Coating and coating formation method
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- JAPAN SUZUKI CO
- Filing Date
- 2023-03-29
- Publication Date
- 2026-04-17
AI Technical Summary
Existing zinc or zinc alloy coatings face issues with peeling under harsh conditions, increase environmental burden due to water usage in electroplating, and involve multiple steps.
A method involving forming a first film with a zinc or zinc alloy on a base material by colliding powders, followed by a second film using a solution containing zinc or zinc alloy, and optionally a silica film, to enhance adhesion and reduce environmental impact.
Improves adhesion of the film, reduces environmental footprint, and minimizes peeling, while maintaining corrosion resistance.
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Abstract
Description
[Technical field]
[0001] The present invention relates to coatings and methods of forming coatings, such as coatings having zinc or zinc alloy coatings. [Background technology]
[0002] In order to improve the corrosion resistance of zinc or zinc alloy coatings, it is known to bake a coating containing zinc, aluminum and a silica compound onto the zinc or zinc alloy coating, and then form a porous silica coating thereon (see, for example, Patent Document 1). [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 2016-84510 A Summary of the Invention [Problem to be solved by the invention]
[0004] According to the method of Patent Document 1, corrosion resistance can be improved. However, under severe conditions, the film may peel off. This may result in a decrease in corrosion resistance. Thus, when a plurality of zinc or zinc alloy films are laminated, the film may peel off. Furthermore, when the zinc or zinc alloy film is formed by electroplating, water is used, which imposes a large environmental load. Furthermore, the number of steps is increased.
[0005] The present invention has been made in consideration of the above problems, and has an object to improve the adhesion of a coating having a zinc or zinc alloy coating. [Means for solving the problem]
[0006] The present invention provides a coating formation method including the steps of forming a first coating, which is a zinc or zinc alloy coating and has an uneven surface, by colliding a plurality of powders containing zinc or a zinc alloy onto the surface of a base material, and forming a second coating containing zinc or a zinc alloy on the surface of the first coating.
[0007] In the above configuration, the plurality of powders may include a rigid powder harder than the zinc or zinc alloy.
[0008] In the above configuration, the plurality of powders may include an alloy containing zinc and iron, or an alloy containing zinc, magnesium, and aluminum.
[0009] In the above configuration, the step of forming the second coating may include a step of applying a solution containing zinc powder and an organosilicon compound to a surface of the first coating, and performing a heat treatment to form the second coating.
[0010] In the above configuration, the step of forming the second coating can include a step of applying a solution containing zinc powder, aluminum powder, and at least one of an alkoxysilane and a hydrolysate thereof to a surface of the first coating, and performing a heat treatment to form the second coating.
[0011] In the above configuration, the base material may be an iron material or an iron alloy material.
[0012] The above-mentioned method may further include forming a silica coating on a surface of the second coating.
[0013] The present invention provides a coating formation method including the steps of forming a first coating, which is a zinc alloy coating having an uneven surface, by colliding a plurality of powders, the powder including zinc or a zinc alloy and a rigid powder harder than the zinc or zinc alloy, onto the surface of a base material, and forming a second coating by applying a solution including zinc powder, aluminum powder, and at least one of an alkoxysilane and a hydrolyzate thereof to the surface of the first coating and subjecting the solution to a heat treatment.
[0014] The present invention provides a coating comprising: a base material; a first coating, which is a zinc or zinc alloy coating having a structure in which a plurality of powder particles containing zinc or a zinc alloy are crushed and bonded to one another and has an uneven surface, and a second coating, which is provided on the surface of the first coating and contains zinc or a zinc alloy.
[0015] In the above configuration, the plurality of powders may include an alloy containing zinc and iron, or an alloy containing zinc, magnesium, and aluminum, and the second coating may include zinc and aluminum. Effect of the Invention
[0016] According to the present invention, it is possible to improve the adhesion of a coating having a zinc or zinc alloy coating. [Brief description of the drawings]
[0017] [Figure 1] 1(a) to 1(d) are cross-sectional views illustrating a coating formation method according to the first embodiment. [Diagram 2] 2(a) and 2(b) are cross-sectional views showing a method for forming the second coating in the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] [Embodiment 1] 1(a) to 1(d) are cross-sectional views illustrating a coating formation method according to the first embodiment.
[0019] [Step 1: Preparation of base material] As shown in Fig. 1(a), a base material 10 is prepared. The base material 10 is, for example, iron (Fe) or an iron alloy, and is, for example, a bolt, a nut, or the like. An iron alloy contains iron at 50 mass% or more. The base material 10 may be a member other than iron or an iron alloy, and may be, for example, a metal material such as copper, aluminum, or an alloy thereof, or a hard resin.
[0020] [Step 2: Formation of first film 14] Next, as shown in FIG. 1(b), a first coating 14 is formed on the surface of the base material 10. FIGS. 2(a) and 2(b) are cross-sectional views showing a method for forming a first coating in the first embodiment. As shown in FIG. 2(a), a first coating 14 (see FIG. 2(b)) is formed on the base material 10 using a mechanical dry plating method. In the mechanical dry plating method, a plurality of powders 20 are collided with the surface of the base material 10 at room temperature. The powders 20 include, for example, zinc powder or zinc alloy powder. The zinc powder does not intentionally include elements other than zinc (Zn). The zinc alloy powder includes, for example, 50% by mass or more of zinc and at least one element of iron (Fe), nickel (Ni), aluminum (Al) and magnesium (Mg). An example of the powders 20 is a zinc alloy including 50% by mass or more of zinc and including iron. Another example of the powders 20 is a zinc alloy including 50% by mass or more of zinc and including aluminum and magnesium. The zinc alloy preferably contains 70% by mass or more of zinc. The powder 20 is, for example, spherical, and the particle size of the powder 20 is, for example, 10 μm or more and 1 mm or less, 0.2 mm or more and 0.7 mm or less, or 0.2 mm or more and 0.3 mm or less. For example, the powder 20 is projected at high speed onto the surface of the base material 10 mainly using centrifugal force when the powder 20 is put into a barrel and the barrel is rotated, or energy other than heat, such as air pressure.
[0021] As shown in FIG. 2(b), when the powder 20 collides with the surface of the base material 10, the powder 20 is crushed by the kinetic energy of the powder 20. The crushed powder 13 adheres to the surface of the base material 10. The crushed powder 13 are bonded to each other and stacked. This forms the first coating 14 in which the crushed powder 13 are bonded. The first coating 14 has an interface where the crushed powder 13 are bonded. In addition, the upper surface of the first coating 14 becomes uneven because the powder 20 collides with it. When the powder 20 is zinc powder, the first coating 14 becomes a zinc coating, and when the powder 20 is zinc alloy powder, the first coating 14 becomes a zinc alloy coating. The thickness of the first coating 14 is, for example, 0.1 μm or more and 15 μm or less, for example, 0.3 μm or more and 3 μm or less.
[0022] In FIG. 2(b), the powder 20 may have a core harder than zinc or a zinc alloy and a zinc layer or a zinc alloy layer around the core. The core is, for example, a metal or an insulator, for example, iron or an iron alloy. The preferred composition of the zinc layer or zinc alloy layer is the same as the preferred composition of the zinc powder or zinc alloy powder described above. In FIG. 2(b), when the powder 20 is collided with the surface of the base material 10, a plurality of powders 20 and a plurality of shot balls may be collided with the surface of the base material 10. The shot balls are, for example, a metal or an insulator harder than the powder 20, for example, iron or an iron alloy. The shot balls are, for example, spherical, and the average particle size of the shot balls is, for example, 10 μm or more and 150 μm or less, for example, 100 μm or less.
[0023] The first coating 14 formed as shown in FIG. 2(a) and FIG. 2(b) has good adhesion between the first coating 14 and the base material 10 because the powder 20 collides with the base material 10. In particular, when the powder 20 has a hard core, or when the shot balls and the powder 20 are collided with the base material 10, the cores or shot balls collide with the surface of the crushed powder 13, so that the crushed powder 13 adheres more firmly to the surface of the base material 10. The crushed powders 13 are firmly bonded to each other. Furthermore, the surface unevenness of the first coating 14 becomes larger. The powder 20 may contain metal powders other than zinc and zinc alloys, such as titanium powder, and ceramic powders, such as aluminum oxide.
[0024] [Step 3: Formation of second film 16] 1(c), a second coating 16 containing zinc or a zinc alloy is formed on the surface of the first coating 14. The zinc compound contains at least one of aluminum, nickel, tin, iron, and magnesium in addition to zinc. The second coating 16 may contain a silicon compound in addition to zinc or a zinc alloy.
[0025] In one method of forming the second coating 16, a solution for the second coating is applied onto the first coating 14, followed by a heat treatment (baking treatment). The solution for the second coating contains zinc powder, an organosilicon compound, and a solvent. The solution for the second coating may contain at least one type of metal powder, such as aluminum powder, nickel powder, tin powder, iron powder, and magnesium powder, in addition to zinc powder. In particular, the solution for the second coating preferably contains zinc powder and aluminum powder. The shape of the zinc powder and the metal powder may be, for example, spherical or scaly. The powder has a minor axis of, for example, 0.05 μm to 5 μm, and a major axis of, for example, 0.5 μm to 100 μm. The zinc powder contains, for example, 90% by mass or more or 99% by mass or more of zinc. The metal powder other than zinc (for example, aluminum powder) contains, for example, 90% by mass or more or 99% by mass or more of a metal element other than zinc (for example, aluminum). The ratio of the mass of the zinc powder to the total powder mass of the zinc powder and the metal powder other than zinc (e.g., aluminum powder) is preferably 50% by mass or more, more preferably 70% by mass or more. The ratio of the mass of the metal powder other than zinc (e.g., aluminum) to the total powder mass of the zinc powder and the metal powder other than zinc (e.g., aluminum powder) is preferably 1% by mass or more, more preferably 5% by mass or more.
[0026] The organosilicon compound includes, for example, at least one of an alkoxysilane and a hydrolyzate thereof. The alkoxysilane is preferably a tetraalkoxysilane having 3 or less carbon atoms, such as tetramethoxysilane, tetraethoxysilane, or tetrapropoxysilane. The solvent of the second coating solution is, for example, an alcohol, an ester, a glycol, or an ether. The solvent is preferably an alcohol, such as methanol, ethanol, propanol, isopropanol, butanol, hexanol, methoxybutanol, or methoxymethylbutanol. The total content of the zinc powder and the metal powder in the second coating solution is, for example, 20 to 60% by mass. The content of the organosilicon compound in the solution is, for example, 5 to 40% by mass. The content of the organic solvent in the second coating solution is, for example, 10 to 60% by mass.
[0027] The solution for the second film is applied to the surface of the first film 14 by, for example, dipping, spraying, or spin coating. The temperature of the heat treatment after applying the solution for the second film is, for example, 100°C to 400°C. The temperature of the heat treatment is equal to or higher than the temperature at which the solvent in the solution for the second film evaporates. The time of the heat treatment is, for example, 10 minutes to 120 minutes. As a result, the second film 16 is formed on the surface of the first film 14. The thickness of the second film 16 is, for example, 1 μm to 20 μm, and is, for example, 8 μm. The total content of the zinc powder and the metal powder other than zinc (for example, aluminum powder) in the second film 16 is, for example, 70 mass% or more and 95 mass% or less, and the content of the silicon compound is, for example, 5 mass% or more and 30 mass% or less. The ratio of the mass of the zinc powder to the total powder mass of the zinc powder and the metal powder other than zinc (for example, aluminum powder) is preferably 50% or more, more preferably 70% or more. As an example, the second coating 16 contains 70% by mass of zinc powder, 15% by mass of aluminum powder, and 15% by mass of silicon compound.
[0028] [Step 4: Formation of silica film 18] Next, as shown in FIG. 1(d), a porous silica film 18 is formed on the second film 16. The porous silica film 18 is formed by applying a silica film solution onto the second film 16 and performing a heat treatment (baking treatment). The silica film solution contains a silicon compound and a solvent. The silicon compound is, for example, at least one of an organosiloxane and a silane coupling agent. The silicon compound may contain an alkali metal silicate. The silica film solution may contain a titanium compound. The titanium compound is, for example, an organic titanate compound. The solvent of the silica film solution is, for example, water, alcohols, esters, glycols, or ethers. The content of the silicon compound in the silica film solution is, for example, 40% by mass or more and 90% by mass or less, and the content of the solvent is, for example, 10% by mass or more and 60% by mass or less. By applying the silica film solution to the surface of the second film 16, a polyorganosiloxane thin film, for example, is formed on the surface of the second film 16.
[0029] The solution for forming a silica film is applied to the surface of the second film 16 by, for example, dipping, spraying, or spin coating. The temperature of the heat treatment after applying the solution for forming a silica film is, for example, 100°C to 400°C. The temperature of the heat treatment is equal to or higher than the temperature at which the solvent in the solution for forming a silica film evaporates. The time of the heat treatment is, for example, 10 minutes to 120 minutes. As a result, the porous silica film 18 is formed on the surface of the second film 16. The thickness of the silica film 18 is, for example, 0.1 μm to 10 μm, for example, 1 μm. When the porous silica film 18 contains a silicon compound and a titanium compound, the content of the silicon compound is, for example, 50 mass% or more and 95 mass% or less, and the content of the titanium compound is, for example, 5 mass% or more and 50 mass% or less, for example, the contents of the silicon compound and the titanium compound are 75 mass% and 25 mass%, respectively.
[0030] In Patent Document 1, the corrosion resistance can be improved by forming a mixed coating equivalent to the second coating 16 on a zinc or zinc alloy coating. However, peeling may occur between the zinc or zinc alloy coating and the mixed coating. In the first embodiment, as shown in FIG. 2(a) and FIG. 2(b), a first coating 14, which is a zinc or zinc alloy coating and has an uneven surface, is formed by colliding a plurality of powders 20 containing zinc or a zinc alloy with the surface of the base material 10. As shown in FIG. 1(c), a second coating 16 containing zinc or a zinc alloy is formed on the surface of the first coating 14. The plurality of powders 20 collide with the surface of the base material 10, so that the base material 10 and the first coating 14 are firmly bonded to each other. In addition, since the surface of the first coating 14 is an uneven surface, the first coating 14 and the second coating 16 are firmly bonded to each other. This can improve the adhesion between the first coating 14 and the second coating 16. The first coating 14 thus formed has a structure in which a plurality of powder particles 13 containing zinc or a zinc alloy are crushed and bonded to one another, as shown in FIG. 2(b).
[0031] In FIG. 2(a), when the first coating 14 is formed, the multiple powders 20 include rigid powder (nuclei or shot balls) harder than zinc or zinc alloy. The rigid powder collides with the zinc or zinc alloy attached to the surface of the base material 10. This makes the base material 10 and the first coating 14 bond more firmly, and the surface of the first coating 14 becomes more uneven, so that the first coating 14 and the second coating 16 bond more firmly. This makes it possible to further improve the adhesion between the base material 10 and the second coating 16. In addition, since no water is used, the environmental load can be reduced. Furthermore, since the number of steps is smaller in dry plating than in electroplating, the number of steps can be reduced.
[0032] The powder 20 includes an alloy containing zinc and iron, or an alloy containing zinc, magnesium, and aluminum, which can further improve the adhesion between the base material 10 and the second coating 16.
[0033] In forming the second coating 16 in Fig. 1(c), a solution containing zinc powder and an organosilicon compound is applied to the surface of the first coating 14, and then heat-treated to form the second coating 16. By forming the second coating 16 on the base material 10 as in Patent Document 1, the corrosion resistance can be improved. However, forming the second coating 16 on the base material 10 reduces the adhesion between the base material 10 and the second coating 16. Therefore, it is preferable to form the first coating 14.
[0034] 1(c), the second coating 16 is formed by applying a solution containing zinc powder, aluminum powder, and at least one of alkoxysilane and its hydrolysate to the surface of the first coating 14, and then heat-treating the solution to form the second coating 16. By forming the second coating 16 on the base material 10 in this way, the corrosion resistance can be improved. However, when the second coating 16 is formed on the base material 10, the adhesion between the base material 10 and the second coating 16 decreases. Therefore, it is preferable to form the first coating 14. The second coating 16 formed in this way contains zinc and aluminum.
[0035] 1(d), a silica coating 18 (porous silica coating) may be formed on the second coating 16. This further improves corrosion resistance. EXAMPLES
[0036] The following experiments were carried out as Example 1 and Comparative Example 1. The steps of the experiments are as follows. Step 1: An M24 hexagonal bolt, an M24 nut and an M24 washer made of SPCC-SD steel were prepared as the base material 10.
[0037] Step 2: A first coating 14 was formed on the surface of the base material 10. The powder 20 was a powder having a spherical iron core and a zinc alloy layer surrounding the iron core. The diameter of the powder 20 was about 0.2 mm to 0.3 mm, and the zinc alloy layer was an alloy of zinc, aluminum, and magnesium, containing 50 mass % or more of zinc. The thickness of the first coating 14 was about 0.3 μm to 3 μm.
[0038] Step 3: A second coating 16 was formed on the surface of the first coating 14. As a solution for the second coating, Metas YC-B17J and Metas YC-B3 manufactured by Yuken Kogyo Co., Ltd. were mixed in a volume ratio of 25:3, and applied to the surface of the first coating 14. Then, a heat treatment was performed at 250°C to 290°C for 30 minutes or more. The above application and heat treatment were repeated twice. YC-B17J contains zinc powder, aluminum powder as a metal powder other than zinc, and tetraethoxysilane as an organic silicon compound. The thickness of the second coating 16 is about 8 μm, and the contents of zinc, aluminum, and silicon compounds in the second coating 16 are 70 mass%, 15 mass%, and 15 mass%, respectively.
[0039] Step 4: A porous silica coating 18 was formed on the surface of the second coating 16. Metas YC-T, Lubras C14 or Lubras C24 manufactured by Yuken Industry Co., Ltd. was used as a silica coating solution and applied to the surface of the second coating 16. Then, a heat treatment was performed at 110°C to 160°C for 10 minutes or more. The thickness of the porous silica coating 18 was about 1 μm, and the contents of the silicon compound and the titanium compound were 75% by mass and 25% by mass, respectively.
[0040] [Comparative Example 1] As Comparative Example 1, instead of the dry plating in step 2, wet electroplating was performed on the base material 10 to form a zinc-nickel alloy coating as the first coating 14. A plating solution was used in which zinc and nickel were dissolved in an aqueous sodium hydroxide solution at a mass ratio of 20:3. After the first coating 14 was formed, the surface of the first coating 14 was washed with water. The thickness of the first coating 14 was about 6 μm, and the zinc content in the first coating 14 was 87 to 92 mass %, and the nickel content was 8 to 13 mass %. Then, a chromate treatment was performed using a solution containing trivalent chromium. Then, steps 3 and 4 were performed in the same manner as in Example 1.
[0041] [Cross-cut method test] The adhesion of the film was evaluated using the cross-cut method specified in JIS-K5600-5-6 (ISO2409). A grid of 6 x 6 cuts was made into the film at 1 mm intervals, and adhesive tape was applied to the film with the cuts and then peeled off. The adhesion of the film was evaluated based on the degree of peeling of the film in the cut areas. The degree of peeling was classified according to JIS-K5600-5-6. Classification 0 indicates almost no peeling, and higher classifications indicate greater peeling.
[0042] Table 1 shows the results of the adhesion evaluation by the cross-cut method test in Comparative Example 1 and Example 1. [Table 1]
[0043] As shown in Table 1, Comparative Example 1 is classified as Class 4 by the cross-cut method and has low adhesion. Example 1 is classified as Class 0 by the cross-cut method and has high adhesion. Comparative Example 1 has high corrosion resistance, but has low adhesion between the base material 10 and the first coating 14 and between the first coating 14 and the second coating 16, so that the first coating 14 is easily peeled off from the base material 10 and the second coating 16 is easily peeled off from the first coating 14. When the first coating 14 is formed on the base material 10 and the second coating 16 is formed on the first coating 14 as in Example 1, the adhesion between the first coating 14 and the second coating 16 is improved.
[0044] As shown in FIG. 2(a) and FIG. 2(b), in Example 1, the powder 20 is collided with the surface of the base material 10 to improve the adhesion between the crushed powder 13 and the base material 10. Therefore, it is considered that the results of Example 1 can be generalized to cases where the base material 10 is other than an iron material or an iron alloy material. Since the surface unevenness of the first coating 14 becomes large, the adhesion between the first coating 14 and the second coating 16 is improved. Therefore, it is considered that the results of Example 1 can be generalized to cases where the second coating 16 is zinc or a zinc alloy. Although the silica coating 18 contributes to improving the corrosion resistance, it is considered that it does not contribute much to the adhesion between the first coating 14 and the second coating 16. Therefore, the results of Example 1 can be generalized to cases where the silica coating 18 is not used.
[0045] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]
[0046] 10 Base material 14 First membrane 16 Second Coating 18 Silica film
Claims
1. A process of forming a first coating which is a zinc or zinc alloy coating with an uneven surface by impacting multiple powders containing zinc or a zinc alloy onto the surface of a substrate material, A step of forming a second film containing zinc or a zinc alloy on the surface of the first film, Includes, A method for forming a film, comprising the step of forming the second film by applying a solution containing zinc powder and an organosilicon compound to the surface of the first film and then heat-treating it to form the second film.
2. A process of forming a first coating which is a zinc or zinc alloy coating with an uneven surface by impacting multiple powders containing zinc or a zinc alloy onto the surface of a substrate material, A step of forming a second film containing zinc or a zinc alloy on the surface of the first film, Includes, A method for forming a film, comprising the step of forming the second film, which involves applying a solution containing zinc powder, aluminum powder, and at least one of an alkoxysilane and its hydrolysate to the surface of the first film and then heating it to form the second film.
3. The method for forming a coating according to claim 1 or 2, wherein the plurality of powders include rigid powders that are harder than zinc or a zinc alloy.
4. The method for forming a coating according to any one of claims 1 to 3, wherein the plurality of powders include an alloy containing zinc and iron, or an alloy containing zinc, magnesium and aluminum.
5. The method for forming a coating according to any one of claims 1 to 3, wherein the base material is made of iron or an iron alloy.
6. A method for forming a film according to any one of claims 1 to 3, comprising the step of forming a silica film on the surface of the second film.
7. A step of forming a first coating which is a zinc alloy coating and has an uneven surface by impacting a plurality of powders containing zinc or a zinc alloy and a rigid powder harder than the zinc or zinc alloy onto the surface of a substrate material, A step of forming a second film by applying a solution containing zinc powder, aluminum powder, and at least one of alkoxysilane and its hydrolysate to the surface of the first film and then heat-treating it, A method for forming a film, including the following.