JP2012167342A - Corrosion control method of metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of preventing a metal from corroding by giving a high corrosion resistance while retaining the functions of a surface of a thin film material.SOLUTION: The method include forming a silane coupling reaction layer of a very thin film having a robust bond on a metal substrate by using a silane coupling agent and an oxidizer in combination, or forming a silane coupling reaction layer of a very thin film having a robust bond on a metal substrate by bringing the metal substrate into contact with a silane coupling liquid after the metal substrate has been oxidatively treated in advance.

Description

  The present invention relates to a surface treatment for preventing corrosion of a metal surface. This method not only improves the corrosion resistance by forming an organic coating layer on the metal surface by using one or more organofunctional silanes and an oxidizing agent in combination, but also heat resistance, solvent resistance, sliding Provides a surface with excellent properties and smoothness. The metal surface targeted by the present invention exhibits very smooth and functional characteristics as represented by the magnetic disk surface, and is intended for thin films.

  As a conventional corrosion-resistant surface treatment, there is a chromate treatment using hexavalent chromium such as chromic acid or dichromic acid. However, surface treatments containing hexavalent chromium have been regulated from the viewpoint of environmental problems in recent years, and the development of non-chromium surface treatments has been vigorously carried out. As such a surface treatment not using hexavalent chromium, for example, Patent Document 1 discloses a method of treating a metal surface with a solution of at least one trivalent chromium chelate complex. As a technique using an inorganic component other than chromium, for example, Patent Document 2 discloses a metal surface containing a vanadium compound and a metal compound containing at least one metal selected from zirconium, titanium, molybdenum, tungsten, manganese, and cerium. A treatment with a treating agent is disclosed. As an anticorrosion method using a silane coupling agent, for example, Patent Document 3 discloses a method of treating a metal plate with an aqueous solution containing a low concentration of an organofunctional silane and a crosslinking agent, and Patent Document 4 discloses a bifunctional polysulfursilane. A method of using and preventing metal corrosion, and a method of applying a long-term coating to a metal substrate by removing the solvent after contacting with a solution containing aminosilane and polysilyl functional silane is also disclosed in Patent Document 5. . Furthermore, Patent Document 6 discloses a specific resin compound (A), a cationic urethane resin (B) having at least one cationic functional group selected from a primary to tertiary amino group and a quaternary ammonium base, and Containing at least one silane coupling agent (C) having a reactive functional group and a specific acid compound (E), and containing a cationic urethane resin (B) and a silane coupling agent (C) There has been disclosed a method for producing a non-chromium surface-treated steel sheet that is excellent in corrosion resistance and further excellent in fingerprint resistance, blackening resistance and paint adhesion by using a surface treatment agent whose amount is within a predetermined range.

  There is a need to provide a surface that not only improves corrosion resistance but also has excellent heat resistance, solvent resistance, and slidability. However, although these conventional techniques use a trivalent chromium chelate complex or vanadium compound, a self-healing property is low, but a corrosion resistance comparable to a chromate film is obtained, but a thick film of several microns is formed. When the thin film is applied to the thin film because the processing environment is a strong acidic region, the target metal disappears in the middle of the processing process, and even if it does not disappear, a thick product is deposited on the surface. There is a problem that the function of the conventional metal surface is lost. Moreover, the anticorrosion method using a silane coupling agent has not been satisfactory in terms of corrosion resistance, heat resistance, solvent resistance, slidability, and particularly corrosion resistance. Furthermore, since the organofunctional silane does not bind well to the metal surface, there is a problem that it is easily removed by rinsing or the like. Moreover, in order to improve anticorrosion performance using a silane coupling agent, a plurality of silane coupling agents are often treated next, and many steps are often required. This is energetically inefficient and time consuming. Therefore, it has many problems regarding practical use. For this reason, there is a strong demand for surface treatment agents and surface treatment methods that are totally satisfactory.

JP 2004-3019 A JP 2002-30460 A US Pat. No. 5,292,549 Special table 2002-519505 gazette JP 2007-291931 A

  An object of the present invention is to provide a method for preventing corrosion of a metal imparted with high corrosion resistance in a state having a metal surface function.

  The present invention provides a silane coupling reaction to a metal substrate by contacting the metal substrate with a solution containing an organofunctional silane that is at least partially hydrolyzed, an oxidizing agent, and a solvent, and then removing the solvent. It is characterized by applying a layer.

  According to the present invention, by using a silane coupling agent in combination with an oxidizing agent for a metal, particularly a transition metal or a metal alloy thereof, it is possible to provide a surface having excellent corrosion resistance and having a metal surface function as it is.

The metal anticorrosion method targeted by the present invention is not only to improve the corrosion resistance but also to provide a surface excellent in heat resistance, solvent resistance, and slidability, and as represented by the magnetic disk surface. It provides a surface that remains very smooth and functional. Therefore, the characteristics required as a material for coating the metal surface are (1) exhibiting the corrosion inhibiting action of the target metal or their alloys.
(2) A smooth and dense film having as few defects as possible is formed.
(3) It has the function of the metal surface as it is. For example, taking a hard disk as an example, it has a structure that does not cause deterioration of magnetic recording characteristics due to an increase in the magnetic distance between the magnetic head and the magnetic recording medium. If a sensor is taken as an example, it may be mentioned that it has a sensing function as it is.

  The corrosive environment is basically the air system or water system, but there are factors such as acidification or alkalinization due to decomposition and dissolution of surrounding substances and air pollutants, and contamination with chlorides. Corrosion resistance is required.

As for (1), as a result of various investigations, in order to give a surface excellent not only in corrosion resistance but also in heat resistance, solvent resistance, slidability and smoothness, the silane coupling layer is stably provided on the metal surface. We have found that it can be achieved by holding on. Furthermore, it has been found that it is important to form an extremely thin oxide on the metal surface in order to stably hold the silane coupling agent on the metal surface. There are the following three methods for forming a very thin oxide on the metal surface and forming a silane coupling layer thereon.
[1] An oxidant having an action of oxidizing a metal is allowed to coexist in a solution containing a silane coupling agent.
[2] Before immersing a metal in a solution containing a silane coupling agent, the metal is immersed in a solution having an action of oxidizing the metal.
[3] Before the metal is immersed in a solution containing a silane coupling agent, the metal is oxidized in a dry environment.

  Regarding (2), when a silane coupling agent such as 1,2-bis- (triethoxysilyl) ethane (hereinafter referred to as BTSE) is used and hydrogen peroxide is used as the oxidizing agent, an extremely thin oxidation is performed on the surface of the metal. In order to form a strong coordinate bond with this oxide and form a strong BTSE molecule film on the metal surface by forming a covalent bond between the BTSE molecules by performing heat treatment. There are no extremely precise defects. A film with excellent adhesion is formed.

  Regarding (3), since BTSE is arranged in molecular order, corrosion can be suppressed to a high degree in a state that provides a surface that maintains a very smooth and functional characteristic as it is.

  By using a silane coupling agent and an oxidizing agent in combination, the present invention provides a surface having excellent corrosion resistance and having the function of the metal surface as it is by forming a stable silane coupling layer on the metal surface. It is about realizing. The present invention can be broadly classified into two methods.

  One is a method of forming a silane coupling layer on a metal surface by immersing the target metal in a solution in which a silane coupling agent and an oxidizing agent coexist. In another method, the surface of the target metal is oxidized by exposing it to a dry environment in advance, or the target metal is immersed in a solution containing an oxidizing agent to form an oxide on the surface. Next, the silane coupling layer is formed on the surface by immersing the oxidized metal in a solution containing a silane coupling agent. Each case is described below.

(1) Regarding the method of coexisting a silane coupling agent and an oxidizing agent [solvent]: Since the solubility of some silane coupling agents in water is limited, basically the solubility of the silane coupling agent In order to improve the solvent, a solvent such as one or two or more alcohols is used as a solvent. Alcohol also improves the stability of the wiping solution as well as the wettability of the metal substrate. Since the Sihilane coupling agent basically needs to be hydrolyzed, a solvent having high affinity with water is preferable. Specifically, methanol, ethanol, propanol, butanol and isomers thereof, ketones such as acetone, methyl ethyl ketone and diethyl ketone, ethers such as dimethyl ether, ethyl methyl ether, diethyl ether and tetrahydrofuran, ethylene glycol and propylene glycol , Glycols such as diethylene glycol are used.

[Oxidizing agent]: Any general oxidizing agent can be used. As an item required as an oxidant, it is a matter of course that it must be capable of oxidizing a metal surface. However, if the oxidizing power is too strong, the above-described solvent is also oxidized, so the type and concentration are very important. Naturally, the main component of the solution is the above solvent, and water is present only to hydrolyze the silane coupling agent described below, so that a solution having an oxidizing action and a high solubility is supplied even at a low concentration. Hydrogen peroxide, chloric acid, perchloric acid, persulfuric acid, nitric acid and their salts, diammonium cerium nitrate, etc. are used.

[Silane coupling agent]
The materials used as silane coupling agents are roughly classified into the following two types. One is represented by the structure of X _3-n SiR′SiX _3-n , n is 0 or 1, and X is a hydrolyzable group (methoxy, ethoxy, methoxyethoxy, propyl, butyl, isobutyl, s-butyl). , T-butyl and acetyl), and X may be the same or different. R 'is also selected from the group consisting of alkyl, alkenyl, alkenyl substituted with at least one amino group or S group. For example, bis-triethoxysilylpropyl sill ethane _{(BTSE) (H 5 C 2} O) 3 Si-CH 2 CH 2 -Si (OC 2 H 5) 3, bis-triethoxysilylpropyl sill propylamine _{(BTSPA) (H 5 C 2} O) 3 Si _{- (CH 2) 3 -NH- (} CH 2) 3 - (OC 2 H 5) 3, bis-triethoxysilylpropyl sill tetrasulfide _{(BTSPS) (H 2 C 2} O) 3 Si- (CH 2) 3 -S 4 _{- (CH 2) 3 -Si (} OC 2 H 5) 3 and the like. Another type is an organofunctional silane represented by the structure X _{3 -n} R _n Si—Y, where n is 0 or 1 and X is a hydrolyzable group (methoxy, ethoxy, methoxyethoxy, propyl, Butyl, isobutyl, s-butyl, t-butyl and acetyl), X may be the same or different and Y is amino, mercapto, phenyl, vinyl, epoxy, methacryl, isocyanate, ureido, sulfur Are selected from the group consisting of organic functional groups and alkaryl groups represented by For example, vinylsilane CH ₂ ═CHSi (OCH ₂ CH ₃ ) ₃ ,
3-glycidoxypropyltrimethoxysilane _{CH 2 - (O) -CHCH 2} OCH 2 CH 2 CH 2 Si (OCH3) 3,
3-mercaptopropyltriethoxysilane HSCH ₂ CH ₂ CH ₂ Si (OCH ₂ CH ₃ ) ₃ ,
3-aminopropyltriethoxysilane H ₂ NCH ₂ CH ₂ CH ₂ Si (OCH ₂ CH ₃ ) ₃ ,
Phenyltriethoxysilane
_{(C 2 H 5 O) 3} Si-C 6 H 5,
3-methacryloxypropyl triethoxy silane _{CH 2 = C (CH 3)} COOCH 2 CH 2 CH 2 Si (OCH 2 CH 3) 3,
3-isocyanatopropyltrimethoxysilane O═C═NCH ₂ CH ₂ CH ₂ Si (OCH ₂ CH ₃ ) ₃ ,
Decyltrimethoxysilane CH ₃ (CH ₂ ) ₉ Si (OCH ₃ ) ₃ ,
3-Ureidopropyltriethoxysilane
(C ₂ H ₅ ) ₃ SiC ₃ H ₆ NHC (O) NH ₂
Etc.

  In addition, octadecyltriethoxysilane, bistriethoxysilethane, bistriethoxysilhexane, bistriethoxysilethylene, bistrimethoxylethylbenzene, etc. are also effective. The above-mentioned silane coupling agent is at least partially, preferably fully hydrolyzed. The concentration of these silane coupling agents is about 0.05 to 10% by weight, more preferably 0.2 to 1% by weight. Since it is necessary to hydrolyze the silane coupling agent, it is necessary to add water. The amount of water to be used is suitably in the range of several percent to 10% with respect to the entire treatment liquid. In the case of hydrogen peroxide water, since it is generally added in a state of about 30%, it is not necessary to newly add water since it already contains water.

  This treatment solution is basically immersed, but can also be applied by spraying or roll coating.

[PH adjuster of silane coupling solution]
The pH of the solution is largely related to the hydrolysis reaction rate and oxide formation rate. From the viewpoint of the hydrolysis reaction, it is preferable that the pH is maintained at about 7 or less. On the other hand, according to the Pourbaix diagram (Document Atlas of Electrochemical Equilibria in Aqueous Solutions, Marcel Pourbaix, NACE International Cebelcor) Can be stably present in the range of pH 7-13, pH 8-12 for Ni, and pH 7-12 for Fe. Therefore, the pH of the treatment solution is maintained in the range 3-12. preferable. As the pH adjusting agent, hydroxides such as potassium hydroxide, ammonia, sulfuric acid, hydrochloric acid, nitric acid and the like are suitable.

(2) Regarding the method of immersing in the silane coupling agent solution after the oxidation treatment [Oxidizing agent]: Any general oxidizing agent can be used. As an item required as an oxidant, it is a matter of course that it must be capable of oxidizing a metal surface. In this method, unlike the method (1), when the treatment is performed in a wet environment, a strong oxidizing agent can be used because it is not necessary to coexist a solvent. Oxidizing agents used in the wet environment include hydrogen peroxide, permanganic acid, chloric acid, dichromic acid, bromic acid, nitric acid, hypochlorous acid, chloric acid and their salts, peracetic acid, ozone water. Etc. can be used. In a dry environment, air oxidation under heating and oxidation by ozone can be used.

[Silane coupling agent]
The silane coupling agent described in the method (1) can be used. In the method (1), it is necessary to hydrolyze the silane coupling agent. However, when oxidation treatment is performed by the wet method (2), many hydroxyl groups are formed on the surface of the generated oxide. There is no need to add water in order for it to be present and cause a hydrolysis reaction of the silane coupling agent. However, when an oxide is generated in a dry environment, it is necessary to add water as in the method (1).

[PH adjuster of silane coupling solution]
Unlike the case of the method (1), since it is not necessary to generate an oxide during silane coupling, it is only necessary to adjust the pH while paying attention only to promoting the hydrolysis reaction. In order to improve the hydrolysis reaction, the pH is preferably maintained at 7 or less, and preferably between 3 and 6 if possible. As the pH adjusting agent, hydroxides such as potassium hydroxide, ammonia, sulfuric acid, hydrochloric acid, nitric acid and the like are suitable.

  In the case of using either method (1) or (2), the time for immersion in the silane coupling agent is suitably about 1 hour, but the concentration of the silane coupling agent is 1 wt% or less. In some cases, the corrosion resistance may be improved by extending to about 24 hours.

  After the silane coupling treatment, the substrate is washed with the used solvent (containing no oxidizing agent and silane coupling agent) and then dried by blowing air. Or you may make it dry by maintaining in the temperature range of room temperature-50 degreeC.

  Further, after the silane coupling treatment, the corrosion resistance can be improved by performing a heat treatment as a post-treatment. As heat processing, the temperature of 100-200 degreeC and time 30 minutes-2 hours are preferable, and the temperature of 100-150 degreeC and time 30 minutes-1 hour are more preferable.

  Furthermore, the corrosion resistance can be further improved by repeating the silane coupling treatment a plurality of times after heat treatment or after drying. In this case, the first silane coupling treatment liquid and the subsequent silane coupling liquid may not be the same.

  The following was performed as a corrosion evaluation. As a sample, titanium oxide was sputtered as an adhesion layer on a silicon wafer, and then a target metal such as cobalt, nickel, iron, etc. was sputtered thereon to form a sample. A silane coupling layer was formed by the above two methods. For some samples, after the silane coupling layer was formed, heat treatment was performed, for example, in air at 100 ° C. for 1 h.

Corrosion resistance was evaluated by the following two methods.
(1) Constant temperature and humidity test: A sample subjected to a silane coupling treatment under conditions of a high temperature and high humidity state at a temperature of 65 ° C. and a relative humidity of 90% RH or more is allowed to stand for 96 hours. A sample formed on a 2.5 inch silicon wafer was used. Next, the number of corrosion points within a radius range of 14 mm to 25 mm was counted using an Optical Surface Analyzer and ranked as follows. A sample having a count number of less than 50 was evaluated as A, a sample having a count of 50 or more and less than 200 was evaluated as B, a sample having a count of 200 or more and less than 500 was evaluated as C, and a sample having a count number of 500 or more was evaluated as D. In practice, a rank of B or higher is desirable.

(2) Electrochemical test: 1 cm ^{2 of} the sample subjected to the silane coupling treatment was left and the other part was sealed. It was immersed in an aqueous borate solution having a pH of 7.47 or an aqueous 3% NaCl solution. When immersed for 10 minutes and the potential was stabilized, the potential was scanned at a scanning speed of 30 mV / min in the anode direction with reference to a potential of −100 mV lower than the immersion potential, and the current was measured. After the measurement, the corrosion current density was determined using Tafel's relational expression. When the corrosion current density is less than 10%, A is 10% or more but less than 20%, B is 20% or more but less than 50%, C is 50% or more, and D is untreated. evaluated.

  Hereinafter, specific examples to which the present invention is applied will be described with reference to tables.

(Comparative Example 1-4)
For untreated Co, Ni, Fe, and Cu, as shown in Comparative Example 1-4 (Table 1), the evaluation regarding the corrosion resistance when the constant temperature / humidity test is performed is D level, and the corrosion resistance is very high. It ’s bad. This test result is used as a standard for the following corrosion evaluation results.

(Example 1-4)
Example 1-4 uses a treatment liquid in which Co, Ni, Fe or Cu is used as a sample, 1 wt% BTSE is added as a silane coupling agent, and 10% of 30% H ₂ O ₂ is added as a coexisting oxidizing agent. Used to produce a silane coupling layer on the metal. The pH was 4.2 and the immersion time was 1 h. Ethanol was used as the solvent. The results of the corrosion evaluation were constant temperature and humidity test, electrochemical test (in borate), Co, Ni and Cu were all A, indicating good corrosion resistance. Regarding Fe, the corrosion evaluation was B in the constant temperature and humidity test and the electrochemical test, and although the corrosion resistance was slightly lower than that of other metals, the corrosion resistance was markedly better than that of the untreated case. Similar results were obtained when acetone, toluene, or ethyl ether was used as the solvent.

(Examples 3, 5-6)
Examples 3 and 5-6 use Fe as a sample, use a treatment liquid to which 1% by weight of BTSE is added as a silane coupling agent, and 10% of 30% H ₂ O ₂ is added as a coexisting oxidizing agent. The influence of the immersion time on the corrosion evaluation when a silane coupling layer is formed is shown. Ethanol was used as the solvent. In the case where the immersion time was 1 h (Example 3), the corrosion evaluation was B in all tests. However, in the immersion time 4 h, the corrosion evaluation in the constant temperature and humidity test was A. In the test, the corrosion evaluation is A, and it can be seen that the corrosion resistance is improved with time.

(Examples 7-15)
Examples 7 to 15 use Co as a sample, use 1 wt% of various silane coupling agents, use a treatment solution to which 10% of 30% H ₂ O ₂ is added as a coexisting oxidizing agent, The corrosion evaluation result when a silane coupling layer is formed on the top is shown. Ethanol was used as the solvent. The silane coupling agents used are polyfunctional silane, vinyl silane, ureido, epoxy silane, mercapto silane, sulfur silane and the like. In any case, the various corrosion evaluation results were A, indicating good corrosion resistance. Although data are not shown here, similar results were obtained for Fe, Ni, and Cu.

(Example 12)
Examples 3 and 16-19 use Co as a sample, use a treatment solution to which 1 wt% of BTSE is added as a silane coupling agent and 10% of 30% H ₂ O ₂ is added as an oxidant to coexist. The influence of pH on corrosion evaluation when a silane coupling layer is formed on the top is shown. Ethanol was used as the solvent. When the pH was 1.5, the dissolution rate of Co was so fast that it was eluted by immersion for 1 hour, so the immersion time was set to 5 minutes. The corrosion evaluation was B in the constant temperature and humidity test, but the corrosion evaluation in the electrochemical test was C. Although an improvement in corrosion resistance was confirmed as compared with the case of no treatment, the corrosion inhibiting action was small. This is because sufficient oxide was not formed on Co due to the low pH of the solution. In all cases where the pH of the treatment solution was 4.0 or higher, the corrosion evaluation result was A, indicating good corrosion resistance. Although data are not shown here, similar results were obtained for Fe, Ni, and Cu.

(Examples 20-23)
Examples 20-23 are used for corrosion evaluation when Co is used as a sample, 1 wt% of BTSE is used as a silane coupling agent, and an oxidizing agent is changed to form a silane coupling layer on a metal. The effect of the type of oxidant on Ethanol was used as the solvent. Those used as oxidizing agents are ammonium persulfate, sodium perchlorate, cerium diammonium nitrate and sodium chlorate. Since these are strong oxidizing agents, their concentrations are set lower than when hydrogen peroxide is used. Corrosion evaluation showed that the corrosion evaluation result was A for both the constant temperature and humidity test and the electrochemical test, regardless of which oxidizing agent was used, indicating good corrosion resistance. Although data are not shown here, similar results were obtained for Fe, Ni, and Cu.

(Examples 24-26)
Examples 24-26 use Fe or Co as a sample, use a treatment liquid containing 1 wt% BTSE as a silane coupling agent and 10% of 30% H ₂ O ₂ as an coexisting oxidizing agent. The result of performing the corrosion evaluation of the heat-treated sample after the formation of the silane coupling layer is shown. In Fe shown in Example 3, various corrosion test evaluation results were B, but the corrosion evaluation result A was obtained by heat treatment. Moreover, since the corrosion evaluation result regarding Co is still A, it can be seen that the heat resistance improves the corrosion resistance. This is because the condensation reaction has been promoted.

(Examples 27-31)
Examples 27-30 relate to the method (2) described above. Prior to the silane coupling process, a pre-oxidation process in a wet environment was performed. Oxidizing agents are 30% H0% H ₂ O ₂ /10%, ammonium sulfate / 10%, sodium perchlorate / 10%, sodium permanganate / 10%, ozone / water 10%. Oxidation in wet environment This is a case where processing is performed. As the silane coupling agent, BTSE having a pH of 4.2 (immersion time: 1 h—ethanol as a solvent) was used. As described above, since many hydroxyl groups are introduced to the surface to be used by the pre-oxidation treatment, it is not necessary to add water for hydrolysis to the BTSE solution. In either case, the corrosion evaluation result was A, indicating good corrosion resistance. Although data are not shown here, similar results were obtained for Fe, Ni, and Cu.

(Examples 31-32)
Examples 31-32 relate to the method (2) described above. Prior to the silane coupling process, a pre-oxidation process in a dry environment was performed. Air or ozone was used as the oxidant. As the silane coupling agent, BTSE having a pH of 4.2 (immersion time: 1 h—ethanol + 10% H ₂ O as a solvent) was used. Since it was necessary to hydrolyze the silane coupling agent, the silane coupling treatment liquid contained 10% water. In either case, the corrosion evaluation result was A, indicating good corrosion resistance. Although data are not shown here, similar results were obtained for Fe, Ni, and Cu.

(Comparative Example 5-13)
Comparative Example 5-13 is a case where a corrosion evaluation was performed in the case of treatment with a silane coupling agent not containing an oxidizing agent. Although not containing an oxidizing agent, 10% of water is added to hydrolyze the silane coupling agent. The main solvent is ethanol. Regardless of the treatment with any silane coupling agent, the corrosion evaluation was C or less in both the constant temperature and humidity test and the electrochemical test, and the corrosion resistance was not exhibited. Although data are not shown here, similar results were obtained for Fe, Ni, and Cu.

(Comparative Example 14-17)
Comparative Examples 14-17 show the corrosion evaluation results when only the oxidation treatment is performed without performing the silane coupling treatment. In both cases of the constant temperature and humidity test and the electrochemical test, the corrosion evaluation was D, indicating no corrosion resistance. Although data are not shown here, similar results were obtained for Fe, Ni, and Cu.

(Examples 33-35 and Comparative Examples 17-19)
Examples 33-35 show the results of measurement and identification by XPS on the surface of Co after the treatment with respect to the system of silane coupling agent + oxidizing agent that showed corrosion resistance. Comparative Examples 17-19 show the results of measuring and identifying the surface of Co after the treatment by XPS with respect to the treatment of only the silane coupling agent that did not exhibit corrosion resistance. In the examples showing the corrosion resistance, it can be seen that the ratio of Oxide in the O1s peak is larger and the oxide is generated more than in the comparative example which does not show the corrosion resistance. Similar results were obtained with respect to the case of the pre-oxidation treatment shown in Example 27. Therefore, it can be seen that in order to impart corrosion resistance with the silane coupling agent, it is necessary to coexist an oxidizing agent or to perform an oxidation treatment in advance.

(Examples 36-38)
In Examples 36-38, an alloy containing various transition metals was used as a sample, and 1 wt% of BTSE was added as a silane coupling agent, and 10% of 30% H ₂ O ₂ was added as a coexisting oxidizing agent. Used to produce a silane coupling layer on the metal. The pH was 4.2 and the immersion time was 1 h. Ethanol was used as the solvent. The results of the corrosion evaluation were A for the constant temperature and humidity test and the electrochemical test (in borate), and all of the alloys containing various transition metals showed good corrosion resistance. Similar results were obtained when acetone, toluene, or ethyl ether was used as the solvent.

Claims (10)

  Applying a silane coupling reaction layer to the metal substrate by contacting the metal substrate with a solution containing an organofunctional silane that has been at least partially hydrolyzed, an oxidant and a solvent, and then removing the solvent. A method for preventing metal corrosion.   After contacting the metal substrate with a solution containing an organofunctional silane that is at least partially hydrolyzed and the solvent, the metal substrate is contacted with the silane by removing the solvent. A method for preventing corrosion of a metal, comprising applying a coupling reaction layer.   A metal substrate characterized by applying a silane coupling reaction layer to a metal substrate by immersing the metal substrate in a solution containing an oxidizing agent and then contacting the solution with a solution containing at least one organofunctional silane. Corrosion prevention method.   4. The method for preventing corrosion of metal according to claim 1, wherein the oxidizing agent is at least one selected from hydrogen peroxide, nitric acid, ammonium persulfate, diammonium cerium, and salts thereof.   3. The method for preventing corrosion of metal according to claim 2, wherein the oxidizing agent used in the oxidation treatment is air or ozone.   2. The method for preventing corrosion of metal according to claim 1, wherein after the silane coupling reaction layer is applied to the metal substrate, a heat treatment is further performed.   3. The method for preventing corrosion of metal according to claim 2, wherein after the silane coupling reaction layer is applied to the metal substrate, heat treatment is further performed.   4. The method for preventing corrosion of metal according to claim 3, wherein after the silane coupling reaction layer is applied to the metal substrate, a heat treatment is further performed. 4. The method for preventing corrosion of a metal according to claim 2, wherein the organofunctional silane is represented by the following formula (1).
_{X 3-n R n Si-} Y or _{X 3-n SiR'SiX 3-n} ... (1)
(Wherein n is 0 or 1, X is selected from hydrolyzable groups (methoxy, ethoxy, methoxyethoxy, propyl, butyl, isobutyl, s-butyl, t-butyl and acetyl), and X is the same or different Y is selected from an organic functional group represented by amino, mercapto, phenyl, vinyl, epoxy, methacryl, isocyanate, ureido, and sulfur, or an alkyl group, R is a methyl group, R 'is an alkyl, Selected from alkenyl, alkenyl substituted with at least one amino group or S group)   10. The method for preventing corrosion of a metal according to claim 1, wherein the metal substrate is Fe, Co, Ni, Cu or an alloy thereof.