JP2011168854A - Method for forming rust preventive film on metallic member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a rust preventive film on a metallic member, in which sufficiently high cleaning power to a deposit on a metal surface is ensured without putting load with a high pressure, so that such deposit can be thoroughly removed in a short period of time, and by which a strong rust preventive film can be uniformly formed without requiring a large treatment apparatus in a subsequent rust preventive film forming step. <P>SOLUTION: The method for forming a rust preventive film on a metallic member includes: removing an oily substance on a surface of the metallic member (copper or copper alloy wire rod 1) with a gas-liquid two-phase flow 8 obtained by mixing heated and pressurized water (washing water 10) and a pressurized gas (nitrogen gas 25); forming a copper oxide layer on the surface; and treating the metallic member (copper or copper alloy wire rod 1) with a solution containing a rust preventive. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention is applied to a metal member such as copper or copper alloy material that has been metal-processed on a plate, wire, pipe, or the like, and can sufficiently remove oil and / or acid on the surface in a short time. In addition, the present invention relates to a method for forming a rust preventive film for a metal member that can uniformly form a strong rust preventive film in the subsequent rust preventive film forming step.

  Generally, benzotriazole (BTA) or a derivative thereof is used as a rust inhibitor for copper or copper alloy material. Hereinafter, BTA and its derivatives are collectively referred to simply as BTA. The antirust effect of BTA is due to the formation of a BTA polymer film on the surface of copper or a copper alloy material. In other words, a thin copper oxide film of atomic order is naturally formed on the surface of copper or a copper alloy material, but BTA molecules form strong coordinate bonds with this copper oxide and Are also covalently bonded to form a strong BTA polymer film on the surface of the copper or copper alloy material. The BTA polymer film thus formed has excellent adhesion to copper or a copper alloy material and exhibits extremely excellent corrosion resistance, and protects the surface of the copper or copper alloy material from corrosion and discoloration caused thereby. To do.

  FIG. 2 shows a conventional method for forming a rust preventive film of copper or a copper alloy material using this BTA. First, copper or a copper alloy material that has been metal-worked into a shape such as a plate, wire, or pipe is degreased by pickling (step 1), washed with water (step 2), and then dried once (step 3). The pickling in step 1 is performed using sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, etc. for the purpose of removing oxides formed on the surface of metal-processed copper or copper alloy material or processing oil. Is done. Further, the drying in Step 3 has an effect that BTA easily reacts with the treatment material because a thin copper oxide layer is formed on the surface of the treatment material of copper or copper alloy material by this drying treatment. Thereafter, the treatment material is immersed in a solution containing BTA, or this solution is applied to the treatment material and subjected to BTA treatment (step 4), and finally dried (step 5) to obtain a product. For the BTA treatment in Step 4, a solution in which BTA is dissolved in a solvent such as water, alcohol, or a chlorinated solvent is used. The temperature of the antirust treatment solution is preferably 40 ° C to 80 ° C.

  In the steps 1 to 5, if the BTA rust preventive film is not coated on the surface of the treatment material to a sufficient thickness, the water washing in step 2, the drying in step 3, the BTA treatment in step 4 and A film having a sufficient thickness is formed through each step of drying in Step 5. In addition, the drying of step 5 is performed in order to strengthen the BTA polymer layer as a rust preventive film. For this drying treatment, hot air of 150 ° C. or lower can be used.

  In addition, the series of steps 2 to 5 shown in FIG. 2 usually ends with only one process, but in practice it is preferable to repeat the process twice or more. In that case, after the end of step 5, weak pickling may be performed, and steps 2 to 5 may be performed after pickling. Steps 2 to 5 are repeated. In some cases, a complete BTA rust preventive film may not be formed in the first treatment. For the defective portion, a complete BTA rust preventive film is formed in the second and subsequent treatments. This is because it tries to form.

  However, this rust preventive film forming method has a problem that even if Steps 2 to 5 are repeated a plurality of times, a BTA rust preventive film is not completely formed and a defective portion remains. Moreover, a time loss also arises by repeating steps 2 to 5 a plurality of times.

Therefore, conventionally, as described in Patent Document 1, hot water at 60 ° C. is sprayed on the surface of copper or a copper alloy material with a high-pressure jet jet having an ejection pressure of 10 to 200 kgf / cm ² , and then copper or A method of BTA treatment of a copper alloy material has been proposed.

  In addition, as described in Patent Document 2, after spraying water on the surface of copper or a copper alloy material with a jet jet as described in Patent Document 2, similarly, a solution containing BTA is sprayed with the jet jet to produce copper or copper. A method for BTA treatment of an alloy material, a method for applying ultrasonic vibration to a solution containing a rust preventive agent such as BTA as described in Patent Document 3, and a pickling process as described in Patent Document 4 A method of spraying an acidic solution onto the surface of copper or copper alloy material with a jet jet, washing with water, and then treating the copper or copper alloy material with BTA, as described in Patent Document 5, the surface of copper or copper alloy material A method of BTA treatment of copper or copper alloy material after spraying a solution containing solid fine particles with a jet jet, as described in Patent Document 6, BTA is applied to the surface of copper or copper alloy material. A solution containing a method of BTA treated copper or copper alloy material by blowing a jet jet has been proposed.

Japanese Patent No. 3192950 JP 2001-220893 A JP-A-9-316671 JP-A-9-316670 JP-A-9-209180 JP-A-9-41167

One feature of the prior art described in Patent Document 1 is that a high-pressure jet jet having an ejection pressure of 10 to 200 kgf / cm ² is used. In the case of this conventional technology, the use of a high-pressure jet jet increases the cleaning power for copper or copper alloy material, but the high pressure causes a large mechanical load, damage to the processing equipment, and in some cases damage to the product. The inherent disadvantage of being large is inherent.

  As a result, since the damage to the processing apparatus is large, the drawback of increasing the work related to maintenance becomes remarkable. For example, the deterioration of the sealing material of the high-pressure pump is rapid, the wear of the high-pressure spray nozzle is large, and the generation of static electricity is large. In addition, due to the large damage to the product, when the copper plate or copper wire as the product is thin or thin, the product is deformed by the high-pressure jet jet, which leads to deterioration of the product quality. .

Also in the prior art described in Patent Documents 2 to 6, when using a high-pressure jet jet having an ejection pressure of 10 to 200 kgf / cm ² , the same problems as described above are inherent.

Further, the prior art described in Patent Document 2 has a drawback that the cleaning power is insufficient when the temperature of water is 60 ° C. or less or when the water injection pressure is 10 kgf / cm ² or less.

  Moreover, in the prior art described in Patent Document 3, since ultrasonic cleaning is used, there is a drawback that the cleaning power in a short time is insufficient. If it is attempted to increase the cleaning power by increasing the cleaning time, there are disadvantages that the processing apparatus becomes very large and the apparatus price becomes expensive.

  Moreover, in the prior art described in Patent Document 4, since a jet jet of an acidic solution is used, there is a drawback that the progress of corrosion of metal parts such as nozzles is accelerated. There is also a risk that acidic mist may diverge around.

  Moreover, in the prior art described in Patent Document 5, since solid particles such as alumina are used in a solution containing BTA, the surface of the copper or copper alloy material as a product becomes uneven, and the surface smoothness is increased. There is an increased risk of adverse effects, i.e. reduced surface quality of the product.

Moreover, in the prior art described in Patent Document 6, when the temperature of water is 60 ° C. or lower or when the water injection pressure is 10 kgf / cm ² or lower, the cleaning power is insufficient. Since BTA is added to itself, there is a drawback that the amount of BTA used becomes very large.

  Therefore, the object of the present invention is that the cleaning ability for the deposits on the metal surface is sufficiently high without applying a load at a high pressure, and such deposits can be sufficiently removed in a short time. It is an object of the present invention to provide a method for forming a rust preventive film for a metal member that can form a strong rust preventive film uniformly in the subsequent rust preventive film forming step.

  In order to achieve the above object, the invention of claim 1 is directed to the surface of a metal member using a gas-liquid two fluid obtained by mixing heated and pressurized water and pressurized gas. Provided is a method for forming a rust preventive film for a metal member, characterized in that after the oily substance is removed and a copper oxide layer is formed on the surface, the metal member is treated with a solution containing a rust inhibitor.

  In the above, nitrogen gas is preferably used as the gas, but it is of course possible to use a gas such as air or water vapor.

  Moreover, it is preferable to use BTA as a rust preventive agent.

  Moreover, it is preferable to use solvents, such as water, alcohol, or a chlorine-type solvent, as a solvent of the solution containing a rust preventive agent.

  According to this method for forming a rust-preventing film on a metal member, the adoption of the above-described configuration particularly uses a gas-liquid two fluid obtained by mixing heated and pressurized water and pressurized gas. By removing the oily substance on the surface of the metal member, the cleaning ability for the deposit on the metal surface is sufficiently high without applying a load at a high pressure, and such deposit is sufficiently removed in a short time. In addition, a large processing apparatus is not required, and a strong rust preventive film can be uniformly formed in the subsequent rust preventive film forming step.

  The invention according to claim 2 provides the method for forming a rust preventive film for a metal member according to claim 1, wherein the pressure of the heated and pressurized water is 0.1 MPa to less than 0.98 MPa. To do.

  In the present invention, in order to increase the cleaning power for the metal member, the pressure of the heated and pressurized water is preferably 0.1 MPa to less than 0.98 MPa. This is because the force to be formed is weak, and usually only the same effect as the water washing that has been carried out can be obtained. On the other hand, when the pressure is 0.98 MPa or more, deformation of the copper or metal member is likely to occur. According to this method, in addition to the above effect, the cleaning power for the metal member can be further increased by adopting the above configuration.

  The invention of claim 3 provides the method for forming a rust preventive film for a metal member according to claim 1 or 2, wherein the temperature of the gas-liquid 2 fluid is 60 ° C to 100 ° C.

  In the present invention, the temperature of the gas-liquid 2 fluid is preferably 60 ° C. to 100 ° C. in order to increase the detergency against the metal member. According to this method, in addition to the above effects, the above configuration is adopted. The cleaning power for the metal member can be further increased.

  In particular, the pressure of the heated and pressurized water is 0.1 MPa to less than 0.98 MPa, and the temperature of the gas-liquid 2 fluid is 60 ° C. to 100 ° C., thereby further improving the cleaning power on the metal member. be able to. This is because the gas-liquid 2 fluid is a self-generated gas-liquid 2 fluid that boils under normal pressure. Further, in this case, the pressure of the pressurized gas is preferably 0.1 MPa to less than 0.98 MPa. According to this method, the gas-liquid 2 fluid is directed from the nozzle to the metal member at an appropriate pressure, for example. By ejecting the droplets toward the metal member and accelerating the collision, oily substances such as processing oil that is a deposit on the surface of the metal member can be easily removed, and at the same time, the metal member A preferable copper oxide layer can be uniformly formed on the surface. Thereby, a strong rust preventive film can be uniformly formed on the surface of the metal member in the subsequent rust preventive film forming process such as BTA treatment.

  A fourth aspect of the present invention provides the method for forming a rust preventive film for a metal member according to any one of the first to third aspects, wherein a droplet diameter of water of the gas-liquid two fluid is 1 μm to 100 μm.

  According to the results of the study by the present inventors, the mechanism by which oily substances such as processing oil that are deposits on the surface of the metal member are removed by the present invention is as follows. That is, an oily substance such as processing oil that is a deposit receives kinetic energy from the colliding gas-liquid two fluid droplets, and when the magnitude of the kinetic energy is greater than or equal to the adhesion energy with the metal member, Detach from the surface. In addition, when an oily substance such as processing oil that is insoluble in water is brought into contact with a gas-liquid 2 fluid mainly composed of water, the oily substance cannot be dissolved in the droplets constituting the gas-liquid 2 fluid. It collects at the interface between the droplet and gas. However, since the surface of the metal member is covered with a liquid film with a certain film thickness, the oily substance that could not gather at the interface between the droplet and the gas reattaches to the surface of the metal member with a certain probability.

  Therefore, in the present invention, the larger the area of the gas-liquid interface that the gas-liquid 2 fluid has, the higher the gathering ability of the oily substance. If so, it can be said that the smaller the droplet diameter, the larger the area of the gas-liquid interface and the higher the cleaning ability for the metal member. According to the study by the present inventors, the upper limit of the droplet diameter is preferably 100 μm. On the other hand, the lower limit of the droplet diameter is determined by the relationship with the evaporation rate of the droplet. That is, for example, even if a droplet is formed at the tip of the nozzle, it does not contribute to cleaning if it evaporates before reaching the surface of the metal member. According to the study by the present inventors, if the droplet diameter is 1 μm or more, the metal member is cleaned before the droplets evaporate by appropriately maintaining the distance between the nozzle and the surface of the metal member. be able to.

  According to this method, in addition to the above effects, the metal member can be reliably and effectively cleaned by adopting the above configuration.

  The invention according to claim 5 provides the method for forming a rust preventive film for a metal member according to claims 1 to 4, wherein the rust preventive agent is benzotriazole or a derivative thereof.

  According to this method, in addition to the above effects, by adopting the above configuration, a strong rust preventive film can be uniformly formed on the surface of a metal member such as copper or a copper alloy material by BTA treatment. it can.

  According to the method for forming a rust-preventing film on a metal member of the present invention, the cleaning ability for deposits on the metal surface is sufficiently high without applying a load at a high pressure, and such deposits are sufficiently removed in a short time. In addition, a large processing apparatus is not required, and a strong rust preventive film can be uniformly formed in the subsequent rust preventive film forming step.

It is explanatory drawing which shows the outline | summary of the rust preventive film formation method of the metal member which concerns on one embodiment of this invention. It is a block diagram which shows each process of the rust preventive film formation method of the conventional metal member.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIG. In the embodiment of FIG. 1, copper or copper alloy wire 1 drawn by drawing through a drawing die (not shown) is used as the metal member. Of course, the present invention can also be applied to copper or copper alloy strips processed by rolling without using a drawing die.

  First, as a pretreatment for the BTA treatment, the wire 1 is horizontally passed in the box-shaped pretreatment container 2 in the arrow direction. In addition, about this pre-processing, since the oxide film is hardly formed on the surface of the wire 1 immediately after the wire 1 is drawn, the pickling process in step 1 in FIG. 2 is omitted. The wire 1 can be passed directly into the pretreatment container 2. On the other hand, when the wire 1 is not immediately after being drawn, the wire 1 is pickled, washed with primary water, and then passed through the pretreatment container 2. The primary water washing is effective for enhancing the pretreatment effect.

  As the acid used for pickling, for example, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid are generally used, and it is preferable to use an inorganic acid having a concentration of 40% or less, more preferably 20% or less. In this embodiment, an aqueous sulfuric acid solution having a concentration of 5% is used.

  The pretreatment container 2 has, for example, a box shape with a side of about 20 cm, and the inlets 5 and 5 for facing the tips 4 and 4 of the two spray nozzles 3 and 3 are formed on the upper wall, respectively. Is formed with a discharge port 6 corresponding to the introduction ports 5 and 5. In addition, passage holes 7 through which the wire 1 passes are formed on both side walls of the pretreatment container 2. The distance between both side walls is about 20 cm. Therefore, the wire 1 is continuously pretreated over a range of 20 cm in length while passing through the pretreatment container 2 in the direction of the arrow. The wire 1 is continuously moved in the direction of the arrow by a delivery device and a winding device (not shown) arranged on the upstream side and the downstream side of the pretreatment container 2. Thereafter, the wire 1 is subjected to BTA treatment (not shown) in order to form a BTA rust preventive film on the surface thereof.

In this embodiment in which the pretreatment container 2 is used for pretreatment and the surface of the wire 1 is cleaned as described above, the wire 1 is moved in the direction of the arrow while the air is discharged from the tips 4 and 4 of the spray nozzles 3 and 3. The liquid 2 fluid 8 is jetted to collide with the surface of the wire 1 in the pretreatment container 2. Thereby, the oxide and oily substance adhering to the surface of the wire 1 are removed, and a thin and preferable copper oxide layer is formed on the surface of the wire 1. Incidentally, this copper oxide is presumed to be Cu ₂ O (cuprous oxide). If the moving speed of the wire 1 at this time is 30 m / min, that is, 0.5 m / sec, the pretreatment time of the wire 1 per 20 cm in length is 0.4 seconds, which is a short treatment time. Regardless, the effect of removing oxides and oily substances adhering to the surface of the wire 1 is very high.

  Here, the outline of the means for generating the gas-liquid two fluid 8 will be described with reference to FIG.

  Wash water 10 is heated by putting wash water 10 into a sealable tank 9 and energizing a heater 11 installed on the outer wall surface of the tank 9. The temperature of the washing water 10 can be adjusted by a temperature controller 13 based on a thermocouple 12 inserted in the tank 9. The temperature of the washing water 10 is adjusted to 60 ° C. to 100 ° C., for example. Reference numeral 14 denotes a wiring connecting the thermocouple 12 and the temperature controller 13.

  Further, a pressure gauge 15 is installed in the tank 9 so that the pressure in the tank 9 can be measured.

  In addition, a stirrer 16 is placed in the tank 9, and the cleaning water 10 is stirred by driving a magnetic stirrer 17 installed in the lower part of the tank 9, so that the temperature of the cleaning water 10 can be kept uniform. Has been.

  On the other hand, a pipe 19 from the nitrogen gas cylinder 18 is connected to the tank 9, and nitrogen gas 21 whose pressure is adjusted by the pressure reducing valve 20 is injected into the tank 9. Thereby, the pressure in the tank 9 can be increased. For example, when the temperature in the tank 9 is about 80 ° C., the pressure in the tank 9 is about 0.1 MPa. Here, the nitrogen gas 21 that has been decompressed to about 0.5 MPa by the pressure reducing valve 20 is supplied to the tank 9. When injected into the tank, the pressure in the tank 9 can be increased to about 0.5 MPa without changing the temperature.

  The washing water 10 heated and pressurized in the tank 9 in this way is guided to the spray nozzle 3 through the pipe 22, the flow rate adjusting valve 23 and the like.

  On the other hand, the nitrogen gas 25 from the nitrogen gas cylinder 24 installed separately from this is led to the spray nozzle 3 via the pressure reducing valve 26, the pipe 27, the flow rate adjusting valve 28 and the like.

  In the spray nozzle 3, the piping 22 of the heated and pressurized cleaning water 10 and the piping 27 of the nitrogen gas 25 are combined, and although not shown, the spray nozzle 3 is heated and pressurized near the tip of the cleaning water 10 and nitrogen. The gas 25 is mixed with the gas 25 to form the gas-liquid 2 fluid 8, and the gas-liquid 2 fluid 8 is discharged from the tips 4, 4 of the spray nozzle 3. Of course, air or water vapor may be used instead of the nitrogen gases 21 and 25. Since the gas-liquid 2 fluid 8 is substantially composed of water and air, it goes without saying that the load on the environment is small even if it is discharged into the atmosphere.

  In the present embodiment, the heated and pressurized washing water 10 has a temperature of 60 ° C. to 100 ° C. and a pressure of 0.1 MPa to less than 0.98 MPa. This is because, when the temperature / pressure is less than 60 ° C./0.1 MPa, the detergency is weak, and usually only the same effect as the water washing that has been performed can be obtained. On the other hand, when the temperature / pressure exceeds 100 ° C. and is 0.98 MPa or more, deformation or discoloration of the copper or copper alloy wire 1 is likely to occur. Moreover, the energy loss for heating is large and it is not economical.

  Moreover, in this Embodiment, the nitrogen gas 25 which is a pressurized gas was made into the pressure of 0.1 MPa-less than 0.98 MPa. This is because, when the pressure is less than 0.1 MPa, the force for forming droplets is weak, and usually only the same effect as the water washing that has been performed can be obtained. On the other hand, when the pressure is 0.98 MPa or more, deformation of the copper or copper alloy wire 1 is likely to occur.

  Moreover, in this Embodiment, although the cleaning power is so high that the distance from the front-end | tips 4 and 4 of the spray nozzle 3 to the wire 1 is so close, since the wire 1 in motion moves, it is actually set as the state which contacts. It is very difficult, and the distance is preferably about 1 mm to 200 mm, for example, and more preferably about 5 mm to 200 mm. Considering this point, in the present embodiment, the distance from the tips 4 and 4 of the spray nozzle 3 to the wire 1 is set to 30 mm.

  After the pretreatment, the wire 1 is subjected to BTA treatment (not shown) in order to form a BTA rust preventive film on the surface thereof. Examples of rust preventives applicable to this BTA treatment include 1H-benzotriazole (referred to as BTA), 4-methyl-1.H-benzotriazole (referred to as TTA), 4-carboxyl-1.H-benzotriazole, sodium tolyltriazzole. 5-methyl-1.H-benzotriazole (referred to as TTA), benzotriazole buthyl ester, silver benzotriazole, 5-chloro-1.H-benzotriazole, 1-chloro benzotriazole and the like.

  According to the method for forming a rust-preventing film for wire 1 according to the present embodiment, the oxides and oily substances adhering to the surface of wire 1 are removed in a short time compared to the conventional pretreatment methods such as pickling, washing and drying. Can be sufficiently removed, and a thin copper oxide layer in which a rust preventive film is easily formed on the surface of the wire 1 can be formed uniformly. Therefore, in the subsequent BTA treatment step, a strong rust preventive film can be uniformly formed on the surface of the wire 1, and the surface of the wire 1 can be reliably protected from corrosion and discoloration.

  Based on FIG. 1, the washing water 10 heated (60 ° C. to 100 ° C.) and pressurized (0.1 MPa to less than 0.98 MPa) and the pressurized (0.1 MPa to less than 0.98 MPa) gas The surface of the copper or copper alloy wire 1 passing through the pretreatment container 2 by injecting the gas-liquid 2 fluid 8 obtained by mixing with a certain nitrogen gas 25 from the tips 4 and 4 of the spray nozzles 3 and 3. The copper or copper alloy wire 1 is washed to remove the oxides and oily substances adhering to the surface, and after forming a thin copper oxide layer on the surface, the copper or copper alloy wire 1 Was so-called BTA-treated with a solution containing benzotriazole or a derivative thereof.

  Next, in order to verify the effects of the present invention, the wire obtained by the above example and the copper or copper alloy obtained by BTA treatment in the same manner after washing with water and drying with hot air based on a conventional example as a comparative example. Each of the wires was dried with hot air and then subjected to a sodium sulfide test.

  This sodium sulfide test is generally carried out as a method for evaluating the anticorrosive effect of copper or copper alloy wire. The test wire is immersed in a 100 ppm sodium sulfide aqueous solution, and after a certain time has elapsed. This is a method for evaluating the degree of discoloration of the surface of the test wire.

  The evaluation results of the sodium sulfide test are shown in Table 1.

  However, in this test, a tough pitch copper wire having a diameter of 0.3 mm was used as the test wire, and the hot air drying condition after the BTA treatment was set to 30 seconds in a stationary state. The BTA treatment was performed by immersing the wire in a BTA 0.1% aqueous solution at 40 ° C. for 1 minute.

  In the evaluation result column in Table 1, “◯” indicates that the surface of the test wire is not discolored at all, “Δ” indicates that the surface is slightly discolored, and “×” indicates that the surface is remarkably discolored.

  From Table 1, it can be seen that for the comparative example, the discoloration of the surface of the test wire progresses with time, and a complete rust preventive film is not formed on the surface of the test wire. On the other hand, with respect to the examples of the present invention, even after 5 minutes of immersion in a sodium sulfide aqueous solution, no discoloration of the surface of the test wire was observed, and an extremely excellent rust preventive film was formed on the surface of the test wire. I understand that Therefore, when using a gas-liquid 2 fluid obtained by mixing heated and pressurized water and pressurized gas, a sufficiently high cleaning is achieved even at a pressure of about 0.5 MPa. It is clear that the ability is obtained and a strong rust preventive film can be uniformly formed in the subsequent rust preventive film forming step.

DESCRIPTION OF SYMBOLS 1 Copper or copper alloy wire 2 Pretreatment container 3 Spray nozzle 4 Tip 5 Inlet 6 Outlet 7 Passage hole 8 Gas-liquid 2 fluid 9 Tank 10 Washing water 11 Heater 12 Thermocouple 13 Temperature controller 14 Wiring 15 Pressure gauge 16 Stirring Child 17 Magnetic stirrer 18, 24 Nitrogen gas cylinder 19, 22, 27 Pipe 20, 26 Pressure reducing valve 21, 25 Nitrogen gas 23, 28 Flow control valve

Claims (5)

  Using a gas-liquid 2 fluid obtained by mixing heated and pressurized water and pressurized gas, the oily substance on the surface of the metal member is removed, and a copper oxide layer is formed on the surface. Then, the metal member is treated with a solution containing a rust preventive agent.   The method for forming a rust preventive film for a metal member according to claim 1, wherein the pressure of the heated and pressurized water is 0.1 MPa to less than 0.98 MPa.   The temperature of the said gas-liquid 2 fluid is 60 to 100 degreeC, The rust preventive film formation method of the metal member of Claim 1 or 2 characterized by the above-mentioned.   The method for forming a rust preventive film on a metal member according to claim 1, wherein the water droplet diameter of the gas-liquid two fluid is 1 μm to 100 μm.   5. The method for forming a rust preventive film for a metal member according to claim 1, wherein the rust preventive agent is benzotriazole or a derivative thereof.

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