Patent Application
20230234115
The present disclosure relates to metals technology in general, but more specifically to extrusion and technology.
Increased needs for fuel efficiency in transportation coupled with ever increasing needs for safety and regulatory compliance have focused attention on the development and utilization of new materials and processes. In many instances, impediments to materials entry into these areas have been caused by the lack of effective and efficient manufacturing methods. For example, the ability to replace steel car parts with materials made from magnesium or aluminum or their associated alloys is of great interest. Additionally, the ability to form hollow parts with equal or greater strength than solid parts is an additional desired end. Previous attempts have failed or are subject to limitations based upon a variety of factors, including the lack of suitable manufacturing process, the expense of using rare earths in alloys to impart desired characteristics, and the high energy costs for production.
What is needed is a process and device that enables the production of items such as components in automobile or aerospace vehicles with hollow cross sections that are made from materials such as magnesium or aluminum with or without the inclusion of rare earth metals. What is also needed is a process and system for production of such items that is more energy efficient, capable of simpler implementation, and produces a material having desired grain sizes, structure and alignment so as to preserve strength and provide sufficient corrosion resistance. What is also needed is a simplified process that enables the formation of such structures directly from billets, powders or flakes of material without the need for additional processing steps. What is also needed is a new method for forming high entropy alloy materials that is simpler and more effective than current processes. The present disclosure provides a description of significant advances in meeting these needs.
Over the past several years researchers at the Pacific Northwest National Laboratory have developed a novel Shear Assisted Processing and Extrusion (ShAPE) technique which uses a rotating ram or die rather than a simply axially fed ram or die as is used in the conventional extrusion process. As described hereafter as well as in the in the previously cited, referenced, and incorporated patent applications, this process and its associated devices provide a number of significant advantages including reduced power consumption, better material properties and enables a whole new set of “solid phase” types of forming process and machinery. Deployment of the advantages of these processes and devices are envisioned in a variety of industries and applications including but not limited to transportation, projectiles, high temperature applications, structural applications, nuclear applications, and corrosion resistance applications.
Various additional advantages and novel features of the present invention are described herein and will become further readily apparent to those skilled in this art from the following detailed description. In the preceding and following descriptions we have shown and described only the preferred embodiment of the invention, by way of illustration of the best mode contemplated for carrying out the invention. As will be realized, the invention is capable of modification in various respects without departing from the invention. Accordingly, the drawings and description of the preferred embodiment set forth hereafter are to be regarded as illustrative in nature, and not as restrictive.
Specific problems have hampered the metallurgic industry, for example, joining magnesium to aluminum can be troublesome because of the formation of brittle, Mg17Al12, intermetallics (IMC) at the dissimilar interface. Conventional welding such as tungsten inert gas [1], electron beam [2], laser [3], resistance spot [4] and compound casting [5] are notorious for thick, brittle, Mg17Al12 interfacial layers since both the Mg and Al go through melting and solidification.
In an effort to reduce the deleterious effects of Mg17Al12, many techniques have been employed. For example, diffusion bonding, ultrasonic spot welding, electrical discharge riveting, and friction stir approaches. Friction stir welding (FSW), and its many derivatives, has received some attention, but researches have yet to adequately address the fundamental problem of forming brittle Mg17Al12 interfacial layers at the dissimilar interface.
Additionally, certain very useful materials such as Mg materials can have an increased use if cost was less of a barrier. For example, in the automotive industry, cost is the first major barrier for using Mg sheet materials. Unlike aluminum and steel, Mg alloys cannot be hot-rolled easily in the as-cast condition due to a propensity for cracking. As such, Mg alloys are typically rolled by twin roll casting process or use a multi-step hot rolling, making the sheet forming process expensive. Cold rolling is even more susceptible to cracking and is therefore limited to small reduction ratios (i.e. low throughput), which also makes the process slow and costly.
In the field of energy conversion and energy transport, there is a need to develop materials (alloys, composites, etc.) with improved electrical performance, specifically higher electrical conductivity and current density, as well as lowered temperature coefficient of resistance (TCR) compared to market alternatives. Currently, parts used for electrical applications such as in overhead conductors, transmission cables, motors, inverters, EV chargers, and generators are developed using copper and aluminum typically. These alloys (such as C10100, C11000, C15000, AA1100, AA1350, AA6201, AA8002) are designed to have minimal impurities, and second phases, but occasionally include additives called alloying additions that improve mechanical performance, wear resistance, and corrosion resistance of the metal substrates but do so sacrificing conductivity. This is because conventionally, introducing additives in a metal increases carrier (electrons, phonons) scattering leading to detrimental carrier transport properties. There is a critical gap in technology where additives are introduced in metals to make alloys or composites for the purpose of improving electrical performance.
Shear assisted extrusion processes (ShAPE) for forming Metal-NCCF extrusions are provided. The processes can include: using a die tool, applying a rotational shearing force and an axial extrusion force to a feedstock material comprising a metal and NCCF (NanoCrystalline Carbon Forms); and extruding a mixture comprising the metal and NCCF through an opening in the die tool to form the Metal-NCCF extrusion.
ShAPE feedstock materials are provided that can include a metal and NCCF.
Solid material mixtures are provided that can include: a metal and/or a combination of metals; and a NCCF that may include one or more of carbon forms such as carbon nanotubes, graphene, nano-graphite, buckyballs, crystalline carbon particles, carbon quantum dots, and nano-diamond. Portions of the metals and NCCF of the material mixtures can have a preferred crystallographic orientation or an isotropic crystallographic orientation.
Assemblies relying in part on conductivity can include: a conductive solid material mixture that includes: a metal; and a NCCF. The metal precursors or feedstock used to manufacture the metal-NCCF ShAPE extrudates can be in the form of chips, particles, powders, films, foils, nuggets, discs, or solid billets, for example. The NCCF can be in the form of foils, films, powders, particles, flakes, chips, nano-rods, micro-rods, ribbons, discs, for example.
The present description provides examples of shear-assisted extrusion processes for forming non-circular hollow-profile extrusions of a desired composition from feedstock material, for example. At a high-level this is accomplished by simultaneously applying a rotational shearing force and an axial extrusion force to the same location on the feedstock material using a scroll face or flat face tool with a plurality of grooves defined therein. These grooves are configured to direct plasticized material from a first location, typically on the interface between the material and the scroll face, through a portal defined within the scroll face to a second location, typically upon a die bearing surface. At this location the separated streams of plasticized material are recombined and reconfigured into a desired shape having the preselected characteristics. However, extrusion can also be performed using flat-faced tools in the absence of scrolls on the tool face.
In some applications the scroll face has multiple portals, each portal configured to direct plasticized material through the scroll face and to recombine at a desired location either unified or separate. In the particular application described the scroll face has two sets of grooves, one set to direct material from the outside in and another configured to direct material from the inside out. In some instances a third set of grooves circumvolves the scroll face to contain the material and prevent outward flashing.
This process provides a number of advantages including the ability to form materials with better strength, higher electrical conductivity, higher ampacity, higher current density, lower TCR, and improved corrosion resistance and minimal porosity characteristics at lower temperatures, lower forces, and with significantly lower extrusion force and electrical power than required by other processes.
For example in one instance the extrusion of the plasticized material is performed at a die face temperature less than 150° C. In other instances the axial extrusion force is at or below 50 MPa. In one particular instance a magnesium alloy in billet form was extruded into a desired form in an arrangement wherein the axial extrusion force is at or below 25 MPa, and the temperature is less than 100° C. While these examples are provided for illustrative reasons, it is to be distinctly understood that the present description also contemplates a variety of alternative configurations and alternative embodiments.
Another advantage of the presently disclosed embodiment is the ability to produce high quality extruded materials from a wide variety of starting materials including, billets, flakes powders, etc. without the need for additional pre or post processing to obtain the desired results. In addition to the process, the present disclosure also provides exemplary descriptions of a device for performing shear assisted extrusion. In one configuration this device has a scroll face configured to apply a rotational shearing force and an axial extrusion force to the same preselected location on material wherein a combination of the rotational shearing force and the axial extrusion force upon the same location cause a portion of the material to plasticize. The scroll face further has at least one groove and a portal defined within the scroll face. The groove is configured to direct the flow of plasticized material from a first location (typically on the face of the scroll) through the portal to a second location (typically on the back side of the scroll and in some place along a mandrel that has a die bearing surface) wherein the plasticized material recombines after passage through the scroll face to form an extruded material having preselected features at or near these second locations.
This process provides for a significant number of advantages and industrial applications. For example, this technology enables the extrusion of metal wires, bars, and tubes used for vehicle components with 50 to 100 percent greater ductility and energy absorption over conventional extrusion technologies, while dramatically reducing manufacturing costs; this while being performed on smaller and less expensive machinery than what is used in conventional extrusion equipment. Furthermore, this process yields extrusions from lightweight materials like magnesium and aluminum alloys with improved mechanical properties that are impossible to achieve using conventional extrusion, and can go directly from powder, flake, or billets in just one single step, which dramatically reduces the overall energy consumption and process time compared to conventional extrusion. Additionally, this process produces copper based wires and rods that are 4-5 percent more electrically conductive than annealed copper at 20 degrees Celsius and 10-15 percent lower TCR.
Applications of the present process and device could, for example, be used to form parts for the front end of an automobile wherein it is predicted that a 30 percent weight savings can be achieved by replacing aluminum components with lighter-weight magnesium, and a 75 percent weight savings can be achieved by replacing steel with magnesium. Typically processing into such embodiments have required the use of rare earth elements into the magnesium alloys to achieve properties suitable for structural energy absorption applications. However, these rare earth elements are expensive and rare and in many instances are found in areas of difficult circumstances, making magnesium extrusions too expensive for all but the most exotic vehicles. As a result, less than 1 percent of the weight of a typical passenger vehicle comes from magnesium. The processes and devices described hereafter, however, enable the use of non-rare earth magnesium alloys to achieve comparable results as those alloys that use the rare earth materials. This results in additional cost saving in addition to a tenfold reduction in power consumption—attributed to significantly less force required to produce the extrusions—and smaller machinery footprint requirements.
As a result the present technology could find ready adaptation in the making of lightweight magnesium components for automobiles such as front end bumper beams and crush cans. In addition to the automobile, deployments of the present invention can drive further innovation and development in a variety of industries such as aerospace, electric power industry, semiconductors and more. For example, this technique could be used to produce creep-resistant steels for heat exchangers in the electric power industry, and high-conductivity copper, and high-conductivity aluminum, and advanced magnets for electric motors. It has also been used to produce high-strength aluminum rods for the aerospace industry, with the rods extruded in one single step, directly from powder, with twice the ductility compared to conventional extrusion. In addition, the solid-state cooling industry is investigating the use of these methods to produce semiconducting thermoelectric materials. As an additional example, this technique produces metal-NCCF composites that are more conductive than annealed copper, and when used in place of standard copper wiring in motor manufacturing may improve motor efficiency by 1-3 percent.
The process of the present disclosure allows precise control over various features such as grain size and crystallographic orientation—characteristics that determine the mechanical and electrical properties of extrusions, like strength, ductility, energy absorbency, current density, TCR, ampacity, and electrical conductivity. The technology produces a grain size for magnesium and aluminum alloys at an ultra-fine regime (<1 micron), representing a 10 to 100 times reduction compared to the starting material. In magnesium, the crystallographic orientation can be aligned away from the extrusion direction, which is what gives the material such high energy absorption by eliminating anisotropy between tensile and compressive strengths. A shift of 45 degrees has been achieved, which is ideal for maximizing energy absorption in magnesium alloys. Control over grain refinement and crystallographic orientation is gained through adjustments to the geometry of the spiral groove, the spinning speed of the die, the amount of frictional heat generated at the material-die interface, and the amount of force used to push the material through the die.
In addition, this extrusion process allows industrial-scale production of materials with tailored structural and electrical characteristics. Unlike severe plastic deformation techniques that are only capable of bench-scale products, ShAPE is scalable to industrial production rates, lengths, and geometries. In addition to control of the grain size, an additional layer of microstructural control has been demonstrated where grain size and texture can be tailored through the wall thickness of tubing—important because mechanical properties can now be optimized for extrusions depending on whether the final application experiences tension, compression, or hydrostatic pressure. This could make automotive components more resistant to failure during collisions while using much less material. ShAPE can also enhance textural match between NCCF additive in metal substrates which possibly decreasing their interfacial gap to improve the material's overall electrical performance.
The process's combination of linear and rotational shearing results in 10 to 50 times lower extrusion force compared to conventional extrusion. This means that the size of hydraulic ram, supporting components, mechanical structure, and overall footprint can be scaled down dramatically compared to conventional extrusion equipment—enabling substantially smaller production machinery, lowering capital expenditures and operations costs. This process generates all the heat necessary for producing extrusions via friction at the interface between the system's billet and scroll-faced die and from plastic shear deformation within the extruding material, thus not requiring the pre-heating and external heating used by other methods. This results in dramatically reduced power consumption; for example, the 11 kW of electrical power used to produce a 2-inch diameter magnesium tube takes the same amount of power to operate a residential kitchen oven—a ten- to twenty-fold decrease in power consumption compared to conventional extrusion. Extrusion ratios up to 200:1 have been demonstrated for magnesium alloys using the described process compared to 50:1 for conventional extrusion, which means fewer to no repeat passes of the material through the machinery are needed to achieve the final extrusion diameter—leading to lower production costs compared to conventional extrusion.
Finally, studies have shown a 10 times decrease in corrosion rate for extruded non-rare earth ZK60 magnesium performed under this process compared to conventionally extruded ZK60. This is due to the highly refined grain size and ability to break down, evenly distribute—and even dissolve— second-phase particles that typically act as corrosion initiation sites. The instant process has also been used to clad magnesium extrusions with aluminum coating in order to reduce corrosion.
Shear-assisted extrusion processes for forming extrusions of a desired composition from feedstock materials are also provided. The processes can include applying a rotational shearing force and an axial extrusion from to the same location on the feedstock material using a scroll having a scroll face. The scroll face can have an inner diameter portion bounded by an outer diameter portion, and a member extending from the inner diameter portion beyond a surface of the outer diameter portion.
Devices for performing shear assisted extrusion are also provided. The devices can include a scroll having a scroll face having in inner diameter portion bounded by an outer diameter portion, and a member extending from the inner diameter portion beyond a surface of the outer diameter portion.
Extrusion processes for forming extrusion of a desired composition from feedstock materials is also provided. The processes can include: providing feedstock for extrusion, with the feedstock comprising at least two different materials. The process can include engaging the materials with one another within a feedstock container, with the engaging defining an interface between the two different materials. The process can continue by extruding the engaged feedstock materials to form an extruded product comprising a first portion comprising one of the two materials bound to a second portion comprising the other of the two materials. In accordance with example implementations, with extensive refinement, it has been shown that billet made from castings can be extruded, in a single step, into high performance extrusions.
Extrusion feedstock materials are also provided that can include interlocked billets of feedstock materials. These interlocked billets can be used for joining dissimilar materials and alloys, for example.
Methods for preparing metal sheets are also provided. The methods can include: preparing a metal tube via shear assisted processing and extrusion; opening the metal tube to form a sheet having a first thickness; and rolling the sheet to a second thickness that is less than the first thickness.
Various advantages and novel features of the present disclosure are described herein and will become further readily apparent to those skilled in this art from the following detailed description. In the preceding and following descriptions exemplary embodiments of the disclosure have been provided by way of illustration of the best mode contemplated for carrying out the disclosure. As will be realized, the disclosure is capable of modification in various respects without departing from the disclosure. Accordingly, the drawings and description of the preferred embodiment set forth hereafter are to be regarded as illustrative in nature, and not as restrictive.
An extrusion feedstock material is provided, the material comprising a length of one material extending from a first end to a second end; and at least one slot extending lengthwise within the one material between the first and second ends of the material.
A process for extruding conductive material is provided, the process comprising providing both rotational and axial forces between a die tool and a length of feedstock material to form a conductive extrusion product, wherein the length of feedstock and conductive extrusion product comprise of Aluminum and NanoCrystalline Carbon Forms (NCCF).
A process for extruding material is provided, the process comprising: providing both rotational and axial forces between a die tool and a length of feedstock material to form an extrusion product, wherein the length of feedstock material comprises a length of material extending from a first end to a second end; and at least one slot extending lengthwise within the material between the first and second ends of the material.
A conductive extrudate material is provided comprising of Aluminum and NanoCrystalline Carbon Forms (NCCF).
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Embodiments of the disclosure are described below with reference to the following accompanying drawings.
This disclosure is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).
The following description including the attached pages provide various examples of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto. Therefore, the present description should be seen as illustrative and not limiting. While the invention is susceptible to various modifications and alternative constructions, it should be understood, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.
In the previously described and related applications various methods and techniques are described wherein the described technique and device (referred to as ShAPE) is shown to provide a number of significant advantages including the ability to control microstructure such as crystallographic texture through the cross sectional thickness, while also providing the ability to perform various other tasks. In this description we provide information regarding the use of the ShAPE technique to form materials with non-circular hollow profiles as well as methods for creating high entropy alloys that are useful in a variety of applications such as projectiles. Exemplary applications will be discussed on more detail in the following.
Referring first now to
This arrangement is distinct from and provides a variety of advantages over the prior art methods for extrusion. First, during the extrusion process the force rises to a peak in the beginning and then falls off once the extrusion starts. This is called breakthrough. In this ShAPE process the temperature at the point of breakthrough is very low. For example for Mg tubing, the temperature at breakthrough for the 2″ OD, 75 mil wall thickness ZK60 tubes is <150 C. This lower temperature breakthrough is believed in part to account for the superior configuration and performance of the resulting extrusion products.
Another feature is the low extrusion coefficient kf which describes the resistance to extrusion (i.e. lower kf means lower extrusion force/pressure). Kf is calculated to be 2.55 MPa and 2.43 MPa for the extrusions made from ZK60-T5 bar and ZK60 cast respectively (2″ OD, 75 mil wall thickness). The ram force and kf are remarkably low compared to conventionally extruded magnesium where kf ranges from 68.9-137.9 MPa. As such, the ShAPE process achieved a 20-50 times reduction in kf (as thus ram force) compared to conventional extrusion. This assists not only with regard to the performance of the resulting materials but also reduced energy consumption required for fabrication. For example, the electrical power required to extrude the ZK60-T5 bar and ZK60 cast (2″ OD, 750 mil wall thickness) tubes is 11.5 kW during the process. This is much lower than a conventional approach that uses heated containers/billets. Similar reductions in kf have also been observed when extruding high performance aluminum powder directing into wire, rod, and tubing.
The ShAPE process is significantly different than Friction Stir Back Extrusion (FSBE). In FSBE, a spinning mandrel is rammed into a contained billet, much like a drilling operation. Scrolled grooves force material outward and material back extrudes around and onto the mandrel to form a tube, not having been forced through a die. As a result, only very small extrusion ratios are possible, the tube is not fully processed through the wall thickness, the extrudate is not able to push off of the mandrel, and the tube length is limited to the length of the mandrel. In contrast, ShAPE utilizes spiral grooves on a die face to feed material inward through a die and around a mandrel that is traveling in the same direction as the extrudate. As such, a much larger outer diameter and extrusion ratio are possible, the material is uniformly process through the wall thickness, the extrudate is free to push off the mandrel as in conventional extrusion, and the extrudate length is only limited only by the starting volume of the billet. ShAPE can be scalable to the manufacturing level, while the limitations of FSBE have kept the technology as a non-scalable academic interest since FBSE was first reported.
An example of an arrangement using a ShAPE device and a mandrel 18 is shown in
The ShAPE process has been utilized to form various structures from a variety of materials including the arrangement as described in the following table.
In addition, to the pucks, rods and tubes described above, the present disclosure also provides a description of the use of a specially configured scroll component referred by the inventors as a portal bridge die head which allows for the fabrication of ShAPE extrusions with non-circular hollow profiles. This configuration allows for making extrusion with non-circular, and multi-zoned, hollow profiles using a specially formed portal bridge die and related tooling.
In the present embodiment grooves 13, 15 on the face 12 of the die 10 direct plasticized material toward the aperture ports 17. Plasticized material then passes through the aperture ports 17 wherein it is directed to a die bearing surface 24 within a weld chamber similar to conventional portal bridge die extrusion. In this illustrative example, material flow is separated into four distinct streams using four ports 17 as the billet and the die are forced against one another while rotating.
While the outer grooves 15 on the die face feed material inward toward the ports 17, inner grooves 13 on the die face feed material radially outward toward the ports 17. In this illustrative example, one groove 13 is feeding material radially outward toward each port 17 for a total of four outward flowing grooves. The outer grooves 15 on the die surface 12 feed material radially inward toward the port 17. In this illustrative example, two grooves are feeding material radially inward toward each port 17 for a total of eight inward feeding grooves 15. In addition to these two sets of grooves, a perimeter groove 19 on the outer perimeter of the die, shown in
In the previously described and related applications various methods and techniques are described wherein the ShAPE technique and device is shown to provide a number of significant advantages including the ability to control microstructure such as crystallographic texture through the cross sectional thickness, while also providing the ability to perform various other tasks. In this description we provide information regarding the use of the ShAPE technique to form materials with non-circular hollow profiles as well as methods for creating high entropy alloys that are useful in a variety of applications. These two exemplary applications will be discussed on more detail in the following.
In use, both an axial force and a rotational force are applied to a material of interest causing the material to plasticize. In extrusion applications, the plasticized material then flows over a die bearing surface dimensioned so as to allow recombination of the plasticized materials in an arrangement with superior grain size distribution and alignment than what is possible in traditional extrusion processing. As described in the prior related applications this process provides a number of advantages and features that conventional prior art extrusion processing is simply unable to achieve.
High entropy alloys are generally solid-solution alloys made of five or more principal elements in equal or near equal molar (or atomic) ratios. While this arrangement can provide various advantages, it also provides various challenges particularly in forming. While conventional alloys can comprise one principal element that largely governs the basic metallurgy of that alloy system (e.g. nickel-base alloys, titanium-base alloys, aluminum-base alloys, etc.) in an HEA each of the five (or more) constituents of HEAs can be considered as the principal element. Advances in production of such materials may open the doors to their eventual deployment in various applications. However, standard forming processes have demonstrated significant limitations in this regard. Utilization of the ShAPE type of process demonstrates promise in obtaining such a result.
In one example a “low-density” AlCuFe(Mg)Ti HEA was formed. Beginning with arc-melted alloy buttons as a pre-cursor, the ShAPE process was used to simultaneously heat, homogenize, and consolidate the HEA resulting in a material that overcame a variety of problems associated with prior art applications and provided a variety of advantages. In this specific example, HEA buttons were arc-melted in a furnace under 10−6 Torr vacuum using commercially pure aluminum, magnesium, titanium, copper and iron. Owing to the high vapor pressure of magnesium, a majority of magnesium vaporized and formed Al1Mg0.1Cu2.5Fe1Ti1.5 instead of the intended Al1Mg1Cu1Fe1Ti1 alloy. The arc melted buttons described in the paragraph above were easily crushed with a hammer and used to fill the die cavity/powder chamber (
Comparison of the arc-fused material and the materials developed under the ShAPE process demonstrated various distinctions. The arc melted buttons of the LWHEA exhibited a cored dendritic microstructure along with regions containing intermetallic particles and porosity. Using the ShAPE process these microstructural defects were eliminated to form a single phase, refined grain and no porosity LWHEA sample.
Typically such microstructures are homogenized by sustained heating for several hours to maintain a temperature near the melting point of the alloy. In the absence of thermodynamic data and diffusion kinetics for such new alloy systems the exact points of various phase formations or precipitation is difficult to predict particularly as related to various temperatures and cooling rates. Furthermore, unpredictability with regard to the persistence of intermetallic phases even after the heat treatment and the retention of their morphology causes further complications. A typical lamellar and long intermetallic phase is troublesome to deal with in conventional processing such as extrusion and rolling and is also detrimental to the mechanical properties (elongation).
The use of the ShAPE process enabled refinement of the microstructure without performing homogenization heat treatment and provides solutions to the aforementioned complications. The arc melted buttons, because of the presence of their respective porosity and the intermetallic phases, were easily fractured into small pieces to fill in the die cavity of the ShAPE apparatus. Two separate runs were performed as described in Table 1 with both the processes' yielding a puck with diameter of 25.4 mm and approximately 6 mm in height. The pucks were later sectioned at the center to evaluate the microstructure development as a function of its depth. Typically in the ShAPE consolidation process; the shearing action is responsible for deforming the structure at interface and increasing the interface temperature; which is proportional to the rpm and the torque; while at the same time the linear motion and the heat generated by the shearing causes consolidation. Depending on the time of operation and force applied near through thickness consolidation can also be attained.
The use of the ShAPE device and technique demonstrated a novel single step method to process without preheating of the billets. The time required to homogenize the material was significantly reduced using this novel process. Based on the earlier work, the shearing action and the presence of the scrolls helped in comminution of the secondary phases and resulted in a helical pattern. All this provides significant opportunities towards cost reduction of the end product without compromising the properties and at the same time tailoring the microstructure to the desired properties. Similar accelerated homogenization has also been observed in magnesium and aluminum alloys during ShAPE of as-cast materials.
In as much as types of alloys exhibit high strength at room temperature and at elevated temperature, good machinability, high wear and corrosion resistance, such materials could be seen as a replacement in a variety of applications. A refractory HE-alloy could replace expensive super-alloys used in applications such as gas turbines and the expensive Inconel alloys used in coal gasification heat exchanger. A light-weight HE-alloy could replace aluminum and magnesium alloys for vehicle and airplanes. Use of the ShAPE process to perform extrusions would enable these types of deployments.
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In accordance with example implementations, Shear assisted processing and extrusion (ShAPE™) can be used to join magnesium and aluminum alloys in a butt joint configuration. Joining can occur in the solid-phase and in the presence of shear, brittle Mg17Al12 intermetallic layers can be eliminated from the Mg—Al interface. The joint composition can transition gradually from Mg to Al, absent of Mg17Al12, which can improve mechanical properties compared to joints where Mg17Al12 interfacial layers are present.
As alluded to joining Mg—Al is difficult to perform without forming a brittle Mg17Al12 interfacial layer at the dissimilar interface. Example applications for material having been joined using the processes of the present disclosure include, but are not limited to:
In accordance with example implementations, materials can be engaged using the ShAPE technology of the present disclosure. For example, Mg alloy ZK60 can be joined to Al alloy 6061, without forming an Mg17Al12 interfacial layer. To accomplish this, the ShAPE™ process can be modified to mix ZK60 and AA6061 into a fully consolidated rod having an Al rich coating as a corrosion barrier. Referring next to
Referring to
The geometry of the interlocking region can be tailored to control the composition and transition length of the Mg—Al joint region. The geometric possibilities are many but two examples are shown in
In accordance with at least one implementation, with triangular spoked interlocks 165, the composition of Mg in Al goes from 0% to 100% at a rate depending on the number of spokes and angle of the triangle's vertex. This method has been used to demonstrate a transition length of 37 mm to illustrate the concept. Because the joint is formed by mixing in the solid phase, an Mg17Al12 interfacial layer will not form. Rather, a gradient in chemical composition and also possibly grain size will form across the dissimilar interface with the intense shear refining and dispersing any Mg17Al12 second phase formations. The composition gradient at the Mg—Al interface has a secondary benefit of also being a galvanically graded interface which can improve corrosion resistance. Referring to
Accordingly, an extrusion process for forming extrusion of a desired composition from a feedstock is provided. The process can include providing feedstock for extrusion, and the feedstock comprising at least two different materials. The process can further include engaging the materials with one another within a feedstock container, with the engaging defining an interface between the two different materials as described herein. The process can include extruding the feedstock to form an extruded product. This extruded product can include a first portion that includes one of the two materials bound to a second portion that can include one of the other two materials.
Accordingly, the interface between the two materials can interlock the one material with the other material and the geometry of the interlock can define a ratio of the two materials where they are bound. This ratio can be manipulated through manipulating the geometry of the engagement. For example, there could be a small amount of one of the materials entering into a perimeter defined by the other of the two materials, and vice versa. In accordance with example implementations and specific examples, one of the materials can be Mg and the other can be Al. The process can also include where the one material is Mg ZK60 and the other material is Al 6061. Accordingly, there could be one material that has one grade and another that has another grade. For example, the material can be AA7075 and the other material can be AA6061. In accordance with example implementations, these billets can be part of the feedstock and the billets can be interlocked.
The extrusion feedstock materials may have a geometry that defines a ratio of the two materials when they are extruded as bound extrusions. The feedstock materials can be aligned along a longitudinal axis, and according to example implementations this can be the extrusion axis. The interlock of the billets can reside along a plane extending normally from the axis, and accordingly, the plane can intersect with both materials.
In order to improve the formability of magnesium sheet materials, the inventors believe that the grain sizes should be less than 5 microns and/or a weakened texture is desirable. It has been demonstrated that the novel Shear Assisted Processing and Extrusion (ShAPE) technology can not only attain the aforementioned microstructure but also help with the alignment of the basal planes (i.e. texture). This technology can also reduce the size and uniformly distribute the second phase particles, which are believed to impede the formability of sheets. In accordance with example implementations, extruded tubes of Mg can be slit open and rolled into the sheet. Extruded tubes of magnesium (ZK60 alloy) using the ShAPE process can be provided which can be 50 mm in diameter and 2 mm in wall thickness, or another diameter and wall thickness. These tubes can be slit open in a press and then rolled parallel to the extrusion axis, for example.
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Regarding
Through a combination of these elements, scattering of electrons can be minimized. During operation, the carriers can move through the conductive material at subscribed velocities corresponding to the temperature of operation. When the carriers encounter graphene, owing to the favorable interfacial properties, the carriers can traverse the energy barrier and enter the additives easily where they move with higher velocities. This ability of the carriers to move through higher conductivity additives with minimal scattering can provide improved electrical properties at higher temperatures.
The high conductivity materials of the present disclosure, particularly copper, can have broad application in industry including all electric machines as well as the electronics, power conversion, energy transport and other electric applications. For example, when square bar wires for stator windings are made by this process, the way automotive traction drives are constructed, sized or powered can change dramatically. High conductivity wire for stator windings could impact permanent magnet motors, where there are strong incentives to improve motor performance in light of the slow progress towards the 400 mile range battery pack. The materials of the present disclosure can have application in small high power induction motors for starters, motors to power ancillary loads (pumps, hvac. etc), or actuators in transmission or driveline. Another industrial application can include the fabrication of shorting bars for the rotors of induction motors. In this application the metal-NCCF ShAPE extrusion can have a noncircular cross-section, and the bars are joined to end caps to form the inner “squirrel cage” of a typical induction rotor assembly. The metal-NCCF ShAPE extrusion shorting bars can lead to increased motor efficiency.
In accordance with example implementations, bulk size conductive solid material mixtures of the present disclosure can have electrical conductivity superior to pure copper. Example implementations provide C10100 pure copper billet and CVD monolayer graphene on copper foil prepared and assembled as a feedstock material for ShAPE. Using ShAPE, copper metal and/or alloys and graphene can be deformed, mixed, and extruded as a Copper-Graphene composite wire with 1 m length and 2.5 mm diameter. The electrical conductivity measured by 4-probe method indicates this wire has 104.8% IACS when 6 ppm graphene is added. Optical and Electron Microscopy show the wire has good integrity with an isotropic crystallographic orientation. The graphene can be barely detectable under Transmission Electron Microscopy due to the low content and monolayer morphology. However, atom probe tomography reveals that the monolayer graphene is distributed along the grain boundaries of the copper substrate predominantly.
Referring to
Accordingly, shear-assisted extrusion processes for forming Metal-NCCF extrusions are provided. The metal of the feedstock, the extrudate, and/or the solid conductive material mixture can include a material that demonstrates enough plasticity to be extruded by ShAPE. Example extrudable metals and/or alloys, and/or mixtures can include Cu, Al, Mg, Fe, Ti and NI and/or alloys, and/or mixtures that include these metals. The NCCF of the feedstock, the extrudate, and/or the solid conductive material mixture can include one or more of graphene, carbon nanotubes, nanographite, buckyballs, nano-diamond, carbon quantum dots or any other form of crystalline carbon materials. The NCCF can be at least 1 ppb by weight of the feedstock, the extrudate, and/or the solid conductive material mixture.
In accordance with example implementations, the feedstock, the extrudate, and/or the solid conductive material mixture can include the metal Cu and the NCCF graphene.
In accordance with an example implementation, copper/graphene billet 306 of a C10100 puck and assembled graphene coated Cu foils 310 can be used to manufacture the Cu/Graphene (G) composites. C10100 (or 101) cooper, which is the Oxygen free high conductivity Copper (OFHC), has a high purity 99.99% and about 101% IACS. Cylindrical copper puck 306 can have a pocket in the center and filled with pure copper foils with CVD deposited monolayer graphene 310. Referring to
In accordance with example implementations, a ShAPE feedstock material is provided that can include a metal and NCCF. The feedstock material can define a billet, and the billet can further include portions of NCCF. The portions of NCCF can be deposited on portions of metal, the NCCF can be dispersed within the metal, the NCCF can be provided in openings within the metal, and/or the feedstock materials can be provided as particles of metal and/or NCCF.
In accordance with example implementations of the present disclosure, the copper and graphene in the form of chips, particles, discs, nuggets, films, powders or foils can be mixed and extruded with the copper billet via, ShAPE, described herein. Accordingly, utilizing ShAPE processes, an extrudate can be formed that includes the metal and NCCF. For example, a 2.5 mm diameter wire can be formed. Referring to
Referring next to
The extrudate materials, for example, the Cu-graphene wires can be cut transversely and longitudinally for metallography inspection. The puck can also be cut vertically to show the material flow and the state of consolidation of the remnants. These samples can be ground and vibrationally polished using 0.05 μm colloidal silica media. Optical micrographs can be obtained using an Olympus BX51 M optical microscope. To identify grain structure and elementary distribution, the transverse cross-sections can be further examined used a JEOL7600F field emission SEM equipped with an Oxford Instruments 170 mm2 X-Max energy dispersive spectrometer (EDS) and Symmetry electron backscatter diffraction (EBSD) CMOS detector by EDS (Energy Dispersive Spectroscopy) and EBSD (Electron backscatter diffraction).
To detect the NCCF, in this case, graphene, Atom Probe Tomography (APT) can be utilized: APT sample preparation can be performed using a FEI Helios dual beam focused ion beam-scanning electron microscope (FIB-SEM) by first depositing a protective Pt capping to protect the material from Ga ion damage during FIB milling. A cantilever can be extracted from the base alloy, pieces of which can be mounted onto a commercial Si micropost array, and individually shaped into needle-shaped APT specimens. A CAMECA local electrode atom probe (LEAP) 4000×HR system equipped with a 355 nm wavelength ultraviolet (UV) laser can be used to acquire APT data with the following user-selected parameters: 100 pJ/pulse laser energy, 100 kHz pulse repetition rate, 35 K specimen base temperature, and 0.005 detected ions/pulse detection rate. The analysis chamber can be kept at a less than 2×10−11 Torr. The detector efficiency of the APT used in this work can be approximately 36%. Data acquired can be reconstructed and analyzed using the Interactive Visualization and Analysis Software (IVAS), version 3.8.4 by CAMECA.
Referring next to
Smaller grains can be seen towards the wire surface while the center of the wire was made of comparatively larger grains.
Referring next to
Referring next to
Electrical conductivity of the solid material mixtures of the present disclosure, for example, the Cu/G composite wires can be measured in accordance with ASTM B193. A length of 300 mm of the sample wire can be suspended with clamp under slight tension across a custom-designed aluminum base. DC current (l) can be provided to the sample using a Keithley 2260B-30-72 DC power supply with an accuracy of 0.1%±70 mA via gold plated leads in a series configuration. A Keithley 2182A nano-voltmeter with an accuracy of ±60 ppm of reading+4 ppm of range can be attached to the sample in parallel configuration to measure a voltage drop (V) across a length (l) along the sample. The diameter of sample wires can be measured using a Keyence LS-7601 optical micrometer with a measurement uncertainty of ±3 μm. Sample lengths can be measured with a Mitutoyo 500-193 digital caliper with a device uncertainty of ±0.01 mm, with a measurement uncertainty taken as ±0.5 mm. The voltage drop across the voltmeter leads can then be used in conjunction with the set current value to determine the electrical conductivity of the sample according to Ohm's law.
The procedures described in ASTM B84 can be used to determine the temperature coefficient of resistance of the friction-extruded samples. The wires can be coated with a black graphite paint with an emissivity of −0.99. DC current ranging from 10-60 A in intervals of 10 A was provided to the sample to increase its temperature due to Joule heating. An FLIR A325sc infra-red thermal camera with a measurement uncertainty of ±2° C. was utilized to determine the highest steady-state temperature (Ts) of the wires corresponding to a current level. Steady-state temperatures were assigned when the change in temperature with respect to time was less than 0.1° C./s (dT/dt<0.1° C./s). Voltage drop across a sample length of 140-150 mm was measured at each current level after steady-state temperature was achieved. Electrical resistance (R), calculated using sample current (l) and voltage drop (V), was plotted against the corresponding Ts. The slope of resistance as a function of steady state temperature was calculated as dR/d Ts for each test sample. Accordingly, TCR was determined per ASTM B84 at 20° C.
Finally, with respect to
More specifically,
Accordingly, the present disclosure provides a conductive solid material mixture that can include a metal and NCCF. Portions of the material mixture can have a preferred crystallographic orientation or an isotropic crystallographic orientation in relation to the nanocrystalline carbon film. The metal can include one or more of Cu, Al, Mg, Fe, Ti, and/or Ni. The NCCF can include one or more of graphene, carbon nanotubes, nanographite, graphite, buckyballs, carbon quantum dots, nano-diamond or any other such crystalline carbon materials.
Additionally, assemblies relying in part on conductivity are also provided. The assemblies can include the conductive solid material mixtures of the present disclosure. Example assemblies can be overhead conductors, busbars, undersea cables, umbilicals, motors, motor parts, inverters, transformers, electrical signal contacts, electronic interconnects, and generators.
In accordance with
The length of the one material of the feedstock can be conductive material, and this conductive material can be aluminum and/or copper, for example. These conductive materials can also be alloys. The materials can also more specifically comprise or include Al or an aluminum alloy. The aluminum alloy can include additional elements such as Cr, B, Li, Sn, Pb, Ga, Mo, and/or Se. The feedstock materials that include the one slot can receive another material within the slot, and this other material can be chemically different from the one material. As an example, the one material can be the conductive material, and the other material that is within the slot can be an NCCF as described herein, including but not limited to a graphene in the form of graphene foil, for example.
In accordance with example implementations where an NCCF is provided to the feedstock material, the one material can include aluminum and/or copper and/or be a conductive alloy. In accordance with example implementations as described herein, the feedstock material can include at least another slot aligned opposing the at least one slot. As well and/or in addition thereto, the feedstock material can include a plurality of slots. In some embodiments, at least a pair of the slots can be aligned opposing one another as shown, for example, in the following figures. These slots can also be uniformly distributed about the length of the material. In accordance with example implementations, the slots can be filled with the same or different materials from the main body of the length of material. Additionally, the slots may extend the entire length of the material or just a portion of the entire length of material.
In accordance with example implementations, processes are also included for extruding conductive material. The processes can include providing both rotational and axial forces between a die tool and a length of feedstock material to form a conductive extrusion product. The length of feedstock material and conductive extrusion product can comprise aluminum and an NCCF as described herein. The feedstock material can be as described above, as well as other feedstock materials.
In accordance with yet another example implementation, conductive extrudate material comprising Al and NCCF is provided. The NCCF can be graphene, and the Al can be an alloy. The NCCF can be at least 0.001 wt. % of the billet material. The conductive extrudate material can have an electrical conductivity of at least 65% IACS).
As can be seen in the following description utilizing shear assisted processing and extrusion technology, an aluminum conductive material having improved properties compared to commercial grade conductive aluminum alloys is provided. In accordance with example implementations, the billet and/or feedstock material configuration as well as shear assisted processing and extrusion process parameters provide an aluminum graphene composite that can include homogenized microstructures demonstrating enhanced electrical conductivity and lower temperature coefficients of resistance over AA1100 materials at relevant operating conditions.
The extruded conductive materials can have reduced graphene oxide nanoparticles (GNP). It has been realized that the processing starting materials and/or parameters can transform the nanoscale particles into desirable forms by effectively dispersing them in the metal substrate while promoting the formation of conductive pathways at the metal/GNP interface. Accordingly, the data shows that an addition of 0.25 wt. % GNP increased the conductivity by 2.6% while 0.1 wt. % GNP decreased the temperature coefficient of resistance by 4.7%. Accordingly, processing aluminum/GNP billets at higher temperatures resulted in enhancing electrical conductivity and decreasing TCR while processing at lower temperatures decreases conductivity.
In accordance with example implementations, as a length of material an AA1100 material was provided that has the characteristics of the Table 4 below.
In accordance with example implementations, NCCF such as graphene was introduced into the AA1100 materials in three different manners as shown in
The extrusion products were then analyzed for microstructure characterization, electrical properties such as electrical conductivity, and TCR. Example procedures include ASTM B193, for example.
Referring to
Referring to
Referring next to
Referring next to
Referring next to
With reference to Table 7 below, characteristics of extruded materials are shown with reference to
In accordance with example implementations, H14 temper 8-slot billets data is shown in Table 8 and 0 temper 8-slot billet data is shown in Table 9. The ShAPE extrusion parameters for this data is shown graphically with reference to
Importantly, with reference to
Al/GNP composite conductive materials as wires (1.5-2.5 mm diameter, 0.5-1 m long) via the shear assisted processing and extrusion technology were produced that provided composite formulations and manufacturing parameters resulting in enhanced electrical conductivity and/or lowered TCR in Al/GNP composites compared to AA1100-only samples (which were also processed under similar conditions).
Billet configurations played a major role in the development of composite microstructures and corresponding material properties. Processing the Al/GNP billets with 0.25 wt. % GNP at higher temperatures resulted in enhancing electrical conductivity and decreasing TCR. Processing temperature greater than 450 C provided improved conductivity.
In compliance with the statute, embodiments of the invention have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the entire invention is not limited to the specific features and/or embodiments shown and/or described, since the disclosed embodiments comprise forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.
This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 63/320,874 filed Mar. 17, 2022, the contents of which are hereby incorporated by reference. This application is a continuation-in-part of U.S. patent application Ser. No. 17/035,597 which was filed Sep. 28, 2020, which claims priority to and the benefit of U.S. Provisional Application Ser. No. 62/906,911 filed Sep. 27, 2019, the contents of each of which are hereby incorporated by reference. U.S. patent application Ser. No. 17/035,597 is a Continuation-In-Part of and claims priority to U.S. patent application Ser. No. 16/562,314 filed Sep. 5, 2019, now U.S. Pat. No. 11,383,280 issued Jul. 12, 2022, which is a Continuation-In-Part of and claims priority to U.S. patent application Ser. No. 16/028,173 filed Jul. 5, 2018, now U.S. Pat. No. 11,045,851 issued Jun. 29, 2021, which is a Continuation-in-Part of and claims priority to U.S. patent application Ser. No. 15/898,515 filed Feb. 17, 2018, now U.S. Pat. No. 10,695,811 issued Jun. 30, 2020, which is a Continuation-in-Part and claims priority and the benefit of both U.S. Provisional Application Ser. No. 62/460,227 filed Feb. 17, 2017 and U.S. patent application Ser. No. 15/351,201 filed Nov. 14, 2016, now U.S. Pat. No. 10,189,063 issued Jan. 29, 2019, which is a Continuation-in-Part and claims priority and the benefit of both U.S. Provisional Application Ser. No. 62/313,500 filed Mar. 25, 2016 and U.S. patent application Ser. No. 14/222,468 filed Mar. 21, 2014, which claims priority to and the benefit of U.S. Provisional Application Ser. No. 61/804,560 filed Mar. 22, 2013; the contents of all of the foregoing are hereby incorporated by reference.
This invention was made with Government support under Contract DE-AC05-76RL01830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.
| Number | Date | Country | |
|---|---|---|---|
| 63320874 | Mar 2022 | US | |
| 62906911 | Sep 2019 | US | |
| 62460227 | Feb 2017 | US | |
| 62313500 | Mar 2016 | US | |
| 61804560 | Mar 2013 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17035597 | Sep 2020 | US |
| Child | 18121563 | US | |
| Parent | 16562314 | Sep 2019 | US |
| Child | 17035597 | US | |
| Parent | 16028173 | Jul 2018 | US |
| Child | 16562314 | US | |
| Parent | 15898515 | Feb 2018 | US |
| Child | 16028173 | US | |
| Parent | 15351201 | Nov 2016 | US |
| Child | 15898515 | US | |
| Parent | 14222468 | Mar 2014 | US |
| Child | 15351201 | US |
