The embodiments herein generally relate to electrodeposition technologies, and more particularly to electrochemical and magnetic systems used for performing electrodeposition.
Compared to other processing techniques, electrodeposition is a fast, economical, and versatile approach to manufacturing composite coatings. The incorporation of particles into the growing metal matrix is common practice for improving deposit properties like wear and corrosion resistance. Several challenges, however, have set severe limits on the full realization of controlled composite coatings. Particle agglomeration and sedimentation, for instance, prevents having an even dispersion in the electrolyte and subsequently produces non-uniform coatings. To mitigate this, quality coatings have often been aided by additives like surfactants, alternative electrolytes like deep eutectic solvents, particular current waveforms like reverse pulse plating, and additional processing techniques like bath agitation. These plating strategies, however, often have drawbacks that influence the coating and/or the coating process in a negative way.
Magnetic fields are a less-invasive approach and have also been shown to supplement particle incorporation and distribution by inducing additional convective stirring (“magnetohydrodynamic” flow), which—given sufficiently high applied currents and/or magnetic strengths—can induce magnetic stirring of the electrolyte. This additional stirring can improve particle incorporation but has only been demonstrated thus far in rather small (<1 cm) electrochemical cells set in the bore of an electromagnet that typically produces high magnetic flux densities (>10 T).
While electromagnets offer users the versatility to turn on and off the field with the flick of a switch, as well as to easily adjust the magnetic strength during operation, they are typically set up in complicated systems requiring a constant (power) supply of electric current and circulating water for cooling and removal of waste heat, thus incurring significant energy consumption. These concerns become significant for scale-up considerations as economic feasibility decreases with increasing system size. Additionally, spatial dimensions dictate that the size of the electrochemical cell is limited entirely by the size of the bore, which would make coating of larger parts and/or unconventional geometries virtually impossible.
Investigations into electrodeposited metal matrix composites are becoming more prevalent as emerging technologies, particularly in aerospace and automotive environments, require more advanced materials. Particle-incorporated coatings offer promising improvements in tribology and wear resistance, as well as lubrication and corrosion protection. Many strategies are used in electrodeposition to introduce particles to coatings but are often disadvantaged with drawbacks to the coating and/or coating process itself. As described above, and as an alternative, magnetic fields have been shown to be a promising noninvasive approach; however, electrochemical cells in studies thus far have been set in the bore of a small electromagnet, typically placing restrictions on system size. As mentioned, generally such a set-up has spatial limitations, is complicated, requires high energy consumption for operation, and thus may not be advantageously primed for industrial scale-up.
In view of the foregoing, an embodiment herein provides an electrochemical system comprising an electrochemical cell comprising an electrolyte solution containing particles; an electrode system positioned in the electrochemical cell, wherein the electrode system comprises a counter electrode, a reference electrode, and a working electrode; and an open-bore magnet arrangement comprising a permanent magnet contacting the electrochemical cell. The permanent magnet may be positioned inside of the electrochemical cell. Moreover, the permanent magnet may be positioned outside of the electrochemical cell. The particles may be magnetic. Furthermore, the particles may be non-magnetic. Additionally, the particles may comprise Eu-doped yttria. The permanent magnet may produce a magnetic field of less than 1 Tesla. More particularly, the permanent magnet may produce a magnetic field of approximately 0.25 Tesla. The permanent magnet may comprise a rare-earth magnet.
Another embodiment provides an apparatus comprising an electrochemical cell comprising an electrolyte solution containing particles and metal ions; an electrode system disposed in the electrolyte solution, wherein the electrode system comprises a counter electrode, a reference electrode, and a working electrode, and wherein the counter electrode and the working electrode are arranged to allow electric current to flow therebetween; and an open-bore magnet arrangement comprising at least one permanent magnet connected to the electrochemical cell and arranged to produce a magnetic field in the electrolyte solution to interact with the electric current to produce an electrodeposition of the particles with metal derived from the metal ions onto the working electrode.
The at least one permanent magnet may be positioned behind the working electrode, and wherein the at least one permanent magnet is positioned parallel to the electric current. The at least one permanent magnet may be positioned perpendicular to the electric current. The at least one permanent magnet may comprise a pair of permanent magnets. The pair of permanent magnets may be positioned parallel to the electric current. The pair of permanent magnets may be positioned perpendicular to the electric current. The pair of permanent magnets may be each positioned at 45° angles with respect to the working electrode.
Another embodiment provides a method of performing electrodeposition of a metal coating containing particles, the method comprising providing an electrochemical cell comprising an electrolyte solution containing particles and metal ions; arranging an electrode system in the electrochemical cell, wherein the electrode system comprises a counter electrode, a reference electrode, and a working electrode; connecting the electrochemical cell to an open-bore magnet arrangement comprising at least one permanent magnet; establishing a magnetic field, by the at least one permanent magnet, in the electrolyte solution; passing an electric current between the counter electrode and the working electrode; and producing movement of the particles in the electrolyte solution, through interaction of the magnetic field and the electric current, to produce an electrodeposition of the particles with metal derived from the metal ions onto the working electrode. The electric current may comprise a current density of approximately 50 mA/cm2. The method may comprise stirring the electrolyte solution during the electrodeposition using a non-magnetic stirrer. The method may comprise arranging the at least one permanent magnet at a selected angle with respect to a flow of the electric current to maximize a Lorentz force applied to the particles.
These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating exemplary embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which:
The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The embodiments herein provide an electrodeposition technique that uses permanent magnets in an open-bore arrangement instead of using conventional electromagnets. This increases experimental versatility (e.g., the permanent magnet can be placed in or outside the electrolyte, and is more primed for large-scale processing). Furthermore, the embodiments herein achieve lower operating costs (i.e., does not require continuous supply of electrical energy or water cooling to the source of the magnetic field). Moreover, the techniques provided by the embodiments herein require less maintenance (e.g., no damage from short circuits as there is with electromagnets), require only minimal field strengths (−0.25 T), and are able to incorporate non-magnetic (vs. magnetic) particles. Referring now to the drawings, and more particularly to
The electrochemical system 10 further comprises an electrode system 30 positioned in the electrochemical cell 15. In an example, the electrode system 30 may be a two-electrode system or a three-electrode system. However, the embodiments herein are not restricted to any particular type of electrode system. According to an example, the electrode system 30 comprises a counter electrode 35, a reference electrode 40, and a working electrode 45, which are arranged in the electrochemical cell 15 and are partially or completely disposed in the electrolyte solution 20. In an example, the electrode system 30 may be arranged to position the counter electrode 35 to be diametrically opposed to the working electrode 45, and with the reference electrode 40 positioned between the counter electrode 35 and the working electrode 45 without interfering with the electrical path between the counter electrode 35 and the working electrode 45. In an example, the reference electrode 40 may be positioned inside a separate chamber or tube 41 that is inserted in the electrochemical cell 15. A voltage source (not shown) may be connected to the electrode system 30 to supply voltage between the reference electrode 40 and the working electrode 45. While not shown in the drawings, the electrode system 30 may be electrically connected using wire. Additionally, while not shown in the drawings, a temperature probe may be inserted in the electrochemical cell 15 to measure the temperature of the electrolyte solution 20 during an electrodeposition process.
The counter electrode 35 may be composed of a conductive material including metals such as gold, silver, copper, nickel, platinum, or graphite, among other suitable materials. In an example, the counter electrode 35 may serve as the anode in the electrode system 30, and the counter electrode 35 may pass current i through the electrolyte solution 20 to the working electrode 45. In this example, the working electrode 45 may serve as the cathode in the electrode system 30 where the metal from the particles 25 are deposited. The working electrode 45 may be composed of a conductive material including metals such as gold, silver, copper, nickel, platinum, or graphite, among other suitable materials. The reference electrode 40 may be used to measure the electrode potential of the working electrode 45 by measuring the electrode potential in the electrolyte solution 20, typically at the location where the reference electrode 40 is positioned in the electrolyte solution 20. The amount of the electrode potential of the working electrode 45 may be controlled by adjusting the amount of voltage applied to the working electrode 45. Some examples of the reference electrode 40 may include a saturated calomel (Hg2Cl2) electrode, silver/silver chloride (Ag/AgCl) electrode, mercury/mercurous sulfate (Hg/Hg2SO4) electrode, and a mercury/mercury oxide (Hg/HgO) electrode, among others.
The electrochemical system 10 further comprises an open-bore magnet arrangement 50 comprising a permanent magnet 55 contacting the electrochemical cell 15. In an example, the permanent magnet 55 may comprise a rare-earth magnet. In some examples, the permanent magnet 55 may comprise neodymium (Nd2Fe14B) or samarium-cobalt (SmCo5) rare-earth magnets, among other types. Although the permanent magnet 55 may have a higher unit cost than conventional electromagnets, the dimensions of the electrochemical cell 15 are not limited by the size of the permanent magnet 55, thus the permanent magnet 55 does not have to scaled up as much as a conventional electromagnet does to enable processing on a larger scale; i.e., it may be possible to use multiple small, lower-cost permanent magnets 55 to affect particle incorporation in larger parts during the electrodeposition process. As such, the use of the permanent magnet 55 eliminates the complicated system requirements and power consumption necessary for conventional electromagnets and therefore the permanent magnet 55 offers greater flexibility when it comes to accommodating transitions from lab-scale to full-scale operations for performing the electrodeposition process.
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The apparatus 100 further comprises an electrode system 130 disposed in the electrolyte solution 120, wherein the electrode system 130 comprises a counter electrode 135, a reference electrode 140, and a working electrode 145. In an example, the electrode system 130 may be a two-electrode system or a three-electrode system. However, the embodiments herein are not restricted to any particular type of electrode system. According to an example, the electrode system 130 comprises a counter electrode 135, a reference electrode 140, and a working electrode 145, which are arranged in the electrochemical cell 115 and are partially or completely disposed in the electrolyte solution 120. The counter electrode 135 and the working electrode 145 are arranged to allow electric current i to flow therebetween.
In an example, the electrode system 130 may be arranged to position the counter electrode 135 to be diametrically opposed to the working electrode 145, and with the reference electrode 40 positioned between the counter electrode 135 and the working electrode 145 without interfering with the electrical path between the counter electrode 135 and the working electrode 145. In an example, the reference electrode 140 may be positioned inside a separate chamber or tube 141 that is inserted in the electrochemical cell 115. A voltage source (not shown) may be connected to the electrode system 130 to supply voltage between the reference electrode 140 and the working electrode 145. While not shown in the drawings, the electrode system 130 may be electrically connected using wire. Additionally, while not shown in the drawings, a temperature probe may be inserted in the electrochemical cell 115 to measure the temperature of the electrolyte solution 120 during an electrodeposition process.
The counter electrode 135 may be composed of a conductive material including metals such as gold, silver, copper, nickel, platinum, or graphite, among other suitable materials. In an example, the counter electrode 135 may serve as the anode in the electrode system 130, and the counter electrode 135 may pass current i through the electrolyte solution 120 to the working electrode 145. In this example, the working electrode 145 may serve as the cathode in the electrode system 130 where the metal from the particles 125 are deposited. The working electrode 145 may be composed of a conductive material including metals such as gold, silver, copper, nickel, platinum, or graphite, among other suitable materials. The reference electrode 140 may be used to measure the electrode potential of the working electrode 145 by measuring the electrode potential in the electrolyte solution 120, typically at the location where the reference electrode 140 is positioned in the electrolyte solution 120. The amount of the electrode potential of the working electrode 145 may be controlled by adjusting the amount of voltage applied to the working electrode 145. Some examples of the reference electrode 140 may include a saturated calomel (Hg2Cl2) electrode, silver/silver chloride (Ag/AgCl) electrode, mercury/mercurous sulfate (Hg/Hg2SO4) electrode, and a mercury/mercury oxide (Hg/HgO) electrode, among others.
The apparatus 100 further comprises an open-bore magnet arrangement 150 comprising at least one permanent magnet 155 connected to the electrochemical cell 115 and arranged to produce a magnetic field {right arrow over (B)} in the electrolyte solution 120 to interact with the electric current i to produce an electrodeposition of the particles 125 with metal 165 derived from the metal ions 160 onto the working electrode 145. In an example, the metal 165 may comprise nickel. According to an example, the at least one permanent magnet 155 may comprise a rare-earth magnet. In some examples, the at least one permanent magnet 155 may comprise neodymium (Nd2Fe14B) or samarium-cobalt (SmCo5) rare-earth magnets, among other types. While
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The embodiments herein may be utilized for several different types of applications, including, but not limited to, thermal management for aircraft using vanadium oxide-embedded coatings, health monitoring of coatings co-electrodeposited with phosphorescing/luminescent particles, wear resistant tool facings, cutting tools, automotive engines that require wear resistance and improved lubrication (e.g., in high performance internal combustion cylinder liners), coatings for corrosion protection (e.g., sacrificial Zn-ceramic coatings on steel, metal-PTFE coatings), and Ni-graphite as 1) thin film battery electrodes for consumer electronics and 2) bipolar plates in polymer electrolyte membrane (PEM) fuel cells.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others may, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein may be practiced with modification within the spirit and scope of the appended claims.
The embodiments herein may be manufactured, used, and/or licensed by or for the United States Government without the payment of royalties thereon.