Composite gasket and method and device for inhibiting galvanic corrosion formed by connecting different metals

Abstract

The invention relates to the field of corrosion protection of metal materials in engineering application, provides a composite gasket, and a method and device for inhibiting galvanic corrosion formed by connection of different metals, and aims to solve the problem that galvanic corrosion formed by connection of a cathode and an anode cannot be cut off only through an insulating material in the prior art. Comprising the following steps: inlaying anode metal on the surface of an insulating spacer in contact with an environmental medium to obtain a composite spacer; a composite gasket is connected between a galvanic couple cathode and a galvanic couple anode which are located in an environmental medium, anode metal embedded in the composite gasket and the galvanic couple anode are connected with an external power source through wires to form a cathode protection current circuit, the composite gasket is connected to the positive electrode of the external power source, and the composite gasket is connected to the negative electrode of the external power source. The galvanic couple anode is connected to the cathode of the external power supply; and adjusting the cathode protection current of the cathode protection current circuit through an external power supply, and monitoring the anode current of the galvanic couple anode at the same time until the measured anode current is reduced to a preset condition.

Description

Technical Field

[0001] The present application relates to the field of corrosion protection of metal materials in engineering applications, and more specifically, to a composite gasket, a method for inhibiting galvanic corrosion of different metal connections, and a device thereof. Background Art

[0002] Different metals in engineering are often connected together to form components exposed to ion-conductive media (such as rainwater, seawater, etc.), and often face serious galvanic corrosion problems. For example, when a magnesium alloy plate is connected to another galvanized steel plate through galvanized steel bolts, nuts, bolt washers, and exposed to salt spray and rainwater at sea, the magnesium alloy plate will form a corrosion galvanic with these galvanized steel bolts, nuts, bolt washers, and galvanized steel plates, greatly accelerating the corrosion of the magnesium alloy plate; or when a carbon steel pipe is connected to another copper alloy pipe through a flange joint, high-strength steel bolts, nuts, and sealing washers to conduct seawater in the pipe, the carbon steel pipe will form a corrosion galvanic with these high-strength steel bolts, nuts, sealing washers, and copper alloy pipes, accelerating the corrosion of the carbon steel pipe. Trying to change the bolt gasket or sealing gasket into an insulating material to cut off the electronic conductive path of the corrosion galvanic couple is difficult to achieve in actual engineering, because the engineering structure of the component is relatively complex. Although the gasket can isolate the direct contact between the positive and negative electrodes of the galvanic couple, there are many other electronic circuits in the actual engineering structure, which can still connect the positive and negative electrodes of the galvanic couple. Changing the bolt gasket or sealing gasket into an insulating material to isolate the direct electronic contact between the positive and negative electrodes only increases the distance between the positive and negative ion circuits. Even if the thickness of the insulating gasket is very large, the suppression of galvanic corrosion is still limited and the galvanic corrosion current cannot be cut off.

[0003] Therefore, the prior art needs to be improved. Summary of the invention

[0004] The purpose of the present application is to provide a composite gasket, a method for inhibiting galvanic corrosion formed by connecting different metals, and a device thereof, so as to solve the problem that the existing direct electronic contact between the anode and the cathode is only isolated by insulating materials, but the galvanic corrosion formed by the connection between the anode and the cathode cannot be cut off.

[0005] To achieve the above objectives, the technical solution adopted in the first aspect of the embodiment of the present application is:

[0006] A device for inhibiting galvanic corrosion of dissimilar metal connections, comprising:

[0007] Embedding anode metal on the surface of the insulating gasket contacting the environmental medium to obtain a composite gasket;

[0008] The composite gasket is connected between a galvanic cathode and a galvanic anode in an environmental medium, and the anode metal embedded in the composite gasket is connected to the galvanic anode through a wire and an external power source, respectively, to form a cathodic protection current circuit, wherein the composite gasket is connected to the positive electrode of the external power source, and the galvanic anode is connected to the negative electrode of the external power source;

[0009] The cathodic protection current of the cathodic protection current circuit is adjusted by the external power supply, and the anode current of the galvanic anode is monitored at the same time until the measured anode current decreases to a preset condition.

[0010] According to the above-mentioned method for inhibiting galvanic corrosion formed by connecting different metals, the step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anode current of the galvanic anode until the measured anode current is reduced to a preset condition specifically includes:

[0011] The cathodic protection current of the cathodic protection current circuit is adjusted by the external power supply, and the potential difference between the potential of the galvanic anode and the potential of the anode metal embedded in the composite gasket is monitored until the measured potential difference reading reaches a preset condition.

[0012] According to the above-mentioned method for inhibiting galvanic corrosion formed by connecting different metals, the step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anode current of the galvanic anode until the measured anode current is reduced to a preset condition specifically includes:

[0013] Providing a reference electrode, placing the reference electrode in the environmental medium near the galvanic anode, and monitoring the potential of the galvanic anode through the reference electrode;

[0014] The cathode protection current of the cathode protection current circuit is adjusted by the external power supply until the potential difference between the galvanic anode and the reference electrode reaches a preset condition.

[0015] According to the above-mentioned method for inhibiting galvanic corrosion formed by connections between different metals, in the step of embedding anode metal on the surface of the insulating gasket that contacts the environmental medium to obtain a composite gasket, the ratio of the thickness of the composite gasket to the maximum diagonal of the maximum surface of the composite gasket is not less than 0.1, and the ratio of the thickness of the composite gasket to the diameter of the composite gasket is not less than 0.1.

[0016] According to the above-mentioned method for inhibiting galvanic corrosion formed by the connection of different metals, in the step of embedding anode metal on the surface of the insulating gasket contacting the environmental medium to obtain a composite gasket, the working surface of the anode metal in contact with the environmental medium accounts for more than 1% of the total area of ​​the composite gasket exposed to the environmental medium.

[0017] According to the above-mentioned method for inhibiting galvanic corrosion formed by connections between different metals, in the step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anodic current of the galvanic anode until the measured anodic current is reduced to a preset condition, the current or potential difference that the external power supply needs to apply is positively correlated with the degree of galvanic corrosion.

[0018] According to the above-mentioned method for inhibiting galvanic corrosion formed by connecting different metals, in the step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anodic current of the galvanic anode until the measured anodic current drops to a preset condition, the potential difference applied by the external power supply is preferably greater than 2V.

[0019] The technical solution adopted in the second aspect of the embodiment of the present application is:

[0020] A device for inhibiting galvanic corrosion formed by connecting different metals, comprising a galvanic cathode, a galvanic anode and a bolt, wherein the galvanic cathode is connected to the galvanic anode through the bolt, and the device further comprises:

[0021] An insulating gasket is arranged on the bolt and located between the galvanic cathode and the galvanic anode, and a mounting groove is provided on the surface of the insulating gasket in contact with the ambient medium;

[0022] an anode metal disposed in the mounting groove and having no direct contact with the galvanic cathode and the galvanic anode;

[0023] The positive electrode of the external power source is connected to the anode metal, and the negative electrode of the external power source is connected to the galvanic anode.

[0024] The technical solution adopted in the third aspect of the embodiment of the present application is:

[0025] A composite gasket is used in the method of inhibiting galvanic corrosion formed by connecting different metals as described above. The composite gasket includes an insulating gasket and an anode metal. A mounting groove is provided on the surface of the insulating gasket in contact with the environmental medium, and the anode metal is embedded in the mounting groove.

[0026] According to the composite gasket described above, when the composite gasket is a composite gasket for bolts, the anode metal is arranged on the outer surface of the insulating gasket.

[0027] According to the composite gasket described above, when the composite gasket is a composite gasket for a pipeline, the anode metal is arranged on the inner surface of the insulating gasket.

[0028] According to the composite gasket described above, the insulating gasket is provided with two pieces, and the anode metal is provided between the two insulating gaskets.

[0029] The composite gasket, method for inhibiting galvanic corrosion of different metal connections and device provided by the present application have at least the following beneficial effects:

[0030] The present application can increase the distance between the galvanic cathode and the galvanic anode in the environmental medium in which they are in common contact through the insulating gasket (insulating layer) in the composite gasket, thereby reducing the galvanic effect; more importantly, it can also use an external power source through the anode metal in the composite gasket to provide cathodic protection to the galvanic anode in galvanic corrosion, thereby inhibiting its galvanic corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 A flow chart of a method for inhibiting galvanic corrosion of different metal connections provided in an embodiment of the present application.

[0033] Figure 2 A structural schematic diagram of Example 1 of a method for inhibiting galvanic corrosion of different metal connections provided in an embodiment of the present application.

[0034] Figure 3 A schematic diagram of the effect of the cathodic protection current on the anode current in Example 1 of a method for inhibiting galvanic corrosion of different metal connections provided in an embodiment of the present application.

[0035] Figure 4 This is a structural schematic diagram of Example 2 of a method for inhibiting galvanic corrosion of different metal connections provided in an embodiment of the present application.

[0036] Figure 5 A schematic diagram of the effect of the cathodic protection current on the anode current in Example 2 of a method for inhibiting galvanic corrosion of a connection between different metals provided in an embodiment of the present application.

[0037] Figure 6 A schematic diagram of one of the structures of a device for inhibiting galvanic corrosion of different metal connections provided in an embodiment of the present application.

[0038] Figure 7 Another schematic diagram of the structure of a device for inhibiting galvanic corrosion of different metal connections provided in an embodiment of the present application.

[0039] Figure 8 A side view of one of the composite gaskets provided in an embodiment of the present application.

[0040] Fig. 9 A front view of one of the composite gaskets provided in an embodiment of the present application.

[0041] Fig.10 A cross-sectional view of one of the composite gaskets provided in the embodiments of the present application.

[0042] Fig.11 A side view of another composite gasket provided in an embodiment of the present application.

[0043] Fig.12 A front view of another composite gasket provided in an embodiment of the present application.

[0044] Fig.13 A cross-sectional view of another type of composite gasket provided in an embodiment of the present application.

[0045] Fig.14 A cross-sectional view of another composite gasket provided in an embodiment of the present application.

[0046] Fig.15 A cross-sectional view of another composite gasket provided in an embodiment of the present application.

[0047] Among them, the reference numerals in the figure are:

[0048] 1. First ammeter; 2. Second ammeter; 3. DC power supply; 41. Magnesium alloy; 42. Stainless steel gasket; 43. Third titanium wire; 44. Fourth titanium wire; 45. Insulating flat washer; 46. Nylon hexagonal nut; 471. Nylon hexagonal screw head; 472. Nylon hexagonal screw tail; 48. Salt spray test chamber; 49. NaCl solution;

[0049] 51. Aluminum bronze tube; 52. Carbon steel tube; 53. Third titanium wire; 54. Flange sealing gasket; 55. Insulating flange cover; 61. Galvanic cathode; 62. Galvanic anode; 63. Bolt; 64. Insulating gasket; 641. Through hole; 65. Anode metal; 66. External power supply. DETAILED DESCRIPTION

[0050] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0051] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be directly or indirectly located on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and cannot be understood as limitations on the present technical solution. The terms "first" and "second" are only used for the convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0052] Different metals in engineering are often connected together to form components exposed to ion-conductive media (such as rainwater, seawater, etc.), and often face serious galvanic corrosion problems. For example, when a magnesium alloy plate is connected to another galvanized steel plate through galvanized steel bolts, nuts, bolt washers, and exposed to salt spray and rainwater at sea, the magnesium alloy plate will form a corrosion galvanic with these galvanized steel bolts, nuts, bolt washers, and galvanized steel plates, greatly accelerating the corrosion of the magnesium alloy plate; or when a carbon steel pipe is connected to another copper alloy pipe through a flange joint, high-strength steel bolts, nuts, and sealing washers to conduct seawater in the pipe, the carbon steel pipe will form a corrosion galvanic with these high-strength steel bolts, nuts, sealing washers, and copper alloy pipes, accelerating the corrosion of the carbon steel pipe. Trying to change the bolt gasket or sealing gasket into an insulating material to cut off the electronic conductive path of the corrosion galvanic couple is difficult to achieve in actual engineering, because the engineering structure of the component is relatively complex. Although the gasket can isolate the direct contact between the positive and negative electrodes of the galvanic couple, there are many other electronic circuits in the actual engineering structure, which can still connect the positive and negative electrodes of the galvanic couple. Changing the bolt gasket or sealing gasket into an insulating material to isolate the direct electronic contact between the positive and negative electrodes only increases the distance between the positive and negative ion circuits. Even if the thickness of the insulating gasket is very large, the suppression of galvanic corrosion is still limited and the galvanic corrosion current cannot be cut off.

[0053] To this end, the present application embeds anode metal on the surface of the insulating gasket contacting the environmental medium to obtain a composite gasket, connects the composite gasket between the galvanic cathode and the galvanic anode in the environmental medium, and connects the anode metal embedded in the composite gasket and the galvanic anode through a wire and an external power source respectively to form a cathodic protection current circuit, wherein the embedded anode metal in the composite gasket is connected to the positive electrode of the external power source, and the galvanic anode is connected to the negative electrode of the external power source; the cathodic protection current of the cathodic protection current circuit is adjusted by the external power source, and the anode current of the galvanic anode is monitored at the same time until the measured anode current is reduced to a preset condition. Therefore, the present application can increase the distance between the galvanic cathode and the galvanic anode in the environmental medium they are in contact with by the insulating gasket (insulating layer) in the composite gasket, thereby reducing the galvanic effect; more importantly, it can also use the external power source to pass through the anode metal in the composite gasket to cathodically protect the galvanic anode in galvanic corrosion and inhibit its galvanic corrosion.

[0054] For this purpose, see Figure 1 In a first aspect, an embodiment of the present application provides a method for inhibiting galvanic corrosion of different metal connections, the method comprising:

[0055] S10, embedding anode metal on the surface of the insulating gasket contacting the environmental medium to obtain a composite gasket;

[0056] S20, connecting the composite gasket between the galvanic cathode and the galvanic anode in the environmental medium, and connecting the embedded anode metal in the composite gasket and the galvanic anode through a wire and an external power source respectively, to form a cathodic protection current circuit;

[0057] S30, adjusting the cathodic protection current of the cathodic protection current circuit by means of the external power supply, and monitoring the anode current of the galvanic anode until the measured anode current decreases to a preset condition.

[0058] Specifically, the composite gasket is connected to the positive electrode of the external power supply, the galvanic anode is connected to the negative electrode of the external power supply, the anode current is a dissolution current that accelerates the corrosion of the galvanic anode, the cathodic protection current is the sum of the cathode current flowing through the cathode galvanic couple and the anode current flowing through the anode galvanic couple, and the preset condition is that the anode current is reduced to a certain threshold value, which can be specifically: the anode current can be reduced to zero, and when the anode current is reduced to zero, the present embodiment can completely suppress the corrosion of the galvanic anode; the galvanic cathode and the galvanic anode are connected to the insulating gasket and have no direct electrical contact with the anode metal. It can be foreseen that the working surface of the anode metal is exposed on the side of the insulating gasket and contacts with the environmental medium, and the other surfaces of the anode metal are wrapped by the insulating gasket and have no contact with the environmental medium, the galvanic cathode and the galvanic anode.

[0059] Optionally, in one embodiment (theoretical illustration), the step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anode current of the galvanic anode until the measured anode current drops to a preset condition specifically includes:

[0060] An ammeter is provided to measure the cathodic protection current of the cathodic protection current circuit regulated by the external power supply, and another ammeter is provided to monitor the galvanic current between the galvanic anode and the galvanic cathode until the measured galvanic current reading reaches a preset condition.

[0061] Specifically, an ammeter (first ammeter) is connected in series between an external power source and a composite gasket, so that the cathodic protection current applied to the composite gasket by the external power source completely passes through the first ammeter, ensuring that the reading of the first ammeter correctly reflects the cathodic protection current applied by the external power source. At the same time, another ammeter (second ammeter) is connected in series between the galvanic anode and the galvanic cathode, so that the galvanic current flowing through the galvanic anode and the galvanic cathode completely flows through the second ammeter, ensuring that the reading of the second ammeter correctly reflects the galvanic current between the galvanic anode and the galvanic cathode, which is the anode current flowing through the galvanic anode. As the cathodic protection current increases, the galvanic current gradually decreases. When the reading of the ammeter connected in series between the galvanic anode and the galvanic cathode is close to zero, it can be considered that the galvanic corrosion of the galvanic anode is suppressed and the preset conditions are met.

[0062] Optionally, in a second embodiment (theoretical illustration), the step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anode current of the galvanic anode until the measured anode current drops to a preset condition specifically includes:

[0063] Providing a reference electrode and a potentiometer, placing the reference electrode in the environmental medium near the galvanic anode, and monitoring the potential between the galvanic anode and the reference electrode by the provided potentiometer;

[0064] The cathode protection current of the cathode protection current circuit is adjusted by the external power supply until the potential between the anode of the galvanic couple and the reference electrode reaches a preset condition.

[0065] Specifically, a reference electrode is placed in the environmental medium, as close as possible to the galvanic anode surface, and as close as possible to the surface of the galvanic anode, and at the same time as close as possible to the embedded anode metal of the composite gasket. The potential of the galvanic anode relative to the reference electrode is measured using the provided potentiometer. As the cathodic protection current applied by the external power source increases, the measured potential of the galvanic anode relative to the reference gradually decreases. When the measured potential is close to the open circuit potential of the galvanic anode (i.e., the potential of the anode relative to the reference electrode when no current flows through the anode), it indicates that the cathodic protection current applied by the external power source has reduced the anode current of the galvanic anode to a preset condition.

[0066] Optionally, in a third embodiment (theoretical illustration), the step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anode current of the galvanic anode until the measured anode current drops to a preset condition specifically includes:

[0067] providing a potentiometer for measuring the potential difference between the potential of the galvanic anode and the anode metal embedded in the composite gasket;

[0068] The cathodic protection current of the cathodic protection current circuit is adjusted by the external power supply, and the potential difference between the potential of the galvanic anode and the potential of the anode metal embedded in the composite gasket is monitored until the measured potential difference reading reaches a preset condition.

[0069] Specifically, the positive and negative ends of the potentiometer are connected to the galvanic anode and the composite gasket, respectively, so that the potential of the galvanic anode relative to the anode metal embedded in the composite gasket is correctly displayed on the potentiometer. As the cathodic protection current applied by the external power source increases, the potential of the measured galvanic anode relative to the anode metal embedded in the composite gasket gradually decreases. When the total amplitude of the potential drop of the measured galvanic anode relative to the anode metal embedded in the composite gasket exceeds the open circuit potential difference between the galvanic anode and the galvanic cathode (i.e., the potential difference between the galvanic cathode and the galvanic anode when the galvanic current is zero), it can be considered that the preset condition has been met.

[0070] Optionally, in one embodiment, the current or potential difference that the external power source needs to apply is positively correlated with the degree of galvanic corrosion, that is, the greater the current or potential difference applied by the external power source, the more it can suppress galvanic corrosion, wherein the potential difference applied by the external power source is preferably greater than 2V.

[0071] Optionally, in one embodiment, when the potential of the anode metal is more than 1 V more negative than the potential of the galvanic anode, no external power source may be required, and the anode metal only needs to short-circuit the galvanic anode and the galvanic cathode.

[0072] Optionally, in one embodiment, the resistivity of the insulating gasket is not less than 109Ω·m, the compressive strength of the insulating gasket is not less than 1MPa, the thickness of the insulating gasket is not less than 0.1mm, the ratio of the thickness of the composite gasket to the maximum diagonal of the maximum surface of the composite gasket is not less than 0.1, and the ratio of the thickness of the composite gasket to the diameter of the composite gasket is not less than 0.1.

[0073] Optionally, in one embodiment, the contact area of ​​the insulating gasket is not less than the contact area of ​​the galvanic cathode / galvanic anode interface.

[0074] Optionally, in one embodiment, the anode metal is chemically stable in the environmental medium, insoluble or difficult to dissolve, the anode metal has a lower polarization resistance or a lower oxygen evolution overpotential and a lower hydrogen evolution overpotential in the environmental medium, and the anode metal, wherein the anode metal in practical applications can be used but is not limited to the anode used in the traditional impressed current cathodic protection system or the electrolysis water oxygen production system or the electrolysis water chlorine-alkali system, such as stainless steel, titanium alloy, titanium-plated steel mesh, nickel-plated steel mesh, graphite, and even platinum alloys, rare earth compounds, highly conductive metal oxides, etc.

[0075] Optionally, in one embodiment, since a through hole is provided in the middle of the insulating gasket, when the environmental medium is located on the inner side of the insulating gasket, the anode metal is arranged on the hole wall of the through hole, and the composite gasket formed at this time can be used to isolate the pipeline composed of different metal segments; when the environmental medium is located on the outer side of the insulating gasket, the anode metal is arranged on the outer side of the insulating gasket, and the composite gasket formed at this time can be used to isolate the connection of the bolt, and the through hole directly isolates the direct electrical connection between the anode metal and the bolt. Wherein, the working surface of the anode metal in contact with the environmental medium accounts for more than 1% of the total area of ​​the composite gasket exposed to the environmental medium.

[0076] In order to verify the inhibition principle of the present application, the inventors conducted two groups of experiments, which were: Experiment 1 was an insulating gasket inlaid with titanium wire to inhibit the galvanic corrosion of AM60 magnesium alloy-304 stainless steel in 5wt.% NaCl salt spray (pH=3.5); Experiment 2 was an insulating gasket inlaid with titanium wire to inhibit the galvanic corrosion of copper pipe-carbon steel pipe filled with artificial seawater.

[0077] Experiment 1

[0078] The galvanic sample of Experiment 1 is as follows: prepare a 5.5×3×0.5cm AM60 sheet magnesium alloy sample, drill a circular hole with a diameter of 8mm at the vertical position of the center thereof, and set it aside; prepare two Φ1mm TA2 titanium wires (a first titanium wire 43 and a second titanium wire 44), one end of each titanium wire is bent into a circular ring with a diameter of 16mm, and except for the titanium wire bent into the circular ring, the remaining titanium wire is covered with a heat shrink tube to avoid contact with environmental salt spray; then prepare an M8×20×2 304 stainless steel gasket, an M8×60 nylon external hexagon screw (including a nylon hexagon screw head 471 and a nylon hexagon screw tail 472), an M8 nylon hexagon nut, and 3 M8×16×1.4 insulating flat washers. Put the prepared 304 stainless steel gasket, insulating flat gasket 45, the first titanium wire 43 of the ring, insulating flat gasket 45, the second titanium wire 44 of the ring, insulating flat gasket 45, and 41 magnesium alloy on the nylon external hexagon screw in sequence, and finally use a nylon hexagon nut to tighten from the nylon hexagon screw tail 472 to the nylon hexagon screw head 471, and fix these materials put on the nylon external hexagon screw in sequence tightly, wherein the outer surface of the ring of the first titanium wire 43 and the second titanium wire 44 is aligned with the outer diameter of the insulating flat gasket, and the first titanium wire and the second titanium wire are short-circuited; the stainless steel gasket 42 and the magnesium alloy 41 are respectively connected to the wires, and the joints are sealed with silicone. For the AM60 magnesium alloy-304 stainless steel electric couple isolated by the entire titanium wire inlaid insulating flat gasket, refer to Figure 2 .

[0079] The experimental assembly of Experiment 1 is as follows: the prepared galvanic sample is placed on the V-groove of the salt spray test box 48, the stainless steel gasket 42 in the sample is located at the upper end, the angle between the axis of the nylon hexagonal screw and the horizontal plane is 45°, the first titanium wire 43 and the second titanium wire 44 in the galvanic sample in the salt spray test box 48 are short-circuited, first connected in series with the DC power supply 3 outside the salt spray test box 48, and then divided into two loops in parallel: loop 1 starts from the DC power supply 3, passes through the first ammeter 1, and then returns to the stainless steel gasket 42 of the galvanic sample in the salt spray test box; loop 2 starts from the DC power supply 3, passes through the second ammeter 2, and then returns to the magnesium alloy 41 of the galvanic sample in the salt spray test box 48. In this way, the reading of the first ammeter represents the cathode current flowing out of the stainless steel gasket 42; the reading of the second ammeter 2 represents the anode current flowing out of the magnesium alloy 41; and the sum of the two is the cathode protection current provided by the DC power supply 3 (external power supply) through the first titanium wire 43 and the second titanium wire 44 of the ring in the pipeline; when the cathode protection current provided by the DC power supply 3 is 0, the current flowing through the magnesium alloy 41 and the stainless steel gasket 42 must be equal in magnitude and opposite in direction, that is, the normal magnesium alloy 41 is accelerated by the galvanic effect of the stainless steel gasket 42. The smaller the anode current flowing out of the magnesium alloy (i.e., the reading of the second ammeter 2), the better, wherein the solution used in the salt spray test box 48 is a 5wt.% NaCl solution with a pH of 3.5 (the pH is adjusted using dilute hydrochloric acid); the salt spray test temperature is 35°C.

[0080] The measurement steps of Experiment 1 are as follows: first, let the salt spray test chamber run for 12 hours to stabilize the temperature, humidity, salinity and cathodic protection current in the chamber, turn on the DC power supply, and adjust the cathodic protection current by adjusting the voltage of the DC power supply. After each adjustment for 2 minutes, measure the current of the stainless steel gasket and the magnesium alloy through the first ammeter and the second ammeter, and calculate the cathodic protection current provided by the DC power supply.

[0081] The measurement results of Experiment 1 are as follows: as the cathodic protection current provided by the DC power supply through the anode metal (the first titanium wire and the second titanium wire) embedded in the insulating gasket increases, the anode current caused by the galvanic effect of the magnesium alloy becomes smaller and smaller until it reaches 0, which proves that the isolation-cathodic protection composite gasket of this embodiment can indeed effectively inhibit galvanic corrosion. Figure 3 .

[0082] Experiment 2

[0083] The electric couple sample of Experiment 2 is as follows: prepare a QAL10-4-4 aluminum bronze tube and a Q235 carbon steel tube, each of which has a flange with an outer diameter of 14 cm welded at both ends, a total length of 1 m, and an inner diameter of 3 cm. They are connected and fixed together by bolts through their flanges and sealing gaskets. At the same time, prepare a 0.5 m long Φ1 mm TA2 titanium wire (third titanium wire 53), wherein one end of the third titanium wire 53 is bent into a spring-shaped ring with a diameter of 29 mm and 5 turns. Except for the ring part, the remaining titanium wire is sealed with a heat shrink tube to insulate it from the ambient medium. The third titanium wire 53 of the ring is placed in the tube at the connection between the aluminum bronze tube 51 and the carbon steel tube 52, and the center of the ring is aligned with the center of the pipe. The tail end of the third titanium wire passes through the flange sealing gasket 54 between the two sections to the outside of the tube. The third titanium wire of the ring has no direct electrical contact with the aluminum bronze tube or the carbon steel tube. The outer pipe openings of the aluminum bronze pipe 51 and the outer pipe openings of the carbon steel pipe 52 are sealed with insulating flange covers 55 respectively. Before the last insulating flange cover 55 is sealed, the two pipes connected in series and completely connected are filled with artificial seawater (ASTMD1141-98). Figure 4 .

[0084] The experimental assembly of Experiment 2 is as follows: the third titanium wire is connected to the positive end of the DC power supply 3 by a wire, the negative end of the DC power supply 3 is connected to the negative end of the first ammeter 1, and the positive end of the ammeter 1 is connected to the aluminum bronze tube 51; at the same time, the negative end of the first ammeter 1 is connected to the negative end of the second ammeter 2 by a wire, and the positive end of the second ammeter 2 is connected to the carbon steel tube 52. In this way, the reading of the first ammeter 1 represents the current flowing out of the aluminum bronze tube 51, and the reading of the ammeter 2 represents the current flowing out of the carbon steel tube 52; and the sum of the two is the cathodic protection current provided by the DC power supply (external power supply) through the third titanium wire in the inner ring of the pipeline; when the cathodic protection current provided by the DC power supply 3 is 0, the currents flowing through the aluminum bronze tube 51 and the carbon steel tube 52 must be equal in magnitude and opposite in direction. The smaller the current flowing out of the carbon steel tube 52 (i.e., the reading of the second ammeter 2), the smaller the electric couple effect of the aluminum bronze tube 51 is, and the slower its dissolution is.

[0085] The measurement steps of Experiment 2 are: turn on the DC power supply 3, adjust the cathodic protection current by adjusting the voltage of the DC power supply 3, and measure the current in the circuits of the aluminum bronze tube (first ammeter 1) and the carbon steel tube (second ammeter 2) after each adjustment is stable for 2 minutes.

[0086] The measurement results of Experiment 2 are as follows: the anodic current of the steel pipe-copper pipe with the inner wall exposed to seawater decreases significantly as the cathodic protection current provided by the composite gasket increases, which once again proves that the isolation / cathodic protection composite gasket of this embodiment can effectively inhibit the anodic dissolution of the galvanic couple it isolates. Figure 5 .

[0087] See also Figure 6 and Figure 7 According to a second aspect of an embodiment of the present application, there is provided a device for inhibiting galvanic corrosion formed by connecting different metals, comprising a galvanic cathode 61, a galvanic anode 62 and a bolt 63, wherein the galvanic cathode 61 is connected to the galvanic anode 62 through the bolt 63, and the device further comprises an insulating gasket 64, an anode metal 65, an external power source 66, a first ammeter (not shown in the figure) and a second ammeter (not shown in the figure), wherein the insulating gasket 64 is disposed on the bolt 63 and is located between the galvanic cathode 61 and the galvanic anode 62, and an installation groove is provided on the surface of the insulating gasket 64 in contact with the ambient medium, the anode metal 65 is disposed in the installation groove and has no direct contact with the galvanic cathode 61 and the galvanic anode 62, and the external power source 66 can be a DC power source, the positive pole of the external power source 66 is connected to the anode metal 65, and the negative pole of the external power source 66 is connected to the galvanic anode 62.

[0088] Optional, see Figure 6 and Figure 7 In one embodiment (theoretical illustration), the device further includes a first ammeter (not shown in the figure) and a second ammeter (not shown in the figure), the first ammeter being connected to the galvanic cathode 61 and the galvanic anode 62, respectively, and being used to detect the galvanic current between the galvanic cathode 61 and the galvanic anode; the second ammeter being connected to the galvanic anode 62 and the external power source 66, respectively, and being used to detect the cathodic protection current flowing through the galvanic anode 62.

[0089] See also Fig.10 and Fig.13 In a third aspect, an embodiment of the present application provides a composite gasket, which is applied to the method for inhibiting galvanic corrosion formed by connecting different metals as described above. The composite gasket includes an insulating gasket 64 and an anode metal 65. A mounting groove is provided on the surface of the insulating gasket 64 that contacts the environmental medium, and the anode metal 65 is embedded in the mounting groove.

[0090] Optionally, in one embodiment, the insulating gasket 64 and the anode metal 65 form a composite gasket, wherein the composite gasket can be set as a composite gasket for the bolt 63, see Figure 8 , Fig. 9 and Fig.10 The composite gasket can also be configured as a composite gasket for pipes, see Fig.11 , Fig.12 and Fig.13 .

[0091] Further, when the composite gasket is a composite gasket for bolts 63, the through hole 641 opened in the middle of the composite gasket is the position for the bolts 63 to pass through, and the mounting groove is opened on the outer surface of the insulating gasket 64, that is, the anode metal 65 is arranged on the outer surface of the insulating gasket 64. At this time, the environmental medium is also on the outer surface of the insulating gasket 64. Figure 8 , Fig. 9 and Fig.10 When the composite gasket is a composite gasket for a pipeline, the through hole 641 opened in the middle of the composite gasket is used to pass the medium in the pipeline, and the mounting groove is opened on the inner surface of the insulating gasket 64, that is, opened on the inner wall of the through hole 641. In other words, the anode metal 65 is arranged on the inner wall of the through hole 641 and contacts with the environmental medium in the through hole 641. Fig.11 , Fig.12 and Fig.13 .

[0092] Optionally, in one embodiment, the anode metal 65 may have the same planar shape as the insulating gasket 64, and is sandwiched between two insulating gaskets 64. The anode metal 65 and the two insulating gaskets 64 constitute a separate "insulating layer / anode layer / insulating layer" laminated gasket, wherein the separate "insulating layer / anode layer / insulating layer" laminated gasket includes a porous laminated gasket and a non-porous laminated gasket, see Fig.14 and Fig.15 .

[0093] In summary, the present application provides a device for inhibiting galvanic corrosion formed by connecting different metals. The present application embeds anode metal on the surface of an insulating gasket that contacts an environmental medium to obtain a composite gasket, connects the composite gasket between a galvanic cathode and a galvanic anode in the environmental medium, and connects the anode metal embedded in the composite gasket to the galvanic anode through a wire and an external power source, respectively, to form a cathodic protection current circuit, wherein the composite gasket is connected to the positive electrode of the external power source, and the galvanic anode is connected to the negative electrode of the external power source; the cathodic protection current of the cathodic protection current circuit is adjusted by the external power source, and the anode current of the galvanic anode is monitored at the same time until the measured anode current is reduced to a preset condition, that is, the present application can increase the distance between the galvanic cathode and the galvanic anode in the environmental medium they are in contact with through the insulating gasket (insulating layer) in the composite gasket, thereby reducing the galvanic effect; more importantly, it can also use the external power source to perform cathodic protection on the galvanic anode in galvanic corrosion through the anode metal in the composite gasket, thereby inhibiting its galvanic corrosion.

[0094] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for inhibiting galvanic corrosion of dissimilar metal connections, characterized in that: include: Embedding anode metal on the surface of the insulating gasket contacting the environmental medium to obtain a composite gasket; The composite gasket is connected between a galvanic cathode and a galvanic anode in an environmental medium, and the anode metal embedded in the composite gasket is connected to the galvanic anode through a wire and an external power source, respectively, to form a cathodic protection current circuit, wherein the composite gasket is connected to the positive electrode of the external power source, and the galvanic anode is connected to the negative electrode of the external power source; The cathodic protection current of the cathodic protection current circuit is adjusted by the external power supply, and the anode current of the galvanic anode is monitored at the same time until the measured anode current decreases to a preset condition.

2. The method for inhibiting galvanic corrosion of different metal connections according to claim 1, characterized in that: The step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anode current of the galvanic anode until the measured anode current decreases to a preset condition specifically includes: The cathodic protection current of the cathodic protection current circuit is adjusted by the external power supply, and the potential difference between the potential of the galvanic anode and the potential of the anode metal embedded in the composite gasket is monitored until the measured potential difference reading reaches a preset condition.

3. The method for inhibiting galvanic corrosion of different metal connections according to claim 1, characterized in that: The step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anode current of the galvanic anode until the measured anode current decreases to a preset condition specifically includes: Providing a reference electrode, placing the reference electrode in the environmental medium near the galvanic anode, and monitoring the potential of the galvanic anode through the reference electrode; The cathode protection current of the cathode protection current circuit is adjusted by the external power supply until the potential difference between the galvanic anode and the reference electrode reaches a preset condition.

4. The method for inhibiting galvanic corrosion of different metal connections according to claim 1, characterized in that: In the step of embedding anode metal on the surface of the insulating gasket contacting the environmental medium to obtain a composite gasket, the ratio of the thickness of the composite gasket to the maximum diagonal of the maximum surface of the composite gasket is not less than 0.1, and the ratio of the thickness of the composite gasket to the diameter of the composite gasket is not less than 0.

1.

5. The method for inhibiting galvanic corrosion of different metal connections according to claim 1, characterized in that: In the step of embedding anode metal on the surface of the insulating gasket contacting the environmental medium to obtain a composite gasket, the working surface of the anode metal contacting the environmental medium accounts for more than 1% of the total area of ​​the composite gasket exposed to the environmental medium.

6. The method for inhibiting galvanic corrosion of dissimilar metal connections according to claim 1, characterized in that: In the step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anode current of the galvanic anode until the measured anode current decreases to a preset condition, the current or potential difference that the external power supply needs to apply is positively correlated with the degree of galvanic corrosion.

7. The method for inhibiting galvanic corrosion of dissimilar metal connections according to claim 1, characterized in that: In the step of adjusting the cathodic protection current of the cathodic protection current circuit by the external power supply and monitoring the anode current of the galvanic anode until the measured anode current drops to a preset condition, the potential difference applied by the external power supply is preferably greater than 2V.

8. A device for inhibiting galvanic corrosion formed by connecting different metals, comprising a galvanic cathode, a galvanic anode and a bolt, wherein the galvanic cathode is connected to the galvanic anode through the bolt, characterized in that: The device also includes: An insulating gasket is arranged on the bolt and located between the galvanic cathode and the galvanic anode, and a mounting groove is provided on the surface of the insulating gasket in contact with the ambient medium; an anode metal disposed in the mounting groove and having no direct contact with the galvanic cathode and the galvanic anode; The positive electrode of the external power source is connected to the anode metal, and the negative electrode of the external power source is connected to the galvanic anode.

9. A composite gasket, characterized in that: It is applied to the method of inhibiting galvanic corrosion formed by connecting different metals as described in any one of claims 1 to 7, wherein the composite gasket includes an insulating gasket and an anode metal, and a mounting groove is provided on the surface of the insulating gasket in contact with the environmental medium, and the anode metal is embedded in the mounting groove.

10. The composite gasket according to claim 8, characterized in that: When the composite gasket is a composite gasket for bolts, the anode metal is arranged on the outer surface of the insulating gasket.

11. The composite gasket according to claim 9, characterized in that: When the composite gasket is a composite gasket for a pipeline, the anode metal is arranged on the inner surface of the insulating gasket.

12. The composite gasket according to claim 8, characterized in that: The insulating gasket is provided with two pieces, and the anode metal is provided between the two insulating gaskets.

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