JPS6158554B2 - - Google Patents
Info
- Publication number
- JPS6158554B2 JPS6158554B2 JP53145460A JP14546078A JPS6158554B2 JP S6158554 B2 JPS6158554 B2 JP S6158554B2 JP 53145460 A JP53145460 A JP 53145460A JP 14546078 A JP14546078 A JP 14546078A JP S6158554 B2 JPS6158554 B2 JP S6158554B2
- Authority
- JP
- Japan
- Prior art keywords
- aluminum alloy
- corrosion resistance
- aluminum
- triethanolamine
- alloy castings
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/68—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous solutions with pH between 6 and 8
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/60—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using alkaline aqueous solutions with pH greater than 8
- C23C22/66—Treatment of aluminium or alloys based thereon
Landscapes
- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
Description
本発明の目的は、従来困難であつたアルミニウ
ム合金鋳物に白色の色調を与えかつ耐食性をもた
せるような簡単な表面処理法を提供することであ
る。
アルミニウムの特徴を生かしたアルミニウム合
金の表面処理法として、従来陽極酸化法および化
成皮膜処理法が汎用されている。
このうち陽極酸化法は、アルミニウム表面に耐
食性のすぐれた酸化アルミニウム皮膜を電解によ
つて人為的に厚く形成する方法であり、アルミニ
ウム純度の高いものやある種の合金、たとえば
Al−Mg系のアルミニウム合金ではアルミニウム
特有の銀白色の美麗な色調が得られ、かつ耐食性
もすぐれている。しかしアルミニウム純度の低い
ものや一般のアルミニウム合金鋳物、たとえば
JIS規定のADC−12ではその色調は灰〜黒色を呈
し外観的にも劣つているばかりでなく、耐食性も
あまり良いものは得られない。このようなアルミ
ニウム合金鋳物の色調と耐食性の向上のため、陽
極酸化用アルミニウム合金鋳物が数種開発され市
販されているが、通常のアルミニウム合金鋳物に
比較するとその価格が割高になつている。
以上のような陽極酸化に対して化成皮膜処理は
やや耐食性は劣るが、処理が簡単で複雑な形状の
ものでも簡単に適用できるなどの特徴があるため
よく使用されている。化成皮膜処理方法には、ク
ロム酸系、ケイ酸系、りん酸系、フツ化物系のも
のなど種々の処理剤を用いる方法があるが、これ
らの方法では、アルミニウム合金は着色し、アル
ミニウム合金特有の銀白色は得られないものがほ
とんどである。これに対して、化成皮膜処理法の
一つであるベーマイト皮膜処理では、アルミニウ
ム合金表面に酸化アルミニウムの一種であるベー
マイト（Al2O3・H2O）が形成され、アルミニウ
ム合金特有の銀白色を呈するとともに、このベー
マイトが安定であることころから、耐食性もすぐ
れたものが得られるため近年注目されている。
ベーマイト皮膜は、沸騰水中にアルミニウム合
金を浸漬すると形成されるが、その皮膜厚を増加
し耐食性を向上させるために、ベーマイト皮膜形
成剤として水酸化アルカリ、アンモニア、有機ア
ミン類を添加して処理するのが一般的である。こ
のうちベーマイト皮膜形成剤としては、有機アミ
ン類であるトリエタノールアミンが最もよく使用
されている。しかしこのようなベーマイト皮膜処
理でも次のような大きな欠点がある。
(1) アルミニウム純度のよいものでは銀白色の色
調が得られ耐食性もよいが、アルミニウム合金
鋳物では灰〜黒色となり耐食性も劣つている。
(2) 使用する水は蒸留水、イオン交換水など純度
の良いものでなければならず、水道水では色調
が悪く耐食性も期待できない。
一般にアルミニウム合金の用途として建材およ
び調理器具関係がある。このうち調理器具関係に
使用される場合はその色調が非常に重要で、一般
に銀白色が要求される。また建材関係ではカラー
サツシにみられるようにその色調は銀白色以外に
も種々の着色が適用されているが、少なくとも均
一な色調が要求される。
ところが上述したように一般のアルミニウム合
金鋳物では陽極酸化法でもベーマイト皮膜処理法
でもその色調は灰〜黒色と劣つており、かつ不均
一なものとなるうえ、その耐食性もまた小さいも
のしか得られないのが現状である。
本発明は、以上のような点に鑑み、とくに調理
器具関係に使用されるアルミニウム合金鋳物の色
調と耐食性を向上させることのできる表面処理法
を提供するものである。
すなわち、本発明はベーマイト皮膜形成剤のト
リエタノールアミンの他に特定のキレート剤を含
む水中でアルミニウム合金鋳物を処理することを
特徴とする。
以下本発明を実施例により説明する。
実施例 １
各種ベーマイト皮膜形成剤0.5W/V%（100ml当
たりの重量（ｇ）をW/V%で示す）とキレート
剤のエチレンジアミン四酢酸（EDTA）１W/V
％を含む水を沸騰させ、この沸騰水中でアルミニ
ウム合金鋳物（JIS規定のADC−12）を５分間処
理した。この処理後のアルミニウム合金鋳物の外
観、および前記の処理後沸騰水道中で0.5時間腐
食試験した場合の外観、アルミニウム溶出量を第
１表に示す。なお表には、ベーマイト皮膜形成剤
およびキレート剤のいずれかまたは両者を含まな
い場合も示した。
An object of the present invention is to provide a simple surface treatment method that gives aluminum alloy castings a white color and corrosion resistance, which has been difficult in the past. Conventionally, anodic oxidation and chemical conversion coating methods have been widely used as surface treatment methods for aluminum alloys that take advantage of the characteristics of aluminum. Among these, the anodizing method is a method of artificially forming a thick aluminum oxide film with excellent corrosion resistance on the aluminum surface by electrolysis.
Al-Mg-based aluminum alloys have a beautiful silvery white color characteristic of aluminum, and also have excellent corrosion resistance. However, aluminum with low purity or general aluminum alloy castings, such as
ADC-12 according to the JIS standard has a gray to black color and is not only inferior in appearance, but also does not have very good corrosion resistance. In order to improve the color tone and corrosion resistance of such aluminum alloy castings, several types of aluminum alloy castings for anodizing have been developed and commercially available, but their prices are relatively high compared to ordinary aluminum alloy castings. Although chemical conversion coating treatment has slightly inferior corrosion resistance compared to the above-mentioned anodic oxidation, it is often used because it is easy to treat and can be easily applied to objects with complex shapes. There are various chemical conversion coating treatment methods that use chromic acid-based, silicic acid-based, phosphoric acid-based, and fluoride-based processing agents, but with these methods, aluminum alloys are colored and have the characteristic properties of aluminum alloys. In most cases, a silvery white color cannot be obtained. On the other hand, in boehmite coating treatment, which is one of the chemical conversion coating treatment methods, boehmite (Al 2 O 3 H 2 O), a type of aluminum oxide, is formed on the surface of the aluminum alloy, resulting in the silvery white color characteristic of aluminum alloys. Boehmite has attracted attention in recent years because it is stable and has excellent corrosion resistance. A boehmite film is formed by immersing an aluminum alloy in boiling water, but in order to increase the thickness of the film and improve its corrosion resistance, it is treated by adding alkali hydroxide, ammonia, and organic amines as boehmite film-forming agents. is common. Among these, triethanolamine, which is an organic amine, is most often used as a boehmite film forming agent. However, even this type of boehmite film treatment has the following major drawbacks. (1) Aluminum with high purity has a silvery white color and good corrosion resistance, but aluminum alloy castings have a gray to black color and poor corrosion resistance. (2) The water used must be of high purity, such as distilled water or ion-exchanged water; tap water has a poor color and cannot be expected to be corrosion resistant. Generally, aluminum alloys are used in building materials and cooking utensils. Among these, when used for cooking utensils, the color tone is very important, and generally a silvery white color is required. Furthermore, in construction materials, various colors other than silver-white are applied, as seen in colored sash, but at least a uniform color tone is required. However, as mentioned above, with general aluminum alloy castings, whether by anodizing or boehmite coating, the color tone is poor, ranging from gray to black, and is non-uniform, and the corrosion resistance is only low. is the current situation. In view of the above points, the present invention provides a surface treatment method that can improve the color tone and corrosion resistance of aluminum alloy castings used particularly for cooking utensils. That is, the present invention is characterized in that aluminum alloy castings are treated in water containing a specific chelating agent in addition to triethanolamine, which is a boehmite film forming agent. The present invention will be explained below with reference to Examples. Example 1 Various boehmite film forming agents 0.5 W/V% (weight (g) per 100 ml is expressed as W/V%) and chelating agent ethylenediaminetetraacetic acid (EDTA) 1 W/V
% was boiled, and an aluminum alloy casting (ADC-12 according to JIS) was treated in the boiling water for 5 minutes. Table 1 shows the appearance of the aluminum alloy castings after this treatment, and the appearance and amount of aluminum eluted when a corrosion test was conducted in boiling water for 0.5 hours after the treatment. The table also shows cases in which either or both of the boehmite film forming agent and the chelating agent were not included.
【表】
第１表に示したように、トリエタノールアミン
単独で処理した場合にはアルミニウム合金鋳物
ADC−12は黒色となる。これは他のベーマイト
皮膜形成剤でも同様である。またエチレンジアミ
ン四酢酸単独では表面処理後は白色のままである
が、沸騰水道水による腐食試験を実施するとその
表面が短時間で黒色となり耐食性がない。これら
に対してベーマイト皮膜形成剤とキレート剤であ
るエチレンジアミン四酢酸とを混合して使用した
場合は、表面処理後も腐食試験後も白色を呈して
おり耐食性もよい。ただし炭酸アンモニウムおよ
びメチルアミンでは腐食試験後の表面がやや灰色
を呈する場合があり、またアルミニウム溶出量の
大小を比較すると、ベーマイト皮膜形成剤として
トリエタノールアミンが最も良好である。
実施例 ２
ベーマイト皮膜形成剤としてトリエタノールア
ミンを用い、これと各種キレート剤とを混合した
沸騰水中で５分間アルミニウム合金鋳物ADC−
12を処理し、さらに実施例１と同条件で腐食試験
をした結果を第２表に示す。[Table] As shown in Table 1, when treated with triethanolamine alone, aluminum alloy castings
ADC-12 will be black. This also applies to other boehmite film forming agents. Furthermore, when using ethylenediaminetetraacetic acid alone, the surface remains white after surface treatment, but when a corrosion test with boiling tap water is carried out, the surface turns black in a short period of time and has no corrosion resistance. When a boehmite film forming agent and a chelating agent, ethylenediaminetetraacetic acid, are used in combination, the product remains white both after surface treatment and after a corrosion test, and has good corrosion resistance. However, with ammonium carbonate and methylamine, the surface may appear slightly gray after the corrosion test, and when comparing the amount of aluminum eluted, triethanolamine is the best boehmite film forming agent. Example 2 Triethanolamine was used as a boehmite film forming agent, and aluminum alloy casting ADC- was mixed with various chelating agents for 5 minutes in boiling water.
Table 2 shows the results of treating No. 12 and conducting a corrosion test under the same conditions as in Example 1.
【表】
第２表のように各種キレート剤の濃度がトリエ
タノールアミンの濃度の２倍量以下の場合は表面
処理後の外観が一部灰色となりアルミニウム溶出
量も大きい。これに対して２倍量以上では外観も
白色のままであり耐食性もよい。従つてキレート
剤の量はトリエタノールアミンの２倍以上必要で
ある。
またトリエタノールアミンの濃度が0.05W/V%
以下では耐食性が劣つており、1.0W/V%を超え
ると耐食性は良いが処理後のアルミニウム合金鋳
物は一部灰色を呈するようになる。したがつてト
リエタノールアミンの最適濃度は0.05〜1.0W/V
％である。
ここで添加されたキレート剤の作用は次のよう
なものと考えられる。すなわちトリエタノールア
ミンを単独で含む溶液中で処理した場合、アルミ
ニウム合金鋳物の表面が着色するのは、鋳物中に
含まれる銅、亜鉛、鉄などの異種金属が表面に露
出したり、いつたん溶解したこれらの金属イオン
が鋳物表面に再析出するためである。これに対し
てキレート剤が添加されている場合はこれらの金
属と安定なキレートを生成するため表面への露出
および再析出を抑制する。したがつて各種キレー
ト剤のうちこれらの金属とのキレートが安定なも
のほどその効果が大きい。この点からは１・２−
シクロヘキサンジアミン四酢酸のキレート生成定
数が最も大きいのでこれの使用が有利である。し
かし、キレート剤の価格およびキレート生成反応
の速度の点からはエチレンジアミン四酢酸が最も
適しているといえる。
なおキレート剤の代わりに一般的な錯化剤、た
とえば酒石酸、クエン酸などの使用も若干の効果
が認められるが、これらの錯化剤では金属の種類
によつては生成する錯イオンが不安定であるこ
と、錯イオン生成定数がキレート生成定数より小
さいことなどから上記キレート剤を使用するもの
に及ばない。
以上のように本発明によれば、従来困難であつ
たアルミニウム合金鋳物の表面が美麗でかつ耐食
性のよい表面処理を簡単に行なうことができ、そ
の効果は大きいものである。[Table] As shown in Table 2, when the concentration of various chelating agents is less than twice the concentration of triethanolamine, the appearance after surface treatment becomes partially gray and the amount of aluminum eluted is large. On the other hand, when the amount is twice or more, the appearance remains white and the corrosion resistance is good. Therefore, the amount of chelating agent is required to be at least twice that of triethanolamine. Also, the concentration of triethanolamine is 0.05W/V%
If it is less than 1.0 W/V%, the corrosion resistance will be poor, and if it exceeds 1.0 W/V%, the corrosion resistance will be good, but the aluminum alloy castings will partially take on a gray color after treatment. Therefore, the optimal concentration of triethanolamine is 0.05-1.0W/V
%. The action of the chelating agent added here is considered to be as follows. In other words, when treated in a solution containing triethanolamine alone, the surface of aluminum alloy castings becomes discolored due to dissimilar metals such as copper, zinc, and iron contained in the casting being exposed to the surface or dissolving once. This is because these metal ions are redeposited on the surface of the casting. On the other hand, when a chelating agent is added, it forms a stable chelate with these metals, thereby suppressing exposure to the surface and redeposition. Therefore, among various chelating agents, the more stable the chelate with these metals, the greater the effect. From this point, 1.2-
The use of cyclohexanediaminetetraacetic acid is advantageous since it has the highest chelation constant. However, in terms of the price of the chelating agent and the speed of the chelate formation reaction, ethylenediaminetetraacetic acid is said to be the most suitable. Note that using general complexing agents such as tartaric acid and citric acid instead of chelating agents has some effect, but these complexing agents may produce unstable complex ions depending on the type of metal. , and the complex ion production constant is smaller than the chelate production constant, making it inferior to those using the above-mentioned chelating agents. As described above, according to the present invention, it is possible to easily perform surface treatment on the surface of aluminum alloy castings to make them beautiful and have good corrosion resistance, which has been difficult in the past, and the effect is great.
Claims (1)
〜1.0ｇ、ニトリロ三酢酸、１・２−シクロヘキ
サンジアミン四酢酸及びエチレンジアミン四酢酸
よりなる群から選んだキレート剤を少なくともト
リエタノールアミン濃度の２倍含む水中でアルミ
ニウム合金鋳物を処理することを特徴としたアル
ミニウム合金鋳物の表面処理法。1 Triethanolamine at 0.05 per 100ml of water
treating the aluminum alloy casting in water containing ~1.0 g of a chelating agent selected from the group consisting of nitrilotriacetic acid, 1,2-cyclohexanediaminetetraacetic acid, and ethylenediaminetetraacetic acid at least twice the concentration of triethanolamine. surface treatment method for aluminum alloy castings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14546078A JPS5573878A (en) | 1978-11-25 | 1978-11-25 | Surface-treating method for aluminum alloy casting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14546078A JPS5573878A (en) | 1978-11-25 | 1978-11-25 | Surface-treating method for aluminum alloy casting |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5573878A JPS5573878A (en) | 1980-06-03 |
| JPS6158554B2 true JPS6158554B2 (en) | 1986-12-12 |
Family
ID=15385736
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14546078A Granted JPS5573878A (en) | 1978-11-25 | 1978-11-25 | Surface-treating method for aluminum alloy casting |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5573878A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5785979A (en) * | 1980-09-18 | 1982-05-28 | Biren Chem Saabisesu Ltd | Surface treating method and solution of aluminum |
| JPS58123881A (en) * | 1982-01-18 | 1983-07-23 | フツカ−・ケミカルズ・アンド・プラスチツクス・コ−ポレ−シヨン | Treatment of aluminum surface and composition |
| FR2930023A1 (en) * | 2008-04-09 | 2009-10-16 | Valeo Systemes Thermiques | Surface treatment method for motor vehicle's charge air cooler, involves carrying out hydrothermal treatment on components and brazing points to cover components and points with boehmite film and protect components and points from corrosion |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS538293B2 (en) * | 1973-03-06 | 1978-03-27 |
-
1978
- 1978-11-25 JP JP14546078A patent/JPS5573878A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5573878A (en) | 1980-06-03 |
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