EP0225343A1 - Maille en metal deploye et structure d'anode revetue. - Google Patents

Maille en metal deploye et structure d'anode revetue.

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Publication number
EP0225343A1
EP0225343A1 EP86903074A EP86903074A EP0225343A1 EP 0225343 A1 EP0225343 A1 EP 0225343A1 EP 86903074 A EP86903074 A EP 86903074A EP 86903074 A EP86903074 A EP 86903074A EP 0225343 A1 EP0225343 A1 EP 0225343A1
Authority
EP
European Patent Office
Prior art keywords
mesh
electrode
valve metal
metal
strands
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP86903074A
Other languages
German (de)
English (en)
Other versions
EP0225343B1 (fr
Inventor
John E Bennett
Gerald R Pohto
Thomas A Mitchell
Claude M Brown
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eltech Systems Corp
Original Assignee
Eltech Systems Corp
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Filing date
Publication date
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Application filed by Eltech Systems Corp filed Critical Eltech Systems Corp
Priority to AT86903074T priority Critical patent/ATE51042T1/de
Publication of EP0225343A1 publication Critical patent/EP0225343A1/fr
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
    • C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
    • C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
    • C23F13/10—Electrodes characterised by the structure
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
    • C25B11/03—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form perforated or foraminous
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/02—Electrodes; Connections thereof
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F2201/00—Type of materials to be protected by cathodic protection
    • C23F2201/02—Concrete, e.g. reinforced

Definitions

  • these dimensionally stable electrodes have been as anodes in chlor-alkali production in mercury cells, diaphragm cells and more recently in membrane cells.
  • Other uses have been as oxygen-evolving anodes for metal electrowinning processes, for hypochlorite and chlorate production, as metal plating anodes and so on.
  • Use as an anode in cathodic protection has also been proposed and as cathodes in certain processes.
  • these dimensionally stable valve metal electrodes have been proposed with various configurations such as rods, tubes, plates and complex structures such as an array of rods or blades mounted on a supporting current conducting assembly as well as a mesh of expanded valve metal typically having diamond shaped voids mounted on a supporting current conducting assembly which provides the necessary rigidity.
  • Electrodes in the form of platinized valve metal wire are known for cathodic protection, but in practically every other application rigidity and dimensional stability of the electrode are critical factors for successful operation. For example, many electrolytic cells are operated with an inter-electrode gap of only a few millimeters and the flatness and rigidity of the operative electrode face are extremely important.
  • the dimensionally stable electrodes operate at relatively high current densities, typically 3-5 KA/ 2 for membrane cells, 1-3 KA/m2 for
  • Typical known valve metal electrodes of the type with expanded titanium mesh as operative face use a mesh having an expansion factor of 1.5 to 4 times providing a void fraction of about 30 to 70 percent.
  • Such titanium sheets may be slightly flexible during the manufacturing processes but the inherent elasticity of the sheet is restrained, e.g. by welding it to a current conductive structure, typically having one or more braces extending parallel to the SWD dimension of the diamond-shaped openings.
  • Such electrode sheets typically have a
  • Electrode configurations are known for special purposes, e.g., a rigid cylindrical valve metal sheet mounted in a linear type of anode structure for cathodic protection (see U.S. Patent No. 4,515,886).
  • Manufacture of the known electrodes usually involves assembly of the electrode valve metal structure, e.g, by welding, followed by surface treatment such as degreasing/etching/sandblasting and application of the electrocatalytic coating by various methods including chemi-deposition, electroplating and plasma spraying.
  • Chemi-deposition may involve the application of a coating solution to the electrode structure by dipping or spraying, followed by baking usually in an oxidizing atmosphere such as air.
  • valve metals e.g., tantalum and zirconium
  • material cost becomes acceptable and they form an ideal structure for cathodic protection.
  • greatly expanded mesh is flexible and coilable and uncoilable about an axis along the L D dimension.
  • the expanded metal can be supplied in the form of large rolls which can be easily unrolled onto a surface to be protected, such as a concrete deck or a concrete substructure.
  • the pattern of voids in the mesh is defined by a continuum of valve metal strands interconnected at nodes and carrying on their surface an electrocatalytic coating.
  • the metal mesh is desirably stretchable along the SWD dimension of the pattern units whereby a coiled electrode roll of the mesh can be uncoiled on, and stretched over, a supporting substrate and into an operative electrode configuration.
  • the electrode system of the present invention satisfies all of the requirements for cathodic protection of reinforcing steel in concrete. It consists of the highly expanded valve metal which is activated by an electrocatalytic coating. Current can be distributed to the expanded valve metal by a welded contact of the same valve metal. A multitude of current paths in the expanded metal structure provide for redundancy of current distribution and hence the distribution of current to the reinforcing steel is excellent. Installation is simple since an electrode of greater than 100 square meters can be quickly rolled onto the surface of a concrete deck or easily cut to size and wrapped around a concrete substructure.
  • the coated mesh of the present invention may be utilized in any operation wherein the electrocatalytic coating on a valve metal substrate will be useful and wherein current density operating conditions up to 10 amps per square meter of mesh area are contemplated. Further details of the aspect of cathodic protection in concrete and the installation of coated mesh for such protection are provided in concurrently filed
  • the electrocatalytic coating used in the present invention is such that the anode operates at a very low single electrode potential, and may have a life expectancy of greater than 20 years in a cathodic protection application. Unlike other anodes used heretofore for the cathodic protection of steel in concrete, it is completely stable dimensionally and produces no carbon dioxide or chlorine from chloride contaminated concrete. It furthermore has sufficient surface area such that the acid generated from the anodic reaction will not be detrimental to the surrounding concrete.
  • the present invention is directed to an electrode for electrochemical processes comprising a valve metal mesh having a pattern of substantially diamond-shaped voids having LWD and S D dimensions for units of the pattern, the pattern of voids being defined by a continuum of valve metal strands interconnected at nodes and carrying on their surface an electrochemically active coating, wherein the mesh of valve metal is a flexible mesh with strands of thickness less than 0.125 cm and having a void fraction of at least 80%, said flexible mesh being coilable and uncoilable about an axis along the LWD dimension of the pattern units and being stretchable by up to about 10% along the SWD dimension of the pattern units and further being bendable in the general plane of the mesh about a bending radius in the range of from 5 to 25 times the width of the mesh, whereby said electrode can be uncoiled from a coiled configuration onto a supporting surface on which the mesh can be stretched to an operative electrode configuration.
  • the present invention is directed to a fast and economical coating technique for coiled mesh of even greatly extended length.
  • Such technique can achieve highly suitable coating results without deleterious strand breakage even for the more delicate meshes of greatly expanded valve metal and which have extremely great void volume.
  • considerably greater electrode areas for instance about 100 or even 200 square meters or even greater electrode surface areas, can be coated as a continuous expanse.
  • this economical coating operation can be undertaken and completed with equipment that typically will be readily available in existing facilities having conventional coating apparatus.
  • the present invention thus pertains to a method of manufacturing an electrode for electrochemical processes, of the type comprising a valve metal mesh provided with a pattern of substantially diamond shaped voids having LWD and SWD dimensions for units of the pattern, the pattern of voids being defined by a continuum of thin valve metal strands interconnected at nodes and carrying on their surface an electrocatalytic coating, with the method comprising: (a) providing a flexible, coiled valve metal mesh, the mesh being as described hereinabove and being coiled about an axis along the direction of the LWD dimension of the pattern, and (b) applying an electrocatalytic coating to the surface of the valve metal mesh while same is coiled to provide a flexible coated mesh electrode in coiled configuration, the mesh being uncoilable from the coiled configuration for use as an electrode.
  • the invention is directed to greatly expanded valve metal mesh as well as to a method for preparing such greatly expanded mesh.
  • FIGURE 1 shows a diamond-shaped unit of a greatly expanded valve metal mesh of the present invention.
  • FIGURE 2 shows a section of greatly expanded valve metal mesh, embodying diamond-shaped structure, and having a current distributor along the LWD dimension and welded to mesh nodes.
  • FIGURE 3 is an enlarged view of a mesh node, particularly showing the node double strand thickness.
  • the metals of the valve metal mesh will most always be any of titanium, tantalum, zirconium and niobium. As well as the elemental metals themselves, the suitable metals of the mesh can include alloys of these metals with themselves and other metals as well as their intermetallic mixtures. Of particular interest for its ruggedness, corrosion resistance and availability is titanium. Where the mesh will be expanded from a metal sheet, the useful metal of the sheet will most always be an annealed metal. As representative of such serviceable annealed metals is Grade I titanium, an annealed titanium of low embrittlement. Such feature of low embrittlement is necessary where the mesh is to be prepared by expansion of a metal sheet, since such sheet should have an elongation of greater than 20 percent.
  • Metals for expansion having an elongation of less than 20 percent will be too brittle to insure suitable expansion to useful mesh without deleterious strand breakage.
  • the metal used in expansion will have an elongation of at least about 24 percent and will virtually always have an elongation of not greater than about 40 percent.
  • metals such as aluminum are neither contemplated, nor are they useful, for the mesh in the present invention, aluminum being particularly unsuitable because of its lack of corrosion resistance.
  • annealing may be critical as for example with the metal tantalum where an annealed sheet can be expected to have an elongation on the order of 37 to 40 percent, which metal in unannealed form may be completely useless for preparing the metal mesh by having an elongation on the order of only 3 to 5 percent.
  • alloying may add to the embrittlement of an elemental metal and thus suitable alloys may have to be carefully selected.
  • a titanium-palladium alloy commercially available as Grade 7 alloy and containing on the order of 0.2 weight percent palladium, will have an elongation at normal temperature of above about 20 percent and is expensive but could be serviceable, particularly in annealed form.
  • the expected corrosion resistance of a particular alloy that might be selected may also be a consideration.
  • Grade I titanium such is usually available containing 0.2 weight percent iron. However, for superior corrosion resistance.
  • Grade I titanium is also available containing less than about 0.05 weight percent iron. Generally, this metal of lower iron content will be preferable for many applications owing to its enhanced corrosion resistance.
  • the metal mesh may then be prepared directly from the selected metal.
  • the mesh be expanded from a sheet or coil of the valve metal.
  • alternative meshes to expanded metal meshes may be serviceable.
  • thin metal ribbons can be corrugated and individual cells, such as honeycomb shaped cells can be resistance welded together from the ribbons. Slitters or corrugating apparatus could be useful in preparing the metal ribbons and automatic resistance welding could be utilized to prepare the large void fraction mesh.
  • a mesh of interconnected metal strands can directly result.
  • a highly serviceable mesh will be prepared using such expansion technique with no broken strands being present.
  • some stretching of the expanded mesh can be accommodated during installation of the mesh. This can be of particular assistance where uneven substrate surface or shape will be most readily protected by applying a mesh with such stretching ability.
  • a stretching ability of up to about 10 percent can be accommodated from a roll of Grade I titanium mesh having characteristics such as discussed hereinbelow in the example.
  • the mesh obtained can be expected to be bendable in the general plane of the mesh about a bending radius in the range of from 5 to 25 times the width of the mesh.
  • the interconnected metal strands will have a thickness dimension corresponding to the thickness of the initial planar sheet or coil. Usually this thickness will be within the range of from about 0.05 centimeter to about 0.125 centimeter. Use of a sheet having a thickness of less than about 0.05 centimeter, in an expansion operation, can not only lead to a deleterious number of broken strands, but also can produce a too flexible material that is difficult to handle. For economy, sheets of greater than about 0.125 centimeter are avoided. As a result of the expansion operation, the strands will interconnect at nodes providing a double strand thickness of the nodes. Thus the node thickness will be within the range of from about 0.1 centimeter to about 0.25 centimeter.
  • the nodes for the special mesh will be completely, to virtually completely, non-angulated.
  • plane of the nodes through their thickness will be completely, to virtually completely, vertical in reference to the horizontal plane of an uncoiled roll of the mesh.
  • the weight of the mesh will usually be within the range of from about 0.05 kilogram per square meter to about 0.5 kilogram per square meter of the mesh. Although this range is based upon the exemplary metal titanium, such can nevertheless serve as a useful range for the valve metals generally. Titanium is the valve metal of lowest specific gravity. On this basis, the range can be calculated for a differing valve metal based upon its specific gravity relationship with titanium. Referring again to titanium, a weight of less than about 0.05 kilogram per square meter of mesh will be insufficient for proper current distribution in enhanced cathodic protection. On the other hand, a weight of greater than about 0.5 kilogram per square meter will most always be uneconomical for the intended service of the mesh.
  • the mesh can then be produced by expanding a sheet or coil of metal of appropriate thickness by an expansion factor of at least 10 times, and preferably at least 15 times.
  • Useful mesh can also be prepared where a metal sheet has been expanded by a factor up to 30 times its original area. Even for an annealed valve metal of elongation greater than 20 percent, an expansion factor of greater than 30:1 may lead to the preparation of a mesh exhibiting strand breakage. On the other hand, an expansion factor of less than about 10:1 may leave additional metal without augmenting cathodic protection. Further in this regard, the resulting expanded mesh should have an at least 80 percent void fraction for efficiency and economy of cathodic protection.
  • the expanded metal mesh will have a void fraction of at least about 90 percent, and may be as great as 92 to 96 percent or more, while still supplying sufficient metal and economical current distribution.
  • the metal strands can be connected at a multiplicity of nodes providing a redundancy of current-carrying paths through the mesh which insures effective current distribution throughout the mesh even in the event of possible breakage of a number of individual strands, e.g., any breakage which might occur during installation or use.
  • suitable redundancy for the metal strands will be provided in a network of strands most always interconnected by from about 500 to about 2000 nodes per square meter of the mesh. Greater than about 2000 nodes per square meter of the mesh is uneconomical. On the other hand, less than about 500 of the interconnecting nodes per square meter of the mesh may provide for insufficient redundancy in the mesh.
  • strands within such thickness range will have width dimensions of from about 0.05 centimeter to about 0.20 centimeter.
  • the total surface area of interconnected metal i.e., including the total surface area of strands plus nodes, will provide between about 10 percent up to about 50 percent of the area covered by the metal mesh. Since this surface area is the total area, as for example contributed by all four faces of a strand of square cross-section, it will be appreciated that even at a 90 percent void fraction such mesh can have a much greater than 10 percent mesh surface area.
  • This area will usually be referred to herein as the "surface area of the metal” or the "metal surface area”. If the total surface area of the metal is less than about 10 percent, the resulting mesh can be sufficiently fragile to lead to deleterious strand breakage. On the other hand, greater than about 50 percent surface area of metal will supply additional metal without a commensurate enhancement in protection. After expansion the resulting mesh can be readily rolled into coiled configuration, such as for storage or transport or further operation. With the representative valve metal titanium, rolls having a hollow inner diameter of greater than 20 centimeters and an outer diameter of up to 150 centimeters, preferably 100 centimeters, can be prepared.
  • rolls can be suitably coiled from the mesh when such is prepared in lengths within the range of from about 40 to about 200, and preferably up to 100, meters.
  • such rolls will have weight on the order of about 10-50 kilograms, but usually below 30 kilograms to be serviceable for handling, especially following coating, and particularly handling in the field during installation for cathodic protection.
  • the gap patterns in the mesh will be formed as diamond-shaped apertures.
  • Such "diamond-pattern” will feature apertures having a long way of design (LWD) from about 4, and preferably from about 6, centimeters up to about 9 centimeters, although a longer LWD is contemplated, and a short way of design (SWD) of from about 2, and preferably from about 2.5, up to about 4 centimeters.
  • LWD long way of design
  • SWD short way of design
  • diamond dimensions having an LWD exceeding about 9 centimeters may lead to undue strand breakage and undesirable voltage loss.
  • FIG. 1 an individual diamond shape, from a sheet containing many such shapes is shown generally at 2.
  • the shape is formed from strands 3 joining at connections (nodes) 4.
  • the strands 3 and connections 4 form a diamond aperture having a long way of design in a horizontal direction.
  • the short way of design is in the opposite, vertical direction.
  • the surface area of the interconnected metal strands 3 When referring to the surface area of the interconnected metal strands 3, e.g., where such surface area will supply not less than about 10 percent of the overall measured area of the expanded metal as discussed hereinabove, such surface area is the total area around a strand 3 and the connections 4.
  • the surface area of the strand 3 will be four times the depicted, one-side-only, area as seen in the Figure.
  • the strands 3 and their connections 4 appear thin, they may readily contribute 20 to 30 percent surface area to the overall measured area of the expanded metal.
  • the "area of the mesh" e.g., the square meters of the mesh, as such terms are used herein, is the area encompassed within an imaginary line drawn around the periphery of the mesh.
  • the area within the diamond i.e., within the strands 3 and connections 4, may be referred to herein as the "diamond aperture ". It is the area having the LWD and SWD dimensions. For convenience, it may also be referred to herein as the "void”, or referred to herein as the "void fraction”, when based upon such area plus the area of the metal around the void. As noted in Fig. 1 and as discussed hereinbefore, the metal mesh as used herein has extremely great void fraction. Although the shape depicted in the figure is diamond-shaped, it is to be understood that many other shapes can be serviceable to achieve the extremely great void fraction, e.g., scallop-shaped or hexagonal. Referring now to Fig.
  • the strands 22 and connections 25 can form a substantially planar configuration.
  • particularly larger dimensional sheets of the mesh may be generally in coiled or rolled condition, as for storage or handling, but are capable of being unrolled into a "substantially planar" condition or configuration, i.e., substantially flat form, for use.
  • the connections 25 will have double strand thickness, whereby even when rolled flat, the substantially planar or flat configuration may nevertheless have ridged connections.
  • the nodes have double strand thickness (2T) .
  • the individual strands have a lateral depth or thickness (T) not to exceed about 0.125 centimeter, as discussed hereinabove, and a facing width (W) which may be up to about 0.20 centimeter.
  • the expanded metal mesh can be usefully coated. It is to be understood that the mesh may also be coated before it is in mesh form, or combinations might be useful. Whether coated before or after being in mesh form, the substrate can be particularly useful for bearing a catalytic active material, thereby forming a catalytic structure. As an aspect of this use, the mesh substrate can have a catalyst coating, resulting in an anode structure.
  • the metal, including coiled metal mesh, before electrocatalytic coating operation, may proceed through one or more of various pretreatment procedures. Such procedures may be simplistic, for example a simple rinse operation. Not infrequently the mesh may have, e.g., as by being imparted from the expansion operation, oils or other surface contamination. Therefore, a suitable pretreatment technique will often include a solvent degreasing operation. This can most always be accomplished with typical halocarbon solvent such as the chlorinated and/or fluorinated solvents as represented by chlorotrifluoromethane, methylene chloride and perchloroethylene.
  • typical halocarbon solvent such as the chlorinated and/or fluorinated solvents as represented by chlorotrifluoromethane, methylene chloride and perchloroethylene.
  • pretreatments for the coiled metal mesh may include the further typical techniques such as pickling and etching, as well as dry honing, i.e., sand blasting.
  • dry honing a gritty and very finely divided, hard particulate can be blasted at the coiled mesh at high velocity.
  • a representative etching operation most usually an aqueous solution of inorganic acid will be used to contact the metal mesh as by spray or dip contact.
  • a strong inorganic acid aqueous solution e.g., hydrochloric acid at a strength of up to about 30 percent concentration or more, can be utilized.
  • combination pretreatment techniques may be employed.
  • Such combination operations can include not only those where two different steps for a single operation are useful, e.g., a combination of spray and dip technique for degreasing, but also a combination such as a washing or rinsing action combined with mild abrasive treatment. Where several pretreatment operations are employed, for example degreasing and etching, intermediate steps between each operation may be used, such as drying and/or rinsing steps and the like.
  • etching may include contact with an aqueous, concentrated hydrochloric acid solution, as by dip coating contact for a time up to about 20 minutes. A contact time of greater than about 20 minutes can lead to deleterious loss of metal in the etching operation.
  • a contact time of greater than about 20 minutes can lead to deleterious loss of metal in the etching operation.
  • the coiled metal mesh will be dipped into the etching solution for a time of at least about 5 minutes to provide sufficient metal surface roughness for enhanced coating adhesion and distribution.
  • the useful concentrated hydrochloric acid solutions can contain acid in an amount within the range from about 5 to about 30 percent.
  • the liquid coating composition used will be such an electrochemically active coating as can be useful when applied as a lightweight coating.
  • This lightweight coating, or "low loading” coating will often be at a coating weight of less than about 0.5 gram of platinum group metal per square meter of the metal mesh substrate.
  • some coatings will be useful when present in an amount of as little as about 0.05 gram of platinum metal per square meter of a metal mesh substrate.
  • active oxide coatings such as platinum group metal oxides, magnetite, ferrite, cobalt spinel or mixed metal oxide coatings. Such coatings have typically been developed for use as anode coatings in the industrial electrochemical industry.
  • Suitable coatings of this type have been generally described in one or more of the U.S. Patents 3,265,526, 3,632,498, 3,711,385 and 4,528,084.
  • the mixed metal oxide coatings can often include at least one oxide of a valve metal with an oxide of a platinum group metal including platinum, palladium, rhodium, iridium and ruthenium or mixtures of themselves and with other metals. It is preferred for economy that the low load electrocatalytic coatings be such as have been disclosed in the U.S. Patent No. 4,528,084.
  • coatings will be applied to the coiled metal mesh by any of those means which are useful for applying a liquid coating composition to a metal substrate. Such methods include dip spin and dip drain techniques. Moreover spray application and combination techniques, e.g., dip drain with spray application can be utilized.
  • a modified dip drain operation of the coiled metal mesh will be most serviceable. In this operation, the coil will be dipped into a bath of coating composition in a manner whereby the axis through the hollow center of the coil is at least substantially parallel to the surface of the liquid coating composition. The coil can be partly immersed or completely submersed in the coating composition.
  • the coil may be immersed and rotated, withdrawn from the coating composition bath, and then reimmersed and rotated, or counterrotated, with such operation being repeated to thoroughly coat the coiled mesh.
  • the hollow center of the coil can be vertical and the coil hung in this manner is then either partially or completely dipped, i.e., up to total coil immersion, in the coating composition.
  • the wet coil may simply dip drain or be subjected to other post coating technique such as forced air drying.
  • Typical curing conditions for the electrocatalytic coating can include cure temperatures of from about 300°C. up to about 600°C. Curing times may vary from only a few minutes for each coating layer up to an hour or more, e.g., a longer cure time after several coating layers have been applied.
  • the curing operation can be any of those that may be used for curing a coating on a metal substrate.
  • oven curing including conveyor ovens may be utilized.
  • infrared cure techniques can be useful.
  • oven curing is used and the cure temperature used will be within the range of from about 450 C. to about 550 C. At such temperatures, curing times of only a few minutes, e.g., from about 3 to 10 minutes, will most always be used for each applied coating layer.
  • the coating is thus particularly suitable for reducing injury in the manual handling operations associated with the coiled mesh. For facilitating the manual handling ease of the mesh, as when a coil is placed into or removed from storage or when proceeding to subsequent operation, such as assembling with other elements, the coating readily lends itself to assisting in this ease of handling.
  • the above-described coating operation can be utilized following coiled mesh production whereby the resulting coated article can not only proceed to subsequent processing operation, but will also lend itself to ready manual handling in such operation.
  • additional metal members can be affix to the mesh, such as after coating.
  • metal current distributor members can be metallurgically bonded to the coated coil. Attachment of additional metal members can occur following the coating operation.
  • the additional metal elements include current distribution members
  • these can be utilized as strips applied to the unrolled mesh and the strips can be spot welded across the mesh at the nodes.
  • the current distributor members can have the low loading of electrocatalytic coating. Electrical resistance welding can be successfully employed to prepare these coated metal assemblies even where the metals for welding in face-to-face contact will each be coated faces.
  • Such current distributor member can then connect outside of the concrete environment to a current conductor, which current conductor being external to the concrete need not be so coated.
  • the current distribution member may be a bar extending through a hole to the underside of the deck surface where a current conductor is located. In this way all mechanical current connections are made external to the finished concrete structure, and are thereby readily available for access and service if necessary. Connections to the current distribution bar external to the concrete may be of conventional mechanical means such as a bolted spade-lug connector.
  • a roll of the greatly expanded valve metal mesh with a suitable electrochemically active coating can be unrolled onto the surface of such deck or substructure.
  • means of fixing mesh to substructure can be any of those useful for binding a metal mesh to concrete that will not deleteriously disrupt the anodic nature of the mesh.
  • non-conductive retaining members will be useful.
  • Such retaining members for economy are advantageously plastic and in a form such as pegs or studs.
  • plastics such as polyvinyl halides or polyolefins can be useful.
  • These plastic retaining members can be inserted into holes drilled into the concrete.
  • Such retainers may have an enlarged head engaging a strand of the mesh under the head to hold the anode in place, or the retainers may be partially slotted to grip a strand of the mesh located directly over the hole drilled into the concrete.
  • an ionically conductive overlay will be employed to completely cover the anode structure. Such overlay may further enhance firm contact between the anode and the concrete substructure.
  • Serviceable ionically conductive overlays include Portland cement and polymer-modified concrete.
  • the anode can be overlaid with from about 2 to about 6 centimeters of a Portland cement or a latex modified concrete.
  • the anode may be generally covered by from about 0.5 to about 2 centimeters of polymer modified concrete.
  • the expanded valve metal mesh substrate of the anode provides the additional advantage of acting as a metal reinforcing means, thereby improving the mechanical properties and useful life of the overlay. It is contemplated that the metal mesh anode structure will be used with any such materials and in any such techniques as are well known in the art of repairing underlying concrete structures such as bridge decks and support columns and the like.
  • the final strand dimension was 0.889 mm (T) x 0.914 mm (W) .
  • a current distribution bar was spot welded to one end of a piece of the expanded titanium, taken from the unrolled mesh, which measured 30 cm x 38 cm.
  • the structure was next vapor degreased in perchloroethylene vapor and etched in a 20 weight percent HCl solution for 5 minutes. It was thereafter water rinsed and steam dried.
  • An anode prepared as described above is then placed on top of a chloride contaminated concrete block and overlaid with 50 mm thickness of Portland cement.
  • a second identical anode is also placed on top of a chloride contaminated concrete block and overlaid with a 38 mm thickness of latex modified concrete. Both structures are judged by visual inspection to have desirable interbonding of the cement to concrete for the one block and of the modified concrete to concrete for the second block. From the hereinabove described accelerated life tests, lifetimes of anodes in these blocks are therefore expected to be very long.
  • the expanded metal coming through the expansion apparatus was easily coiled into a roll.
  • the resulting roll had an approximately 30 cm diameter interior hollow zone and an overall outside diameter of about 40 cm.
  • the weight of the roll was approximately 11.8 kilos. Titanium metal tie wires were used to prevent the roll from uncoiling in further operation.
  • a support rod was passed through the central hollow zone of the roll and the rod extended beyond the roll at each end whereby lines attached to each end from overhead were used with lifting apparatus. By means of this support rod assembly the roll was then lowered into a degreasing machine containing boiling perchloroethylene solvent. The roll was retained in the overhead vapor zone for about 20 minutes.
  • the degreased coil was immersed for 10 minutes in an aqueous solution of 20 weight percent hydrochloric acid, which solution was maintained at 95°C. Following this etching operation the coil was removed from the etching solution, water rinsed for about 15 minutes followed by steam drying for about 20 minutes.
  • the coil was then dipped into a bath of coating solution for providing an electrochemically active coating on the coil.
  • Coating solutions such as the one of this bath fall under the U.S. Patent No. 3,632,498, example 1. Since this depth of coating solution was less than the diameter of the coil, the coil was slowly rotated to expose the entire coil to the coating solution. Furthermore, the coil was lifted from the solution, rotated slightly around the support rod, redipped into the coating solution and rerolled through the solution. Upon final removal from the coating solution, the coil was agitated by a light manual shaking and then was retained over the tank of coating solution for approximately 30 minutes to permit solution that has been temporarily retained in corners of the diamond-shaped units to drain, as well as to permit the coil to dry.
  • the dried coil was maintained on its support rod apparatus and by means of this support was then introduced to a conveyor oven.
  • the coil proceeded through the oven in a time of 4 minutes whereby the wire mesh facing the hollow central zone of the coil attained a temperature of - 23 -
  • the coil Upon removal from the oven, the coil was reconveyed for a second 4 minute pass through the oven. After the second pass, the coil is permitted to cool. It was then subsequently uncoiled and found to contain no broken strands or adjacent strands stuck together by such coating and curing operation, and thus was easily and completely uncoiled.
  • the coating In analysis of coils coated in this manner, wherein the coils have been uncoiled and test pieces cut out for analysis, the coating has been found to provide mixed oxides of titanium and ruthenium in which the ruthenium content is 0.35 gram per square meter. Furthermore, such coating has been found to be sufficiently distributed throughout the mesh that all randomly selected areas for analysis demonstrate desirable coating content. Anodes prepared from such randomly selected samples and subjected to accelerated life testing have all demonstrated enhanced performance sufficient for these mesh anodes to serve in cathodic protection, such as protection of steel reinforced concrete. The coating and curing process using the mesh in coiled form, is thus judged to be highly desirable for supplying coated mesh which will be serviceable as such anodes.
  • the mesh will be connected to a current distribution member.
  • a current distribution member will most always be a valve metal and preferably is the same metal alloy or intermetallic mixture as the metal most predominantly found in the expanded valve metal mesh.
  • This current distribution member must be firmly affixed to the metal mesh.
  • One preferred manner of firmly fixing the member to the mesh is by welding, e.g., electrical resistance welding such as spot welding. Moreover, the welding can proceed through the coating.
  • a coated current distributor strip can be laid on a coated mesh, with coated faces in contact, and yet the welding can readily proceed.
  • the strip can be spot welded to the mesh at every node and thereby provide uniform distribution of current thereto.
  • Such a current distributor strip member positioned along a piece of mesh about every 30 meters will usually be sufficient to serve as a current distributor for such piece.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Mechanical Engineering (AREA)
  • Prevention Of Electric Corrosion (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Electrolytic Production Of Metals (AREA)

Abstract

La présente invention se rapporte essentiellement à une maille en métal à soupape d'électroconducteur avec un taux de vides extrême. Le mode de réalisation le plus important de ladite invention se rapporte à une application de la maille en tant que structure d'électrode, de manière à empêcher la corrosion de l'acier, notamment l'acier du béton armé, par protection cathodique. Afin de préparer la structure d'électrode, la maille métallique enroulée est enduite d'un revêtement électrocatalytique provenant d'une composition liquide. L'opération d'enduction peut s'effectuer par contact de la maille avec une composition de revêtement liquide, la maille étant maintenue dans sa forme enroulée. Cette méthode d'enduction très efficace est prolongée par une opération de vulcanisation, la maille revêtue étant toujours maintenue dans sa forme enroulée. La maille revêtue peut ensuite être déroulée et des distributeurs de courant peuvent être soudés à ladite maille qui peut alors être utilisée comme électrode, par exemple pour une protection cathodique.
EP86903074A 1985-05-07 1986-04-28 Maille en metal deploye et structure d'anode revetue Expired - Lifetime EP0225343B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86903074T ATE51042T1 (de) 1985-05-07 1986-04-28 Streckmetallnetz und beschichtete anodenstruktur.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US73142085A 1985-05-07 1985-05-07
US731420 1985-05-07

Publications (2)

Publication Number Publication Date
EP0225343A1 true EP0225343A1 (fr) 1987-06-16
EP0225343B1 EP0225343B1 (fr) 1990-03-14

Family

ID=24939430

Family Applications (2)

Application Number Title Priority Date Filing Date
EP86903075A Expired - Lifetime EP0222829B2 (fr) 1985-05-07 1986-04-28 Systeme de protection cathodique pour une structure en beton arme et procede d'installation
EP86903074A Expired - Lifetime EP0225343B1 (fr) 1985-05-07 1986-04-28 Maille en metal deploye et structure d'anode revetue

Family Applications Before (1)

Application Number Title Priority Date Filing Date
EP86903075A Expired - Lifetime EP0222829B2 (fr) 1985-05-07 1986-04-28 Systeme de protection cathodique pour une structure en beton arme et procede d'installation

Country Status (8)

Country Link
EP (2) EP0222829B2 (fr)
JP (2) JPS62502820A (fr)
AU (2) AU583627B2 (fr)
CA (2) CA1311442C (fr)
DE (2) DE3666232D1 (fr)
SA (2) SA90110113B1 (fr)
SG (2) SG64190G (fr)
WO (2) WO1986006758A1 (fr)

Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1986006758A1 (fr) * 1985-05-07 1986-11-20 Eltech Systems Corporation Maille en metal deploye et structure d'anode revetue
EP0264421B1 (fr) * 1986-05-02 1992-08-26 Norwegian Concrete Technologies A.S. Re-alcalinisation electrochimique du beton
US4855024A (en) * 1986-09-16 1989-08-08 Raychem Corporation Mesh electrodes and clips for use in preparing them
DE3826926A1 (de) * 1988-08-09 1990-02-15 Heraeus Elektroden Anode fuer kathodischen korrosionsschutz
GB8903321D0 (en) * 1989-02-14 1989-04-05 Ici Plc Metal mesh and production thereof
CA2018869A1 (fr) * 1989-07-07 1991-01-07 William A. Kovatch Anode en mailles et feuille de separation faite de polymere utilisees avec le beton arme
US5062934A (en) * 1989-12-18 1991-11-05 Oronzio Denora S.A. Method and apparatus for cathodic protection
FI87241C (fi) * 1990-06-20 1992-12-10 Savcor Consulting Oy Foerfarande foer att faesta ett elektrodarrangemang som anvaends vid katodisk skydd av betongkonstruktioner samt faestelement
US5531873A (en) * 1990-06-20 1996-07-02 Savcor-Consulting Oy Electrode arrangement to be used in the cathodic protection of concrete structures and a fixing element
US7866342B2 (en) 2002-12-18 2011-01-11 Vapor Technologies, Inc. Valve component for faucet
US8555921B2 (en) 2002-12-18 2013-10-15 Vapor Technologies Inc. Faucet component with coating
US7866343B2 (en) 2002-12-18 2011-01-11 Masco Corporation Of Indiana Faucet
US20070026205A1 (en) 2005-08-01 2007-02-01 Vapor Technologies Inc. Article having patterned decorative coating
JP4654260B2 (ja) * 2008-03-27 2011-03-16 住友大阪セメント株式会社 電気防食の陽極設置間隔の決定方法及びそれに用いる電極装置
US11643739B2 (en) 2014-01-15 2023-05-09 Tosoh Corporation Anode for ion exchange membrane electrolysis vessel, and ion exchange membrane electrolysis vessel using same
WO2018131519A1 (fr) 2017-01-13 2018-07-19 旭化成株式会社 Électrode pour électrolyse, cellule électrolytique, stratifié d'électrode et procédé de renouvellement d'électrode
US20220341049A1 (en) 2019-06-18 2022-10-27 Thyssenkrupp Uhde Chlorine Engineers Gmbh Electrolysis electrode and electrolyzer

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GB240561A (en) * 1924-07-07 1925-10-07 Novocrete And Cement Products Improvements in or relating to the manufacture of reinforced building or constructional elements or materials
GB896912A (en) * 1959-02-19 1962-05-23 Ici Ltd Improvements relating to electrode structures
JPS6039157B2 (ja) * 1979-08-10 1985-09-04 三菱重工業株式会社 コンクリ−ト構造物の劣化防止法
JPS581900B2 (ja) * 1980-07-01 1983-01-13 福島 博夫 白調味液の製造方法
IT1150124B (it) * 1982-01-21 1986-12-10 Oronzio De Nora Impianti Struttura anodica per protezione catodica
GB2140456A (en) * 1982-12-02 1984-11-28 Taywood Engineering Limited Cathodic protection
AU582559B2 (en) * 1983-12-13 1989-04-06 Raychem Limited Novel anodes for cathodic protection
AU583480B2 (en) * 1984-09-26 1989-05-04 Eltech Systems Corporation Composite catalytic material particularly for electrolysis electrodes and method of manufacture
WO1986006758A1 (fr) * 1985-05-07 1986-11-20 Eltech Systems Corporation Maille en metal deploye et structure d'anode revetue
US4653719A (en) * 1985-06-21 1987-03-31 Coulter Electronics, Inc. Fluid conduit and pinch valve for use therewith

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Also Published As

Publication number Publication date
JPH0510436B2 (fr) 1993-02-09
WO1986006759A1 (fr) 1986-11-20
AU5867886A (en) 1986-12-04
SG64190G (en) 1990-09-07
DE3669545D1 (de) 1990-04-19
SG71390G (en) 1990-10-26
WO1986006758A1 (fr) 1986-11-20
AU583627B2 (en) 1989-05-04
JPS62503040A (ja) 1987-12-03
AU587467B2 (en) 1989-08-17
EP0222829A1 (fr) 1987-05-27
EP0222829B2 (fr) 1992-08-26
SA90110113B1 (ar) 2006-05-23
EP0225343B1 (fr) 1990-03-14
DE3666232D1 (en) 1989-11-16
CA1311442C (fr) 1992-12-15
JPH0551678B2 (fr) 1993-08-03
EP0222829B1 (fr) 1989-10-11
JPS62502820A (ja) 1987-11-12
CA1289910C (fr) 1991-10-01
AU5868786A (en) 1986-12-04
SA90110114B1 (ar) 2004-03-20

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