EP4353866A1 - Mischmetalloxidbeschichtungen für titanlegierungen - Google Patents

Mischmetalloxidbeschichtungen für titanlegierungen Download PDF

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EP4353866A1
EP4353866A1 EP22382977.1A EP22382977A EP4353866A1 EP 4353866 A1 EP4353866 A1 EP 4353866A1 EP 22382977 A EP22382977 A EP 22382977A EP 4353866 A1 EP4353866 A1 EP 4353866A1
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Prior art keywords
titanium alloy
mmo
titanium
oxide
metal oxide
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English (en)
French (fr)
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Alejandro SAMANIEGO MIRACLE
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Titanium Technology SL
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Titanium Technology SL
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Priority to EP22382977.1A priority Critical patent/EP4353866A1/de
Priority to PCT/EP2023/078259 priority patent/WO2024079222A1/en
Publication of EP4353866A1 publication Critical patent/EP4353866A1/de
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    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/02—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using non-aqueous solutions
    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
    • C23C18/1204—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material inorganic material, e.g. non-oxide and non-metallic such as sulfides, nitrides based compounds
    • C23C18/1208—Oxides, e.g. ceramics
    • C23C18/1216—Metal oxides
    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
    • C23C18/1225—Deposition of multilayers of inorganic material
    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
    • C23C18/125—Process of deposition of the inorganic material
    • C23C18/1295—Process of deposition of the inorganic material with after-treatment of the deposited inorganic material
    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/73—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process
    • C23C22/74—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process for obtaining burned-in conversion coatings
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/26—Anodisation of refractory metals or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D9/00—Electrolytic coating other than with metals
    • C25D9/04—Electrolytic coating other than with metals with inorganic materials
    • C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
    • C25D9/12—Electrolytic coating other than with metals with inorganic materials by cathodic processes on light metals

Definitions

  • the present invention belongs to the field of coatings and methods for protecting, particularly from corrosion and biofouling, titanium alloys destined to be immersed in aqueous environments.
  • it relates to a method for preparing a titanium alloy having a mixed metal oxide (MMO) on its surface, to a titanium alloy having a MMO on its surface, particularly obtained or obtainable by said method of preparation, a shaped part destined to be subjected to mechanical stress comprising a titanium alloy having a MMO on its surface, and a method for protecting a titanium alloy having a MMO on its surface by application of a voltage.
  • MMO mixed metal oxide
  • Titanium alloys may be used in equipment and structures destined to be immersed, for instance in aqueous environments and in particular in seawater, such as ship and boat hulls, a propeller, a shaft, a rudder, other aquatic or marine equipment such as heat exchangers, drilling platforms, dry dock equipment, oil production rigs, aquaculture equipment and netting and pipes, which are immersed in water, or have water running through them.
  • aqueous environments and in particular in seawater such as ship and boat hulls, a propeller, a shaft, a rudder, other aquatic or marine equipment such as heat exchangers, drilling platforms, dry dock equipment, oil production rigs, aquaculture equipment and netting and pipes, which are immersed in water, or have water running through them.
  • biofouling or biological fouling
  • aquatic organisms such as algae (including green and/or brown), microorganisms, or small animals such as barnacles, mussels, sponges and the like
  • Biofouling poses problems on, e.g., ship and boat hulls, because it increases frictional resistance during movement through water. As a consequence, speed is reduced and fuel consumption increased.
  • Cathodic protection may involve subjecting the structure or shaped parts to be protected to cathodic polarization and connecting it to a sacrificial material that acts as anode, by which the oxidation reactions occur on the anode, and the life of material acting as cathode is prolonged, by reducing the degree of corrosion.
  • Impressed current cathodic protection is another method used, which involves sacrificial anodes connected to an external power source.
  • the external power source often a DC power supply, provides the current necessary to drive the electrochemical reaction required for cathodic protection to occur.
  • JP2003328164A discloses a method for preventing the adhesion of the marine organisms to the titanium ship having a structure to electrically insulate screw propellers and their shaft from the hull comprises maintaining reference electrodes for bringing the hull of the titanium ship into contact with seawater at a potential of 1.2 to 1.4 V (based on a saturated KCI Ag/AgCI reference electrode).
  • a fuel cell electrode comprises a core of titanium which has been degreased and pickled and coated with platinum by electrodeposition or with platinum or platinum nickel alloy by a chemical compound decomposition process and the platinum coating has been oxidized, e.g., to a depth of 5 to 25% of its thickness, by heating in an oxidizing atmosphere or by electrolysis.
  • oxides of platinum metals have the particular advantage that the threshold value at which they are capable of dissociating an electrolyte is lower than that of the pure metal, so that the overall electric energy that needs to be supplied to the electrode is considerably reduced.
  • precious metal (oxide)s such as ruthenium and iridium
  • DSA diamond-like structure
  • These have also been used for oxygen or chlorine evolution, by oxidation of water, hydroxide or chloride respectively, which may be present in the aqueous environment and in seawater in particular, whereby the surface of the metal act as anode, protecting the metal which they cover.
  • oxygen and/or chlorine on the surface may act as a biocide and prevent the appearance of biological fouling.
  • a problem with these approaches is the high price of precious metals, which for its application on large surfaces, the hull of a ship, becomes difficult to sustain economically.
  • An alternative to precious metals for the elaboration of DSA's are coatings based on oxides of metals other than precious metals, such as tin oxide (SnO 2 ) doped with antimony (Sb), what may also be referred to as a mixed metal oxide (MMO). Oxides of such alternative metals have been applied to titanium pure electrodes. Reference is made, e.g., to the following publications.
  • Tin used in these approaches is known to form a structure with oxygen known as cassiterite (SnO 2 ).
  • This oxide has a low electrical conductivity.
  • antimony which dissolves easily in tin oxide, gives it the appropriate properties.
  • Sb(V) the presence of Sb(V) in the vacancies in the structure provides an extra valence electron that greatly improves conductivity.
  • Sb(III) present on the surface and grain boundaries would offer active sites for the generation of hydroxyl radicals.
  • a surface treatment on a titanium alloy comprising titanium oxide on its surface for the formation of a mixed metal oxide (MMO) on the surface of the titanium alloy not only can be achieved but also provides the titanium alloy with a modified surface, which is protected with respect to bio-fouling and corrosion when immerged in an aqueous environment, such as seawater.
  • MMO mixed metal oxide
  • the instant invention relates to a method for preparing a titanium alloy having a mixed metal oxide (MMO) on its surface comprising:
  • the instant invention also relates to a titanium alloy having a mixed metal oxide on its surface, in particular, obtained by or obtainable by a method of preparation as described herein.
  • a titanium alloy may also be referred to herein as MMO surface modified titanium alloy, or MMO activated titanium alloy.
  • a titanium alloy with a MMO on its surface as described herein requires the application of a relatively low anodic voltage, of below 3 V Ag/AgCl , to achieve anti-biofouling properties when immersed.
  • the breakdown potential of the protective oxide layer of a titanium alloy such as grade 5 titanium alloy has been found to be at an anodic voltage of around 3 V Ag/AgCl .
  • the breakdown potential may be defined as the surface potential at which the surface's passive film breaks down. This leads to active electrochemical reaction, causing corrosion or re-passivation of the surface in the working conditions. Accordingly, by being able to work at voltages below 3 V Ag/AgCl , a method as described herein advantageous allows obtaining an antibiofouling effect working at voltages below or under the breakdown potential of titanium alloys.
  • Such voltages have also been found to slow down the dissolution of the MMO into the aqueous environments. This advantageously requires a reduced energy consumption, increases the active live time of the MMO modified titanium alloy surface, and provides the possibility of tackling biofouling in titanium alloy structures immersed in aqueous medium, e.g., in seawater, in particular for prolonged periods of time.
  • the present invention also relates to a method for protecting a titanium alloy surface which comprises the steps of:
  • a MMO on the surface of a titanium alloy favours the electrical conductivity of the surface of the titanium alloy acting as anode and favours the electrocatalytic properties for the oxidation of species, such as water, hydroxide and in particular chloride ions present in aqueous environments such as seawater, upon the application of a voltage onto the titanium alloy surface having MMO such that the surface acts as an anode.
  • species such as water, hydroxide and in particular chloride ions present in aqueous environments such as seawater
  • the high conductivity facilitates the flow of electrons through the surface of the coating, generated during oxidation reactions in the electrolyte, i.e., the aqueous environment and seawater in particular. This is achieved even at voltages of below 3 V Ag/AgCl , which result in
  • the instant invention relates to a method for preparing a titanium alloy having a mixed metal oxide (MMO) on its surface, comprising:
  • Titanium alloys suitable for a method as described herein include titanium alloys suitably used for equipment and structures destined to be immersed in or to be in contact with an aqueous environment, and in particular seawater.
  • equipment and structures may include, for instance ship and boat parts typically immersed in or in constant contact with water such a hull of a boat or a ship, a propeller, a shaft, a rudder, other aquatic or marine equipment such as heat exchangers, drilling platforms, dry dock equipment, oil production rigs, aquaculture equipment and netting and pipes.
  • Such equipment and structures may be particularly selected from ship and boat parts and more in particular may be the hull of a boat or ship.
  • Titanium alloys that can be used for such equipment and structures are known in the art.
  • titanium grades 1, 2, 3 and 4 which are regarded as commercially pure titanium's (with more than 98.5 wt.% titanium and which may include impurities to different degrees)
  • titanium alloys comprise elements other than titanium, as alloying elements, as functional elements or as impurities, including inevitable impurities.
  • alloying elements are present in higher amounts than functional elements and impurities, and functional elements, if present, may be present in higher amounts than impurities.
  • Some impurities may be kept to a minimum, their presence being defined typically only as a maximum wt.%. In the present specification such elements other than titanium may be collectively referred to as "other elements".
  • a suitable titanium alloy may comprise from 70 to 98.5 wt.% of titanium based on the total weight of the titanium alloy, and the remaining up to 100 wt.% of other elements including alloying elements, functional elements, and inevitable impurities.
  • the titanium alloy may comprise from 75 to 97.5 wt.% of titanium, more in particular from 80 to 95 wt.% of titanium, yet more in particular from 85 to 92.5 wt.%, and yet more in particular from 87.5 to 91 wt.% of titanium, with the corresponding wt.% remaining up to 100 wt.% of other elements.
  • alloying elements including alloying elements, functional elements, and inevitable impurities may be selected from aluminum, vanadium, tin, molybdenum, niobium, tantalum, zirconium, manganese, iron, chromium, cobalt, nickel, copper, palladium, silicon, oxygen, nitrogen and carbon.
  • Some impurities such as the presence of interstitial elements (such as interstitial oxygen, nitrogen and carbon), may be particularly controlled, for example some titanium alloys are referred to as ELI (extra-low interstitial), to referrer to the extra-low amount of interstitial elements.
  • Some preferred titanium alloys may comprise, aluminum and/or vanadium and optionally other elements such as tin, palladium, chromium, zirconium, nickel, molybdenum, niobium and ruthenium and optionally impurities (e.g., oxygen, iron, carbon). It may be preferred for the titanium alloy to comprise both aluminum and vanadium.
  • the amount of aluminum in the titanium alloy may be from 2 to 10 wt.% of aluminum, in particular from 2.5 to 7.5 wt.% aluminum, more in particular from 3 to 7 wt.% of aluminum.
  • the amount of vanadium may be from 1 to 10 wt.% of vanadium, in particular from 1.5 to 7 wt.% of vanadium, and more in particular from 2 to 5 wt.% of vanadium.
  • the titanium alloy comprises from 70 to 98.5 wt.% of titanium, and further comprises from 2 to 10 wt.% of aluminium and from 1 to 10 wt.% of vanadium, the wt.% based on the total weight of the titanium alloy.
  • the preferred or particular ranges of titanium, aluminum and vanadium, and the presence of other elements as described above also apply.
  • a titanium alloy may be selected from grade 5 titanium alloy, grade 6 titanium alloy, grade 9 titanium alloy, grade 18 titanium alloy, grade 19 titanium alloy, grade 20 titanium alloy, and grade 21 titanium alloy.
  • a grade 5 titanium alloy may be used.
  • grades 5, 6, 9 ,18, 19, 20 and 21 are a titanium alloys having defined compositions. Such titanium alloys are known in the art and are readily available.
  • Grade 5 titanium alloys are considered alpha-beta alloys, with aluminum stabilizing the alpha phase and vanadium stabilizing the beta phase, and may be defined according to the ASTM standard ASTM B265.
  • Grade 5 titanium alloy typically comprises from 88 to 91 wt.% titanium, from 5.5 to 6.8 wt.% aluminum, from 3.5 to 4.5 wt.% vanadium, with a maximum amount of 0.40 wt.% of iron, although a maximum of 0.25 wt.% of iron may be preferred, and a maximum amount of 0.2 wt.% of oxygen.
  • grade 5 titanium alloy also gives it the name of Ti-6AI-4V or Ti 6-4, owing to the percentages of Al (about 6 wt.%) and V (about 4 wt.%) present in the titanium alloy.
  • Grade 5 titanium alloy is one of the most commonly used titanium alloys and represents about 50% of the worldwide titanium consumption.
  • Grade 6 titanium alloy comprises about 3 wt.% of aluminum and about 2.5 wt.% of tin.
  • Grade 9 titanium alloy comprises about 3 wt.% of aluminum and about 2.5 wt.% of vanadium.
  • Grade 18 titanium alloy comprises about 3 wt.% aluminum, 2.5 wt.% vanadium and 0.04 to 0.08 wt.% palladium.
  • Grade 19 titanium alloy comprises about 3 wt.% aluminum, about 8 wt.% vanadium, about 6 wt.% chromium, about 4 wt.% zirconium, and about 4 wt.% molybdenum.
  • Grade 20 titanium alloy comprises about 3 wt.% aluminum, about 8 wt.% vanadium, about 6 wt.% chromium, about 4 wt.% zirconium, about 4 wt.% molybdenum and from 0.04 to 0.08 wt.% palladium.
  • Grade 21 titanium alloy comprises about 15 wt.% molybdenum, about 3 wt.% aluminum, about 2.7 wt.% niobium, and about 0.25 wt.% silicon.
  • a method described herein comprises providing titanium alloys comprising titanium oxide on its surface. Titanium alloys comprising titanium oxide on the surface are readily available as, typically, a layer of titanium oxide will be formed on the surface of a titanium alloy upon exposure to atmospheric oxygen. Titanium alloys comprising titanium oxide on its surface may accordingly be provided commercially. Thus, titanium alloys may comprise a layer of titanium oxide is generated by natural passivation of the titanium alloy.
  • titanium alloys may comprise titanium (IV) oxide TiO 2 (also known as rutile) and/or titanium (II) oxide (TiO), in particular TiO 2 or both TiO 2 and TiO, more in particular, if both TiO 2 and TiO are present, TiO 2 may be present in a higher amount than TiO.
  • Titanium alloys comprising other metals, such as aluminum, which also tend to oxidate naturally upon contact of atmospheric oxygen, may also have oxides of such metals on their surface.
  • titanium alloys comprising aluminum as alloying element may also comprise aluminum oxide, in particular aluminum (III) oxide (Al 2 O 3 ) on the surface of the titanium alloy.
  • Such alloys may typically have a mixture of titanium oxide and aluminum oxide on its surface.
  • a mixture of titanium oxide and such other metal oxides is not a MMO since the two metal oxides coexists independently, without sharing the same crystal network.
  • the titanium oxide layer may cover the titanium alloy surface in whole or in part, but typically covers the surface of the titanium alloy in whole.
  • the titanium oxide and, if present, of other oxides such as aluminum oxide on the surface of the titanium alloy, and the thickness of the titanium oxide layer may be characterized by X-Ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and/or Energy Dispersive X-ray spectroscopy (EDX) as described below for the characterization of the MMO formed on the surface of the titanium alloy.
  • XRD X-Ray Diffraction
  • XPS X-ray photoelectron spectroscopy
  • EDX Energy Dispersive X-ray spectroscopy
  • the titanium oxide, and if present other oxides such as aluminum oxide, may form a layer typically covering the whole surface of the titanium alloy.
  • Such layer including titanium oxide and optionally other oxides of metals present in the titanium alloy, such as aluminium oxide, may be referred to as the titanium oxide layer.
  • the surface treatment comprises forming a mixed metal oxide (MMO) on the surface of the titanium alloy.
  • MMO mixed metal oxide
  • mixed metal oxide generally refers to an oxide of more than one metal, including oxides of multiple metals or a metal oxide of one metal doped with another metal.
  • Mixed metal oxides have interstitial spaces which allow for increased electrical conductivity of the titanium alloy surface on which they are formed.
  • Mixed metal oxides are distinct from mixtures of metal oxides in that in mixtures of metal oxides each metal has its own crystal structure and in contrast, in mixed metal oxides the two metals share the same crystal network.
  • a mixed metal oxide may be formed on the surface of the titanium alloy on top of the titanium oxide present on the surface of the titanium alloy, e.g., forming a MMO layer on top of the titanium oxide layer (optionally in combination with other metal oxides such as aluminium oxide), or may be formed within the titanium oxide layer present on the surface of the titanium alloy, e.g., providing a mixed layer of MMO and titanium oxide and optionally other metal oxides that may be present in the titanium oxide layer.
  • the MMO may also be formed within the layer of the titanium oxide and further on top of the titanium oxide layer, e.g., providing a mixed layer of MMO and titanium oxide (optionally in combination with other metal oxides such as aluminium oxide) and a layer MMO on top of the mixed layer.
  • a MMO formed in a method as described herein may be a mixed metal oxide of two or more metals selected from tin, antimony, lead, nickel, cobalt, and precious metals.
  • a precious metal may be particularly selected from ruthenium (Rh) and iridium (Ir).
  • a MMO formed in a method as described herein may be preferably selected from a tin-antimony oxide, tin-antimony-lead oxide, a nickel-cobalt oxide and/or a precious metal oxide of two or more precious metals.
  • a MMO may be preferably selected from tin-antimony oxide, tin-antimony-lead oxide, a nickel-cobalt oxide, and may preferably be a tin-antimony oxide or tin-antimony-lead oxide, to reduce the costs of the titanium alloy having a MMO on its surface.
  • the formation of MMO on the surface of the titanium alloy reduces the amount of titanium oxide present on the surface of the titanium alloy, by the presence of the MMO within the titanium oxide layer as described above.
  • the formation of the MMO on the surface of the titanium alloy may also reduce or eliminate the presence of titanium oxide on the surface by the formation of, e.g., a mixed layer of MMO and titanium oxide as also described above or a MMO layer on top of the titanium oxide layer or on top of the mixed layer.
  • the formation of the MMO on the surface of the titanium alloy therefore replaces the presence of titanium oxide (in whole or in part) on the surface of the titanium alloy and provides the titanium alloy surface with high electrical conductivity and electrocatalytic properties for the oxidation of species which have been found to be advantageous for antifouling applications.
  • the amount of MMO formed on the surface of the titanium alloy surface may be determined by methods known in the art, such as gravimetric analysis. For instance, the weight of the titanium alloy prior to the surface treatment may be measured and compared to the weight of the titanium alloy after the surface treatment by which a MMO is formed on the surface of the titanium alloy. The amount of weight increase will correspond to the amount of MMO formed on the surface of the titanium alloy.
  • composition of the surface of the titanium alloy and the presence (or absence) of titanium oxide, other metal oxides (such as aluminum oxide) and/or mixed metal oxides formed in a method described herein, may be monitored by methods known in the art.
  • X-Ray Diffraction may be used to determine of the most predominant crystal phases on the surface of the titanium alloy and the % amounts thereof.
  • XRD may be performed by methods know in the art, using a commercially available apparatus (e.g., an X-ray diffractometer X'pert PROMRD, from PANalytical, Holland B.V.), as described in for instance Shao et al. cited above.
  • X-ray photoelectron spectroscopy may be used to obtain, on the one hand, the elemental composition of the different elements that present in the modified surface and on the other hand the state of oxidation in which these elements are found.
  • XPS X-ray photoelectron spectroscopy
  • XPS may be performed by methods know in the art, using a commercially available apparatus.
  • EDX Energy Dispersive X-ray spectroscopy
  • EDX may be used to also determine the elemental composition of the titanium alloy surface. EDX may be performed by methods known in the art, using a commercially available apparatus.
  • the titanium oxide present on the surface of the titanium alloy is replaced by the mixed metal oxides formed in a method as described herein. If titanium oxide is replaced in whole, e.g., by the formation of a MMO layer which does not contain titanium oxide on top of the titanium oxide layer the signals relating to the presence of titanium oxide can no longer be observed in the, e.g., XRD and XPS diffractogram.
  • a mixed metal oxide onto the surface of the titanium alloy may be performed by methods known in the art.
  • Known methods include forming a mixed metal oxide on the surface of the titanium alloy from a metal oxide precursor.
  • the surface treatment of step b) may comprise forming the MMO using a metal oxide precursor.
  • a MMO formed on the surface of the titanium alloy contains more two or more metals providing from two or more metal oxide precursors.
  • a MMO may be formed by applying two or more metal oxide precursors onto the surface of the titanium alloy and forming the mixed metal oxide from the two or more metal oxide precursors.
  • the mixed metal oxide advantageously facilitates the formation of a MMO on the titanium alloy surface, and in particular its integration within and/or on top of the titanium oxide layer. Accordingly, it may be preferred for the mixed metal oxide to be formed from a metal oxide precursor. This may be achieved, by for instance, thermal decomposition or electrochemical methods such as electrodeposition. Such methods are known in the art and it is within the scope of a person skilled in the art to choose adequate conditions for thermal decomposition or electrodeposition of a mixed metal oxide of choice, in terms of the choice of one or more metal oxide precursor, concentration of solutions of metal oxide precursors and reaction parameters (e.g., time, temperature, intensity and voltage as applicable). As a mode of example thermal decomposition or electrodeposition may be carried out as detailed in the following.
  • Thermal decomposition methods may be preferably used.
  • Thermal decomposition may comprise applying two or more metal oxide precursors to the surface of the titanium alloy, using one or more deposition steps, and heating the titanium alloy with the two or more metal oxide precursors on its surface to form a MMO on the surface of the titanium alloy to provide a MMO modified titanium alloy.
  • the surface of the titanium alloy to be modified may be contacted with a solution containing two or more the metal oxide precursors, such as a salt of the metals that are to form the MMO, in particular a metal chloride, e.g., by dipping the surface to be modified into the solution or by applying such solutions onto the surface of the titanium alloy where the MMO is to be formed, by brushing, spraying, rolling, flow coating, or pouring.
  • the solvent of the solution is allowed to dry and, thirdly, the treated surface is heated to elevated temperatures for the decomposition of the one or more salts and the formation of the mixed metal oxide. Drying of the solvent may be performed by methods known in the art.
  • the titanium alloy with the solution of the metal oxide precursor on its surface may left to dry, air dried and/or dried by heating, e.g., in an oven.
  • the surface may be left to dry and be subsequently heated in an oven, e.g., at a temperature from 250 to 450 °C, in particular from 300 to 400 °C, for 1 to 15 minutes, in particular for 5 to 10 minutes.
  • Such a deposition step is typically repeated one or more times.
  • from 2 to 50 deposition steps may be performed, more in particular from 3 to 40 deposition steps may be performed, and yet more in particular 5 to 30 deposition steps may be performed, yet more in particular from 10 to 25 deposition steps may be performed, and yet more in particular from 15 to 20 deposition steps.
  • the higher the number of deposition steps the higher the amount of MMO formed on the titanium ally surface, and higher the thickness of the layer of MMO being ultimately formed on the titanium alloy.
  • the amount of MMO or thickness of the MMO layer will also determine the useful life time of the MMO modified surface.
  • the useful life time or active life span of the MMO modified titanium alloy surface refers to the time that the MMO modified titanium alloy surface can be actively used, by application of a voltage, to prevent biofouling, without observing damage of the MMO modified titanium alloy surfacae.
  • heating the treated surface to elevated temperatures may be typically performed in, e.g., an oven, in particular at a temperature from 500 to 700 °C, more in particular 550 to 650 °C, and yet more in particular at a temperature of about 600 °C.
  • Heating is typically performed until, as described above, the presence of titanium oxide on the surface of the titanium alloy, has been replaced in part or in whole, preferably in whole, by the formation of the MMO within the titanium oxide layer and/or on top of the titanium oxide layer.
  • This can be monitored by, e.g., taking a control sample from the oven at several time intervals and monitoring the amount of titanium oxide and/or mixed metal oxide on the surface by the XRD and/or XPS methods indicated above. Such methods may also be used to determine the amount of MMO formed on the surface of the titanium alloy and/or the thickness of the layer of the MMO formed.
  • Heating may be stopped once the desired amount/thickness of mixed metal oxide has been formed on the surface of the titanium alloy.
  • the heating at elevated temperatures may be performed for from 15 minutes to 3 hours, in particular from 30 minutes to 2 hours, and more in particular for 45 to 1.5 hours, and yet more in particular for about 1 hour.
  • a treatment of these lengths ensure the formation of MMO to provide the titanium alloy surface with the desired properties.
  • the instant invention may relate to a method as described herein, wherein the surface treatment of step b) is performed by thermal decomposition, in particular wherein the thermal decomposition comprises the steps of:
  • Electrodeposition methods may also be used. Accordingly in a method as described herein the surface treatment of step b) is performed by electrodeposition.
  • electrodeposition may comprise immersing the titanium alloy having titanium oxide on its surface in a solution of two or more metal oxide precursors, connected to an activated titanium anode, cathodically polarizing the titanium alloy by applying a current (e.g., having an intensity from 100 to 800 mA, in particular from 150 to 600 mA, and more in particular from 200 to 500 mA) to induce the formation of the mixed metal oxide onto the titanium alloy surface.
  • a current e.g., having an intensity from 100 to 800 mA, in particular from 150 to 600 mA, and more in particular from 200 to 500 mA
  • Activated titanium anodes are known in the art.
  • the instant invention may relate to a method as described herein, wherein the surface treatment of step b) is performed by electrodeposition, in particular wherein the electrodeposition comprises:
  • the current may be applied for a period of time sufficient to obtained a desired amount of deposited mixed metal oxide.
  • the current may be applied for a period of time of, e.g., from 0.5 to 5 minutes, in particular from 1 to 4 minutes.
  • Suitable amounts of MMO formed on the surface of the titanium alloy may be from 1 to 20 g/m 2 , in particular from 1.5 to 15 g/m 2 , and more in particular from 2 to 10 g/m 2 .
  • the thickness of a MMO layer formed on top of the titanium oxide layer or on top of a mixed titanium oxide layer and MMO layer may be from 0.001 microns to 1 micron, in particular from 0.01 to 0.5 microns, yet more in particular from 0.02 to 0.1 microns.
  • the amount/thickness of the MMO formed on the surface of the titanium alloy may be monitored as described above by XRD and/or XPS.
  • Precursors of a metal oxide may be selected from a metal salt, in particular from metal halides, more in particular from metal chlorides, and may preferably be a mixture of two or more metal chlorides.
  • two or more metal oxide precursors may be selected from tin chloride, antimony chloride, lead chloride, nickel chloride, cobalt chloride, and/or precious metal chloride.
  • the precursor of the metal oxide may be a mixture of tin (IV) chloride (SnCl 4 ), antimony (III) chloride (SbCl 3 ), and lead (IV) chloride (PbCl 4 ).
  • Solutions of the two or more metal oxide precursors in a solvent may be typically used for both thermal decomposition and electrodeposition.
  • the solvent may be selected from, for instance, low alkyl alcohol, e.g., selected from C1 to C4 primary alcohols, preferably ethanol, other suitable solvents may include ethylene glycol.
  • the solvent may be ethanol or ethylene glycol.
  • the solvent may include, e.g., an acid, such as HCI.
  • a solution of the metal oxide precursors may have a concentration from 0.05 to 1.5 % w/v of each metal oxide precursor in the solvent, e.g., ethanol, based on the weight amount of metal oxide precursor per volume of solvent, namely a 1% w/v being 1 g of metal oxide precursor per 100 ml of solvent.
  • the concentration of each metal oxide precursor may be from 0.1 to 1.25 % w/v.
  • a solution of the metal oxide precursor e.g., a metal chloride
  • the metal oxide precursor may have a concentration from 0.01 to 2 M, of each metal oxide precursor in the solvent, e.g., ethylene glycol, in particular from 0.05 to 1.5 M, more in particular from 0.1 to 1.2 M.
  • the surface treatment may include further steps prior to or after forming a mixed metal oxide on the surface of the titanium alloy.
  • the surface of the titanium alloy may be roughened and/or cleaned prior to forming the mixed metal oxide onto the surface of the titanium alloy.
  • the titanium alloy surface may be roughened and subsequently cleaned. Such steps may improve, e.g., electrodeposition and the adhesion of the metal oxide precursor onto the surface of the titanium alloy and subsequently improve the formation of the mixed metal oxide upon the thermal decomposition.
  • a method described herein, prior to applying the surface treatment of step b), comprises:
  • the surface of the titanium alloy may be roughened by methods known in the art such as sanding with a sand paper or sandblasting.
  • the surface of the titanium alloy may be cleaned by methods known in the art, such as using water with detergents and/or an appropriate solvent, e.g., ethanol, acetone. After cleaning the surface may be dried, e.g., using an air dryer.
  • the instant invention further relates to titanium alloy having a MMO on its surface (also referred to herein as MMO modified titanium alloy).
  • MMO modified titanium alloy may be obtained or obtainable by a process as described herein.
  • the MMO modified titanium alloy comprises a mixed metal oxide on the surface of the titanium alloy, accordingly the mixed metal oxide present on the surface of the titanium alloy may be referred to or regarded as a mixed metal oxide coating.
  • metal oxides that are present in the surface of the MMO modified titanium alloy, including, for instance, the absence of titanium oxide or the presence of MMO on the surface of the titanium alloy, may be stablished as described above, by using known techniques such as XRD and XPS.
  • a MMO modified titanium alloy as described herein does not contain titanium oxide on its surface as evidenced, e.g., by XRD and/or XPS. These techniques may be also used to establish the amount of metal oxides which are present on the surface of the MMO modified titanium alloy.
  • the instant invention particularly relates to titanium alloy having a MMO on its surface, wherein the mixed metal oxide is selected from a tin-antimony oxide, tin-antimony-lead oxide, a nickel-cobalt oxide, and/or a precious metal oxide.
  • the mixed metal oxide is selected from a tin-antimony oxide, tin-antimony-lead oxide, a nickel-cobalt oxide, and/or a precious metal oxide.
  • Such titanium alloy having a MMO on its surface may particularly be obtainable by or obtained by a method as described herein.
  • the present invention also relates to a shaped part destined to be subjected to mechanical stress, comprising a titanium alloy having a MMO on its surface as described herein, in particular obtained by or obtainable by a method as described herein.
  • Shaped parts comprising a titanium alloy having a MMO on its surface may be formed from the MMO modified titanium alloy or may be formed from a titanium alloy and may be subsequently subjected to a surface treatment as described herein to form a MMO on the surface of the shaped part.
  • Appropriate shaped parts may include parts such as ship and boat hulls, a propeller, a shaft, a rudder, other aquatic or marine equipment such as heat exchangers, drilling platforms, dry dock equipment, oil production rigs, aquaculture equipment and netting and pipes, which are typically immersed in water, or have water running through them.
  • a titanium alloy with a modified surface as described herein requires the application of a current at a relatively low voltage, of under 3 V Ag/AgCl , to achieve the anti-biofouling properties when immersed in, e.g., an aqueous environment such as seawater.
  • working at such potentials allows working below the breakdown potential of the passivation layer of titanium alloys which for grade 5 titanium alloy has been found to be around 3 V Ag/AgCl .
  • the present invention also relates to a method for protecting a titanium alloy having a MMO on its surface from biofouling, which comprises the steps of:
  • a method for protecting a titanium alloy may also comprise the steps of preparing a titanium alloy having a mixed metal oxide (MMO) on its surface as described above.
  • MMO mixed metal oxide
  • a method for protecting a titanium alloy may comprise:
  • Immersing as used herein includes the partial or total immersion of the surface modified titanium alloy in the aqueous environment. Immersing may also refer to the contact of the inner surface of a tubing or a pipe with an aqueous medium flowing through it.
  • MMO modified titanium alloys as described herein are chiefly destined to be used in aqueous environments, and seawater in particular. Accordingly, in a method as described herein immersing in the aqueous environment may generally take place during the purposed use of the titanium alloy.
  • the aqueous environment may preferably seawater. Different seawaters may have different properties and some may be more propense to biofouling than other, due to changes in temperature, in sea life and in types and concentrations of solutes.
  • the seawater may be the Mediterranean Sea, the Atlantic Ocean, the Pacific Ocean, the Nordic Sea, etc.
  • titanium alloy surfaces immersed in waters of the Mediterranean Sea may be more propense to biofouling than if immersed in other seawaters.
  • the titanium alloy the having a mixed metal oxide (MMO) on its surface may be immersed in waters of the Mediterranean Sea.
  • a voltage under 3 V Ag/AgCl may be performed by methods known in the art.
  • a voltage under 3 V Ag/AgCl means a voltage which is below 3V with respect to a Ag/AgCI reference electrode, that contacts the aqueous medium in which the surface onto which the voltage is applied is immersed.
  • applying the voltage to the surface may be achieved by connecting the surface to voltage source in any appropriate means known in the art.
  • a voltage under 3 V Ag/AgCl may particularly be from 0.5 to 2.75 V Ag/AgCl , in particular from 0.75 to 2 V Ag/AgCl , more in particular from 1 to 1.6 V Ag/AgCl , yet more in particular from 1.1 to 1.5 V Ag/AgCl , and yet more in particular from 1.2 to 1.4 V Ag/AgCl .
  • a current density can be generated that is sufficient to provide an anti-biofouling effect. Accordingly, a method as described herein allows to achieve anti-biofouling whilst preventing damage to the titanium alloy, which typically occurs at voltages above 3 VAg/AgCI.
  • the voltage is applied such that the surface of the titanium alloy having a MMO acts as an anode.
  • This mode of operation may be also referred to as anodic polarization, in the present case, of the titanium alloy surface having a MMO.
  • This allows the oxidation of species (e.g., Cl - , OH - and H 2 O) present in the aqueous medium, in particular seawater, to generate oxidated species (e.g., Cl 2 and/or O 2 ) which prevent, reduce or remove biofouling.
  • Chlorine may further evolve to hypochlorite, which is very reactive contributes to the antifouling effect: (2) Cl 2 + H 2 O ⁇ HCIO + Cl - + H + (3) HCIO ⁇ ClO - +H +
  • the oxidated species are generated from species originally found in the aqueous medium as such, the products derived from the reactivity of such species against the biological material responsible of the biofouling are not harmful to the environment. Accordingly, such methods of protection of the titanium surface having MMO against biofouling, advantageously do not generate waste products which are harmful to the environment.
  • the antibiofouling properties of the titanium alloy surface having MMO are obtained with current densities of 5 mA/m 2 and above, in particular of at least 10 mA/m 2 .
  • the higher the density of the current density generally the higher the antibiofouling effect.
  • the higher the current density the higher the power consumption and the shorter the active life span of titanium alloy surface as anode, because the MMO on the surface tend to degrade with time, and the properties conferred to the surface by the MMO are lost.
  • a range of suitable current densities to achieve the antibiofouling effect may be from 5 mA/m 2 to 1 A/m 2 and, in particular from 7 mA/m 2 to 500 mA/m 2 , more in particular from 10 mA/m 2 to 250 mA/m 2 , yet more in particular of 15 mA/m 2 to 150 mA/m 2 , and yet more in particular from 20 mA/m 2 to 100 mA/m 2 .
  • the voltage may be applied permanently or in pulses, it may be preferred to apply the voltage in pulses.
  • a pulse may be defined as a period of time for which a voltage is applied. Permanent application of voltages may be of interest for surface modified titanium alloys conforming structures which are permanently immersed in an aqueous environment, e.g., for preventing, reducing or removing biofouling. The use of pulses may be appropriate for reducing the energy consumption and ultimately reducing the costs of the protection of the titanium alloy surface. Pulses may also be appropriate, e.g., for executing a specific cleaning operation, to facilitate the removal of biofouling, including, e.g., constant voltage pulses, alternate pulses or periodic pulses.
  • the pulses may be applied by alternating anodic application of the pulses, so that the titanium alloy having MMO on the surface acts as anode, and cathodic application, so that the titanium alloy having MMO on the surface acts as cathode. Alternating anodic and cathodic application of the pulses may also be preferred to reduce the consumption of energy.
  • the application of pulses as described in the European patent application No. 22382464 may also applied to a method as described herein.
  • Such voltages can be applied by methods known in the art, by providing the titanium alloy having MMO on its surface with appropriate means for voltage application and anodic polarization in particular.
  • the titanium alloy having MMO on its surface will act as an anode and will be connected to a reference electrode (typically a Ag/AgCl reference electrode) and to a metal acting as a cathode, which are also immersed in the aqueous environment, by means known in the art.
  • Said electrodes may be connected to a power source, e.g., a battery or a generator such as fuel powered motor for the generation of electricity.
  • a power source e.g., a battery or a generator such as fuel powered motor for the generation of electricity.
  • the titanium alloy having a MMO on its surface may be divided in two electrically isolated areas, by which one area may be anodically polarized and the other area may be cathodically polarized.
  • the active life span of a titanium alloy having MMO on its surface acting as anode will vary depending on the amount of MMO present on the surface of the titanium alloy, the thickness of the MMO layer, the actual working conditions and the aqueous environment in which it is immersed.
  • the active life span of a titanium alloy having MMO on its surface acting as anode immersed in seawater may be of up to 25 years, e.g., from 6 months to 20 years, in particular from 1 year to 15 years.
  • the high conductivity due to the presence of mixed metal oxides replacing the titanium oxides originally present on the titanium alloy surface facilitates the flow of electrons through the surface of the titanium alloy, generated during oxidation reactions in the electrolyte upon the application of a current.
  • Anodic polarization of untreated grade 5 titanium alloy under conditions for antifouling properties useful in pure titanium A propeller of untreated grade 5 titanium alloy was subjected to anodic polarization under conditions established to be sufficient for grade 2 titanium alloy to generate chlorine in sea water, as described in the European patent application No. 22382464 .
  • the propeller was immerged in seawater and an anodic potential of 7 V Ag/AgCl was applied to the propeller.
  • Example 1 grade 5 titanium alloy
  • the properties of the surface modified grade 5 titanium alloy were analysed as follows.
  • Table 1 shows the mass before treatment, M 0 , after, M and the difference of both values.
  • Table 1 Sample M 0 (g) M (g) ⁇ M (mg) 1 27.4391 27.4595 20.4 2 27.3648 27.3861 21.3 3 27.4613 27.4877 26.4
  • the surface treatment resulted in an increase of the mass of the sample due to the thermal decomposition of the metal oxide precursor (metal chloride) deposited onto the surface of the titanium alloy into metal oxide.
  • the surface modified grade 5 titanium alloy samples were subjected to an increasing anodic polarization up to 6 V Ag/AgCl using a potentiostat using a Nova 1.7 software, to test the resistance to corrosion of the surface modified grade 5 titanium alloy, by immersing in seawater the surface treated grade 5 titanium alloy samples as working electrodes, and grade 5 titanium alloy samples without a surface treatment as counter electrodes.
  • test conditions were the following:
  • the breakdown potential of grade 5 titanium alloy, without any protection or coating, is known to be of approximately 2.5 V Ag/AgCl , much lower than the maximum potential reached during the test with the surface modified titanium alloy (6 V Ag/AgCl ). With this test it was intended to verify if the surface treatment applied protected the surface from corrosion (pitting) when the potential was raised above said potential. It was also intended to verify how long it took before the metal oxide on the surface of the titanium alloy was lost and the consequences of the loss, on the surface having the base titanium alloy exposed.
  • the same test was executed using the test conditions with untreated grade 5 titanium alloy as working anode and using a potential of up to 3 V Ag/AgCl .
  • the untreated grade 5 titanium used was the same as the samples used for MMO modification.
  • Figure 2A graphically represents the intensities (A) (left) and current densities (A/m 2 ) (right) obtained in the test for MMO modified grade 5 titanium alloy
  • Figure 2B shows the same graphs (left and right) for the comparative test for grade 5 titanium alloy without modification.
  • the coating is positively affecting the amount of current that is mined through the surface, being both the intensity and the current density, several orders of magnitude higher for the MMO modified titanium alloy (of about 0.6 A and about 300 A/m 2 for a potential of about 2.5 V Ag/AgCl ) when compared to the untreated titanium alloy (of about 0.0002 A and 0.04 A/m 2 for a potential of 2.5 V Ag/AgCl ).
  • the current intensities and densities recorded indicate that for the MMO modified titanium alloy, around 1.6 V Ag/AgCl a reaction occurs which has been identified as the generation of Cl 2 from the seawater electrolyte.
  • both curves for the surface modified and the non-modified grade 5 titanium alloy are shown superimposed for potential ranges below 2.2 V Ag/AgCl (in particular in ranges from 0.0 to 1.2 V Ag/AgCl in A), from 1.2 to 1.8 V Ag/AgCl in B), and from 1.8 to 2.20 V Ag/AgCl in C)).
  • the curves show a similar initial growth, diverging noticeably from 1 V Ag/AgCl , and completely masking the intensity peak that occurs in grade 5 titanium alloy around 1.5 V Ag/AgCl .
  • titanium alloy with MMO on its surface the recording of densities starts at 0.0023 A/m 2 and increases to 0.168 A/m 2 .
  • a titanium alloy with MMO on its surface as described herein displays a higher current intensities and densities at the potential of chlorine generation, which is indicative of clearly sufficient amounts of chlorine generation for an anti-fouling effect, and at the same time no electrode failure is observed at potentials of around 3 V Ag/AgCl , which is indicative of the suitability of MMO modified titanium alloys for anti-fouling applications at voltages below 3 V Ag/AgCl .
  • Cl 2 generation may be accompanied by other oxidation reactions such as water oxidation as detailed above.
  • the mass of chlorine generated can be determined without subtracting the uncoated intensity, by equation (1), where ⁇ Cl is the yield of the generation, Q is the integral of the intensity curve of the MMO modified sample, F is the Faraday constant, and MW Cl 2 is the molecular weight of CI2.
  • m Cl 2 Q 2 F ⁇ MW Cl 2 ⁇ ⁇ Cl
  • Example 2 grade 2 titanium alloy
  • the properties of the surface modified grade 5 titanium alloy were analysed as follows.
  • the samples were weighed to obtain the effect on the mass of the samples from the surface treatment.
  • Table 2 shows the mass before treatment, M 0 , after, M and the difference of both values.
  • Table 2 Sample M 0 (g) M (g) ⁇ M (mg) 1 27.4154 27.4288 13.4 2 25.7089 25.7211 12.2 3* 21.1542 21.1576 3.4 *control sample
  • the main crystalline phases observed are titanium and titanium oxides, in particular titanium (IV) oxide (TiO 2 ) and in minor amounts titanium (II) oxide (TiO).
  • XPS X-ray photoelectron spectroscopy
  • the 3d3/2 component has been used for the adjustment and knowing the relation of position (+9.3eV) and of the areas (1:1.5) that it has with respect to the peak 3d5/2 this has been calculated. In this way, the position of 530.5 eV has been obtained, which could correspond to Sb(III).
  • Sn its position indicates the presence of Sn(IV) and Ti would be as Ti(IV).
  • Fe it is also interfered with by the Sn2p3/2 component and in, in this case, the breakdown of components has been done, setting the most common positions for Fe(ll) and Fe(III), 709.4 and 711 eV, respectively.
  • the surface modified grade 2 titanium samples were subjected to an increasing anodic polarization up to 6 V Ag/AgCl as described above for the MMO modified grade 5 samples, under the same conditions.
  • Figure 4 shows the overlap of the current density (A/m 2 ) graphs obtained for the MMO modified grade 5 titanium alloy and the MMO modified grade 2 titanium alloy.
  • the potentiostat does not register currents above certain value and the MMO modified grade 2 alloy also shows a flat plateau which does not correspond to the real intensities reached.

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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1147442A (en) 1965-05-12 1969-04-02 Henri Bernard Beer Improvements in or relating to electrodes for electrolysis
JPS51105942A (ja) * 1975-03-14 1976-09-20 Kobe Steel Ltd Sukimafushokuookosanai kagakusochi
US4005004A (en) * 1974-09-27 1977-01-25 Asahi Kasei Kogyo Kabushiki Kaisha Electrode coating consisting of a solid solution of a noble metal oxide, titanium oxide, and zirconium oxide
JPH06306670A (ja) * 1993-04-27 1994-11-01 Daiso Co Ltd 酸素発生用電極の製法
JP2003328164A (ja) 2002-05-02 2003-11-19 Nippon Steel Corp チタン製船舶の海生生物付着防止方法
US7258778B2 (en) * 2003-03-24 2007-08-21 Eltech Systems Corporation Electrocatalytic coating with lower platinum group metals and electrode made therefrom
US20100126851A1 (en) * 2003-07-28 2010-05-27 De Nora Elettrodi S.P.A. Electrode for electrochemical processes and method for producing the same
US8007643B2 (en) * 2006-10-12 2011-08-30 Industrie De Nora S.P.A. Anode for electrolysis
US20140224666A1 (en) * 2013-02-08 2014-08-14 Nano-X-Gmbh Electrocatalyst, electrode coating and electrode for the preparation of chlorine
US20140331912A1 (en) * 2013-05-07 2014-11-13 Kee-Rong Wu Apparatus using an electro-catalytic coating to reduce ship's friction and prevent biofouling

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4345981A (en) * 1978-11-24 1982-08-24 Diamond Shamrock Corporation Anodically polarized surface for biofouling and scale control

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1147442A (en) 1965-05-12 1969-04-02 Henri Bernard Beer Improvements in or relating to electrodes for electrolysis
US4005004A (en) * 1974-09-27 1977-01-25 Asahi Kasei Kogyo Kabushiki Kaisha Electrode coating consisting of a solid solution of a noble metal oxide, titanium oxide, and zirconium oxide
JPS51105942A (ja) * 1975-03-14 1976-09-20 Kobe Steel Ltd Sukimafushokuookosanai kagakusochi
JPH06306670A (ja) * 1993-04-27 1994-11-01 Daiso Co Ltd 酸素発生用電極の製法
JP2003328164A (ja) 2002-05-02 2003-11-19 Nippon Steel Corp チタン製船舶の海生生物付着防止方法
US7258778B2 (en) * 2003-03-24 2007-08-21 Eltech Systems Corporation Electrocatalytic coating with lower platinum group metals and electrode made therefrom
US20100126851A1 (en) * 2003-07-28 2010-05-27 De Nora Elettrodi S.P.A. Electrode for electrochemical processes and method for producing the same
US8007643B2 (en) * 2006-10-12 2011-08-30 Industrie De Nora S.P.A. Anode for electrolysis
US20140224666A1 (en) * 2013-02-08 2014-08-14 Nano-X-Gmbh Electrocatalyst, electrode coating and electrode for the preparation of chlorine
US20140331912A1 (en) * 2013-05-07 2014-11-13 Kee-Rong Wu Apparatus using an electro-catalytic coating to reduce ship's friction and prevent biofouling

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
CHAPLIN,B.P.: "Critical review of electrochemical advanced oxidation processes for water treatament applications.", ENVIRON. SCI.: PROCESSES IMPACTS, vol. 16, no. 6, 2014, pages 1182 - 1203, Retrieved from the Internet <URL:https://doi.org/10.1039/c3em00679d>
MIRZAEI ALAVIJEH MEHDI ET AL: "A selective and efficient precious metal-free electrocatalyst for chlorine evolution reaction: An experimental and computational study", CHEMICAL ENGENEERING JOURNAL, ELSEVIER, AMSTERDAM, NL, vol. 421, 21 November 2020 (2020-11-21), XP086621438, ISSN: 1385-8947, [retrieved on 20201121], DOI: 10.1016/J.CEJ.2020.127785 *
MONTILLAF. MONTILLAE. MORALLONA. DE BATTISTIJ. L. VAZQUEZ ET AL.: "Preparation and Characterization of Antimony-Doped Tin Dioxide Electrodes", THE JOURNAL OF PHYSICAL CHEMISTRY B, vol. 108, no. 16, 2004, pages 5036 - 5043
SHAODAN SHAOWEI YANLU CAOXIAOLIANG LIHAO XU ET AL.: "High-performance Ti/Sb-Sn02/Pb 04 electrodes for chlorine evolution: Preparation and characteristics", JOURNAL OF HAZARDOUS MATERIALS, vol. 267, 2014, pages 238 - 244, ISSN: ISSN 0304-3894
SUNYI SUNSHAOAN CHENGZHEN YULONGXIN LICHAOCHAO LIJIAWEI YANG ET AL.: "Elucidating deactivation mechanisms of Pd-doped and un-doped Ti/Sn0 -Sb electrodes", JOURNAL OF ALLOYS AND COMPOUNDS, vol. 834, 2020, pages 155184, ISBN: ISSN 0925-8388

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