Copper Insert Research Articles

Лазерное сварное соединение титанового сплава ВТ1-0 и стали 12Х18Н10Т с промежуточной медной вставкой

Лазерное сварное соединение титанового сплава ВТ1-0 и стали 12Х18Н10Т с промежуточной медной вставкой

Role of insert material on process loads during FSW

In FSW, insert materials are often used to both control the loading conditions as well as to trace the nature of materials flow. This current study aims at understanding the role played by inserts materials by using two different materials, copper and tin as inserts. The copper and tin have higher and lower melting points respectively as compared to aluminum. The metal strips are sandwiched between aluminum plates and friction stir welded at two different rotational speeds. The process loads and torque were recorded during the welding and compared with that obtained for normal butt-welding of aluminum sheets. In the case of copper insert, copper gets distributed in the matrix and it is possible to trace the flow of copper inside the aluminum. In the case of tin, it melts during the welding. The molten tin is squeezed out of faying surface and coats tool shoulder. This lowers the friction and which in turn lowers the torque (55%) and the consequent heat generation. The resultant reduction of temperature in the weld leads to higher tangential and normal loads. Compared to the case without insert, the normal loads for FSW processing with tin insert were higher by 2.2 times and tangential loads were higher by 5.5 times.

Increasing Wear Resistance of Internal Combustion Engines Cylinders with Work Friction Surface Metal Coating

The block of cylinders is one of the main and expensive parts of the internal combustion engine. The work surfaces of cylinders are subject to wear causing reduced performance characteristics of the engine. Therefore, improving the wear resistance of the cylinders work surfaces is a topical problem. The wear of the cylinder block is suggested to be reduced by forming a layer of metal with low shearing resistance on its working surface. The necessary ratio of the area of non-ferrous metal inserts and the area of the cylinder working surface, as well as the angle of inclination of the insert to the diametrical plane of the cylinder, is calculated. Considering that the width of each of the six copper inserts is 1.5 mm, the calculated angle of inclination of the insert to the diametral plane of the sleeve is equal to 17.2°. The greatest reduction in friction at inclination angles from 15° to 25°, has been experimentally proved. At the same time, the cylinder wear decreased on the average by 3 times.

An Approach for Estimation of Cathode Voltage Drop in an Aluminum Reduction Cell with an Inclined Carbon Block and a Copper Insert

Numerical models of a cathode block assembly in a Hall–Heroult cell, comprising of liquid aluminium, carbon block, current collector, ramming paste and a copper insert were built and the finite element method simulations were carried out to model the cathode voltage drop (CVD), the current distribution and, the effect of geometrical parameters on the CVD. The objective of the study was to quantify the drop in the CVD for different cathode assembly design. Flat- and inclined-interface carbon block top-surface and a copper insert versus the conventional insert-free designs were simulated with a myriad of other geometrical parameters to optimise the design. The results informed about the optimum insert positioning to about 75 mm from the collector base and the energy saving possibilities due to reduction in the CVD with a cathode design with inclined-interface carbon block and copper insert in the collector bar.

3D microwave cavity with magnetic flux control and enhanced quality factor

Three-dimensional (3D) microwave cavities have been extensively used for coupling and interacting with superconducting quantum bits (qubits), providing a versatile platform for quantum control experiments and for realizing hybrid quantum systems. While having high quality factors (>106) superconducting cavities do not permit magnetic field control of qubits. In contrast, cavities made of normal metals are transparent to magnetic fields, but experience lower quality factors (∼104). We have created a hybrid cavity which is primarily composed of aluminium but also contains a small copper insert reaching the internal quality factor of ≃105, an order of magnitude improvement over all previously tested normal metal cavities. In order to demonstrate precise magnetic control, we performed spectroscopy of three superconducting qubits, where individual control of each qubit’s frequency was exerted with small external wire coils. An improvement in quality factor and magnetic field control makes this 3D hybrid cavity an attractive new element for circuit quantum electrodynamics experiments.

Numerical study of Heat Modes of laser welding of dissimilar metals with an intermediate insert

A 3D model of heat transfer in inhomogeneous materials taking into account phase transitions for analysis of laser welding of dissimilar metals using intermediate insert is developed. Based on the proposed model, an algorithm is constructed and numerical studies are carried out of the distribution of temperature fields in the weld joint of titanium and stainless steel with an intermediate copper insert. The processes of melting, evaporation, and solidification of the materials depending on the beam power, its speed, and position of the focal spot in the system are studied. The welding modes reducing interaction of elements of the materials welded and, thus, preventing formation of brittle intermetallic phases in the weld joint are found.

The improvement of friction bearing manufacturing technology by using copper alloy

The research objective is to increase the operational life of friction bearings by technological methods, particularly, in relation to kinematic mechanisms used for conversion of motion in the tractor-type internal combustion engines. The research object is the process of friction and wear in friction bearings. Theoretical regularities related to change in friction and wear parameters in the bearings were used, depending on the used materials and load conditions. The studies were conducted by the selection of variants of friction pairs for friction bearings used in kinematic mechanisms of internal combustion engines operating at high radial loads and under rapidly changing load modes. In the course of this study, the authors selected the best design and technological characteristics for bearings with certain pairs of friction and studied the friction and wear regularities of the selected pairs of friction bearings. The study also implied the analysis of the initial data for the evaluation of wear resistance of the selected pairs of friction bearings and the development of technical specifications for their use in internal combustion engines. The use of copper for manufacturing the bearing shell was determined as one of the promising ways to increasing their quality indicators. Highly effective properties of copper for manufacturing the supporting elements of plain bearings were experimentally confirmed. The operational life of bearings can reach 14,000 motor-hours, which exceeds the operational life of a standard serial bearing shell by more than eight times. The economic result of applying the copper inserts implies the fact that given an increase in engine cost approximately by 2 %, repair costs per 1 h of the engine run are reduced by more than eight times. Design features of the proposed shells differ from the standard ones only by material; their dimensions and configuration are completely analogous to the standard inserts that allow using the new type of inserts for all currently used engine models. The most significant theoretical result of this study is the obtained functional connection of the friction and wear performance, expressed as a thermal stability coefficient, which gives the possibility to justify the choice of materials for the kinematic mechanisms of motion conversion in the tractor-type internal combustion engines based on studying thermal properties, characteristics of the materials employed, and the expected operating conditions. Industrial implementation of research results will give the economic effect—application of the developed bearings results in repair cost reduction by more than eight times.

Simulation of the elastic deformation of laser-welded joints of an austenitic corrosion-resistant steel and a titanium alloy with an intermediate copper insert

The macro- and microstructures and the distribution of elements and of the values of the microhardness and contact modulus of elasticity along the height and width of the weld metal and heat-affected zone of austenitic corrosion-resistant 12Kh18N10T steel (Russian analog of AISI 321) and titanium alloy VT1-0 (Grade 2) with an intermediate copper insert have been studied after laser welding under different conditions. The structural inhomogeneity of the joint obtained according to one of the regimes selected has been shown: the material of the welded joint represents a supersaturated solid solution of Fe, Ni, Cr, and Ti in the crystal lattice of copper with a uniformly distributed particles of intermetallic compounds Ti(Fe,Cr) and TiCu3. At the boundaries with steel and with the titanium alloy, diffusion zones with thicknesses of 0.1–0.2 mm are formed that represent supersaturated solid solutions based on iron and titanium. The strength of such a joint was 474 MPa, which corresponds to the level of strength of the titanium alloy. A numerical simulation of the mechanical behavior of welded joints upon the elastic tension–compression has been performed taking into account their structural state, which makes it possible to determine the amplitude values of the deformations of the material of the weld.

Simulation of heat transfer processes in laser welding of dissimilar metals with an insert

A 3D model of heat transfer in inhomogeneous materials taking into account phase transitions is developed to analyze the process of laser welding of dissimilar metals with the use of an insert. Based on the proposed model, a numerical algorithm is constructed. The investigation of the distribution of temperature fields in the area of the welded joint of titanium and stainless steel with an intermediate copper insert is carried out. The processes of melting, vaporization, and solidification of materials are studied depending on the power of the laser beam and its speed and the position of the focal spot in the system. Modes of welding to reduce the interaction of the elements of the welded materials and thereby prevent the formation of brittle intermetallic phases in the weld are found.

Forge Welding of Magnesium Alloy to Aluminum Alloy Using a Cu, Ni, or Ti Interlayer

The forge-welding process was examined to develop a high-strength bonding application of magnesium (Mg) alloy to aluminum (Al) alloy under high-productivity conditions. The effect of the insert material on the tensile strength of the joints, under various preheat temperatures and pressures, was investigated by analyzing the reaction layers of the bonded interface. The tensile strengths resulting from direct bonding, using pure copper (Cu), pure nickel (Ni), and pure titanium (Ti) inserts were 56, 100, 119, and 151 MPa, respectively. The maximum joint strength reached 93 pct with respect to the Mg cast billet. During high-pressure bonding, a microscopic plastic flow occurred that contributed to an anchor effect and the generation of a newly formed surface at the interface, particularly prominent with the Ti insert in the form of an oxide layer. The bonded interfaces of the maximum-strength inserts were investigated using scanning electron microscopy–energy-dispersive spectroscopy and electron probe microanalysis. The diffusion reaction layer at the bonded interface consisted of brittle Al-Mg intermetallics having a thickness of approximately 30 μm. In contrast, for the three inserts, the thicknesses of the diffusion reaction layer were infinitely thin. For the pure Ti insert, exhibiting the maximum tensile strength value among the inserts tested, focused ion beam–transmission electron microscopy–EDS analysis revealed a 60-nm-thick Al-Ti reaction layer, which had formed at the bonded interface on the Mg alloy side. Thus, a high-strength Al-Mg bonding method in air was demonstrated, suitable for mass production.

銅インサートメタルを用いたアルミニウム大気中自発的溶融·凝固接合における変位+荷重制御に関する検討

銅インサートメタルを用いたアルミニウム大気中自発的溶融·凝固接合における変位+荷重制御に関する検討

Investigation of the structure and properties of titanium-stainless steel permanent joints obtained by laser welding with the use of intermediate inserts and nanopowders

Results of an experimental study of the structure, the phase composition, and the mechanical properties of laser-welded joints of 3-mm thick titanium and 12Kh18N10T steel sheets obtained with the use of intermediate inserts and nanopowdered modifying additives are reported. It is shown that that such parameters as the speed of welding, the radiation power, and the laser-beam focal spot position all exert a substantial influence on the welding-bath process and on the seam structure formed. In terms of chemical composition, most uniform seams with the best mechanical strength are formed at a 1-m/min traverse speed of laser and 2.35-kW laser power, with the focus having been positioned at the lower surface of the sheets. Under all other conditions being identical, uplift of the focus to workpiece surface or to a higher position results in unsteady steel melting, in a decreased depth and reduced degree of the diffusion-induced mixing of elements, and in an interpolate connection formed according to the soldering mechanism in the root portion of the seam. The seam material is an over-saturated copper-based solid solution of alloying elements with homogeneously distributed intermetallic disperse particles (Ti(Fe, Cr)2 and TiCu3) contained in this alloy. Brittle fracture areas exhibiting cleavage and quasi-cleavage facets correspond to coarse Ti(Fe, Cr)2 intermetallic particles or to diffusion zones primarily occurring at the interface with the titanium alloy. The reported data and the conclusions drawn from the numerical calculations of the thermophysical processes of welding of 3-mm thick titanium and steel sheets through an intermediate copper insert are in qualitative agreement with the experimental data. The latter agreement points to adequacy of the numerical description of the melting processes of contacting materials versus welding conditions and focal-spot position in the system.

Texture Evolution and Twinning During the Expansion of Hot Extruded AZ31 + Sr Seamless Tubes

Seamless tubes of AZ31, AZ31 + 0.4, and 0.8 wt pctSr were extruded at elevated temperatures. By compressing pure copper inserts inside the tubes, the extruded tubes were expanded at room and elevated temperatures [373 K and 473 K (100 °C and 200 °C)]. Microstructural examinations reveal the formation of twining in the as-extruded and expanded tubes. The amount of twinning decreased with increasing level of Sr in the expanded microstructures as a result of grain refinement and of decreasing Al in solution that facilitates dislocation motion. During expansion at room temperature, AZ31 shows higher elongation and lower strength than the alloys containing Sr. At 473 K (200 °C), compared to the lower temperatures, the Sr containing alloys exhibit lower flow stress and no fracture in the strain range investigated (40 pct reduction in cylinder height). The textures of the extruded alloys contain two main components named as RD (c-axis parallel to the radial direction) and HD (c-axis parallel to the hoop direction) based on their orientation with the sample coordinates. During expansion, extension twinning in the HD grains reorients the lattice to strengthen the RD and form a new ED (c-axis parallel to the extrusion direction) component. By increasing the temperature or level of Sr, the ED component is weakened due to the decrease in twinning. During expansion, the RD grains undergo contraction and double twining which reduce the overall texture strength.

Aging Tests of the High Current Aluminum–Copper Contact Connections in the ITER DC Busbar System

In ITER, the superconducting coils will be connected with ac/dc converters by water-cooled aluminum busbars, whose segments will be interconnected by copper flexible inserts to compensate for cyclic thermal expansion. This paper presents the experimental data obtained during development and testing of high-current aluminum-copper contact connections with various coatings protecting against corrosion and oxidation including multilayer and composite coatings, coatings with an additional interlayer. With the testing results, the coating method has been chosen for the protection of the contact surfaces of aluminum busbars and flexible copper inserts, which will be used during manufacturing of the busbars for the power supply system of the ITER magnet system coils.

Aluminum: Bauxite-Alumina-Carbon Reduction

The aluminum section of the February issue of JOM has a unique combination of articles regarding past and future electrolytic technologies in HallHeroult cells. In the article, ‘‘Cathode Characterization With Steel and Copper Inserts in Collector Bars in an Electrolytic Cell’’ by Subrat Das, Yos Morsi, and Geoffrey Brooks, one-quarter cell threedimensional (3-D) finite-element-method model simulation results are presented for one of the newest innovations—cathode copper inserts in collector bars in industrial cells that demonstrate the potential for lower cathode voltage drop, improvement in current distribution, and a decrease in Lorentz forces. A historical perspective is presented in ‘‘Very High Purity Aluminum: An Historical Perspective’’ by Stephen J. Lindsay for the production of highpurity aluminum metal grades that approach the practical limits of purity from conventional aluminum electrolytic cells. Many of the work methods, systems, and subprocesses that have enabled the production of ‘‘very high purity’’ ingot in aluminum reduction cells since the early twentieth century are now obsolete for the designs of new smelters. Yet, a few primary aluminum smelters can, and do, produce limited quantities of super purity metal that is between 99.95% and 99.97+%Al. The last paper in this section is ‘‘The Evolution of Soderberg Aluminum Cell Technology in North and South America’’ by Mike Barber and Alton T. Tabereaux. The evolution of Soderberg technology in North and South America is illustrated beginning with the proliferation of Soderberg aluminum smelters during the 1940s and continued into the 1970s due to the increased demand for aluminum metal. In the 1970s, 24 Soderberg smelters located in North and South America had a primary aluminum capacity greater than 3 million tpy. At the outset, the less expensive Soderberg cell technology provided a distinct advantage compared with the small Hall-Heroult prebake cell smelters at that time due to its lower costs and ability to increase the initial low amperage in the 1950s–1960s. However the higher-amperage modern prebake cells developed in the 1970s operated more efficiently with higher productivity. Eventually, Soderberg cells proved to be more difficult to automate and had significant environmental and health issues. JOM, Vol. 66, No. 2, 2014

Investigation on interface of Al/Cu couples in compound casting

The joining of Al and Cu commercially pure metals using the compound casting process has been investigated where an aluminium melt is cast onto a solid cylindrical copper insert. The microstructure of the interface between copper core and surrounding aluminium was characterised by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and Vickers hardness tests. Results showed that five separate reaction layers are formed in the reaction interface of core and surrounding Al. These layers included Cu9Al4, AlCu and Al2Cu intermetallic compounds; a eutectic layer; and a eutectic α-Al dendritic structure layer. Owing to the presence of hard and brittle intermetallic compounds within reaction layers, microhardness profile showed a peak of 300 HV where both parent metals have hardness <50 HV. Microhardness profile also showed that hardness decreases from the copper to the aluminium side.

J044102 界面層形成・接合法による脆性機能繊維/アルミニウム複合材料の大気中創製の試み([J04410]知的材料・構造システム(10))

This paper proposes a method for simple and easy fabrication of brittle and highly functional ceramic fiber/aluminum composites by the interphase forming/bonding (IF/B) method in air. In the previous researches, brittle functional fibers such as optical fiber and piezoelectric ceramic fiber have been successfully embedded in an aluminum matrix by the IF/B method using copper insert in a vacuum. In this study, optical fiber/aluminum composites were fabricated by using the newly developed compact hot-pressing equipment capable of quick operation in air, and the main results can be summarized as follows: 1) By changing the fabrication atmosphere from vacuum to air, the oxidation could be improved simply by increasing the heating rate, which became possible by using the new compact equipment. 2) The pre-pressing process in the IF/B method in air was proved to be useful to minimize the oxidation

Measurements of Neutron Spectrum in the High-Energy DAΦNE Accelerator Complex with an Extended Range Bonner Sphere Spectrometer

In the framework of the radiation protection monitoring around DAΦNE, the high-energy Φ factory of the Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Frascati (INFN-LNF), a characterization of the neutron field was performed. As a suitable neutron spectrometer, a specially designed Bonner sphere system, whose energy range was extended up to hundreds mega-electron-volts by means of three spheres equipped with copper or lead inserts, was employed. The response matrix of the system was derived with MCNPX and experimentally validated with reference neutron fields. The neutron spectrum has been unfolded with the FRUIT (FRascati Unfolding Interactive Tool) code, a new unfolding code developed at INFN-LNF for the needs of operational radiation protection. This paper presents the results of the measurements in the DAΦNE complex, underlying the achievements of the new unfolding code. Moreover, the impact of these kinds of measurements on routine radiation protection practices is briefly addressed.

Sintered porous heat sink for cooling of high-powered microprocessors for server applications

This paper experimentally investigates the sintered porous heat sink for the cooling of the high-powered compact microprocessors for server applications. Heat sink cold plate consisted of rectangular channel with sintered porous copper insert of 40% porosity and 1.44 × 10 −11 m 2 permeability. Forced convection heat transfer and pressure drop through the porous structure were studied at Re ⩽ 408 with water as the coolant medium. In the study, heat fluxes of up to 2.9 MW/m 2 were successfully removed at the source with the coolant pressure drop of 34 kPa across the porous sample while maintaining the heater junction temperature below the permissible limit of 100 ± 5 °C for chipsets. The minimum value of 0.48 °C/W for cold plate thermal resistance ( R cp ) was achieved at maximum flow rate of 4.2 cm 3 /s in the experiment. For the designed heat sink, different components of the cold plate thermal resistance (R cp ) from the thermal footprint of source to the coolant were identified and it was found that contact resistance at the interface of source and cold plate makes up 44% of R cp and proved to be the main component. Convection resistance from heated channel wall with porous insert to coolant accounts for 37% of the R cp . With forced convection of water at Re = 408 through porous copper media, maximum values of 20 kW/m 2 K for heat transfer coefficient and 126 for Nusselt number were recorded. The measured effective thermal conductivity of the water saturated porous copper was as high as 32 W/m K that supported the superior heat augmentation characteristics of the copper–water based sintered porous heat sink. The present investigation helps to classify the sintered porous heat sink as a potential thermal management device for high-end microprocessors.

Effect of copper insert on the microstructure of gray iron produced via lost foam casting

The effect of insert diameter and pouring temperature on the microstructure of gray iron are studied by inserting the copper wires with diameters of 0.4, 1, and 2 mm into polystyrene patterns, followed by pouring the gray iron melt at two temperatures of 1230 and 1370 °C. The graphite morphology in the reference sample (without copper insert) was type A flake graphite which changed to type B, D or E in the specimens containing copper insert. The aforementioned variations can be attributed to the degree of undercooling developed during solidification. Copper dissolved up to 0.9 wt.% in the matrix and copper particles exceeding the limits of solubility dispersed throughout the matrix or segregated at the bottom of the melt. The process utilized in the present research, can be regarded as a promising approach for in-mold alloying, production of bi-metals, and study the interfacial reactions between a given melt and a supposed solid insert.