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
• • 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
• • 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
• • 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
  • C23F2213/00—Aspects of inhibiting corrosion of metals by anodic or cathodic protection
  • C23F2213/30—Anodic or cathodic protection specially adapted for a specific object
  • C23F2213/31—Immersed structures, e.g. submarine structures

Definitions

• the invention relates to the cathodic protection of immersed installations in a brackish or saline environment.
• a sacrificial anode consisting of a more electronegative metal than the one to be protected.
• a polarization occurs, the shell becoming the cathode of an electrochemical cell and the sacrificial anode becoming the anode of the same cell.
• M constituents of the sacrificial anode that undergo the effects of corrosion by seawater and not those of the shell.
• Sacrificial anodes protecting the submerged steel parts of a boat or other fixed gear are usually aluminum-zinc (2-6%) - indium (0.01-0.05%), or aluminum -gallium (0.01%) or zinc alloy-AI (0.1 -0.5%).
• the disadvantage of this protection is that it releases in the marine environment ions of the metals constituting the sacrificial anodes. If this disadvantage is relatively minimal in the case of boats moving on the open sea, it is to be considered significantly more seriously when the boats are immobilized in a port, because the metals of the anode will accumulate in the water and in the water. the seabed of the parking areas, where they are going to be absorbed by the living beings who stay there.
• the object of the invention is to provide a solution for preventing the release into the external environment of the cations resulting from the dissolution of an anode of a cathodic protection device.
• the subject of the invention is a device for cathodic protection of a metal wall against corrosion in a salt medium, comprising an anode and means for connecting said anode to said wall, said anode being at an electrochemical potential. higher than said wall, characterized in that said anode is placed in a compartment delimited by an electron-permeable wall and, possibly, water, comprising:
• porous outer layer made of a material chosen from: polymer materials, ceramic materials or hydrated inorganic materials;
• the material constituting said at least one layer being chosen from osmotic membranes, activated carbon, a cation exchange resin such as a zeolite, a nano-cations cation-capturing polymer, cation-capturing mineral compounds such as phyllosilicates and inosilicates, microporous organic semi-permeable nanofiltration membranes of a cation-retaining type.
• Said wall may also include a membrane trapping negatively charged contaminants.
• the anode may be a sacrificial anode whose electrochemical potential is naturally greater than that of the metal wall.
• the device may comprise means for imposing on the anode an electrochemical potential greater than that of the metal wall.
• connection means of the anode to the metal wall may be in contact with the wall outside the compartment and pass through the porous wall of the compartment.
• the means for connecting the anode to the metal wall may be in contact with the metal wall inside the compartment, and the porous wall of the compartment is sealingly connected to the metal wall.
• the device may comprise means for keeping the anode away from the metal wall. It may comprise a plurality of layers having the capacity to capture the cations emitted by the anode during its dissolution, each layer preferably capturing cations different from those picked up in a preferred manner by the other layers.
• the invention consists in placing the anode in a compartment delimited by a series of porous membranes permeable to at least electrons, or even to water, arranged in layers.
• the outer layer is constituted by a porous non-metallic membrane, intended to reduce the hydraulic flow in the vicinity of the anode.
• the other porous layer (s) act as a cation barrier or trap, which prevents cations from dissolution of the anode from escaping out of the compartment into the external environment.
• the membranes are all permeable to water, the space between the anode and the wall of the compartment fills with water naturally. If at least one of the membranes is not permeable to water but only to electrons, it is necessary, during installation of the device, to fill the compartment with water, preferably with water. seawater to obtain good electrical conductivity, in order to bathe the anode in an electron-conducting medium and to give the compartment its operational form, with internal and external pressures that balance out.
• a sacrificial anode 3 is disposed in the vicinity of the wall 1, to which it is connected by electrical connectors 4, 5.
• the sacrificial anode 3 is made around a single steel connector, and in this case, the connectors 4, 5 shown are in fact the two ends of this single connector.
• the constituent material of the sacrificial anode 3 is conventional for this purpose (Al-In, Al-Ga or Zn alloy for example), and its choice is not a characteristic of the invention.
• the sacrificial anode 3 is included in a compartment 6 which is delimited by a set of membrane forming layers, and surrounds the anode 3 at a distance, for example, of the order of 1 cm.
• the outermost layer 7 is a porous electron-permeable layer and, preferably, also water, intended to reduce the hydraulic flow between the external environment and the interior space 8 of the compartment.
• the material constituting it is selected from polymeric materials, ceramic materials or hydrated inorganic materials.
• thermoplastic polymers of the polyethylene or high density polyethylene type or industrial mullite or alumina type porcelains.
• this material is electrically insulating, it must have porosity. Indeed, the polarization of the anode corresponds to the establishment of a small electrochemical circuit, which can only work if the electrons circulate. The open porosity allows the electrons to pass into the liquid even though the layer 7 is insulating.
• This outermost layer 7 whose thickness is generally of the order of mm, serves to protect the anode and the other membranes of the compartment 6 against hydraulic abrasion. It must have suitable properties of resistance to wear and impacts, resistance to deformation in the presence of a fluid in motion.
• the permeability of the layer 7 is, for example, of the order of 10 ml / min for 1 cm 2 of anode surface.
• the other layer or layers of the wall of the compartment 6 (there are two, 9, 10, in the example shown) is or consist of one or more materials serving as cation traps, and which capture the cations emitted by the sacrificial anode 3 to prevent them from being found in the marine environment 2.
• materials may be suitable: osmotic membranes, activated carbon powder or granules, a cation exchange resin such as a zeolite, a cation-attracting negative nanocharging cationic polymer, mineral cation-capturing compounds such as phyllosilicates and inosilicates.
• osmotic membranes activated carbon powder or granules
• a cation exchange resin such as a zeolite
• a cation-attracting negative nanocharging cationic polymer such as phyllosilicates and inosilicates.
• mineral cation-capturing compounds such as phyllosilicates and inosilicates.
• An activated alumina membrane or a functionally equivalent compound can be added to them, which in turn traps negatively charged contaminants, such as As and fluorides, that could decrease the efficiency of cation-trapping membranes.
• Semipermeable membranes used in electrolytic ion exchange processes can also be used.
• Microporous organic semi-permeable nanofiltration membranes of a cation-retaining type may also be suitable.
• the number of layers of cation sensor materials can be arbitrary, at the user's choice. These layers may advantageously be of multiple natures, each layer species being able, for example, to preferentially absorb one or more of the chemical species that the sacrificial anode 3 is capable of releasing.
• the thickness of the layers, in particular of the layer 10, can vary from about 1 mm to a few cm, depending on the size of the anode 3 and, therefore, the amount of cations to trap.
• compartment 6 In the case where the entire wall defining the compartment 6 is permeable to water, the water penetrates inside the compartment 6 and a pressure balance is reached between the inside and the outside of the compartment 6 The compartment 6 thus permanently takes its nominal form and its wall does not undergo crushing which could lead to its rupture.
• the entire wall defining the compartment 6 is permeable to water. It may be permeable only to electrons, but then pre-filling compartment 6 with water, preferably seawater, is necessary during commissioning of the device according to the invention.
• the progressive dissolution of the sacrificial anode 3 is carried out without pollution of the external medium by the cations resulting from this dissolution, these being captured by the layer or layers 9, 10.
• These must have advantageously a total absorption capacity of the various cations and an absorption volume sufficient to not reach saturation before the end of life of the sacrificial anode 3.
• the electrical conductors 4, 5 are in contact with the metal wall 1 in areas outside the compartment 6. It is necessary to therefore ensure a sealing of the wall of the compartment 6 in the areas where it is crossed by the conductors 4, 5. But alternatively, as shown in Figure 2, the contacts between the conductors 5, 6 and the metal wall 1 may be located inside the compartment 6. The wall of the compartment 6 is then in sealing contact with the metal wall 1 to be protected.
• the sacrificial anode 3 is not in direct contact with the wall 1 to be protected. This avoids creating short circuits between the anode 3 and at least the area of the wall 1 which is opposite it. In this way, a greater part of the surface of the wall 1 can be protected under the best conditions by the same anode 3.
• Means for holding the anode 3 away from the wall 1 are therefore provided, preferably (not shown in the figures). But in practice, they can often be constituted by the connectors 4, 5, which are generally made of steel and have due to their material and their dimensions, a sufficient rigidity to achieve the maintenance of the anode 3 at a distance from the wall 1.
• the invention is also applicable in the case where the anode is not a sacrificial anode in the sense that it naturally has a higher electrochemical potential than that of the wall 1 to be protected, but is placed at this potential by a DC or rectified current generator to which it is connected by conductors which pass through the wall of the compartment 6 sealingly.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Prevention Of Electric Corrosion (AREA)
• Separation Using Semi-Permeable Membranes (AREA)

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• 2012
  • 2012-02-01 FR FR1250946A patent/FR2986241B1/fr not_active Expired - Fee Related
• 2013
  • 2013-01-31 EP EP13705736.0A patent/EP2809830A1/fr not_active Withdrawn
  • 2013-01-31 AU AU2013214235A patent/AU2013214235B2/en not_active Ceased
  • 2013-01-31 CA CA2862349A patent/CA2862349A1/en not_active Abandoned
  • 2013-01-31 CN CN201380007762.8A patent/CN104080953A/zh active Pending
  • 2013-01-31 WO PCT/EP2013/051837 patent/WO2013113777A1/fr active Application Filing
  • 2013-01-31 JP JP2014555191A patent/JP2015505583A/ja active Pending
  • 2013-01-31 KR KR1020147024276A patent/KR20140122739A/ko not_active Application Discontinuation
• 2014
  • 2014-07-25 US US14/341,029 patent/US20140332373A1/en not_active Abandoned
  • 2014-07-29 CL CL2014002004A patent/CL2014002004A1/es unknown

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