System and method for in-situ formation of barrier coating on metallic article in contact with or exposed to water within a water system

Abstract

The present invention provides a system for in-situ formation of a barrier coating on a metallic article in contact with or exposed to water within a water system, comprising: a generator connected to a power supply unit for generating electromagnetic wave having a time varying frequency, and one or more treatment assemblies each comprising two treatment units electrically coupled to the generator and positioned in a spaced-apart fashion to come into contact with the water. Each of the treatment units comprises an inductor coil load and a capacitive load connected in series, and the time-varying frequency electromagnetic wave is applied across the two treatment units to produce a synergistic effect of inductance field, capacitance electric field and a flow of ionic wave current in the water, whereby the water is energized in an oxidizing state having an oxidizing potential sufficient to induce precursor ions of the metal which are reactive with hydroxyl groups in the water for in-situ formation of a passivating metal oxide or salt as the barrier coating on a surface of the metallic article. The invention also provides a method for in-situ formation of a barrier coating on a metallic article.

What is claimed is: 
     
         1 . A system for in-situ formation of a barrier coating on a metallic article in contact with or exposed to water within a water system, comprising:
 a generator for generating electromagnetic wave having a time varying frequency;   a power supply unit connected to the generator for applying a driving voltage to the generator to drive the generation of the electromagnetic wave; and   one or more treatment assemblies each comprising two treatment units positioned in a spaced-apart fashion to come into contact with the water, wherein each of the treatment units comprises an inductor coil load and a capacitive load connected in series, and the two treatment units are electrically coupled respectively to first and second terminals of the generator to apply the time-varying frequency electromagnetic wave generated by the generator across the two treatment units to produce a synergistic effect of one or more of the following:
 a time varying inductance field in and around the respective coil load, 
 a capacitance electric field across the capacitive loads of the two treatment units, and 
 a flow of ionic wave current travelling in a pulsating and time-varying manner in the water between the two treatment units, 
   whereby the water is energized in an oxidizing state having an oxidizing potential sufficient to induce precursor ions of the metal which are reactive with hydroxyl groups in the water for in-situ formation of a passivating metal oxide or salt as the barrier coating on a surface of the metallic article.   
     
     
         2 . The system as claimed in  claim 1 , wherein:
 a bypass switch is provided to create a bypass path between the two treatment units so as to short circuit the capacitive loads of the two treatment units; or   the two treatment units are spaced at a distance in the range 2 to 20 mm, preferably 2 to 10 mm, to produce a capacitive close field, preferably a plurality of treatment assemblies are assembled together in a treatment chamber to enhance the capacitive close field; or   any combination thereof.   
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . The system as claimed in  claim 1 , wherein the two treatment units are spaced far apart from each other to produce a resistive far field. 
     
     
         6 . The system as claimed in  claim 1 , wherein the water in the oxidizing state is achieved by producing a positive oxidation reduction potential (ORP) shift in the water, preferably the positive ORP is shifted to more than +200 mV vs Ag/AgCl. 
     
     
         7 . (canceled) 
     
     
         8 . The system as claimed in  claim 1 , wherein the capacitive load is provided in the form of plate, rod, tube or mesh. 
     
     
         9 . The system as claimed in  claim 1 , wherein the generator is configured to generate a direct current (DC) biased time-varying frequency pulsating electromagnetic wave comprising an alternating current (AC) and a biased DC component. 
     
     
         10 . The system as claimed in  claim 1 , wherein the frequency of the electromagnetic wave ranges from about 500 Hz to about 1,000,000 Hz, preferably from about 200 Hz to about 5,000 Hz, and the electromagnetic field has a sweeping frequency of 10 to 100 Hz. 
     
     
         11 . The system as claimed in  claim 1 , the metallic article is iron-based, and the induced precursor ions are Fe 2+  ions which react with the hydroxyl groups to form passivating magnetite as the barrier coating on the surface of the iron-based article, preferably the iron-based article is well servicing equipment of oil production field. 
     
     
         12 . (canceled) 
     
     
         13 . The system as claimed in  claim 1 , wherein the metallic article is copper-based, and the induced precursor ions are Cu +  ions which react with the hydroxyl groups to form passivating cuprous oxide as the barrier coating on the surface of the copper-based article, preferably the induced precursor Cu +  ions react with the hydroxyl groups to form a composite coating consisting of an inner layer of the passivating cuprous oxide on the surface of the copper-based article and an outer layer of passivating cupric oxide on the inner layer. 
     
     
         14 . (canceled) 
     
     
         15 . The system as claimed in  claim 1 , wherein the frequency of the electromagnetic wave is selected to excite the metallic article so that a skin effect is created on the surface of the metallic article to allow the electromagnetic wave to travel on said surface. 
     
     
         16 . The system as claimed in  claim 1 , further comprising means for enhancing the oxidizing potential of the water to facilitate formation of the precursor ions. 
     
     
         17 . A method for in-situ formation of a barrier coating on a metallic article in contact with or exposed to water within a water system, comprising the steps of:
 generating electromagnetic wave having a time varying frequency; and   applying the time-varying frequency electromagnetic wave to one or more treatment assemblies each comprising two treatment units positioned in a spaced-apart fashion to come into contact with the water, wherein each of the treatment units comprises an inductor coil load and a capacitive load connected in series so that the application of the time-varying frequency electromagnetic wave across the two treatment units produces a synergistic effect of one or more of the following:
 a time varying inductance field in and around the respective coil load, 
 a capacitance electric field across the capacitive loads of the two treatment units, and 
 a flow of ionic wave current travelling in a pulsating and time-varying manner in the water between the two treatment units, 
   subjecting the water to the synergistic effect, whereby to energize the water in an oxidizing state having an oxidizing potential sufficient to induce precursor ions of the metal which are reactive with hydroxyl groups in the water for in-situ formation of a passivating metal oxide or salt as the barrier coating on a surface of the metallic article.   
     
     
         18 . The method as claimed in  claim 17 , wherein the water in the oxidizing state is achieved by producing a positive oxidation reduction potential (ORP) shift in the water. 
     
     
         19 . The method as claimed in  claim 17 , comprising shifting the positive ORP to more than +200 mV vs Ag/AgCl. 
     
     
         20 . The method as claimed in  claim 17 , wherein:
 the water in the oxidizing state is achieved by producing a positive oxidation reduction potential (ORP) shift in the water, and wherein the positive ORP shift is caused by a method selected from the group consisting of DC electrolysis, ozonation, hydrogen peroxide, and oxidant dosing; or   comprising shifting the positive ORP to more than +200 mV vs Ag/AgCl, and wherein the positive ORP shift is caused by a method selected from the group consisting of DC electrolysis, ozonation, hydrogen peroxide, and oxidant dosing.   
     
     
         21 . The method as claimed in  claim 17 , comprising providing a bypass switch to create a bypass path between the two treatment units so as to short circuit the capacitive loads of the two treatment units. 
     
     
         22 . The method as claimed in  claim 17 , wherein the two treatment units are spaced at a distance in the range 2 to 20 mm, preferably 2 to 10 mm, to produce a capacitive close field, preferably assembling a plurality of treatment assemblies together to enhance the capacitive close field. 
     
     
         23 . (canceled) 
     
     
         24 . The method as claimed in  claim 17 , wherein the two treatment units are spaced far apart from each other to produce a resistive far field. 
     
     
         25 . The method as claimed in  claim 17 , wherein the generating step comprises configuring the time-varying frequency electromagnetic wave to have a DC biased component. 
     
     
         26 . The method as claimed in  claim 17 , wherein the frequency of the electromagnetic wave ranges from about 500 Hz to about 1,000,000 Hz, preferably from about 200 Hz to about 5,000 Hz, and the electromagnetic field has a sweeping frequency of 10 to 100 Hz. 
     
     
         27 . The method as claimed in  claim 17 , the metallic article is iron-based, and the induced precursor ions are Fe 2+  ions which react with the hydroxyl groups to form passivating magnetite as the barrier coating on the surface of the iron-based article, preferably the iron-based article is well servicing equipment of oil production field. 
     
     
         28 . (canceled) 
     
     
         29 . The method as claimed in  claim 17 , wherein the metallic article is copper-based, and the induced precursor ions are Cu +  ions which react with the hydroxyl groups to form passivating cuprous oxide as the barrier coating on the surface of the copper-based article, preferably the induced precursor Cu +  ions react with the hydroxyl groups to form a composite coating consisting of an inner layer of the passivating cuprous oxide on the surface of the copper-based article and an outer layer of passivating cupric oxide on the inner layer. 
     
     
         30 . (canceled) 
     
     
         31 . The method as claimed in  claim 17 , wherein the frequency of the electromagnetic wave is selected to excite the metallic article so that a skin effect is created on the surface of the metallic article to allow the electromagnetic wave to travel on said surface. 
     
     
         32 . (canceled) 
     
     
         33 . The system as claimed in  claim 2 , wherein:
 the two treatment units are spaced far apart from each other to produce a resistive far field; or   the water in the oxidizing state is achieved by producing a positive oxidation reduction potential (ORP) shift in the water, preferably the positive ORP is shifted to more than +200 mV vs Ag/AgCl; or   the capacitive load is provided in the form of plate, rod, tube or mesh; or   the generator is configured to generate a direct current (DC) biased time-varying frequency pulsating electromagnetic wave comprising an alternating current (AC) and a biased DC component; or   the frequency of the electromagnetic wave ranges from about 500 Hz to about 1,000,000 Hz, preferably from about 200 Hz to about 5,000 Hz, and the electromagnetic field has a sweeping frequency of 10 to 100 Hz; or   the metallic article is iron-based, and the induced precursor ions are Fe 2+  ions which react with the hydroxyl groups to form passivating magnetite as the barrier coating on the surface of the iron-based article, preferably the iron-based article is well servicing equipment of oil production field; or   the metallic article is copper-based, and the induced precursor ions are Cu +  ions which react with the hydroxyl groups to form passivating cuprous oxide as the barrier coating on the surface of the copper-based article, preferably the induced precursor Cu +  ions react with the hydroxyl groups to form a composite coating consisting of an inner layer of the passivating cuprous oxide on the surface of the copper-based article and an outer layer of passivating cupric oxide on the inner layer; or   the frequency of the electromagnetic wave is selected to excite the metallic article so that a skin effect is created on the surface of the metallic article to allow the electromagnetic wave to travel on said surface; or   further comprising means for enhancing the oxidizing potential of the water to facilitate formation of the precursor ions; or   any combination thereof.   
     
     
         34 . The method as claimed in  claim 20 , wherein:
 comprising providing a bypass switch to create a bypass path between the two treatment units so as to short circuit the capacitive loads of the two treatment units; or   the two treatment units are spaced at a distance in the range 2 to 20 mm, preferably 2 to 10 mm, to produce a capacitive close field, preferably assembling a plurality of treatment assemblies together to enhance the capacitive close field; or   the two treatment units are spaced far apart from each other to produce a resistive far field; or   the generating step comprises configuring the time-varying frequency electromagnetic wave to have a DC biased component; or   the frequency of the electromagnetic wave ranges from about 500 Hz to about 1,000,000 Hz, preferably from about 200 Hz to about 5,000 Hz, and the electromagnetic field has a sweeping frequency of 10 to 100 Hz; or   the metallic article is iron-based, and the induced precursor ions are Fe 2+  ions which react with the hydroxyl groups to form passivating magnetite as the barrier coating on the surface of the iron-based article, preferably the iron-based article is well servicing equipment of oil production field; or   the metallic article is copper-based, and the induced precursor ions are Cu +  ions which react with the hydroxyl groups to form passivating cuprous oxide as the barrier coating on the surface of the copper-based article, preferably the induced precursor Cu +  ions react with the hydroxyl groups to form a composite coating consisting of an inner layer of the passivating cuprous oxide on the surface of the copper-based article and an outer layer of passivating cupric oxide on the inner layer; or   the frequency of the electromagnetic wave is selected to excite the metallic article so that a skin effect is created on the surface of the metallic article to allow the electromagnetic wave to travel on said surface; or   any combination thereof.