JP2020015984A - Corrosion protection using sacrificial anode - Google Patents

Abstract

To provide a corrosion prevention method of steel in concrete, by using a sacrificial anode.SOLUTION: By positioning an anode assembly 12 containing both a sacrificial anode 20 touching the concrete and an impressed current anode 21, an impressed current is supplied from a power source to the anode. The impressed current anode forms a perforated sleeve by surrounding a rod of the sacrificial anode material with an activated ionically-conductive filler material 22 disposed therebetween. The system can be used without the power source in a sacrificial mode or when the power source is connected, the impressed current anode can be powered to provide an impressed current system and/or to recharge the sacrificial anode from sacrificial anode corrosion products.SELECTED DRAWING: Figure 1

Description

  The present invention relates to corrosion protection using sacrificial materials.

  U.S. Patent No. 6,346,188 (Shuster), assigned to ENSER Corporation and issued on February 12, 2002, discloses that the anode is located within a jacket surrounding the pile at the water level and the applied current is jacketed. Disclosed is a method for corrosion protection of a marine pile, in which a battery is mounted on a pile above the water level to provide between the anode of the stake and the steel of the pile. The anode is preferably made of titanium or other non-corrosive materials of high scale. However, the patent states that although other materials such as zinc may be used, they are also disadvantageous because they tend to corrode. The purpose is to ensure that the applied current is in place during the life of the marine pile, keeping in mind that the battery has a long life and is effectively maintained, so that saltwater in the marine environment is particularly corrosive. That is, it remains.

  Such applied current systems may use other types of power supplies, including common rectifiers, that rectify the AC voltage from a suitable source to the DC voltage required for the applied current between the anode and steel. it can. It is also known to provide solar panels for charging batteries used in such systems.

  In all cases, such an applied current system should be maintained and regulated regularly to ensure that the power supply does not lead to unexpected and unacceptable corrosion of the steel in the structure to be protected. Needs to be checked. While such maintenance is performed, and thus the power supply can be verified, this is a relatively expensive process.

  For anodes that are electronegative enough to ensure that current is generated to provide corrosion protection, choosing an appropriate material provides an electrical voltage between the steel and the anode, thus providing an alternative. In addition, a galvanic system that avoids the need for any power supply can be used. These systems have achieved considerable results and are widely used.

  Conventional galvanic anodes, such as those used in reinforced concrete, have two main limitations. The first concerns the mass of zinc per anode, which limits the useful life of the anode, depending on the required current output. The second is the actual current output of the anode, which may or may not be sufficient to stop corrosion of the steel. The current output is a fundamentally fixed characteristic and is limited by the drive voltage, which depends on the exposure conditions, the age of the anode, and the accumulation of corrosion products over time.

  One object of the present invention is to provide an improved method for corrosion protection.

According to one aspect of the present invention, there is provided a method of use in preventing corrosion of metal parts in an ionically conductive coating material, the method comprising:
Positioning a sacrificial anode of the sacrificial material in ionic contact with the ion conductive material;
Preferentially eroding the sacrificial anode relative to the metal portion, such that ions of the sacrificial material are generated from the sacrificial anode and thus consume the sacrificial anode as the sacrificial anode erodes;
And recharging the sacrificial anode with ions of the sacrificial anode material.

  Preferably, the sacrificial anode is the first of a DC power supply for positioning the applied current anode in ionic contact with the ionically conductive material and for flowing an ionic current through the material for depositing the sacrificial anode ions on the sacrificial anode. It is recharged by connecting one terminal to the applied voltage anode.

  Preferably, the sacrificial anodic ions are present in the ionic conductive material.

  Preferably, the recharging produces hydroxide ions at the surface of the sacrificial anode.

  Preferably, the recharging regenerates the alkaline environment near the sacrificial anode.

  Preferably, in a first step, the sacrificial anode is connected to the metal part to provide corrosion protection of the metal part by corrosion of the sacrificial anode resulting in the composition of the corrosion product of the sacrificial anode, and In a second step after the corrosion has occurred, the current supplied by the DC power supply causes the sacrificial anode to redeposit ions of the sacrificial material from the sacrificial anode corrosion products.

  Preferably, the DC power supply is applied temporarily.

  Preferably, there are ions of the sacrificial material available to be deposited.

  Preferably, the ions of the sacrificial material are soluble.

  Preferably, the ions of the sacrificial material are electrochemically mobile.

  Preferably, the metal part is steel and the ionic conductive material is concrete or mortar.

According to a second aspect of the present invention, there is provided a method of use in preventing corrosion of a metal part in an ionically conductive coating material, the method comprising:
Positioning the applied current anode in ionic contact with the ionic conductive material;
Positioning the sacrificial anode in ionic contact with the ionic conductive material;
Providing a DC power supply;
Connecting a first terminal of the DC power supply to the applied current anode;
Connecting a second terminal of a DC power supply to the sacrificial anode in order to pass an ionic current to the material on which the sacrificial anode is to be deposited.

  Preferably, a connection is provided between the sacrificial anode and the metal part, such that the sacrificial anode provides corrosion protection.

  Preferably, when the DC power supply is active, the connection between the sacrificial anode and the metal part remains in place.

  In one arrangement, at least a portion of the sacrificial anode is created in the ionically conductive material by deposition of ions of the sacrificial material.

  In this case, the method includes the step of incorporating the ions of the sacrificial material into the ionically conductive material, wherein the sacrificial anode is deposited on the sacrificial anode by the ionically conductive material. Generated during.

  Preferably, the second terminal of the DC power supply is connected to the sacrificial anode and the metal part.

  Preferably, the connection of the applied current anode and the DC power supply across the metal part creates a current between the metal part and the applied current anode used to make the metal part passive.

  Preferably, the connection of the applied current anode and the DC power supply across the metal part comprises a connection between the metal part and the applied current anode where the ions of the sacrificial metal are deposited on the sacrificial anode while providing corrosion protection for the metal part. Create a current.

  Preferably, the sacrificial anode and the applied current anode include the common components of the anode device, so that when the common components of the anode device are located on the ionically conductive material, the sacrificial anode and the applied current anode are Each is under ionic conductive communication with each other and with the metal part.

  Preferably, the applied current anode and the sacrificial anode are electrically separated to prevent electrical transmission therebetween.

  Preferably, the applied current anode is perforated to allow ionic current in the ionically conductive material to pass through the applied current anode.

  Preferably, the sacrificial anode forms a rod and the applied current anode forms a sleeve surrounding the rod.

  Preferably, the applied current anode and the sacrificial anode include adjacent plates.

  Preferably, an ionic conductive filler material is provided between the applied current anode and the sacrificial anode.

  Preferably, the ionic conductive filler material is different from the ionic conductive material.

  Preferably, the ionic conductive filler material includes sacrificial anodic ions.

  Preferably, the ionic conductive filler material is porous.

  Preferably, the ionic conductive filler material is deformable.

  Preferably, the ionic conductive filler material includes at least one activator to ensure continued corrosion of the sacrificial anode.

  Preferably, the ionic conductive filler material is hygroscopic.

  Preferably, the ionic conductive filler material has a sufficiently high pH for sacrificial sacrificial anode corrosion to occur and for passive film formation on the sacrificial anode to be avoided.

  Preferably, a plurality of sacrificial anodes are provided, wherein the applied current anode is separated from said sacrificial anode.

  Preferably, a plurality of applied current anodes are provided, wherein the sacrificial anode is separated from said applied current anode.

  Preferably, the applied current anode is arranged such that it is temporarily mounted to provide a current through the surface of the ionically conductive material.

  Preferably, there are sacrificial anode ions available to be deposited.

  Preferably, the sacrificial anodic ions are soluble.

  Preferably, the sacrificial anode ion is electrochemically mobile.

  Typically, but not necessarily, this arrangement is designed for use where the metal part is steel and the ionic conductive material is concrete or mortar.

  In some cases, a portion of the structure or sacrificial anode is wetted.

  In some cases, the applied current anode is temporarily attached for the purpose of depositing ions of the sacrificial material.

The above method can be performed using an anodic device to cathodic protect metal parts in the ionically conductive material, the anodic device comprising:
Sacrificial anode of a material less noble than metal parts;
Applied current anode;
A first electrical connector arranged for connection to a sacrificial anode;
And a second electrical connector arranged for connection to an applied current anode,
The sacrificial anode and the applied current anode include components of an anode device, such that when the components of the anode device are positioned in contact with the ion conductive material, each of the sacrificial anode and the applied current anode is Under ionic conductive communication with the other, and with the metal part;
The applied current anode and the sacrificial anode are electrically separated to prevent electrical transmission therebetween.

  This anode device can be used in a method of corrosion protection of metal parts in an ionically conductive coating material, where both the applied current anode and the sacrificial anode are positioned in contact with the ionically conductive material and a direct current A power source is connected between the applied current anode and the metal portion to create a current between the metal portion and the applied current anode used to make the metal portion passive; Is terminated, there is a connection between the sacrificial anode and the metal part, so that the sacrificial anode continues to provide corrosion protection.

  Preferably, in a first step, the sacrificial anode is connected to the metal portion by providing corrosion protection of the metal portion by corrosion of the sacrificial anode producing a corrosion product of the sacrificial anode material in the ionically conductive material; and In a second step after sacrificial anode corrosion has occurred, the current applied by the DC power supply through the ion conductive material causes the sacrificial anode ions from the corrosion products of the sacrificial anode material to be redeposited on the sacrificial anode. Next, the anode device is used. In a similar manner, sacrificial anode ions can be deposited to create a sacrificial anode or to increase the size of an existing sacrificial anode.

In this way, the charging or deposition process is more than possible with a certain amount of zinc in the anode or other galvanic materials such as aluminum, magnesium, or other materials (not as precious as the metal parts to be protected). It can also be used repeatedly and periodically to ensure continued operation of the anode device for much longer periods of time. This can be done, for example, using solar cells, where recharging occurs daily. Alternatively and more typically, this is done by periodic maintenance, where the operator periodically visits the site and applies power for as long as necessary to achieve recharging.

  In one particular aspect of the present invention, which is independently patentable, for cathodic protection of metal parts in ionic conductive materials, including conductors capable of forming an applied current anode and consequently a sacrificial anode. Wherein the sacrificial anode and the applied current anode include the components of the anode device, such that, when the components of the anode device are positioned in contact with the ionically conductive material, the sacrificial anode and the applied current anode are provided. Each of the applied current anodes is under ionic conductive communication with each other and with the metal part. Thus, the charging of the sacrificial anode described above can occur entirely in situ, such that the ions are applied onto the conductor by deposition from an ionically conductive material. As mentioned above, the applied current anode and the sacrificial anode must be electrically separated to prevent electrical transmission therebetween.

  In one configuration, to provide the ions, the applied current anode may be formed of a sacrificial anode material such as zinc, such that the application of a DC power supply causes corrosion of the applied current anode and deposits on the sacrificial anode. To produce sacrificial anodic ions that can be used later. However, the ions of the sacrificial material may be provided in the ionically conductive material itself or in an additional filler material at or adjacent to the sacrificial anode.

  Preferably, simultaneously with the connection of the second terminal of the DC power supply to the sacrificial anode, the second terminal of the DC power supply also has the first terminal of the power supply connected to the applied current anode and the second terminal of the power supply connected to the sacrificial anode and Connected to the metal part as if it were connected to the metal part. This configuration creates a larger protection current than the galvanic current alone to achieve the passivation of the steel (metal part), as well as to cause a recharging effect, while simultaneously recharging the sacrificial anode. By providing options, it can be used to cause an effect to provide enhanced protection of the metal part.

  The connection of the sacrificial anode to the metal part may provide a galvanic corrosion protection backup to provide corrosion protection to the metal part if the DC power or applied current anode system is not functional. Should the applied current anode fail, connecting a sacrificial anode to the metal part provides a simple and automatic corrosion protection backup system.

The term “applied current anode” as used herein is intended to distinguish it from a sacrificial anode, where the sacrificial anode preferentially corrodes against the metal part to be protected. Formed of a material (typically zinc) that is less noble than a metal part. The applied current anode is used with an external power supply and need not be as noble as the metal part. Typically, such applied current anodes are made of titanium, carbon, and other noble metals, and oxides that do not readily corrode, or they can be made of steel or less noble materials such as zinc. .

  The sacrificial anode and the applied current anode preferably form common components of the anode device. That is, a device as supplied for use includes both components as a general system. However, they may or may not be assembled into common accessory structures that can be inserted into the material or applied on a surface as a general assembly. The general assembly is, of course, preferred for convenience, but the components may be separately inserted, for example, in one or separate drilled holes or slots in the concrete structure, placed in new concrete, or placed on a concrete surface or It can be applied separately to other places. The applied current anode may be temporarily applied to an outer surface of an ionically conductive material, such as a plate attached to the outer surface of the concrete, for charging a sacrificial anode in the body of the concrete.

  The device preferably includes a DC power supply with a positive terminal and a negative terminal as parts of the device. This is any form of device that can provide a DC output at the required voltage, such as a battery, solar cell, etc., or can be a rectifier. Power may also be supplied separately and / or temporarily so as not to be an integral component of the device itself. However, in the use of the system, a suitable source of DC power must be used for at least some time.

  As a further component of the device, preferably a switchable connection box comprising connectors for connection to the positive and negative terminals of the power supply, to the first and second electrical connectors and to the metal parts. Provided. However, this can be provided as a separate component and again is not an integral part of the system. Connections can also be made where there are no specific switchable junction boxes.

  Preferably, the applied current anode is perforated to allow ionic current to pass through the applied current anode. However, this is not essential, as the applied current anode and the sacrificial anode may include separate elements that are simply positioned in adjacent cooperative relationships in the material. The ionic current must pass from the sacrificial anode to the metal portion, which can pass through the applied current anode or remain around the applied current anode or around a portion of the applied current anode. However, if the sacrificial anode and the applied current anode are formed as a general assembly, the ionic current preferably passes through or remains around the applied current anode. Therefore, the applied current anode may be formed as a separate piece or spaced to allow current to pass through the metal portion. Thus, for example, the applied current anode may be pierced by a macroscopic hole formed through or cut into the anode.

  In another preferred example, the applied current anode is formed from electrically conductive components in the matrix, providing space in the matrix between the conductive components that allows ionic current to pass through the matrix. . This can be achieved, for example, by sintering the anode material and / or other materials, or by reducing the oxides to form an electrically conductive matrix.

  When the process is used to obtain a uniform, symmetrical deposition of the anode material on the sacrificial anode during recharging, the applied current anode surrounds the sacrificial anode, Preferably, the anode is arranged in a plane containing the sacrificial anode to completely, almost completely, partially or separately surround the anode, so that the sacrificial anode is rotated 360 degrees in the plane. Pass through the applied current anode. If the applied current anode is wholly or partially located on one side, the deposition occurs preferentially on that side and may therefore not be deposited very effectively. Thus, preferably, in a coaxial arrangement, the sacrificial anode forms a rod and the applied current anode forms a sleeve surrounding the rod. Alternatively, the sacrificial anode is in the form of a plate, rod, ribbon, or other similar element, and the applied current anode is located on one side of the plate, such that one side of the sacrificial anode on which the applied current anode is located First, deposition can occur.

  Preferably, an ionic conductive filler material is provided, not the ionic conductive material itself, located between the applied current anode and the sacrificial anode, and thus, preferably in a coaxial arrangement, the filler material forms a cylinder surrounding the rod. . Preferably, the ionic conductive filler material is in ionic contact with at least a portion of the surface of the sacrificial anode.

  For use in the sacrificial or galvanic phase of the operation of the above method, the ionic conductive filler material preferably includes at least one activator to ensure continued corrosion of the sacrificial anode. However, activators can also be located elsewhere in the system. Suitable filler materials can be in solid, gel, or liquid form. Suitable activators include alkali hydroxides, wetting agents, catalytic materials, and other materials that are corrosive to the sacrificial anode metal. The activators can be used alone or in combination.

  For use in the sacrificial or galvanic phase of the operation of the above-described method, the ionic conductive filler material is preferably used for corrosion of the sacrificial anode to occur and for passivation film formation on the sacrificial anode to be avoided. , With a sufficiently high pH. Alternatively, the filler material may comprise a low pH and / or activator for sacrificial sacrificial anode corrosion to occur and for passive film formation on the sacrificial anode to be avoided.

  The anodes and methods herein are preferably designed for use where the metal part is steel and the ionic conductive material is concrete or mortar.

  The anode device, including the applied current and sacrificial components, is typically buried in concrete or other solid material so that it is completely covered by the concrete, but this is not essential and the anode is partially It can only be buried or in physical or ionic contact with concrete.

  The anode device, including the applied current anode and the sacrificial component, can be surrounded by an encapsulating material or an ionically conductive filler material, which can be a porous material or a porous mortar material. Suitable encapsulating materials may be inorganic or organic and may be any cementitious, polymeric, or non-cementitious material or mortar, including geopolymer or modified Portland cement. The encapsulation material may be solid, gel, or liquid, and may be deformable.

  The purpose is therefore the arrangement described in more detail below for coupling the galvanic anode to the applied current anode for use with an applied current and / or rechargeable galvanic anode system. The configuration allows the applied current anode to deliver current to either the rebar or galvanic anode, or simultaneously to both the rebar and galvanic anode. The anode assembly can be used in three different ways: a) as a normal galvanic anode, b) as an applied current anode, and c) importantly as a rechargeable galvanic anode. The assembly preferably includes an internal zinc core, acting as a galvanic anode, surrounded by a suitable activating electrolyte. The zinc and activator are preferably covered in a porous or mesh type applied current electrode.

  Thus, the galvanic anode provided herein is flexible in operation so that continuous protection can be provided to the structure or components of the structure over a period compatible with the applied current corrosion protection system. possible.

  The configuration may allow the applied current anode to deliver cathodic current to either the rebar or galvanic anode, or both to the rebar and galvanic anode. The anode assembly must be used in three different ways: as a normal galvanic anode, as an applied current anode, and most importantly, as a rechargeable galvanic anode. The latter ability allows multiple use of the same mass of zinc, as it is recycled into the activating electrolyte and returns from the electrolyte in the charging process, eliminating the need for the use of a larger amount of anode for long-term protection .

  In a preferred arrangement in the alkaline activator, the zinc corrosion product is ultimately believed to be primarily zinc oxide. Therefore, it is possible to reverse the corrosion process and redeposit zinc metal onto the anode assembly. The arrangement described herein provides a method for redepositing zinc metal without removing the anode assembly from the protecting structure. A counter or applied current anode is provided that can be used as an anode to recharge zinc. This counter electrode is preferably part of the anode assembly. Thereafter, the same electrodes can be utilized if the settings need to be changed to an applied current system.

  The sacrificial anode can be any of a number of more electronegative materials, such as zinc, aluminum, magnesium, or alloys thereof.

  The DC power supply can be a battery. The power supply may be a rectifier that generates DC power from an AC applied voltage. Preferably, the DC power supply has a potential greater than 1.5V. If the power source is a battery, it may be rechargeable. If the power source is a battery, it may be replaceable in the assembly. This is a routine and convenient way to provide charging and / or to provide an additional step of applying current to the steel by simply inserting a new battery and leaving it to be exhausted. Yes, and shortly thereafter, the system operates galvanically until the depleted battery is removed and another is inserted. The battery can be mounted at any convenient location, such as a junction box, monitoring unit, or other convenient location. A single battery can power a group of anodes.

  The power supply may include a solar panel that drives an applied current anode and a rechargeable galvanic anode to provide long-term protection when solar power is turned on and off.

In accordance with another aspect of the present invention, there is provided a method of preventing corrosion of a metal portion in an ionically conductive coating material, the method comprising:
Positioning the applied current anode in contact with the ionic conductive material;
Positioning a sacrificial anode of a material less noble than a metal part in contact with the ionically conductive material;
Providing a DC power supply;
Providing a connection of a direct current power supply across the applied current anode and the metal portion to create a current between the metal portion and the applied current anode to provide corrosion protection of the metal portion;
And providing a connection between the sacrificial anode and the metal portion such that the sacrificial anode provides corrosion protection for the metal portion.

  The connection across the applied current anode and the connection to the sacrificial anode may be in place at the same time, or connected when either is needed. Either connection can be made using a simple connector or manually using a switch box or by an automatic control system.

  In one configuration of the above method, the connection of the DC power supply across the applied current anode provides an initial applied current, and if the initial applied current terminates, the connection between the sacrificial anode and the metal portion is: Continue to provide corrosion protection.

  In another configuration of the above method, the connection between the sacrificial anode and the metal portion provides corrosion protection, and after the time of corrosion protection provided by the sacrificial anode, the DC power supply is further protected by the metal portion. Connected across the applied current anode. This can be performed periodically during operation of the sacrificial anode. After initialization, the initial action in prevention can be either a sacrificial anode or an applied current anode, as selected by one skilled in the art according to the state of the configuration.

  In both cases, the connection of the sacrificial anode may be in place while the applied current is connected, or may be connected when the applied current terminates.

  Preferably, the initial current provided by the applied current anode is sufficient to passivate the metal part. However, the specific effects obtained in the first step are not essential, and other effects can be advantageously obtained using this method.

  Preferably, the sacrificial anode and the applied current anode include the common components of the anode device, so that when the common components of the anode device are located on the ionically conductive material, the sacrificial anode and the applied current anode are Each is under ionic conductive communication with each other and with the metal part. However, separate anode elements can also be provided.

  Preferably, the applied current anode and the sacrificial anode are electrically separated to prevent electrical transmission therebetween.

  Preferably, a connector is provided for connection of the power supply to the positive and negative terminals, wherein the first electrical connector is connected to an applied current anode and the second electrical connector is connected to a sacrificial anode and / or a metal part.

  Preferably, the applied current anode is perforated to allow ionic current in the ionically conductive material to pass through the applied current anode. Many different techniques can be provided to obtain the effect of perforation so that the ionic current can pass.

  Preferably, the sacrificial anode forms a rod and the applied current anode forms a sleeve surrounding the rod. However, other configurations, such as parallel or adjacent plates, may be provided.

  Preferably, an ionic conductive filler material is provided adjacent to the sacrificial anode, wherein the ionic conductive filler material is different from the ionic conductive material.

  Preferably, the ionic conductive filler material includes at least one activator to ensure continued corrosion of the sacrificial anode. Various types of actives are available and can be used.

  Preferably, the ionic conductive filler material has a sufficiently high pH for sacrificial sacrificial anode corrosion to occur and for passive film formation on the sacrificial anode to be avoided.

  In one example, a plurality of separate sacrificial anodes are provided, and the applied current anode is separated from the sacrificial anodes.

  In another example, a plurality of applied current anodes are provided, wherein a sacrificial anode is separated from the applied current anodes. However, typically, the sacrificial anode and the applied current anode are part of a common structure.

  In another arrangement that may be used, the applied current anode is temporarily mounted to provide a current through the surface of the ionically conductive material. That is, the applied current anode is arranged to be temporarily attached (utilized / installed and operated) during charging of the sacrificial anode.

  The structures and methods proposed herein are designed especially when the metal part is steel and the ionic conductive material is concrete or mortar. However, the same configuration can be used in other corrosion protection systems, such as pipes or other structures in the soil, and in many other systems where the anode can be used.

  Preferably, a porous or deformable material is provided for absorbing corrosion products from the sacrificial anode. This can be an encapsulating component or present on the sacrificial anode itself.

  Preferably, the assembly is an anode such as that disclosed in U.S. Patent No. 7,226,532 issued June 5, 2007 to Whitmore, which may be cited for further details. Forces, such as expansion, shrinkage, and deformation forces, which can be caused by corrosion, sacrificial anodic ion deposition, and other physical / environmental forces such as freezing, thawing, wetting, drying, and thermal expansion / contraction. And a reinforcing layer for suppressing and resisting.

One embodiment of the present invention will now be described in combination with the accompanying drawings.
FIG. 2 is a schematic diagram of a corrosion prevention method according to the present invention using a first arrangement of anode devices. FIG. 2 is a schematic diagram of FIG. 1 showing the connection of components for operation in a sacrificial protection mode. FIG. 2 is a schematic diagram of FIG. 1 showing the connection of components for operation in an applied current protection mode. FIG. 2 is a schematic diagram of FIG. 1 showing the connection of components for operation in a recharge mode. FIG. 2 is a schematic diagram of FIG. 1 showing the connection of components for operation in a combination of modes of recharging and applied current. FIG. 4 is a schematic view of a corrosion prevention method according to the present invention using a second arrangement of anode devices. Further corrosion protection method according to the invention using a further arrangement of the anode device, when the existing sacrificial anode is recharged by a temporary plate electrode mounted on the outer surface of the ionic conductive material of the concrete FIG. 1 is a cross-sectional view through a first example of an anode device according to the invention. 9 is a graph of the current output of the anode of FIG. 8 to a) steel with an anode as originally made and b) an anode after a charging period via a porous conductive applied current anode. 9 is a graph of the accumulated charge output of the anode of FIG. 8 to a) a steel with an anode as originally made and b) a steel after a charge period via a porous conductive applied current anode. FIG. 4 is a cross-sectional view of a second example of the device according to the invention. FIG. 12 is a plan view of a test arrangement for the embodiment of FIG.

  In the drawings, like reference characters indicate corresponding parts in different drawings.

  FIG. 1 shows a coating material (10), a steel material (11) embedded therein and an anode body (12).

  The coating material (10) is a suitable material that allows the transfer of ions through the coating material between the anode body (12) and the steel (11). The coating material is typically concrete, but may also include mortar or masonry material, or soil, water, or other ionic conductive materials, where steel structures requiring corrosion protection to prevent or inhibit corrosion Exists. While the steel material (11) is shown in a rebar arrangement, other steel elements may be protected in the manner of the arrangement shown herein, including lintels, steel beams and columns, pipes, tanks, or concrete. Alternatively, it includes a steel structural member, such as another element in contact with another coating material.

  The anode member is disclosed in U.S. Patent No. 6,027,633 issued February 22, 2000; 6,165,346 issued December 26, 2000; 6,572 issued June 3, 2003. No. 6,793,800 issued on September 21, 2004, No. 7,226,532 issued on June 5, 2007, and No. 7,914,661 issued on March 29, 2011. No. 7,959,786 of the present invention, issued on June 14, 2011, No. 6,022,469 (Page) issued on February 8, 2000, assigned to Vector Corrosion Technologies and October 10, 2001. No. 6,303,017 (Page and Sergi), published on March 16, Vector Corrosion Tech. 6,193,857 (Davison) issued February 27, 2001; Bennett No. 6,217,742 issued April 17, 2001; No. 7,160,433, No. 8,157,983 issued Apr. 17, 2012, assigned to Vector Corporation Technologies, and No. 6,471,851 issued Oct. 29, 2002, Aug. 2011. No. 7,998,321 of Giorgini issued on the 16th, No. 7,851,022 of Schwarz issued on Dec. 14, 2010, and No. 8, 211,289 of Glass et al. Issued on Jul. 3, 2012 No. 8,002,964 issued on August 23, 2011 and No. 7,749,362, 20 issued on July 6, 2010. Includes or includes the features shown in 7,909,982 issued March 22, 2011 and 7,704,372 issued April 27, 2010, assigned to Vector Corrosion Technologies. And citations to them must be made for further details as needed.

  A DC power supply (14) is provided that generates a voltage at terminals (15) and (16) of the power supply.

  In the embodiment shown, a lead-acid battery with an output of 6 or 12 volts and a life of 1 to 20 weeks, or providing an output voltage on the order of 1.5 volts and having a life on the order of 3 to 5 years The battery forms the power source, which can be a well-known and commercially available zinc-air battery. The voltage may drop from a nominal value of 1.5 volts to as low as possible 1.0 volts during the current flow in operation. Such batteries of this type are commercially available from ENSER Corporation or others. A suitable battery may have a capacitance of up to 1200 amp hours.

  Alternative power supplies can be used, including solar panels and conventional rectifiers, which require an external AC applied voltage and convert the AC supply to DC voltage at terminals (15) and (16).

The anode device (12) includes a sacrificial anode (20) of zinc or other material less noble than a metal part, along with an applied current anode (21). The sacrificial anode (20) is in the form of a rod, and the applied current anode (21) is generally an ion conductive material (10) positioned as a cylinder between the applied current anode (21) and the sacrificial anode (20). No, in the form of a sleeve surrounding the rod with an ion conductive filler material (22). In this coaxial combined configuration, the applied current anode is positioned in the radial plane of the rod's center of gravity axis to completely surround the periphery of the sacrificial anode, so that the ionic current through the sacrificial anode rotates 360 degrees in the plane. Generally passes through the applied current anode on the path to the steel (11).

  Thus, the sacrificial anode (20) and the applied current anode (21) form a common component of the anode device (12), so that each of the sacrificial anode (20) and the applied current anode (21) Under ionic conductive communication with each other and with metal parts. The filler material is not electrically conductive such that the applied current anode and the sacrificial anode are electrically separated to prevent electrical transmission therebetween.

  A switchable junction box (23) is provided, comprising connectors (231) and (232) for connection of the power supply to the positive and negative terminals. The junction box further comprises a connector (233) for the lead (236) to the applied current anode (21), a connector (234) for the lead (237) to the sacrificial anode (20), and a lead () to the metal part (11). 238) to the connector (235). Leads (236), (237), and (238) are preferably wires and are preferably corrosion resistant. The lead (236) has the greatest need for corrosion resistance because it is connected to the applied current anode during operation. Examples of corrosion resistant materials for applied current connections include titanium, niobium, nickel, platinum plated wires, and insulated wires.

  The applied current anode is perforated with either macroscopic holes (211) or macroscopic structures to allow ionic current from the anode (20) to pass through the applied current anode. Macroscopic holes can be provided by the formation of an applied current anode in discrete pieces.

  In configurations where the anode (21) is macroscopically drilled, the applied current anode has sufficient porosity and sufficient porosity and space within the applied current anode material to allow ionic current to pass through the applied current anode material. An ion conductive material is provided.

  The ionic conductive filler material (22) preferably includes at least one activator to ensure continued corrosion of the sacrificial anode. The ionic conductive filler material preferably has a sufficiently high pH for sacrificial sacrificial anode corrosion to occur and for passive film formation on the sacrificial anode to be avoided or minimized. For zinc, this pH is typically greater than 12, and may be greater than 13, 13.3, or 13.4. It is preferred that the zinc corrosion products remain partially or substantially soluble. This can be achieved by incorporating ions or other chemicals that are corrosive to the sacrificial anode material and / or protect the surface of the sacrificial anode material from passivation. Examples of materials that produce soluble corrosion products and / or help prevent passivation are disclosed in the above referenced patents.

  The ionic conductive material (22) is also preferably very ionic conductive, hygroscopic, and accommodates volume changes as the sacrificial anode is charged and released. The ionic conductive filler material may also be porous or deformable to accommodate these changes.

  In FIG. 6, the second of the anode devices in which the sacrificial anode (20A) and the applied current anode (21A) are formed as two parallel plates, meshes, ribbons or wires with filler material (22A) in between. A schematic diagram of a method using the configuration is shown. In this case, recharging of the sacrificial anode can occur primarily on one side. In an alternative construction, two parallel layers of plate or mesh may be applied to the surface of the coating material.

  In FIG. 7, the existing sacrificial anode (40) is recharged by a temporary surface applied to the electrode (applied current anode) (41) on the outer surface of the concrete (10) forming the ionic conductive material. A schematic diagram of a method using a further configuration is shown. In this case, the conductor (42) connects the applied current anode to one terminal of the power supply (14), and the conductor (43) connects the buried sacrificial anode (40) to the other terminal of the DC power supply. . At the same time, if protection of the steel is intended to last during the recharging process, the second terminal may be connected to the steel. Surface applied electrodes are a preferred embodiment for charging existing sacrificial anodes, but other applied current anodes, such as embedded applied current anodes, may be used.

  The four distinct functions provided by the junction box can be performed simply as follows. These functions can also be performed manually without the need for a junction box by direct connection of appropriate connectors.

  a) Normal galvanic anode as shown in FIG. 2: The zinc core is connected to the steel via a junction box. The applied current anode is placed in the off position. This allows the anode to act as a simple galvanic anode.

  b) Applied current anode as shown in FIG. 3: The zinc anode is placed in the off position and the applied current anode is connected to the steel via a DC power supply. The current output can be adjusted by controlling the applied voltage.

  c) Recharging of the galvanic anode as shown in FIG. 4: The applied current anode is connected to the zinc anode via a DC power supply. Steel is installed in the off position. This allows zinc ions or zinc corrosion products present in the electrolyte to be deposited on the zinc core as zinc metal which builds the thickness of the zinc anode. Zinc oxide and zinc hydroxide are two common corrosion products that are produced while the zinc anode is in operation.

  d) Rechargeable anode and applied current as shown in FIG. 5: The applied current anode is connected to both the zinc anode and steel via a DC power supply. This allows the recharging process described in c) and the applied current described in b) to proceed simultaneously.

  The first two functions are well understood and require no further explanation. However, the arrangement in which both selections are available (and operable) simultaneously is novel.

A third function is novel with respect to the use of galvanic anodes for rebar protection, and comprises the step of making the zinc anode a cathode that allows for zinc deposition. Zinc can be deposited from many zinc compounds through various reactions, possibly including reactions 1, 2, and 3 when zinc is in an alkaline environment.
ZnO + 2OH ⁻ + H ₂ O → Zn (OH) ₄ ²⁻ (1)
Zn (OH) ₄ ²⁻ → Zn ²⁺ + 4OH ⁻ (2)
Zn ²⁺ + 2e ⁻ → Zn (3)

  In theory, all zinc oxide and other zinc ions and zinc corrosion products can be redeposited on the core as zinc that can be used for later consumption. In fact, as with rechargeable alkaline batteries, the level of charge after each is probably reduced.

A typical reaction at an applied current anode is probably as follows:
2OH ⁻ → 1 / 2O ₂ + H ₂ O + 2e ⁻ (4) or H ₂ O → 1 / 2O ₂ + 2H ⁺ + 2e ⁻ (5)

  Therefore, there is a net balance of hydroxide ions, meaning that there is no overall loss in alkalinity in the assembly. A net increase in hydroxide ions on the surface of the zinc anode, which is first beneficial in applying large amounts of soluble zincate ions once the anode is used again in galvanic mode to protect the rebar Exists. The reaction at the applied current anode (Eq 4 or 5) involves the production of oxygen gas that needs to escape from the assembly to the concrete pore structure. The applied current anode must therefore be porous, in the form of a net, or vented.

  The preferred method of using the anode arrangement herein is to first install it as a normal galvanic anode and allow it to run for a period of about 10-20 years depending on exposure conditions. To Occasional monitoring determines when charging of the anode is required. Thereafter, an external power supply is used to charge the anode for a relatively short period of time, preferably less than 14-60 days. Thereafter, the anode can generate a suitable current for an additional period, about 5-20 years. The process may be repeated several times until the charging is essentially invalid. If needed, the applied current portion of the anode can then simply be used as part of an applied current corrosion protection system. Therefore, protection of the rebar can be achieved over the entire life of the structure.

  The assembly provides great flexibility, allowing for variable application types. For example, preliminary use of the applied current portion of the anode is to pass an initial high level charge over a limited time to passivate the steel to substantially stop any ongoing corrosion Can be. Alternatively, the applied current portion of the anode transfers the stored charge to increase the alkalinity of the concrete surrounding the steel and to reduce further corrosion and current demand from the galvanic anode. Can be operated as follows. An applied charge of 20,000 to 150,000, and more typically 70,000 to 100,000 coulombs per square meter of steel has been shown to be sufficient to passivate the steel. An applied charge of about 700,000 coulombs / m 2 was effective in re-alkalizing carbonated concrete (increasing pH). The charge required to increase the pH of non-carbonated concrete is less than 700,000 coulombs / m2. It then follows the lower level of galvanic current to maintain the passivity of the steel. Using an applied current anode to transmit a high initial charge, this prevents unnecessary consumption and degradation of the sacrificial anode, allows smaller sacrificial anodes to be used, and reduces the This is beneficial because it allows the sacrificial anode to provide higher current after passing through a higher initial charge. If necessary, charging of the anode can still be performed. Further, if steel passivity is lost and the current from the sacrificial anode is not enough to polarize the steel, or if either the corrosion potential or the corrosion rate of the steel increases the desired level, further Externally applied current can be transmitted through the applied current anode of the assembly. The assembly also has the ability to operate primarily as an applied current anode with a rechargeable galvanic anode backup during periods when the applied current anode is offline or otherwise non-functional. Similarly, an applied current anode may be available to act as a backup to the sacrificial anode should the sacrificial anode become non-functional.

  In a preferred configuration, the insoluble anode is capable of delivering high levels of current, as low as 1 mA / cm2. Therefore, the resistance of the electrolyte is preferably as low as possible so that the gel may be more suitable than a solid. Significant levels of oxygen gas can be generated during charging that need to be properly dispersed through the anode wall and surrounding concrete.

The electrolyte is preferably very alkaline so that the anode can be recharged. Accordingly, it believed to condense as ZnO by supersaturation, after dissolution of zinc allows for Zn ^{_(OH) 4} high concentrations of ^2-in solution. These reactions are believed to be as described in equations 6 and 7 below, which are essentially the inverse of reactions 1 and 2.
^{_{Zn + 4OH - → Zn (OH}} ) 4 2- + 2e - (6)
Zn (OH) ₄ ^2- → ZnO + 2OH ⁻ + H ₂ O (7)

  Other electrolytes, which are not very alkaline, are also suitable as long as soluble or electrochemically mobile zinc ions are present.

  Preferably, the assembly is highly ionically conductive and contains sufficient moisture to allow the sacrificial anode ions to become mobile during charging or recharging. Wetting agents, gels, and other hygroscopic materials can be beneficial in this regard. In an alternative arrangement, the charging or recharging of the sacrificial anode is performed by applying water or another wettable material to at least a portion of the structure and / or specifically to the sacrificial anode that maintains sufficient conductivity during the charging or recharging process. It can be improved by applying a solution.

  Tests have shown that zinc can be deposited on many substrates, including zinc, titanium, copper, steel, and stainless steel. Thus, partially sacrificed and completely consumed sacrificial anodes can be regenerated.

<Example 1>
In one example, an 8 cm long cast zinc anode with a minimum diameter of 0.7 cm was positioned in a ZnO / thixotropic paste packed inside a conductive ceramic applied current anode tube. A zinc paste was made from a solution saturated with LiOH with 2M KOH and 20% ZnO with a thickener of sodium carboxymethylcellulose. The paste was packed in the space between the zinc anode and the inside of the 28 mm tube. Tests have shown that the ions can pass through the porous tube wall, so that the zinc anode can conduct current on the external steel bars, even if positioned inside the applied current anode. Was done. Subsequently, charging of the zinc can be achieved by reversing the flow of ions through the porous tubular anode of the applied current by applying an external voltage between the applied current anode and the sacrificial anode. An applied voltage of about 6-8 volts resulted in up to 1.6 A of current delivered to the internal zinc anode achieving a total charge / recharge of just under 40,000 coulombs. Surprisingly, the zinc anode was better performed after recharging than the original. After charging the zinc anode, when the zinc anode is reconnected to the steel, the current output and accumulated charge output of the zinc anode charged by the porous tubular applied current anode leading to the steel are compared to the original zinc anode And increased. The exact reason for this improvement in performance is unknown, but the current output of the anode after charging increases.

  In FIG. 8, there is shown an example of a sacrificial device (30) as previously described, wherein the device has a cast zinc core inside a 28 mm diameter porous conductive applied current anode (32). (31). The upper end is closed by an attached disc (33) forming a porous shape, and the lower end is closed by a porous fabric cap (36). The core material (31) and the cylindrical anode (32) are provided with a filler material (35) of LiOH + 2M KOH + 20% ZnO + sodium carboxymethylcellulose. The core is attached to a steel wire (34) for the connection as described above.

  FIG. 9 is a graph of the current output of the anode of FIG. 8 to steel with a) an anode as originally made and b) an anode after a charging period via a porous conductive applied current anode.

  FIG. 10 is a graph of the accumulated charge output of the anode to steel after a charge period via a) a) the anode as originally made and b) a porous conductive applied current anode.

<Example 2>
An assembly (49) to demonstrate the ability to charge / recharge the anode in situ was constructed as shown in FIG. It consists of a zinc wire (50) partially immersed in a very alkaline (7-molar OH-) gel (51). A copper wire connector (53) for the sacrificial anode formed in situ was also dipped in the same gel. The gel was contained in a perforated plastic tube (54), which was lined both internally and externally, by layers of a textile fabric (55) and an ion conductive membrane (56). Between the outer fabric and the tube, a titanium mesh (57) coated with mixed metal oxide (MMO) was fixed around, which was equipped with a titanium connecting wire (58) attached to one side. The entire assembly was covered with LiOH-rich mortar (59).

  The anode assembly (49) was cast centrally in a 80mm x 50mm x 40mm high cement mortar prism, ensuring that the entire assembly was covered within the cement mortar (59). As shown in FIG. 12, the prism was then placed in a larger container (61), which was filled to almost prism height with the alkaline solution (60). An outer mesh of titanium (62) coated with MMO was placed along the perimeter of the container to act as a metal part. A zinc wire (50) was electrically connected to the external titanium mesh (62). The assembly (49) was then considered to act as a galvanic anode, passing current through the external titanium mesh (metallic part) and producing zinc corrosion products until all available zinc was consumed.

  An external power supply (not shown) is then applied to the internal MMO-coated titanium mesh anode (57) in the anode assembly (49) and copper wire (53) to ensure that copper is the cathode. Connected. Zinc corrosion products from spent (corroded) zinc wire (50) were deposited on copper wire (53) to form a sacrificial anode during this charging step. After the connection of the copper wire (53), current is passed between the charged anode (53) and the metal part (62), now carrying the deposited zinc and an external MMO coated titanium mesh (metal part). It became possible. The current produced by the charged anode (copper wire with deposited zinc) was comparable to the current produced by the original zinc wire. A comparison of the current generated by the original "discharge" of zinc deposited on zinc wire and copper wire is shown in Table 1.

Claims (25)

A method for preventing corrosion of a metal part in an ion conductive coating material, the method comprising:
Positioning the applied current anode in ionic contact with the ionic conductive material;
Positioning a sacrificial anode of a material less noble than a metal part in ionic contact with the ionically conductive material;
Providing a DC power supply;
Providing a connection of a direct current power supply across the applied current anode and the metal portion to create a current between the metal portion and the applied current anode to provide corrosion protection of the metal portion;
And providing a connection between the sacrificial anode and the metal portion such that the sacrificial anode acts to provide metal portion corrosion protection.   The application of a DC power supply between the applied current anode and the metal part provides an initial applied current, and upon termination of the initial applied current, the connection between the sacrificial anode and the metal part provides corrosion protection of the metal part, The method of claim 1, wherein:   Corrosion protection of the metal part is provided by the connection of the sacrificial anode and the metal part, and after a period of corrosion protection provided by the sacrificial anode, a DC power supply is applied between the applied current anode and the metal part to further protect the metal part. The method of claim 1, wherein protecting.   4. The method according to claim 1, wherein the sacrificial anode remains connected to the metal part during the applied current.   The method according to any of the preceding claims, comprising the step of passivating the metal part with an applied current.   6. The current provided by the applied current anode is applied until a minimum total charge of 20,000 coulombs per square meter is applied to the metal part. Method.   A method according to any of the preceding claims, comprising charging the sacrificial anode with sacrificial anode material from ions of the sacrificial anode material. An ionic conductive coating in which the sacrificial anode in ionic contact with the ionically conductive material is preferentially eroded against the metal portion such that the ions of the sacrificial material are depleted from the sacrificial anode as the sacrificial anode erodes. A method of use in preventing corrosion of a metal part in a material, the method comprising:
Charging the sacrificial anode with a sacrificial anode material from ions of the sacrificial anode material.   The sacrificial anode is charged by positioning the applied current anode in ionic contact with the sacrificial anode and by connecting a DC power source to the applied current anode such that the sacrificial anode ions are deposited on the sacrificial anode. The method according to claim 7 or 8, wherein   10. The applied current anode is comprised of a sacrificial anode material, and the application of DC power causes corrosion of the applied current anode to produce sacrificial anode ions deposited on the sacrificial anode. the method of.   The method according to any of the preceding claims, wherein the applied current anode is temporarily mounted in or on the coating material.   The method of any of claims 7 to 11, wherein the ions of the sacrificial material are provided for charging from a sacrificial anode, from a material surrounding the sacrificial anode, or from an ionically conductive material.   In a first step, the sacrificial anode is connected to the metal portion to provide corrosion protection of the metal portion by corrosion of the sacrificial anode resulting in the composition of the sacrificial anode corrosion product, and the sacrificial anode corrosion is reduced. 13. The method according to claim 1, wherein, in the second step after the occurrence, the current supplied by the DC power supply causes the ions of the sacrificial material from the corrosion products of the sacrificial anode to be redeposited on the sacrificial anode. The method according to any one of the above.   A DC power supply is connected to the applied current anode and to the metal part and the sacrificial anode, wherein the metal part is protected while the sacrificial anode is charged with ions of the sacrificial material. 14. The method according to any of 13.   Incorporating sacrificial material ions into the ionically conductive material or into a material adjacent to the sacrificial anode, wherein depositing the sacrificial material incorporated ions on the sacrificial anode causes the sacrificial anode to become ionically conductive. 15. The method according to any of the preceding claims, comprising the step of being produced or assembled into a material.   The method according to any of the preceding claims, wherein a DC power supply is applied temporarily.   17. The method according to any of the preceding claims, wherein the DC power supply is applied by photovoltaic cells or by periodic battery replacement. An anode device for cathodic protection of a metal part of an ion conductive material, the anode device comprising:
Sacrificial anode of a material less noble than metal parts;
Applied current anode;
Electrical connection to the sacrificial anode;
And including an electrical connection to the applied current anode,
The sacrificial anode and the applied current anode include components of an anode device, such that when the components of the anode device are positioned in contact with the ion conductive material, each of the sacrificial anode and the applied current anode is Under ionic conductive communication with the other, and with the metal part;
The anode device, wherein the applied current anode and the sacrificial anode are electrically separated to prevent electrical transmission therebetween.   19. The anode device according to claim 18, comprising a DC power supply.   20. The anode device according to claim 18, wherein the DC power supply includes a photovoltaic cell or a battery.   21. An anode device according to any of claims 18 to 20, wherein the applied current anode is perforated to allow the passage of ionic current through the applied current anode.   22. The anode device according to claim 19, wherein the applied current anode surrounds at least a part of the sacrificial anode.   22. The anode device according to claim 19, wherein the applied current anode and the sacrificial anode include adjacent elements.   24. An anode device according to any of claims 19 to 23, wherein an ionic conductive filler material is provided adjacent to the sacrificial anode.   25. An anode device according to any of claims 19 to 24, wherein the anode device is provided as a pre-assembled assembly.