JP3839362B2 - Methods for cleaning and passivating light alloy surfaces - Google Patents
Methods for cleaning and passivating light alloy surfaces Download PDFInfo
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- JP3839362B2 JP3839362B2 JP2002179814A JP2002179814A JP3839362B2 JP 3839362 B2 JP3839362 B2 JP 3839362B2 JP 2002179814 A JP2002179814 A JP 2002179814A JP 2002179814 A JP2002179814 A JP 2002179814A JP 3839362 B2 JP3839362 B2 JP 3839362B2
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- phosphoric acid
- solution containing
- light alloy
- alcohol
- containing phosphoric
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- 238000000034 method Methods 0.000 title claims abstract description 52
- 238000004140 cleaning Methods 0.000 title claims abstract description 31
- 229910001234 light alloy Inorganic materials 0.000 title claims description 31
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 52
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 26
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 24
- 230000008569 process Effects 0.000 claims abstract description 14
- 239000011248 coating agent Substances 0.000 claims abstract description 7
- 238000000576 coating method Methods 0.000 claims abstract description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims description 17
- -1 fluoride ions Chemical class 0.000 claims description 10
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 7
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 239000007800 oxidant agent Substances 0.000 claims description 4
- 238000001465 metallisation Methods 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 2
- 230000003647 oxidation Effects 0.000 abstract description 7
- 238000007254 oxidation reaction Methods 0.000 abstract description 7
- 229910001092 metal group alloy Inorganic materials 0.000 abstract 2
- 229910045601 alloy Inorganic materials 0.000 description 14
- 239000000956 alloy Substances 0.000 description 14
- 238000002161 passivation Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 150000001298 alcohols Chemical class 0.000 description 5
- 239000010408 film Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- MIMUSZHMZBJBPO-UHFFFAOYSA-N 6-methoxy-8-nitroquinoline Chemical compound N1=CC=CC2=CC(OC)=CC([N+]([O-])=O)=C21 MIMUSZHMZBJBPO-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000007739 conversion coating Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 2
- 229920000548 poly(silane) polymer Polymers 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 101001108245 Cavia porcellus Neuronal pentraxin-2 Proteins 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000004512 die casting Methods 0.000 description 1
- 150000002009 diols Chemical class 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000006082 mold release agent Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- DAFQZPUISLXFBF-UHFFFAOYSA-N tetraoxathiolane 5,5-dioxide Chemical compound O=S1(=O)OOOO1 DAFQZPUISLXFBF-UHFFFAOYSA-N 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
- C25F1/02—Pickling; Descaling
- C25F1/04—Pickling; Descaling in solution
Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、軽合金表面を処理する方法に関する。この処理の目標は清浄化と、清浄化した表面をある程度保護することである。本発明が対象とする軽合金は、主としてＡｌ及び／又はＭｇを含有している。
【０００２】
【従来の技術】
軽合金表面を清浄化するための多数の方法が知られている。これら公知の方法の一部は、比較的多数の相連続する処理工程、したがって比較的大きいコストが必要な点が短所である。他方、公知の方法は特定の物質については清浄化効果が不十分であり、たとえばポリシランなどの離型剤残滓を真に確実に除去されない。
【０００３】
さらに、清浄化プロセスの後、軽合金表面を酸化処理によって不動態化し、それによってある程度保護できることが知られている。ここでは酸化の概念は、化学の一般的な意味で理解されるべきであり、Ａｌの割合が高い合金の場合に考慮される酸素との反応のほかに、Ｍｇの割合が比較的高い合金におけるフッ化物イオンとの反応も包含している。
【０００４】
公知の清浄化法及び不動態化法の一部は、健康にとって問題のある物質、たとえば硝気を放出する硝酸を包含している点が短所である。さらに、不動態化の前に清浄化された表面の品質が不動態化の前に劣化しないような仕方で、不動態化工程を清浄化工程と組み合わせることは従来困難であった。
【０００５】
【発明が解決しようとする課題】
総じて本発明の技術的課題は清浄化性質の点でも、合金組成に対する不感性の点でも、さらにまた経済的な観点でも効率的な、軽合金表面の清浄化及び不動態化の方法を提供することである。
【０００６】
【課題を解決するための手段】
本発明は、表面を酸化工程で不動態化することによって軽合金表面を清浄化及び不動態化する方法であって、リン酸及びアルコールを含有した溶液中で表面を陽極に接続した処理工程を特徴とする方法を対象とする。
【０００７】
本発明による方法の有利な構成が、従属請求項に記載されている。
本発明による陽極清浄化法により、非常に強力で、同時に広範な清浄化効果が達成されることが明らかとなった。リン酸及びアルコールを含有した溶液中の陽極清浄化工程は、表面の脱脂の点でもエッチングの点でも効率が良く、その上、ポリシラン系離型剤など問題のある残滓も除去することができる。
【発明の実施の形態】
【０００８】
本発明による清浄化法は、陽極運転の結果として、軽合金表面の陽極酸素反応により過大な材料損耗が防止されることにより、一定の抑制効果を有している。このことはＡｌ含量が比較的高い軽合金にも、Ｍｇ含量が比較的高い軽合金にも該当する。
【０００９】
詳しくは、清浄化作用、特にエッチング作用は陽極清浄化運転の電気的パラメータの選択によって、特に検討の対象となる合金に応じて最適に調整される。たとえば特定の陽極電流密度によって作業できる。これにより、溶液の組成を変えない最適化パラメータが得られる。また１つの溶液でも種々の合金を用いて最適に作業できる。もちろん溶液の組成も合金に応じて最適化できるが、発明者はこれについて臨界的な対応関係は確認できなかった。
【００１０】
アルコールとしては、メタノール、エタノール、プロパノール、ブタノールなど通常のアルコール、及びより高価なアルコール、ならびにそれらの誘導体、たとえばイソプロパノールが考慮される。ジオール、ポリエーテル、及びその他のアルコールも可能である。特に好都合なのはブタノールとイソプロパノールである。もちろん２種類以上のアルコールを混合してもよい。
【００１１】
本発明による別の構成では、表面の不動態化を達成するためにフッ化物イオンを使用する。フッ化物イオンは、そのほかにリン酸を含んだ溶液に投入されるが、この処理工程でも表面は陽極に接続されている。この処理工程はその他の点では、リン酸とアルコールを含む溶液中で実施される上述の処理工程と組み合わせることができ、その場合に溶液はリン酸とアルコールのほかに、フッ化物イオンを含有する。しかしこれらの工程は切り離すこともでき、その場合はフッ化物イオンを含有した溶液を用いた工程が、最初に述べた工程よりも時間的に後に行われる。この時間的に後の工程では、溶液は清浄化性質を最適化するために、リン酸とフッ化物イオンのほかに、なんらかのアルコール（もしくはなんらかのアルコール混合物）を含むことができる。
【００１２】
フッ化物イオンは極めて多様な形式において、たとえばフッ化アルカリ、重フッ化アンモニウム又はフッ化水素酸として存在できる。フッ化物イオン溶液を用いた処理は、特に主としてＭｇを含有する軽合金に適しており、これらの軽合金においてＭｇＦ２が不動態化薄膜として、あるいは不動態化薄膜内に生じる。軽合金がＭｇ成分を５０重量パーセント以上有する場合は、フッ化物イオンを用いた工程が特に好都合である。
【００１３】
さらに、フッ化物イオン工程はＳｉ成分を含有する軽合金に適しており、Ｓｌ成分が０．１重量パーセント、特に０．５又は１又は２重量パーセント以上であると好都合である。Ｓｉ濃度が低い場合は低濃度のフッ化物イオンを選択する。つまり、フッ化物イオン工程は、Ｍｇ成分が少ないか、又は微量しか存在しない軽合金においても有利であり得る。
【００１４】
本発明による清浄化法及び不動態化法は、好ましくはアルカリ洗浄工程で、たとえばｐＨが好ましくは１０以上のアルカリ水において完了できる。アルカリ洗浄工程は、いずれもｐＨが上述のように高いケースで、特に不動態化表面においてＭｇＦ2が主体の場合は好都合であり、Ａｌ2Ｏ3が主体の場合はそれほど有利ではない。
【００１５】
Ａｌの割合が高い場合、特に６０重量パーセント以上の場合は、リン酸とアルコールを含有する溶液中の処理工程、場合によってはフッ化物を含有する処理工程、また場合によっては別の処理工程（本発明では優先されない）の最後に、水性酸化剤中で追加的な不動態化工程を行うことができる。この酸化剤は、たとえば過硫酸塩溶液又はペルオキソモノ硫酸（カロー酸）であってよい。酸化剤中の不動態化工程は、フッ化物溶液中の処理工程を行う場合にはその後で行う。
【００１６】
酸化物で被覆した、Ｍｇ成分比の高い軽合金の表面には酸化工程は必要ない。この工程を過度に酸性の領域（およそｐＨ６以下）で実施すると、フッ化物不動態化も損傷することがある。
【００１７】
以下の定量的領域が有利であることが分かった。当該全溶液中のフッ化物イオンの割合が、下限として０．１、０．３又は０．５重量パーセントと、上限として３０、２０又は１０重量パーセントとの間の値を取ることができる。
【００１８】
陽極に分極した軽合金表面の陽極電流密度は、有利には下限として１０、３０又は５０Ａ／ｍ2と、上限として５００Ａ／ｍ2との間に位置することができ、上述したように、軽合金組成、代表的な材料損耗及び必要な清浄化効果に応じた最適化パラメータとして使用される。
【００１９】
陽極清浄化工程の溶液に対する有利な温度は、１０〜４０℃である。
陽極清浄化工程の全処理時間（数工程の合計）は、たとえば１０秒〜５分であり、調整された電流密度、代表的な材料損耗及び汚染度に強く左右される。
陽極清浄化工程のための溶液に含まれるリン酸の割合は３０〜９０容積パーセントであり、この容積比の範囲内でリン酸は５０〜９５重量パーセントであることができる。これは特にアルコールを含有した溶液を基準としており、この溶液は、好ましくは上記のリン酸３０〜９０容積パーセント以外に、主としてアルコール（混合物）と場合によってはフッ化物からなる。
【００２０】
本発明による方法の清浄化効果は非常に強力で、広範に渡るため、リン酸とアルコールを含有した溶液中に投入する前に化学的前処理工程を省略でき、また経済的な理由からも省略するのが有利であろう。すなわち、処理すべき表面は直接、乾燥した状態で投入できる。
【００２１】
さらに本発明の特別の利点は、再生された軽合金によっても良好な結果を達成できること、特にスラッジが発生しないことである。慣用的な方法では再生材料の金属不純物は、清浄化における著しい問題を招き、しばしば清浄化とその後の良好な被覆を完全に阻害した。Ａｌ含有量が多い場合も、本発明による陽極浴中で表面は金属的な光沢を保ち、上述した後続の酸化は硝酸なしで行うこともできる。
【００２２】
本発明の好適な応用は、後続の任意の種類の被覆のために軽合金表面を準備することである。被覆の品質にとって表面が清浄であることは、見た目でも被覆の耐久性の点でも非常に重要である。特に本発明は外部電流を用いずに行われる、後続の金属化に関する。その限りで本発明は、上記の清浄化と不動態化、及び後続の被覆、特に金属化からなる方法全体を対象とする。
【００２３】
以下に、本発明の２つの実施例について説明するが、ここに開示される特徴は単独でも、他の特徴との組み合わせにおいても本発明にとって本質的である。
Ｍｇ含量が比較的高い合金の典型的な例としてＡＺ９１を選択するが、ＡＭ５０又はＡＺ３１も考慮されよう。ＡＺ９１合金は他の化学的清浄化を施すことなく、乾燥した状態で、リン酸（Ｈ3ＰＯ4）６０容積パーセントとブタノール４０容積パーセントからなる浴に投入し、陽極に分極できる。電流密度は、たとえば室温２５℃で２０Ａ／ｍ2であり、処理時間は約３０秒であってよい
【００２４】
次いで、ＡＺ９１合金を、上記の組成と同じ組成を有し、そのほかに重フッ化アンモニウム２重量パーセントを含有した第２の浴に入れる。さらに２０秒間、同じ電流密度でもう１度陽極清浄化が行われる。
【００２５】
その後、ＡＺ９１分をアルカリ水（ｐＨは１０をやや上回る）中で洗浄する。ＡＺ９１表面はフッ化物薄膜によってのみ不動態化されて、慣用的な方法で金属化できる。この実施例では、Ｚｎ、ＮｉもしくはＣｕあるいはこれらの元素からなる合金による化学的な化成被覆を選択する。
【００２６】
第２の実施例は、Ａｌ含量が多い合金、つまり工業アルミニウム、すなわちＧｄＡｌＳｉ８Ｃｕ３を対象とする。この合金はＳｉを含んでいるので、第１の実施例で述べたフッ化物浴をここでも使用する。同じ定量的パラメーターを選択できるが、アルカリ水中の洗浄工程は省かれる。その代わり中性水（およそｐＨ７）で洗浄し、その後過硫酸塩溶液で追加的に酸化して、不動態化薄膜を強化する。この処理は、たとえばＧｄＡｌＳｉ９Ｃｕ３に対しても該当する。
【００２７】
このように処理した部片を再び化学的に亜鉛めっき、ニッケルめっき、銅めっきし、又はこれらからなる合金で被覆できる。化学的な化成被覆において、不動態化薄膜を溶解もしくは化成すると、金属の間に良好な直接的接触が生じる。
【００２８】
特別の利点は、金属光沢のある表面が存在するため、Ａｌ合金の最終的な酸化は硝酸なしに行われ得ることである。これにより慣用的な方法におけるように硝気は発生せず、したがって一方では吸引及び排ガス浄化のための技術的コストはなくなり、他方では関連規則（ドイツ騒音防止法）に従う許可義務はない。
【００２９】
軽合金がたとえばダイカスト法で作られた場合は、離型剤によって汚染されているのが普通である。これらの離型剤も、上述した清浄化法により確実に、かつ完全に除去できる。
【発明の効果】
以上詳述したように、この発明によると清浄性及び経済性に優れるという効果を奏する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of treating a light alloy surface. The goal of this treatment is to clean and to some extent protect the cleaned surface. The light alloy targeted by the present invention mainly contains Al and / or Mg.
[0002]
[Prior art]
A number of methods are known for cleaning light alloy surfaces. Some of these known methods are disadvantageous in that they require a relatively large number of consecutive processing steps and thus a relatively high cost. On the other hand, the known methods have insufficient cleaning effect for certain substances, and the release agent residue such as polysilane cannot be removed with certainty.
[0003]
Furthermore, it is known that after the cleaning process the light alloy surface can be passivated by oxidation treatment and thereby protected to some extent. Here the concept of oxidation should be understood in the general sense of chemistry, in addition to the reaction with oxygen, which is considered in the case of alloys with a high Al proportion, in alloys with a relatively high proportion of Mg. Reaction with fluoride ions is also included.
[0004]
Some of the known cleaning and passivation methods are disadvantageous in that they include substances that are problematic for health, such as nitric acid, which releases nitrogen. Furthermore, it has been difficult in the past to combine the passivation process with the cleaning process in such a way that the quality of the surface cleaned before the passivation does not deteriorate before the passivation.
[0005]
[Problems to be solved by the invention]
In general, the technical problem of the present invention is to provide a method for cleaning and passivating light alloy surfaces that is efficient in terms of cleaning properties, insensitivity to the alloy composition, and also from an economic standpoint. That is.
[0006]
[Means for Solving the Problems]
The present invention is a method for cleaning and passivating the surface of a light alloy by passivating the surface in an oxidation step, comprising the step of connecting the surface to an anode in a solution containing phosphoric acid and alcohol. Intended for featured methods.
[0007]
Advantageous configurations of the method according to the invention are described in the dependent claims.
It has been found that the anodic cleaning method according to the invention is very powerful and at the same time achieves a wide range of cleaning effects. The anodic cleaning step in a solution containing phosphoric acid and alcohol is efficient both in terms of degreasing the surface and in etching, and in addition, problematic residues such as polysilane release agents can be removed.
DETAILED DESCRIPTION OF THE INVENTION
[0008]
The cleaning method according to the present invention has a certain suppression effect by preventing excessive material wear due to anodic oxygen reaction on the surface of the light alloy as a result of anode operation. This applies to both light alloys having a relatively high Al content and light alloys having a relatively high Mg content.
[0009]
Specifically, the cleaning action, particularly the etching action, is optimally adjusted by the selection of the electrical parameters for the anode cleaning operation, in particular according to the alloy to be studied. For example, it can work with a specific anode current density. This provides optimization parameters that do not change the composition of the solution. In addition, even one solution can be optimally operated using various alloys. Of course, the composition of the solution can also be optimized according to the alloy, but the inventor has not been able to confirm a critical correspondence for this.
[0010]
As alcohols, ordinary alcohols such as methanol, ethanol, propanol, butanol, and more expensive alcohols, and derivatives thereof such as isopropanol are considered. Diols, polyethers, and other alcohols are possible. Particularly advantageous are butanol and isopropanol. Of course, two or more kinds of alcohols may be mixed.
[0011]
In another configuration according to the invention, fluoride ions are used to achieve surface passivation. Fluoride ions are also added to a solution containing phosphoric acid, but the surface is also connected to the anode in this treatment step. This process step can be combined with the above-described process step that is otherwise performed in a solution containing phosphoric acid and alcohol, in which case the solution contains fluoride ions in addition to phosphoric acid and alcohol. . However, these steps can also be separated, in which case the step using a solution containing fluoride ions is performed after the first step. In this later step in time, the solution can contain some alcohol (or some alcohol mixture) in addition to phosphoric acid and fluoride ions to optimize the cleaning properties.
[0012]
Fluoride ions can exist in a wide variety of forms, for example as alkali fluoride, ammonium bifluoride or hydrofluoric acid. The treatment using the fluoride ion solution is particularly suitable for light alloys mainly containing Mg, and in these light alloys, MgF 2 is generated as a passive film or in a passivated thin film. When the light alloy has an Mg component of 50 weight percent or more, a process using fluoride ions is particularly advantageous.
[0013]
Furthermore, the fluoride ion process is suitable for light alloys containing Si components, and it is advantageous if the Sl component is 0.1 weight percent, especially 0.5 or 1 or 2 weight percent or more. When the Si concentration is low, a low concentration fluoride ion is selected. In other words, the fluoride ion process can be advantageous even in light alloys that have a low Mg content or only a trace amount.
[0014]
The cleaning and passivation methods according to the invention can be completed preferably in an alkaline washing step, for example in alkaline water with a pH of preferably 10 or more. All of the alkali cleaning steps are advantageous when the pH is high as described above, particularly when MgF 2 is mainly used on the passivated surface, and not so much when Al 2 O 3 is mainly used.
[0015]
When the proportion of Al is high, in particular 60% by weight or more, a treatment step in a solution containing phosphoric acid and alcohol, a treatment step containing a fluoride in some cases, and a separate treatment step (sometimes present) At the end of the (not preferred in the invention) additional passivating step can be carried out in the aqueous oxidant. This oxidant may be, for example, a persulfate solution or peroxomonosulfuric acid (caroic acid). The passivating step in the oxidant is performed after the treatment step in the fluoride solution.
[0016]
An oxidation step is not necessary on the surface of a light alloy coated with an oxide and having a high Mg component ratio. If this step is performed in an overly acidic region (approximately below pH 6), fluoride passivation may also be damaged.
[0017]
The following quantitative areas have proved advantageous. The proportion of fluoride ions in the total solution can take values between 0.1, 0.3 or 0.5 weight percent as the lower limit and 30, 20 or 10 weight percent as the upper limit.
[0018]
The anode current density of the light alloy surface polarized to the anode can advantageously be located between 10, 30 or 50 A / m 2 as the lower limit and 500 A / m 2 as the upper limit, It is used as an optimization parameter depending on the alloy composition, typical material wear and the required cleaning effect.
[0019]
An advantageous temperature for the solution of the anodic cleaning process is 10-40 ° C.
The total processing time of the anode cleaning process (total of several processes) is, for example, 10 seconds to 5 minutes, and strongly depends on the adjusted current density, typical material wear and contamination.
The proportion of phosphoric acid contained in the solution for the anodic cleaning process is 30 to 90 volume percent, and within this volume ratio the phosphoric acid can be 50 to 95 weight percent. This is in particular based on a solution containing alcohol, which preferably consists mainly of alcohol (mixture) and optionally fluoride, in addition to the above-mentioned 30-90 percent by volume of phosphoric acid.
[0020]
The cleaning effect of the method according to the present invention is very strong and widespread, so that the chemical pretreatment step can be omitted before being put into a solution containing phosphoric acid and alcohol, and also for economic reasons. It would be advantageous to do so. That is, the surface to be treated can be charged directly in a dry state.
[0021]
Furthermore, a particular advantage of the present invention is that good results can be achieved even with recycled light alloys, in particular no sludge is generated. In conventional methods, metal impurities in the recycled material have caused significant problems in cleaning, often completely inhibiting cleaning and subsequent good coverage. Even when the Al content is high, the surface remains metallic in the anode bath according to the invention, and the subsequent oxidation described above can also be carried out without nitric acid.
[0022]
A preferred application of the present invention is to prepare a light alloy surface for any subsequent type of coating. A clean surface for coating quality is very important both in appearance and in durability of the coating. In particular, the present invention relates to subsequent metallization performed without the use of an external current. To that extent, the present invention is directed to the entire process consisting of the cleaning and passivation described above and the subsequent coating, in particular metallization.
[0023]
In the following, two embodiments of the present invention will be described. The features disclosed herein are essential to the present invention either alone or in combination with other features.
AZ91 is selected as a typical example of an alloy with a relatively high Mg content, but AM50 or AZ31 will also be considered. The AZ91 alloy can be put into a bath consisting of 60 volume percent phosphoric acid (H 3 PO 4 ) and 40 volume percent butanol and can be polarized to the anode without any other chemical cleaning. The current density can be, for example, 20 A / m 2 at room temperature 25 ° C. and the treatment time can be about 30 seconds.
The AZ91 alloy is then placed in a second bath having the same composition as above, but additionally containing 2 weight percent ammonium bifluoride. Another 20 seconds of anodic cleaning is performed at the same current density.
[0025]
Thereafter, AZ91 minutes are washed in alkaline water (pH slightly higher than 10). The AZ91 surface is passivated only by fluoride films and can be metallized in a conventional manner. In this embodiment, chemical conversion coating with Zn, Ni or Cu or an alloy made of these elements is selected.
[0026]
The second embodiment is directed to an alloy having a high Al content, that is, industrial aluminum, that is, GdAlSi8Cu3. Since this alloy contains Si, the fluoride bath described in the first embodiment is also used here. The same quantitative parameters can be selected, but the washing step in alkaline water is omitted. Instead, it is washed with neutral water (approximately pH 7) and then additionally oxidized with a persulfate solution to strengthen the passivating film. This process is applicable to GdAlSi9Cu3, for example.
[0027]
The pieces thus treated can again be chemically galvanized, nickel-plated, copper-plated, or coated with an alloy thereof. In a chemical conversion coating, good direct contact between the metals occurs when the passivated film is dissolved or formed.
[0028]
A special advantage is that the final oxidation of the Al alloy can be done without nitric acid because of the presence of a metallic glossy surface. As a result, no vitreous is generated as is the case in conventional methods, so that on the one hand there is no technical cost for suction and exhaust gas purification, and on the other hand there is no licensing obligation in accordance with the relevant regulations (German Noise Prevention Act).
[0029]
When light alloys are made, for example, by die casting, they are usually contaminated with a release agent. These mold release agents can also be reliably and completely removed by the cleaning method described above.
【The invention's effect】
As described above in detail, according to the present invention, there is an effect that it is excellent in cleanliness and economy.
Claims (18)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP01114981A EP1270767B1 (en) | 2001-06-20 | 2001-06-20 | Process for cleaning and passivating light metal alloy surfaces |
| EP01114981.2 | 2001-06-20 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2003049299A JP2003049299A (en) | 2003-02-21 |
| JP3839362B2 true JP3839362B2 (en) | 2006-11-01 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2002179814A Expired - Fee Related JP3839362B2 (en) | 2001-06-20 | 2002-06-20 | Methods for cleaning and passivating light alloy surfaces |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US20030056807A1 (en) |
| EP (1) | EP1270767B1 (en) |
| JP (1) | JP3839362B2 (en) |
| KR (1) | KR100502863B1 (en) |
| CN (1) | CN1316067C (en) |
| AT (1) | ATE256770T1 (en) |
| DE (1) | DE50101194D1 (en) |
| DK (1) | DK1270767T3 (en) |
| SI (1) | SI1270767T1 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7578921B2 (en) * | 2001-10-02 | 2009-08-25 | Henkel Kgaa | Process for anodically coating aluminum and/or titanium with ceramic oxides |
| AU2002338880A1 (en) * | 2002-10-09 | 2004-05-04 | Wolf-Dieter Franz | Method for cleaning and passivating light alloy surfaces |
| WO2005051553A1 (en) * | 2003-11-20 | 2005-06-09 | Bae Systems Plc | Surface preparation prior to coating |
| CN101591799B (en) * | 2008-05-30 | 2011-04-20 | 比亚迪股份有限公司 | Electrolytic polishing solution of magnesium alloy and magnesium alloy surface polishing processing method |
| CN101591797B (en) * | 2008-05-30 | 2012-08-08 | 中芯国际集成电路制造(上海)有限公司 | Al pad electrochemical etching method |
| JP6557984B2 (en) * | 2015-02-06 | 2019-08-14 | 栗田工業株式会社 | Aluminum or aluminum alloy sealing method and sealing device |
| CN105603409B (en) * | 2016-01-15 | 2018-10-09 | 华南理工大学 | A kind of Aluminum Alloy Room Temperature alkalinity chromium-free passivation liquid and passivating method |
| DE102017109739A1 (en) * | 2017-05-05 | 2018-11-08 | Fischer Oberflächentechnik GmbH | Aqueous solution and method for removing acid residues from metal surfaces |
| CN107829122A (en) * | 2017-11-24 | 2018-03-23 | 绩溪山合机械有限公司 | A kind of chain inactivating treatment liquid and its passivation process |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3627654A (en) * | 1969-11-19 | 1971-12-14 | Atomic Energy Commission | Electrolytic process for cleaning high-carbon steels |
| US3920471A (en) * | 1974-10-10 | 1975-11-18 | Teletype Corp | Prevention of aluminum etching during silox photoshaping |
| FR2298619A1 (en) * | 1975-01-22 | 1976-08-20 | Pechiney Aluminium | PROCESS AND SURFACE TREATMENT OF AN ALUMINUM WIRE FOR ELECTRICAL USE |
| JPS60248898A (en) * | 1983-06-30 | 1985-12-09 | Chobe Taguchi | Derusting solution for electrolysis |
| FR2633945B1 (en) * | 1988-07-06 | 1992-09-04 | Pechiney Aluminium | PROCESS OF CONTINUOUS ENAMELLING OF ALUMINUM ALLOY WIRES FOR THE MANUFACTURE OF ELECTRIC WINDINGS |
| US5015298A (en) * | 1989-08-22 | 1991-05-14 | Halliburton Company | Composition and method for removing iron containing deposits from equipment constructed of dissimilar metals |
| US5217586A (en) * | 1992-01-09 | 1993-06-08 | International Business Machines Corporation | Electrochemical tool for uniform metal removal during electropolishing |
| ES2143085T3 (en) * | 1994-12-19 | 2000-05-01 | Alcan Int Ltd | CLEANING OF ALUMINUM PARTS. |
| CN1049259C (en) * | 1994-12-29 | 2000-02-09 | 华中理工大学 | Electrochemical polishing method for aluminum or aluminum alloy welding wire |
| US5601695A (en) * | 1995-06-07 | 1997-02-11 | Atotech U.S.A., Inc. | Etchant for aluminum alloys |
| US6579439B1 (en) * | 2001-01-12 | 2003-06-17 | Southern Industrial Chemicals, Inc. | Electrolytic aluminum polishing processes |
-
2001
- 2001-06-20 SI SI200130069T patent/SI1270767T1/en unknown
- 2001-06-20 DK DK01114981T patent/DK1270767T3/en active
- 2001-06-20 AT AT01114981T patent/ATE256770T1/en active
- 2001-06-20 DE DE50101194T patent/DE50101194D1/en not_active Expired - Lifetime
- 2001-06-20 EP EP01114981A patent/EP1270767B1/en not_active Expired - Lifetime
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2002
- 2002-06-19 KR KR10-2002-0034323A patent/KR100502863B1/en not_active IP Right Cessation
- 2002-06-20 JP JP2002179814A patent/JP3839362B2/en not_active Expired - Fee Related
- 2002-06-20 CN CNB021248060A patent/CN1316067C/en not_active Expired - Fee Related
- 2002-06-20 US US10/176,308 patent/US20030056807A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| CN1397667A (en) | 2003-02-19 |
| EP1270767B1 (en) | 2003-12-17 |
| ATE256770T1 (en) | 2004-01-15 |
| SI1270767T1 (en) | 2004-06-30 |
| US20030056807A1 (en) | 2003-03-27 |
| DK1270767T3 (en) | 2004-04-13 |
| KR100502863B1 (en) | 2005-07-25 |
| DE50101194D1 (en) | 2004-01-29 |
| KR20020097002A (en) | 2002-12-31 |
| JP2003049299A (en) | 2003-02-21 |
| CN1316067C (en) | 2007-05-16 |
| EP1270767A1 (en) | 2003-01-02 |
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