promote the diffusion of aluminum atoms into the coating. Interestingly, an alloy containing 50 wt% zinc reaches a thermal conductivity as high as 166 W mK−1. The microstructural characteristic at the interfaces and the ramifications with respect to applications are discussed.

Microstructural characterization and mechanical properties of aluminum 6061-T6 plates welded with copper insert plate (Al/Cu/Al) using friction stir welding

Abstract Friction stir welding was used to join two aluminum 6061-T6 plates with an insert of a pure copper plate (Al/Cu/Al), and then the influence of the copper insert on the joint performance was studied. The dissimilar welding results were also compared with AA 6061 friction stir welds produced without copper insert (Al/Al). Optical and scanning electron microscopes were used for the microstructural observations of the welded samples. X-ray diffraction analysis was used to analyze phase component of the Al/Cu/Al specimen. A defect-free joint was observed for the Al/Cu/Al joint at a rotational speed of 950 r/min and a welding speed of 50 mm/min. Microstructural observation of the weld nugget zone (WNZ) demonstrates the formation of composite-like structure which promotes metallurgical bonding of aluminum and copper. XRD results show the formation of intermetallic compounds (IMCs), such as Al4Cu9 and Al2Cu. Furthermore, it was observed that the hardness of the weld with the Cu insert plate is higher than that of other samples due to more dislocation density and a distinct rise in hardness values was observed due to the presence of IMCs. The ultimate tensile strength of the joint with copper insert plate is higher than that of the other sample due to the strong metallurgical bonding between Al and Cu.