Cathode corrosion protection using a current limiter

Abstract

To provide a method of protecting and / or passivating a metal reinforcing bar in an ionically conductive material.SOLUTION: In a method for cathodically protecting and / or passivating a metal section in an ionically conductive material such as steel reinforcement in concrete or mortar, an impressed current anode or sacrificial anode communicates ionic current to the metal section and a storage component of electrical energy which can be a cell, battery or capacitor is provided as a component of the anode. The storage component can have replacement energy introduced by re-charging or replacing the component from an outside supply. Typically, the cell or storage capacitor has an outer case which carries an anode material as an integral outer component. A mechanical clamp is provided to attach the assembly to a reinforcing bar. A current limiter is provided which prevents excess current draining from the supply.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for cathodic protection and / or passivation of a metal part in an ion-conductive material and / or an anode assembly using a battery or a battery of batteries to supply voltage, and more particularly to a configuration for restricting the supply of current by an electrode assembly.

Background Art

[0002] External power supply methods using batteries are known. Such external power supply methods can use other types of power sources including a common rectifier that rectifies an alternating voltage to a direct current voltage required for an impressed current between an anode and steel from a suitable power source. It is also known to provide a solar panel used in this type of system.

[0003] In either case, such external power supply methods require normal maintenance and inspection of the power source state to ensure that the power source does not cause unexpected unacceptable corrosion or overprotection of the steel within the structure to be protected. While such maintenance is carried out and thus the safety of the power source is ensured, this is a relatively costly process.

[0004] Alternatively, a direct current electrical system that does not require a power source can be used, since a voltage between the steel and the anode is provided by selecting a suitable material for the anode that is sufficiently electrochemically negative to reliably generate a current that provides cathodic protection. These systems have been very successful and are widely used.

[0005] Conventional galvanic anodes, such as those used in steel-reinforced concrete structures, have two main constraints. The first constraint concerns the mass of zinc per anode, which limits the anode's service life depending on the required current output. The second constraint is the actual current output of the anode, which may or may not be sufficient to stop steel corrosion. The current output is limited by the driving voltage and is either inherently stable or fluctuates over time due to exposure conditions, anode age, and the generation of corrosion products.

[0006] U.S. Patent No. 8,961,746 (Sergi), issued February 24, 2015, U.S. Patent No. 8,968,549 (Sergi), issued March 3, 2015, and U.S. Patent No. 7,264,708 (Whitmore), issued September 4, 2007 are also cited, all of which are granted to the assignee, and the disclosures of such documents are incorporated herein by reference or may be referenced for further relevant information. [Overview of the project]

[0007] According to one aspect of the present invention, an anode assembly is provided for use in ion-conductive materials to prevent corrosion and / or passivate metal reinforcing bars, the anode assembly being: an anode body for at least partially mounting within an ion-conductive material; The anode body includes an anode for transmitting ionic current to the metal reinforcing bar via an ionic conductive material; An anode body configured and positioned such that when the anode is ionically connected to an ionically conductive material, a voltage difference is generated between the anode and the metal reinforcing bar, thereby allowing an electric current to flow through the ionically conductive material between the anode and the metal reinforcing bar to provide cathode protection for the metal reinforcing bar; and A mounting assembly for fixing and installing an anode body to a metal reinforcing bar so that it is at least partially supported by the reinforcing bar within an ion-conducting material, so that current can flow from the anode to the metal reinforcing bar; An elongated rod member extending forward from the anode body to the front end of the elongated rod member, positioned for engagement with the first adjacent surface of the metal reinforcing bar; Hook member for engaging with the second opposing surface of a metal reinforcing bar Mounting assemblies including; and To secure the metal reinforcing bars in between, it is equipped with a connecting part for pulling the front end of the rod member and the hook member together.

[0008] According to another aspect of the present invention, an anode assembly is provided for use in ion-conductive materials to prevent corrosion and / or passivate metal reinforcing bars, the anode assembly being: an anode body for at least partially mounting within an ion-conductive material; The anode body includes an anode for transmitting ionic current to the metal reinforcing bar via an ionic conductive material; An anode body configured and positioned such that when the anode is ionically connected to an ion-conducting material, a voltage difference is generated between the anode and the metal reinforcing bar, thereby allowing an electric current to flow through the ion-conducting material between the anode and the metal reinforcing bar to provide cathode corrosion protection for the metal reinforcing bar; and A mounting assembly for fixing and installing an anode body to a metal reinforcing bar so as to be supported by ionic contact with an ion-conducting material, allowing an ionic current to flow from the anode to the metal reinforcing bar; A first contact member extending forward from the anode body to the front end of the first contact member, positioned for engagement with the first adjacent surface of the metal reinforcing bar; A second contact member for engaging with the second opposing surface of a metal reinforcing bar; The mounting assembly includes a first contact member having at least a portion thereof having a male thread, and a second contact member having a connecting portion with a female thread that engages the male thread for pulling the second contact member toward the anode body to fasten a metal reinforcing bar between them.

[0009] According to another aspect of the present invention, an anode assembly is provided for use in ion-conductive materials to prevent corrosion and / or passivate metal reinforcing bars, the anode assembly being: an anode body for at least partially mounting within an ion-conductive material; Anode for transmitting ionic current to metal reinforcing bars in ion-conducting materials: Includes an electrical energy storage component having first and second poles for transmitting electric current generated by releasing electrical energy; The first pole has an electrical connection to the anode, and A mounting assembly for fixing and installing an anode body to a metal reinforcing bar so that it is supported by the metal reinforcing bar through ionic contact with an ion-conducting material, allowing an ionic current to flow from the storage component through the anode to the metal reinforcing bar; Connected to the second pole for the electrical connection of the second pole to the metal reinforcing bar; A first contact member connected to an anode body for engaging with one face of a metal reinforcing bar; A second contact member for engaging with the second opposing surface of a metal reinforcing bar; and The mounting assembly includes a connecting section for pulling together first and second contact members to secure a metal reinforcing bar between them.

[0010] This configuration specifically relates to attaching an anode to conventional steel reinforcing bars that are attached to anchoring materials such as concrete or other cement materials such as mortar. However, this configuration may be usable in other locations depending on the circumstances.

[0011] According to one key feature of the present invention that can be used with any configuration of this specification, the hook member includes two equilibrium hooks spaced longitudinally along the reinforcing bar and connected together for general engagement with the reinforcing bar. This acts to engage the reinforcing bar at three longitudinally spaced positions with a first contact portion or rod on one intermediate surface and with two hook portions on either side of the opposing surfaces. In other words, the hook member preferably includes two surface portions, each positioned to engage the metal reinforcing bar at positions directly opposite each other on the first surface.

[0012] According to one key feature of the present invention, which can be used with any of the configurations specified herein, the anode body is mounted on an elongated rod or a first contact member, and as a result, the rotation of the anode body drives the rotation of the front end of the elongated rod member relative to the first face of the reinforcing bar. In this configuration, preferably, the front end of the elongated rod member includes one or more projections for biting into the metal reinforcing bar. This can be provided by one or more projections on the outer rounded end of the rod end or on the face itself.

[0013] According to one important feature of the present invention that can be used in conjunction with any of the configurations specified herein, an elongated rod member is at least partially screwed along its length so as to act as a screw to drive the female threaded portion of the second contact member toward the anode body.

[0014] According to one important feature of the present invention that can be used in conjunction with any of the configurations described herein, the hook member includes a female threaded portion for engaging an elongated rod member to pull together with the front end of the rod member or first abutment and the hook member or second abutment in order to fasten a metal reinforcing bar between them.

[0015] Preferably, the female threaded portion is fixed to the hook member such that the rotation of the rod member moves the hook member toward the anode. However, other configurations are available in which the female portion includes a nut that rotates around the thread relative to the second contact so as to drive the second contact toward the anode.

[0016] According to one important feature of the present invention that can be used in conjunction with any of the configurations described herein, a hook member or second contact engages an elongated rod member at a position spaced apart from the anode body to prevent contact between the anode body and the metal reinforcing bar. This is particularly important when the anode is powered by a battery or a power source forming part of the anode body to prevent a short circuit in the power supply to the metal reinforcing bar.

[0017] In accordance with one important feature of the invention that can be used in conjunction with any of the configurations of this specification, the elongated rod member is rigidly connected to the anode body for fixing and holding it at a predetermined distance and orientation with respect to the metal reinforcement. Thus, the anode body can be placed on the reinforcement before pouring concrete or other materials. Therefore, the anode body is held in place with respect to the metal reinforcement and other adjacent metal reinforcements to better arrange a series of anodes with respect to the metal reinforcement. Alternatively, the hook member may be rigidly connected to the anode body, and the threaded elongated member may be used to hold the anode body at a predetermined distance and orientation with respect to the metal reinforcement.

[0018] The configuration disclosed in this specification can be used in conjunction with an anode body that includes an anode of a material that is not as expensive as the metal reinforcement and can be sacrificed.

[0019] Alternatively, in other embodiments, the voltage difference is generated by an electrical energy storage component having two poles for transmitting the current generated by the release of electrical energy, by electrically connecting one pole to the metal reinforcement, and by electrically connecting the other pole to the anode on the anode body.

[0020] According to one aspect of the invention, a method for preventing corrosion and / or passivating a metal part in an ion-conductive material is provided, the method comprising: providing an anode for transmitting a current to the metal part in the ion-conductive material; generating a voltage difference between the anode and the metal part so as to cause a current to flow through the ion-conductive material between the anode and the metal part to provide cathodic protection for the metal part; and providing an electrical component for limiting the current to a maximum value.

[0021] The above configuration provides a mechanical clamp for the anode body on the reinforcement. This configuration can provide the following advantages:

[0022] The contact acts to bite into the rebar; the contact provides a secure bond even if the surface of the rebar is not clean, such as being contaminated with rust or concrete residue.

[0023] The clamp is compatible with different rebar sizes / diameters and sizes / diameters caused by corrosion.

[0024] The clamp creates a firm bond.

[0025] The clamp supports the anode at a distance from the connection point.

[0026] Because the mounting device is held in a position not too close to the reinforcing bar where the anode is located, it promotes a more uniform current distribution, and therefore allows most of the current to flow more uniformly by reducing differences in resistance.

[0027] The clamp does not rotate easily around the steel rebar, unlike a wire wrap connection.

[0028] The clamp connection will not loosen as a result of any rotation of the anode body relative to the rebar.

[0029] The anode does not rotate or move downwards due to gravity.

[0030] Mechanical clamps allow the installer to position the anode on selected reinforcing bars within the concrete / mortar portion that is to be cast.

[0031] The connector allows for the manufacture of an anode having a standard threaded rod as the first contact.

[0032] In configurations using a power supply, the coupling acts to ensure that one pole of the power supply is firmly connected to the rebar, and that the other pole is spaced apart and does not come into contact with the steel, because this would cause a short circuit, drain the battery, and fail to provide corrosion protection to the steel.

[0033] Different connectors may be available for different size ranges.

[0034] A tooth or knife / sharp edge can be positioned within a cavity opening defined by a hook member to bite into the reinforcing bar.

[0035] The concave end and additional teeth on the end of the threaded rod can act to cut into the reinforcing bar.

[0036] These features ensure a secure and robust physical and electrical connection.

[0037] According to another aspect of the present invention, a method is provided for preventing corrosion and / or passivating a metal portion in an ionic conductive material, the method being: A process for providing an anode for transmitting electric current to a metal part in an ionic conductive material; A step of generating a voltage difference between the anode and the metal part so as to cause an ion-conducting material to pass an electric current between the anode and the metal part in order to provide cathode corrosion protection for the metal part; The process includes providing an electrical component that limits the current to a maximum value.

[0038] According to another aspect of the present invention, an anode assembly is provided for use in preventing corrosion and / or passivating a metal portion in an ionic conductive material, the anode assembly being: An anode for transmitting ionic current to a metal part in an ion-conducting material; An electrical energy storage component having first and second poles for transmitting electric current generated by releasing electrical energy; A connector for electrically connecting the first pole to a metal part; The second pole is connected to the anode; The anode is positioned to be attached in ionic contact with an ion-conducting material so that ion current can flow from the storage component through the anode to the metal part; The anode assembly also includes electrical components that limit the current to a maximum value.

[0039] In this configuration, which is preferably exposed to the maximum available voltage from the storage component, the current can be varied by the electrical component from a maximum value to a lower value depending on the conductivity of the ionic conductive material, so that the component acts as a limiter rather than a regulator. In this way, the power draw by the limiter can be kept very low. The current is not maintained at a value higher than the intrinsic value resulting from the voltage of the electrical component and the inherent resistance of the system.

[0040] In this way, electrical components act to extend the lifespan of batteries, other power systems, or galvanic anode systems, which have limited capacity and cease to function after that limited capacity is consumed.

[0041] Preferably, the electrical component includes a transistor, where the current through the transistor is limited to a maximum value. The transistor may be a conventional transistor or an FET. In this configuration, preferably, the electrical component uses the voltage difference between the first and second poles, or the voltage difference between the anode and the metal part, as the reference voltage for the transistor. Of course, this draws almost no current, and as a result, the electrical component is configured to consume less than 1 μA of power. Thus, the circuit is very simple and can consist solely of a transistor and a resistor. Other low-power limiters are available, but typically high-power regulators are not suitable because they draw more current than is saved by limiting the current between the anode and the resistor. In addition, in other configurations, a second sacrificial anode is provided, and the electrical component uses the voltage difference between the two anodes and a resistor to generate a reference current for the electrical component.

[0042] Typically, the current can be limited to a maximum value of + / - 20%, 10%, 5%, or 2%, depending on the stability of the voltage source, the gain of the transistor, and the resistance of the resistor.

[0043] Preferably, the electrical components form part of a combined unit including an anode and a connector for connection to the reinforcing bar, for example, a configuration of the type described above.

[0044] Preferably, the current limiter described above is associated with a single anode, operates only for a single anode, and is not part of a larger system that limits or regulates current across multiple anodes.

[0045] In one particularly preferred method, the anode is mounted and connected to a metal part, while the ion-conducting material is detached, and current limiting by electrical components prevents gas generation during the curing of the ion-conducting material. Gas generation during setup is a significant problem as it causes bubbles to form in the concrete.

[0046] The configuration described herein can be used in systems in which a voltage difference is generated by electrically connecting one pole to a metal part and the other pole to an anode, by an electrical energy storage component having two poles for transmitting the current generated by the release of electrical energy. However, the same current limiting system and the same mechanical connection can be used with a sacrificial anode or a galvanic anode, and can also be used in composite systems in which both an applied current anode driven by a power source and a separate sacrificial anode are present.

[0047] In this configuration, preferably, both the anode and the storage component are at least partially embedded in or embedded in an ion-conductive material, typically concrete. In this configuration, preferably, the storage component is connected as a single unit to the applied current anode or non-sacrificial anode and / or sacrificial anode.

[0048] In this configuration, preferably, the storage component is contained within a closed or sealed canister defining an anode on its outer surface. In this case, the anode can be made from stainless steel.

[0049] In this configuration, electrical energy can be introduced, in some cases, by recharging the storage component or by replacing the storage component, in order to provide long-life replacement.

[0050] The storage component may be a battery or a battery recharger, or it may be a capacitor.

[0051] Therefore, the above configuration provides a configuration that acts to limit the current between the anode and the reinforcing bar. This configuration can provide one or more of the following features:

[0052] It acts to regulate the current from the battery or galvanic anode.

[0053] It uses the voltage difference across the poles of the energy storage device, or between the energy storage device and the steel, or between the galvanic anode and the steel as the reference voltage.

[0054] It provides a simple limiting system, typically formed with only two components: a conventional transistor or FET and a resistor that determines the transistor's adjustment voltage.

[0055] The circuit consumes very little power, possibly less than 1 μA.

[0056] These devices have limited capacity (limited stored energy) and cease to function after their limited capacity is consumed, making them ideal for battery or saprostatic anode systems.

[0057] The current can be limited across a wide range of circuit resistances, from short circuits to resistances, and the available voltage is sufficient to produce a set current value.

[0058] The current can be adjusted within +20%, 10%, 5%, or 2% depending on the stability of the voltage source (battery / anode).

[0059] The current limiter may be part of a composite unit including a battery or capacitor, or part of the anode and connector.

[0060] Current limiters allow for the installation and connection of batteries / high-power anodes to steel in fresh concrete / mortar without the harmful effects of high current density release through low-resistance fresh materials. The cans are used to prevent gas generation (oxygen and hydrogen) during hardening, which generates and releases gas bubbles, reduces bonding to steel, and leaves holes / capillaries in the concrete / mortar. Hole / cavity formation allows water and salts to penetrate, and CO2 to enter the steel, carbonizing the concrete. All of these lead to premature corrosion of the steel.

[0061] As mentioned above, when the anode is not sacrificed to the metal, the material is typically electronegative to the metal. However, sometimes parts of the anode are sacrificed, or the anode may be sacrificed completely.

[0062] The configurations described herein can be used when the anode takes the form of multiple associated anodes, all connected to a battery or a battery of batteries.

[0063] The storage components defined above may be batteries, batteries, or batteries of batteries / batteries, or they may be capacitors, supercapacitors, or ultracapacitors, which provide a system for charge storage different from conventional electrolytic cells or batteries. A supercapacitor is a high-capacity electrochemical capacitor with a much higher capacitance value than other capacitors. These capacitors typically have lower voltage limits than standard or conventional capacitors. They typically store 10 to 100 times more energy per unit volume or unit mass than standard capacitors, can accept and deliver much more charge than batteries, and allow for many more charge-discharge cycles than rechargeable batteries. Supercapacitors do not use the conventional solid dielectric of standard capacitors. Supercapacitors instead use electrostatic double-layer capacitance, or electrochemical pseudo-capacitance, or a combination of both. Electrostatic double-layer capacitors use carbon electrodes or derivatives with a much higher electrostatic double-layer capacitance than electrochemical pseudo-capacitance, achieving charge isolation in the Helmholtz double layer at the interface between the conductive electrode surface and the electrolyte. The charge separation is much smaller than that in conventional capacitors, being only a few angstroms (0.3-0.8 nm).

[0064] Supercapacitors represent a significant advancement over conventional capacitors, as they can store high charge once fully charged. A 2.7V 200F supercapacitor can hold over 500C (A x s) of charge. Since a typical cathodic protection system requires approximately 170-400C / m² of steel per day, such a fully charged capacitor can provide enough charge to protect more than 1m² of steel per day. This corresponds to a current density of 2-5mA / m². For example, doubling this value would require doubling the capacitance to approximately 400F. Theoretically, if the capacitors are recharged routinely, a system utilizing supercapacitors of this size spaced apart to provide current to more than 1m² of steel could be an effective cathodic protection system. Routine recharging can easily be provided by solar panels, but other means, such as generating moderately regular bursts of current, may also be used as charging components for supercapacitors. Examples of such means may include piezoelectric materials that can be incorporated into roads, parking lots, bridges, runways, etc., and that enable the generation of electric currents by the load and / or movement of structures or vehicles passing over them.

[0065] In other words, piezoelectric materials may be used to generate electricity in order to directly supply power to an external power supply system, or to charge / recharge a battery or capacitor / supercapacitor.

[0066] In some embodiments, the anode is a sacrificial anode formed from a material less noble than the metal being protected. However, in other cases, the anode is less noble than the metal being protected and is therefore as noble as, or more noble than, the metal, typically steel; and is therefore partially or completely inert during the process. If the anode is formed from a sufficiently inert material, it will not corrode significantly while electrons are flowing.

[0067] High current output is required from storage components such as batteries. As described above, one electrode is connected to a corrosion-resistant metal part. Electrons flow from the storage component to the metal part so as to reduce corrosion of the metal part. The other electrode is connected to the anode, or, if appropriate, the casing of the storage component itself can be used as the anode. In the case of zinc-alkaline batteries, the polarity of the battery is such that the battery case acts as the anode if it is made of a suitable material and can distribute the required current through an ion-conducting material such as mortar or concrete. Most other batteries, such as lithium batteries, typically have only a small electrode with suitable polarity, which may not be large enough to transfer the required current to the ion-conducting material. A separate anode may be provided for connection to a suitable electrode. The anode may enclose or coat the entire storage component, such as a battery or capacitor. The anode can be made of MMO-coated titanium or other precious metals, or any inert conductive material such as submetals, conductive coatings, conductive ceramic materials, etc., and can be embedded in an inert material such as alkaline mortar or sand to which an alkaline solution may be added. Stainless steel can also serve as a suitable current carrier when embedded in mortar or compacted sand to which an alkali, such as a saturated solution of lithium hydroxide, has been added. The anode may also contain sacrificial material, such as zinc, that is not as noble as the metal part being protected from corrosion.

[0068] Preferably, in some embodiments, the storage component is initially charged or subsequently recharged during in situ, i.e., while in contact with an ion-conductive material. The configuration may, or preferably, include an automatic switching system to perform a periodic charging process. For example, the storage component can be charged by a solar cell or by an external power source such as a second battery or power supply. Additionally, a system may be provided that operates to continue recharging automatically, repeatedly, or periodically.

[0069] In other cases, the storage component is subsequently recharged by a recharge power supply, which is an integrated unit comprising the anode and the storage component. However, the system may also operate as a periodic maintenance program in which the power supply is periodically activated if necessary to perform the recharging of the anode assembly or a set of anode assemblies in the structure.

[0070] Preferably, the storage component is further recharged by directly applying a voltage between both terminals, or between the first connection to the terminals of the storage component and the second connection to the metal part.

[0071] In one configuration, the anode includes a sacrificial anode material, or the anode being sacrificed to a metal part is attached to or electrically in contact with the body of the sacrificial anode material that causes a current boost until the sacrificial anode material is consumed, and thereafter the current discharge is through that anode.

[0072] In one configuration, the storage component is connected to a metal part and charged during the initial charging process or during subsequent recharging, after being installed by connection to one terminal and a second connection to the metal part. This connection method acts to allow excess current to flow to the metal part during the charging or recharging process that passivates the metal part, or to reduce future current requirements in order to maintain the passivation of the metal part or to reduce corrosion.

[0073] Typically, a single unit comprising a storage component and an anode(s) is embedded at least partially in an ion-conducting material. However, applications to mounting surfaces or other forms where the anode is in ionic contact with the material may be used.

[0074] In one particularly preferred configuration, the storage component includes a battery having an outer casing, where the outer casing is formed entirely or partially from an anode material, and thus the anode is formed by the outer casing of the same material, or as a coating or layer on the outer surface of the outer casing. In this case, the outer casing or at least the outer layer can be formed from a material nobler than steel. In this configuration, the anode directly forms the outer casing of the battery, where the outer casing includes and houses the battery, electrolyte, anode material, and cathode material of the other components of the battery. In other words, in this embodiment, the anode is defined by a layer or coating on the outer surface of the storage component itself, or is actually the outer surface of the storage component and is not a separate, additional element from the storage component. If the storage component is a battery, the outer casing of the battery can directly support the anode material, or the outer casing of the battery may even be the anode. The anode material may cover the entire surface or be a partial coating that exposes other areas.

[0075] In another case, the outer casing and the anode are formed independently, and the anode forms a separate body that matches the shape of the battery's outer casing. Typically, such batteries are cylindrical, but other shapes are also available. This configuration is particularly applicable when the battery is replaceable rather than rechargeable to take in additional energy after the original battery has been sufficiently depleted to no longer be effective.

[0076] In another case, the anode is a separate body electrically connected to one terminal of the storage component.

[0077] The above characteristics make it possible to use it for corrosion protection of steel reinforcement members or structural members in concrete or mortar materials where corrosion is known to cause concrete collapse due to the expansive force of corrosion products and the reduction in steel strength. However, use in other situations may also occur.

[0078] The term "applied current anode" as used herein is intended to distinguish it from a sacrificial anode, which is made of a material that is less noble than the metal and therefore corrodes preferentially over the metal being protected, typically zinc. An applied current anode is an anode that is used in conjunction with an external power source and needs to be less noble than the metal. Typically, such applied current anodes can be made from titanium, platinum, niobium, carbon, and other noble metals and oxides that do not corrode readily, or from less noble materials such as iron or zinc.

[0079] With regard to the use of the above method between the sacrificial or galvanic phases, the ion-conductive filler preferably includes at least one activator to ensure continuous corrosion of the sacrificial anode. However, the activator may also be placed elsewhere in the system. A suitable filler may be in solid, gel, or liquid form.

[0080] The gel may contain carboxymethylcellulose, starch and their derivatives, fumed silica or polymer gel electrolytes, such as bentonite, propylene carbonate, and / or alumina, in an aqueous potassium hydroxide solution or acrylic acid in a polyvinyl chloride / acetate-KOH composite material. The alkali hydroxide in these gels acts as a suitable activator.

[0081] Suitable activators include alkali hydroxides, wetting agents, catalytic materials, and other materials that are corrosive to the sacrificial anode metal. The activators may be used alone or in combination.

[0082] With regard to the use of the above method between the sacrificial phase and the galvanic phase, the ion-conductive filler preferably has a sufficiently high pH to prevent corrosion of the sacrificial anode and the formation of a passivation film on the sacrificial anode. Alternatively, the filler has a lower pH and / or contains other activators to prevent corrosion of the sacrificial anode and the formation of a passivation film on the sacrificial anode.

[0083] The anodes and methods described herein are preferably designed for use when the metal part is steel and the ion-conducting material is concrete or mortar.

[0084] The anode apparatus, including the applied current component and the sacrificial component, is typically embedded in concrete or other solid material so as to be completely encased in concrete or filler, but this is not mandatory, and the anode may simply be partially embedded or in direct or indirect physical or ionic contact with the concrete.

[0085] The anode apparatus, including the applied current component and the sacrificial component, may be surrounded by a sealing material or ion-conductive filler, which may be a porous material or a porous mortar material. Suitable sealing materials may be inorganic or organic, and may be any ion-conductive cementitious polymer, non-cementitic material, or geopolymer, or mortar containing modified Portland cement. The sealing material may be solid, gel, or liquid, and may be deformable.

[0086] The power source may include a solar panel that drives an applied current anode and a rechargeable galvanic anode to provide long-term corrosion protection when solar power generation is intermittent.

[0087] The structures and methods proposed herein are designed particularly assuming that the metal parts are steel and the ion-conducting material is concrete or mortar. However, the same configuration may be used in other corrosion protection systems such as pipes or other structures in soil, and in a number of other systems where such anodes are available.

[0088] Preferably, the assembly includes a reinforcing layer as disclosed in U.S. Patent No. 7,226,532 granted to Whitmore on June 5, 2007, which is incorporated by reference, or may be referenced for further details not disclosed herein, to suppress and resist forces such as expansion, contraction, and strain forces that may be caused by anode corrosion, sacrificial anode ion deposition, and other physical / environmental forces such as freezing, thawing, wetting, drying, and thermal expansion / contraction.

[0089] The present invention as defined and described herein can also be provided as an assembly, in contrast to a method for cathode protection and / or passivation of the metal portion of an ion-conductive material. Accordingly, the following definitions of the present invention presented herein are incorporated herein by reference. Each of these independent definitions can be used in conjunction with one or all of the dependent features as defined above. [Brief explanation of the drawing]

[0090] Herein, embodiments of the present invention are described with reference to the accompanying drawings. [Figure 1] This is a cross-sectional view of an anode assembly used in the corrosion prevention method according to the present invention. [Figure 2] This is an enlarged view of the current limiting circuit for use with the battery, and the mounting of the first contact to the anode. [Figure 2A] This is a schematic diagram of a current limiting circuit for use with a galvanic anode that uses battery voltage to generate a reference current. [Figure 2B] This is a schematic diagram of a current limiting circuit for use with a galvanic anode, which uses two anodes, with the second anode being used to generate a reference current. [Figure 2C] This is a schematic diagram of a current limiting circuit for use in a system where both an applied current anode and a galvanic anode are used, with a battery supply unit, and the voltage across the resistor is used to control the FET. [Figure 3] This is a front view of an anode assembly similar to that shown in Figure 1, where the anode body uses a sacrificial anode. [Figure 4] Figure 3 is an isometric view of the anode assembly. [Figure 5] This is a plan view of an anode assembly similar to that in Figure 1, for patch repair in a concrete assembly, ready for the addition of unset fresh concrete to be applied to the patch.

[0091] In the diagrams, references to similar features indicate corresponding parts in different diagrams. [Modes for carrying out the invention]

[0092] In the example shown in Figure 1, a battery that may be rechargeable is provided, as shown in the earlier concurrently contested application No. 15 / 341532 filed November 2, 2016, the disclosure of which may be by reference or incorporated herein by reference, or may be a simple non-rechargeable battery. The battery may form part of the anode structure, or the anode and the battery may be physically separated. As shown in Figure 1, the anode body (10) is defined by a typical alkali manganese dioxide-zinc, and the rechargeable battery includes the following main units: a steel can (12) defining a cylindrical internal space, a manganese dioxide cathode (14) formed by a plurality of cavity cylindrical pellets (16) pressed into the can, a lead anode (18) made of anode gel and positioned inside the cavity of the cathode (14), and a cylindrical separator (20) separated from the cathode (14). The ionic conductivity (electrolyte) between the anode and cathode is provided by the presence of potassium hydroxide, KOH, and electrolyte, which are added to the battery in predetermined amounts. Other types of rechargeable batteries contain similar main components (can, cathode, anode, separator, and electrolyte), but the composition of these components may differ. However, some types of batteries may have different structures, such as lead-acid batteries or lithium batteries.

[0093] The bottom of the can (12) is closed and has a central circular pip (22) that becomes the positive terminal. The top of the can (12) is sealed to prevent air from entering by a battery closure assembly which includes a negative cap (24) formed of a thin metal sheet, a current collector (26) attached to the negative cap (24) and permeating into the anode gel to bring it into electrical contact with the anode, and a plastic top (28) that electrically insulates the negative cap (24) from the can (12) and separates the gas layer formed over the cathode and anode structures, respectively.

[0094] The separator (20) is made of two different materials: a first material (30) made of a fibrous sheet material that can be wetted by the electrolyte, and a second material (32) that does not allow small particles to pass through but retains ion permeability. A material favored for the first layer is a sheet material of nonwoven polyamide fibers that is absorbent and serves as a reservoir for the electrolyte. The macroporous structure of the absorbent layer cannot prevent internal short circuits by zinc dendrites or precipitates during discharge / charge cycles.

[0095] Short circuits are prevented by a second material (32), which may be a layer(s) of microporous or nonporous material that can be rolled thinly onto or coated onto a fibrous sheet material. One suitable material is one or more cellophane films rolled thinly onto a nonwoven polyamide sheet. Another suitable material is one or more coatings of regenerated cellulose or viscose that are coated onto and partially impregnated onto the nonwoven polyamide sheet, resulting in a composite material.

[0096] Other types of rechargeable batteries may be used. In this configuration, the above types are used in a method for cathode protection and / or passivation of metal parts such as steel reinforcing bars (40) of an ion-conductive material such as concrete (41). Thus the battery includes a first terminal (42) and a second terminal (43) defined by an outer casing (12). The first terminal (42) is connected to a pin or claw (26) that engages with an anode material (18). The terminal (42) is connected to a connecting wire (42A) extending from the terminal (42) for a final connection to the steel reinforcing bar (40) shown in Figure 1, through a mounting assembly generally shown in (50) which mechanically and electrically mounts the anode body to the steel reinforcing bar (40).

[0097] In Figure 1, the anode (44) is applied as a coating on the battery casing (12). In this embodiment, the anode (44) is an inert material and therefore nobler than steel. Examples of such materials are well known. Thus, during the cathode corrosion protection process, the anode material (44) does not corrode, or corrodes significantly.

[0098] In this configuration, the application of the anode (44) to the outer surface of the casing (12) provides a structure as a general single unit, where the anode is directly connected to the battery and forms an integrated element with the battery. The anode (44) may include one or more layers, and may include layers of mixed metal oxide (MMO), catalyst, or sub-oxide.

[0099] In this embodiment, since the anode (44) is formed from an inert material that does not corrode in the corrosion protection process, the anode and cell described herein can be directly incorporated into or embedded in concrete or other ion-conducting materials without the need for intervening sealing materials such as a porous mortar matrix. Since no corrosion products are present, there is no need to absorb such products or the expansion forces they generate. Since the process is not affected by the continuous corrosion of the sacrificial anode, activators are not required on the surface of the anode. Because chemical reactions on the surface of the insoluble anode during operation produce acid (or consume alkali), it is beneficial to embed the anode in an alkaline material such as concrete or highly alkaline mortar to prevent the material near the anode from becoming acidic. If desired, additional alkali may be added to the concrete or other material in contact with the anode.

[0100] The apparatus described herein generally includes an anode body indicated by (10), which is connected to the reinforcing bar (40) by a mounting assembly indicated by (50). In addition, the anode body includes a current limiting system indicated by (51), which limits the flow of current from the anode body to the reinforcing bar (40).

[0101] As previously described, the anode body can be defined by a power source in the form of a battery, which typically has an anode (44) on the outer surface of the battery and other terminals of the battery provided at the ends of the battery for connection to the reinforcing bars (40).

[0102] In other embodiments described below, the battery can is omitted when the anode body includes a sacrificial material that is not as noble as steel reinforcing, such as zinc, where the voltage between the anode and the reinforcing includes the voltage of the DC electricity between the two metallic components.

[0103] In yet another embodiment, the anode body may include a combination of both an applied current anode and a sacrificial anode. Thus, the anode is configured and positioned such that when the anode is ionically connected to the concrete, a voltage difference is generated between the anode (44) and the reinforcing bar (40), thereby passing an electric current through the concrete between the anode and the reinforcing bar (40) to provide corrosion protection and / or passivation of the concrete reinforcing bar.

[0104] In the embodiments shown in Figures 1, 3, and 4, the mounting assembly (50) includes a first contact (52) in the form of a threaded rod (53) attached to the anode body (10) at one end. The opposing end (54) of the threaded rod forms a face to engage with one side of the reinforcing bar (40). As shown in Figures 2 and 4, the end face (54) of the threaded rod (53) includes a peripheral annular end (55) and an intervening projection (56) positioned to bite into the face of the reinforcing bar (40) upon compression contact.

[0105] The mounting assembly (50) further includes a second contact (57) to engage substantially with opposing faces of the reinforcing bar (40) at the surface (59). Generally, the second contact forms hook members that contact the opposing or rear faces of the reinforcing bar (40) at at least two positions (59) and (60) on either side of the diameter (61) extending from the surface (54) through the reinforcing bar (40). In this way, the reinforcing bar (40) contacts three ends (54), (59), and (60) that are positioned at regular intervals around the axis (62) of the reinforcing bar system to provide a stable engagement.

[0106] The hook member defined by faces (59) and (60) forms part of a C-shaped structure (63) having a bottom intersecting member (64) and an upper intersecting member (65) that support the faces at (59) and (60). These intersecting members are connected to each other by extending outward legs (66) that extend parallel to the threaded rod (53). The intersecting member (64) includes a flange (67) perpendicular to the threaded rod (53) having a threaded hole (68) through the flange, and the flange acts as a nut on the threaded rod, so that rotation on the threaded rod drives the nut toward the anode body, pulling faces (59) and (60) toward face (54) and securing the reinforcing bar (40) between them.

[0107] The surfaces (59) and (60) may also be formed with teeth or other projections (59A) or sharp blades (59B) that bite into the surface of the reinforcing bar (40) and cooperate with the teeth (55) and (56) of the surface (54). In this way, a strong physical connection is provided between the first and second contacts and the reinforcing bar (40), and further, a strong electrical connection is provided between the rod (53) and the reinforcing bar (40). Some or all of these teeth or sharp blades on the contact surfaces may bite into any contaminants on the surface of the reinforcing bar, such as corrosion or concrete residue, to ensure effective engagement with the metal of the reinforcing bar and electrical contact. In other words, each of the first and second contact members includes a component for cutting into the surface of the reinforcing bar, thus avoiding the need to clean the surface of the reinforcing bar.

[0108] According to other independent features of the present invention, a sensor can be provided to measure the effect of a connection in order to ensure that the projection and blade provide the necessary engagement with the metal of the reinforcing bar. This can be done, for example, by measuring the resistance across the connection by bridging the point on the reinforcing bar and the connection in such a way that the resistance of the connection meets the required low level of resistance. This output is provided to an indicator to provide instructions to the installer, for example, visually or audibly, regarding whether the connection properly meets the set criteria.

[0109] The hook member may include a single object on one side of the rod (53). However, as best shown in Figure 4, the hook member is typically formed by two separate hook portions (68) and (69) connected by a rear plate (70). Thus, the rod (53) is included between the portions (68) and (69) and the rear plate (70). The hook portions (68) and (69) each include surfaces (59) and (60) that engage with the rear surface of the reinforcing bar (40). Thus, the force pulling the second contact member toward the anode body pulls on both hook portions and on both surfaces (59) and (60), providing four engagement points cooperating with the single point of engagement from surface (54) of the rod (53).

[0110] In this embodiment, the female thread is provided by a threaded hole passing through the flange (67). Thus, the screwing action of pulling the second contact member toward the anode body is provided by rotating the rod (53). This can be done most effectively by manually grasping the anode body and using it as a handle to rotate the rod (53). Of course, this requires a strong connection between the bottom end of the rod (53) and the anode body. In the configuration shown in Figure 2, this connection is provided by a base plate (71) mounted on the bottom end of the rod (53) and firmly engages with the upper end of the anode body. In configurations using a sacrificial material solid anode (74), the rod (53) can be cast inside the anode body to provide the necessary structure and electrical connections. In Figure 3, the solid anode object (74) includes a conventional cover of mortar material (75) to hold corrosion products and support the conventional active material described herein.

[0111] In other configurations (not shown), the female threaded portion engaged with the rod (53) may be formed by a separate nut that can rotate itself relative to a second contact member (67) on the flange. In this embodiment, the flange (67) can be driven toward the anode by rotating the nut rather than rotating the rod. Other configurations of the threaded connection can also drive the second contact member toward the anode. In other examples, the hook is part of the anode, and the thread is rotated to press the rebar against the hook.

[0112] Now, looking at Figure 2, the connection between the battery terminals (42) and the rod (53) electrically connected to the reinforcing bar (40) is shown in more detail.

[0113] Terminal (42) is connected to wire (42A), and wire (42A) is connected to transistor (78).

[0114] The output wiring (79) of the transistor (78) is connected to the base plate (71) which is connected to the rod (53). The transistor (78) may be a conventional transistor, in which case the base of the transistor (78) has a control current provided by a wire (80) connected through a resistor (81) which is connected via a wire (82) to the positive terminal of the battery which is connected to the anode (44).

[0115] The transistor (78) could also be an FET, in which case the wire (80) controls the gate of the FET via the resistor (81).

[0116] Since the transistor (78) is connected to the steel rebar (40) and the wire (82) is connected to the anode (44), the control current to the transistor (78) is determined by the voltage across the battery and the resistance of the resistor (81). Since this voltage is typically relatively constant until the battery is nearing the end of its life, this constant control current controls the amount of current that flows from the battery through the transistor to the rebar (40). As is well known, the resistor (81) can be selected to provide current based on the control of the transistor, which sets the current flow through the transistor to a maximum value. This maximum value is maintained regardless of the conductivity between the anode (44) and the rebar (40) through the concrete. If the conductivity through the concrete is very high, for example, during initial installation, the current is maintained at the maximum value. If the conductivity through the concrete drops to a lower level, the current is maintained at the desired level until the maximum voltage of the battery is reached. If the conductivity drops to an even lower level, the current through the transistor further decreases in proportion to the conductivity and is not maintained in the operation of the transistor. Therefore, the combined circuit provided by the resistor and transistor does not act as a regulator, but instead acts only as a current limiter.

[0117] Figures 2A and 2B show applications of current limiting devices used in conjunction with galvanic anodes.

[0118] Figure 2A shows a galvanic anode (86) connected to the transistor (78). A separate battery (87) is connected to the resistor (81) and to the transistor (78) to provide a control current to the transistor so that it controls the maximum current flowing into the reinforcing bar (40).

[0119] Figure 2B shows a galvanic anode (88) connected to a transistor (78). In this case, the control current to the transistor is provided by a second galvanic anode (89) and a resistor (81). As in the example above, the control current controls the maximum current flowing into the reinforcing bar (40).

[0120] Figure 2C shows a current limiting circuit for use with the system, in which both an applied current anode (10) and a galvanic anode (90) with a battery supply are used, and the voltage across resistor (81) is used to control FET (78). The outputs from anode (10) and anode (90) are applied downstream of the FET, or the current from anode (10) generated by the battery is limited using the current limiting circuit. Thus, the current from the applied current anode is used to "top up" the current from the galvanic anode to maintain a current suitable to provide the necessary corrosion protection. As is known, the current from anode (90) may vary depending on the changing state of the concrete so that it is used only when top-up from the battery is necessary. Because the current obtained from the battery is limited, the system can be designed so that the battery life can be matched with the anode (90) life.

[0121] If the electrical circuit includes a FET that is normally closed, the FET can prevent the flow of current from the galvanic anode (86) to the reinforcing bar (40) after the separate battery or separate galvanic anode mentioned above has ceased to function.

[0122] This current limit to a maximum value set during manufacturing by the selection of resistor (81) can ensure that the current remains at a relatively low level throughout the life of the system, and thus can dramatically increase the battery life compared to typical values ​​without a current limiter, which could be, for example, a more suitable lifespan of about 1 year to up to 10 years. In this way, the current is maintained at a value where there is no excessive current exceeding this desirable value, which is suitable for cathode corrosion protection but could damage the concrete or prematurely deplete the battery and fail to provide corrosion protection within the desired timeframe.

[0123] This configuration is particularly valuable with respect to configurations that use a non-sacrificial applied current anode and a battery as a power source to generate the required voltage. In such configurations, the current generated between the anode (44) and the rebar (40) can, in some cases, significantly exceed the desired value. In addition, the mechanical mounting of the anode body on the rebar provides an effective electrical connection. Furthermore, the strong physical connection between the anode body and the rebar ensures that the anode body can be positioned in a desired orientation relative to gravity, for example, the anode body can be on one side of the rebar or on top of the rebar as needed.

[0124] An insulating or protective collar (83) is provided to surround the transistor (78) and resistor (81) for connecting the terminal (42) to the rod (53). The bottom end of the collar is attached to the top end of the battery, and the top end of the collar receives the base plate (71) in the appropriate receptacle portion. The collar (83) is attached to the battery (44) by surrounding an insulating layer (84) of appropriate plastic material. Inside the collar (83) is provided conventional potting material (85), which surrounds the electrical components and wires to maintain the connection and prevent damage from moisture penetration. The structure is therefore strong enough to securely attach the base plate (71) to the battery in a manner that allows the battery to be grasped manually and turned as a driving handle to rotate the rod (53).

[0125] As shown in Figure 5, the anode body, generally indicated as (90), is installed within a patch repair (91) of concrete material (92). The anode body includes a mounting assembly (50) as previously described, which includes a rod (53) and a hook portion (57). In this embodiment, the anode body (90) is made of a battery (93) and a sacrificial material portion (94). The battery (93) has an outer surface (95) that acts as the applied current anode. The battery has a terminal (96), which is attached by a wire (97) that includes a diode (98) that sends voltage from the terminal (96) to the rod (53). During initial operation, the system therefore operates primarily as an external power supply system, where the battery generates most of the current flowing between the anode of (95) and the reinforcing bar (40). However, when the battery is depleted, cathode protection is taken over by the sacrificial anode (94) which is directly connected to the rod (53). In this configuration, the diode (98) can act to reverse the sacrificial process, preventing reverse current flow through the battery (93) which would instead more aggressively corrode the steel. The battery (93) and the anode (94) are appropriately connected by a structural mounting element (99), which is only schematically shown, and the structural mounting element (99) is physically attached to the anode (94) so ​​as to prevent the battery from detaching from the anode during installation.

[0126] As shown in Figure 5, the anode body (90) is positioned outward toward one side of the reinforcing bar (40) within the patch. In this manner, the anode body is supported at a distance from the reinforcing bar (40) defined by the length of the rod (53) and the mechanical connection of the clamp assembly. The mechanical connection of the clamp assembly ensures that the anode body remains in its horizontal extension direction while the patch (91) is filled with additional concrete. During the setting of the additional concrete, the current limiting system described above prevents the generation of gases on the surfaces of the anode and reinforcing bar that could penetrate the set concrete and cause significant damage to the concrete.

[0127] Various modifications may be made to the invention as described herein, and obviously different embodiments may be made within the spirit and scope of the claims without departing from such spirit and scope; therefore, all matters contained in the appended specification are intended to be construed as illustrative only and not restrictive.

Claims

1. A method for cathode protection and / or passivation of a steel reinforced member of an ion-conductive concrete or mortar material, the method being: A step of providing an anode for transmitting an ionic current to the steel reinforcing member of the ion-conductive concrete or mortar material, A step of generating a voltage difference between the anode and the steel reinforcing member so as to cause an electric current to flow through the ion-conducting concrete or mortar material between the anode and the steel reinforcing member in order to provide the cathode corrosion protection of the steel reinforcing member, and A step of providing an electrical component that limits the current to a maximum value that is maintained regardless of the conductivity between the anode and the steel reinforcing member via the ion-conductive concrete or mortar material. Includes, The electrical component includes at least one wire connected between the electrical component and the anode. The anode apparatus, including the electrical components and the wires, forms a single unit. A method wherein the anode apparatus defined by the single unit, including the anode, the electrical components and the wires, is embedded in the ion-conductive concrete or mortar material.

2. The voltage difference is generated by the discharge of electrical energy and by an electrical energy storage component having two poles for transmitting current generated by electrically connecting one pole to the steel reinforcing member and by electrically connecting the other pole to the anode. The method according to claim 1, wherein the storage component forms part of the single unit embedded in the ion-conductive concrete or mortar material.

3. The method according to claim 2, wherein the electrical component includes a transistor, and the current passing through the transistor is limited to a maximum value.

4. The method according to claim 3, wherein the electrical component uses the voltage difference between the poles of the storage component and a resistor to generate a reference current for the transistor.

5. The method according to claim 4, wherein the electrical component comprises the transistor and the resistor.

6. The method according to claim 4 or 5, wherein the transistor is an FET.

7. The method according to any one of claims 1 to 6, wherein the electrical component is configured to consume power of 1 μA or less.

8. The method according to any one of claims 1 to 7, wherein the current is limited to within 20% of the maximum value depending on the stability of the voltage source.

9. The method according to any one of claims 1 to 8, wherein the anode is mounted and connected to the steel reinforcing member while the ion-conductive concrete or mortar material is not yet hardened, and the current limiting by the electrical component prevents the generation of gas bubbles in the ion-conductive concrete or mortar material during hardening.

10. The method according to any one of claims 1 to 9, wherein the single unit is contained within a closed or sealed canister defining the anode on its outer surface.

11. The method according to claim 10, wherein the anode comprises stainless steel.

12. The method according to claim 1, wherein the anode comprises a material that is less noble than the steel reinforcing member, so as to be sacrificed.

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