JP2004018901A - Surface treatment method for magnesium material product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently perform anodic oxidation treatment known as a means for increasing the corrosion resistance and wear resistance of a magnesium material product and the adhesion of a coating film, and to form a transparent film in which the polished face of metallic luster can be obtained. <P>SOLUTION: Oxidation treatment is performed by energizing where on-off is repeated every several seconds under low voltage for a treatment time of about 10 s in an on time of about 1 to 2 s and an off time of ≥1 s using an anodic oxidation liquid obtained by adding a film formation smoothing agent to an alkali electrolytic liquid with a current stabilizer added. Thereafter, sealing treatment of the oxide film is performed with a transparent coating material. <P>COPYRIGHT: (C)2004,JPO

Description

【００１７】
そして定法通り試料片の表面を清浄にして、所定の電極接続を行い、電圧４０Ｖで、最大電流を１０Ａ（１６．６Ａ／平方ｄｍ）で、オンタイム１秒、オフタイム３秒のインターバル通電を２〜３サイクル行う。
【００１８】
前記の通電によって試料片の表面には、陽極酸化処理による透明な被膜が形成される。この透明酸化被膜越しの試料片表面は、研磨された金属光沢がそのまま現れている。
【００１９】
次に定法とおり洗浄し、クリア塗料を混入した電着槽に浸漬し、透明酸化被膜の表面に更にクリア塗料による電着塗装を施す。これによって透明酸化皮膜の多孔質の表面が封孔されると共に、塗膜による保護膜が形成されることになる。
【００２０】
而して試料片の表面には、研磨された金属光沢が全く損なわれることなく現出する透明保護膜が形成されることになる。
【００２１】
更に前記透明酸化被膜形成のためのインターバル通電の通電条件（デューティ比の変更、継続オンタイム）を種々変化させて実験させた結果、通電処理時間（オンオフ通算時間）を１０秒として実施した結果が表２である。
【００２２】
【表２】

【００２３】
従って１秒の通電でも透明酸化皮膜が形成されることが確認でき、５秒以上継続するオンタイムを採用すると、酸化被膜によって僅かな色変調（白色半透明）を呈し、金属光沢が明確に現出する透明被膜とはならないことが確認された。なお約２０分の通電処理（デューティ比２５％）を行うと、透明度が無くなり白色を呈することが確認できた。
【００２４】
次に本発明の第二実施形態について説明する。第二実施形態は、所望の色調を備えたマグネシウム材料製品の製出に関するものである。
【００２５】
第二実施形態は、陽極酸化処理、染色処理、封孔処理を順次行う表面を処理する方法で、陽極酸化処理は、所定の電解液（第一実施形態と同様に、アルカリ溶液、電流安定化剤、膜平滑化剤で構成される。）を使用し、適宜にオンオフを繰り返すインターバル電源をもって実施する。この陽極酸化処理における通電処理時間は、オンオフのデューティ比並びにオンタイム、並びに形成しようとする膜厚に対応して適宜定められるものである。
【００２６】
陽極酸化処理を施したマグネシウム材料製品は、洗浄の後に染色処理を行うもので、所望の色彩の染料の水溶液に、マグネシウム材料製品をどぶ漬けして行う。これによって染料水溶液は、酸化被膜のポーラス層の孔部分に進入し、マグネシウム材料製品の酸化被膜表面を所望の色に着色する。
【００２７】
染色処理を終了すると、所定の洗浄後に封孔処理を行う。封孔処理は、前記第一実施形態と同様に、クリア塗料を混入した電着槽に浸漬し、透明酸化被膜の表面に更にクリア塗料による電着塗装を施してなるものである。
【００２８】
従って、所望の染料をもって所望の色彩に着色した保護被膜を備えたマグネシウム材料製品を得ることができたもので、特に陽極酸化処理においてインターバル電源を採用することによって、被膜形成効率を高めると共に、堅牢な被膜を得ることができたものである。
【００２９】
本発明は、前記の第一実施形態及び第二実施形態に示した例に限定されるものではなく、陽極酸化処理における電解液の組成並びにその濃度、さらには電圧を変更しても可能である。
【００３０】
具体的には、電圧を２０Ｖ、６０Ｖ、１００Ｖに変更して、同時に電解液の組成濃度を変更して実験を繰り返したところ、下記の表３，４の通り確認できた。
【００３１】
【表３】

【００３２】
【表４】

【００３３】
実験は、オンタイム１秒、オフタイム３秒のインターバルで、２〜３サイクルの例を示したもので、所定の透明被膜の形成が確認されたのが「丸印」、完全透明被膜は形成されないが酸化被膜が形成された場合は「三角印」で、被膜形成が認められない場合には「×印」とした。
【００３４】
そして実験の結果、表３に示すとおり、液温が第一実施形態の５０℃から、実験した２５℃で、且つ電圧が２０〜４０Ｖの場合に透明被膜の形成が確認できた。
【００３５】
また表４に示すとおり、電解液組成物の濃度変更をした結果から、アルカリ溶液の濃度を高めても透明被膜形成に問題は無く、濃度を低くすると、最適電圧が低電圧に移行することが確認できた。また電流安定化剤及び膜平滑化剤の濃度は、膜形成への影響は少ないことが確認された。
【００３６】
更に電解液の使用材料を変更した例を表５に示した。
【００３７】
【表５】

【００３８】
表５に示すとおり、本発明の実施形態に示した電解液構成の代替物質を採用しても、インターバル電源を採用しての陽極処理による酸化被膜形成が実現するものである。また、他の合金であるＡＺ６１についても同様の試験を実施したところ、同様の酸化被膜を得ることができる。
【００３９】
【発明の効果】
以上のとおり本発明は、必要に応じて電流安定化剤を加えたアルカリ電解液に、皮膜形成平滑剤を付加した陽極酸化液を使用し、低電圧で、数秒毎のオンオフを繰り返す通電を行ってマグネシウム材料製品の表面に陽極酸化処理を施し、然る後酸化被膜の封孔処理を行ってなるマグネシウム材料製品の表面処理方法で、通電初期の効率的な膜形成を繰り返して所望の厚みの酸化皮膜を得るようにしたもので、堅牢な皮膜を効率よく形成することで、マグネシウム材料製品の高品質化に貢献できたものである。
【００４０】
また特に前記処理方法において、オンタイム１〜２秒程度でオフタイム１秒以上とし、全体で１０秒前後の処理時間で酸化処理を行って、透明酸化被膜を形成した後、透明塗料で封孔処理を行ってなる表面処理方法で、研磨状態の金属光沢面を備え且つ耐食性、耐摩耗性を有するマグネシウム材料製品を提供できたものである。[0001]
[Industrial applications]
TECHNICAL FIELD The present invention relates to a surface treatment method that mainly performs anodizing treatment on a surface of a magnesium material product.
[0002]
[Prior art]
2. Description of the Related Art Anodizing treatment of a product surface has been known as a means for improving the corrosion resistance, abrasion resistance, and adhesion of a coating film of a magnesium material product. Specifically, the JIS 5 method, the JIS 6 method, the HAE method, the phosphoric acid method and the like are known. However, in the above-mentioned known means, since a heavy metal such as dichromic acid is used as the electrolytic solution, a problem arises in waste liquid treatment. Therefore, anodizing treatment using an alkaline aqueous solution as an electrolytic solution has been conventionally proposed.
[0003]
Specifically, Japanese Patent Application Laid-Open No. 9-176894 discloses an electrolyte containing an alkali metal or alkaline earth metal hydroxide, a carbonate aqueous solution and a film-forming stabilizer, It discloses that an oxide film is formed by applying a current of dm2 for 20 minutes.
[0004]
JP-A-11-209893 and JP-A-23698 disclose that it is difficult to form a transparent film exhibiting metallic luster by the above-mentioned means, and to use phosphates and aluminates and an organic compound having a hydroxyl group as a stabilizer. It is disclosed that a transparent film was obtained by performing DC electrolysis at an electrolytic voltage of 80 V for 30 seconds using the contained electrolytic solution. However, when the film is formed by the above-mentioned means, the film is thick, and it is not always possible to say that it is a transparent film.
[0005]
Further, a high voltage treatment of 220 to 250 V DC with an electrolytic solution containing ammonia (Japanese Patent Application Laid-Open No. 11-502567), a film growth treatment by repeating inversion addition using electropolishing by an inversion power supply (Japanese Patent Application Laid-Open No. 2001-49493), etc. Means are known.
[0006]
[Problems to be solved by the invention]
First, in the above-mentioned conventional means, even if it shows a metallic luster, the color tone of the metallic substrate slightly changes, and it is difficult to form a robust transparent film.
[0007]
Secondly, although the detailed cause is unknown, the thickness and the robustness of the oxide film were not proportional to the current-carrying time, and it was experimentally confirmed that the film was formed efficiently at the beginning of current-carrying. Therefore, the oxidizing means for continuing the energization for a predetermined time as in the past is not always efficient.
[0008]
Therefore, the present invention proposes a surface treatment method for a magnesium material product employing a novel anodic oxidation treatment capable of reliably obtaining a transparent film and efficiently obtaining an oxide film.
[0009]
[Means to solve the problem]
The surface treatment method of the magnesium material product according to the present invention uses an anodic oxidizing solution to which a film-forming smoothing agent is added to an alkali electrolyte solution to which a current stabilizer is added as necessary, and at a low voltage, every few seconds. It is characterized in that anodization is performed on the surface of the magnesium material product by applying current repeatedly to turn on and off, and then the oxide film is sealed.
[0010]
Therefore, in the initial stage of energization, oxygen ions in the electrolyte on the surface of the object to be treated (anode) act immediately to form an oxide film, and in the subsequent film formation by energization, the efficiency of film formation is enhanced by the movement of oxygen ions in the liquid. bad. Therefore, by providing an off-time, the oxygen ion concentration of the electrolyte on the surface of the object to be treated (anode) returns to the initial state. Thickness.
[0011]
Further, the present invention particularly provides the above-mentioned processing method, wherein the on-time is about 1 to 2 seconds, the off-time is 1 second or more, and the oxidizing treatment is performed for a total processing time of about 10 seconds to form a transparent oxide film. It is characterized by being subjected to sealing treatment with paint.
[0012]
Therefore, in the anodic oxidation treatment, the film thickness is thin and transparent, and the metallic luster can be clearly recognized as it is. Further, when a sealing treatment is performed with a transparent paint, a magnesium material product having a polished metallic glossy surface and having corrosion resistance and abrasion resistance can be obtained.
[0013]
Further, the present invention is characterized in that a predetermined sealing treatment is performed after immersion in a dyeing solution after anodizing treatment, and a magnesium material product having a desired color tone can be efficiently produced. .
[0014]
Embodiment
Next, an embodiment of the present invention will be described. The first embodiment is an example that is recognized as the optimal implementation of the surface treatment method for a magnesium material product having a transparent film.
[0015]
A thin rolled plate of AZ31 alloy was used as a sample piece, and constituent liquids as shown in Table 1 were used as an anodizing electrolyte.
[0016]
[Table 1]

[0017]
Then, the surface of the sample piece is cleaned according to a standard method, predetermined electrode connections are made, and a voltage of 40 V, a maximum current of 10 A (16.6 A / sq. Dm), an on-time of 1 second, and an off-time of 3 seconds are applied. Perform 2-3 cycles.
[0018]
Due to the energization, a transparent film is formed on the surface of the sample by anodizing. The polished metallic luster appears as it is on the surface of the sample piece through the transparent oxide film.
[0019]
Next, it is washed as usual, immersed in an electrodeposition tank mixed with a clear paint, and further electrodeposited with a clear paint on the surface of the transparent oxide film. As a result, the porous surface of the transparent oxide film is sealed, and a protective film of a coating film is formed.
[0020]
Thus, a transparent protective film that appears without any loss of polished metallic luster is formed on the surface of the sample piece.
[0021]
Furthermore, as a result of conducting experiments by changing the energizing conditions (change in duty ratio, continuous on-time) of the interval energizing for forming the transparent oxide film, the results obtained by setting the energizing processing time (total on-off time) to 10 seconds were obtained. Table 2.
[0022]
[Table 2]

[0023]
Therefore, it was confirmed that a transparent oxide film was formed even with 1 second of energization, and when an on-time lasting 5 seconds or more was adopted, slight color modulation (white translucent) was exhibited by the oxide film, and the metallic luster was clearly exhibited. It was confirmed that the resulting transparent film was not formed. In addition, it was confirmed that when the energization process (duty ratio 25%) was performed for about 20 minutes, the transparency was lost and the color turned white.
[0024]
Next, a second embodiment of the present invention will be described. The second embodiment relates to production of a magnesium material product having a desired color tone.
[0025]
The second embodiment is a method of treating a surface in which an anodic oxidation treatment, a dyeing treatment, and a sealing treatment are sequentially performed. The anodic oxidation treatment is performed by using a predetermined electrolytic solution (as in the first embodiment, an alkaline solution, a current stabilizing method). And a film smoothing agent) and using an interval power supply that repeats on and off as appropriate. The energization processing time in the anodic oxidation processing is appropriately determined according to the ON / OFF duty ratio and the ON time, and the film thickness to be formed.
[0026]
The anodized magnesium material product is subjected to a dyeing process after washing, and is performed by immersing the magnesium material product in an aqueous solution of a dye having a desired color. As a result, the aqueous dye solution enters the pores of the porous layer of the oxide film, and colors the oxide film surface of the magnesium material product to a desired color.
[0027]
When the dyeing process is completed, a sealing process is performed after a predetermined washing. In the sealing treatment, similarly to the first embodiment, the transparent oxide film is immersed in an electrodeposition tank mixed with a clear paint, and the surface of the transparent oxide film is further subjected to electrodeposition with a clear paint.
[0028]
Therefore, it was possible to obtain a magnesium material product provided with a protective coating colored in a desired color with a desired dye. In particular, by adopting an interval power supply in the anodizing treatment, the film forming efficiency was improved and the robustness was improved. A good film could be obtained.
[0029]
The present invention is not limited to the examples shown in the first embodiment and the second embodiment, and it is possible to change the composition of the electrolytic solution and its concentration in the anodizing treatment, and even change the voltage. .
[0030]
Specifically, when the voltage was changed to 20 V, 60 V, and 100 V, and at the same time the composition concentration of the electrolytic solution was changed and the experiment was repeated, it was confirmed as shown in Tables 3 and 4 below.
[0031]
[Table 3]

[0032]
[Table 4]

[0033]
The experiment shows an example of 2 to 3 cycles with an interval of 1 second on time and 3 seconds off time. The formation of a predetermined transparent film was confirmed by a circle, and a completely transparent film was formed. However, when an oxide film was formed, a triangle mark was formed, and when no film was formed, a cross mark was formed.
[0034]
As a result of the experiment, as shown in Table 3, formation of a transparent film was confirmed when the liquid temperature was 50 ° C in the first embodiment, the experiment was 25 ° C, and the voltage was 20 to 40V.
[0035]
Also, as shown in Table 4, from the result of changing the concentration of the electrolytic solution composition, there is no problem in the formation of the transparent film even when the concentration of the alkaline solution is increased, and when the concentration is lowered, the optimum voltage may shift to a low voltage. It could be confirmed. It was also confirmed that the concentrations of the current stabilizer and the film smoothing agent had little effect on film formation.
[0036]
Table 5 shows examples in which the materials used for the electrolytic solution were changed.
[0037]
[Table 5]

[0038]
As shown in Table 5, even if an alternative material of the electrolytic solution configuration shown in the embodiment of the present invention is employed, an oxide film can be formed by anodizing using an interval power supply. When a similar test was performed on AZ61, which is another alloy, a similar oxide film can be obtained.
[0039]
【The invention's effect】
As described above, the present invention uses an anodic oxidizing solution to which a film-forming smoothing agent is added to an alkaline electrolyte to which a current stabilizer has been added as necessary, and performs low-voltage, repeated energization on and off every few seconds. Anodizing treatment is performed on the surface of the magnesium material product, and then the oxide film is sealed. An oxide film was obtained, and by forming a robust film efficiently, it was possible to contribute to high quality magnesium material products.
[0040]
Further, in particular, in the above-mentioned processing method, the on-time is about 1 to 2 seconds, the off-time is 1 second or more, the oxidation processing is performed for a total processing time of about 10 seconds, and a transparent oxide film is formed. The present invention has provided a magnesium material product having a polished metallic glossy surface and having corrosion resistance and abrasion resistance by a surface treatment method obtained by performing a treatment.

Claims (4)

If necessary, use an anodic oxidizing solution with a film-forming smoothing agent added to an alkaline electrolyte with a current stabilizer added to it, and apply a low voltage at a constant voltage to turn on and off every few seconds. A method for treating a surface of a magnesium material product, comprising performing anodizing treatment and then performing sealing treatment of an oxide film. The energization ON time is about 1 to 2 seconds, the OFF time is 1 second or more, the oxidation processing is performed for a processing time of about 10 seconds in total, a transparent oxide film is formed, and the sealing processing is performed with a transparent paint. The surface treatment method for a magnesium material product according to claim 1. 2. The surface treatment method for a magnesium material product according to claim 1, wherein a predetermined sealing treatment is performed after immersion in the dyeing solution after the anodizing treatment. 4. The magnesium material product according to claim 1, wherein the alkaline electrolyte is a combination of any one of sodium hydroxide, potassium hydroxide, and sodium carbonate, and any one of aluminum hydroxide, sodium phosphate, and sodium aluminate. Surface treatment method.