JPS634053A - Method for forming patina film on surface of copper product or the like - Google Patents
Method for forming patina film on surface of copper product or the likeInfo
- Publication number
- JPS634053A JPS634053A JP14729186A JP14729186A JPS634053A JP S634053 A JPS634053 A JP S634053A JP 14729186 A JP14729186 A JP 14729186A JP 14729186 A JP14729186 A JP 14729186A JP S634053 A JPS634053 A JP S634053A
- Authority
- JP
- Japan
- Prior art keywords
- copper
- patina
- film
- product
- concn
- 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.)
- Granted
Links
- 239000010949 copper Substances 0.000 title claims abstract description 35
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 29
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 27
- 241001311547 Patina Species 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000010408 film Substances 0.000 claims abstract description 11
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 10
- 229910000881 Cu alloy Inorganic materials 0.000 claims abstract description 7
- 239000010409 thin film Substances 0.000 claims abstract description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 20
- 239000001569 carbon dioxide Substances 0.000 claims description 10
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 10
- 229940116318 copper carbonate Drugs 0.000 abstract description 3
- GEZOTWYUIKXWOA-UHFFFAOYSA-L copper;carbonate Chemical compound [Cu+2].[O-]C([O-])=O GEZOTWYUIKXWOA-UHFFFAOYSA-L 0.000 abstract description 3
- 229910000069 nitrogen hydride Inorganic materials 0.000 abstract 2
- 239000008246 gaseous mixture Substances 0.000 abstract 1
- 239000011248 coating agent Substances 0.000 description 9
- 238000000576 coating method Methods 0.000 description 9
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 3
- PRYBYZBYRVRKQY-UHFFFAOYSA-L C([O-])([O-])=O.[Cu+2].[Cu]=O Chemical compound C([O-])([O-])=O.[Cu+2].[Cu]=O PRYBYZBYRVRKQY-UHFFFAOYSA-L 0.000 description 3
- 239000001099 ammonium carbonate Substances 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 235000012501 ammonium carbonate Nutrition 0.000 description 2
- 239000000908 ammonium hydroxide Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 description 1
- 239000005749 Copper compound Substances 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 235000014676 Phragmites communis Nutrition 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- OVFCVRIJCCDFNQ-UHFFFAOYSA-N carbonic acid;copper Chemical compound [Cu].OC(O)=O OVFCVRIJCCDFNQ-UHFFFAOYSA-N 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- 150000001880 copper compounds Chemical class 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
- 229910000009 copper(II) carbonate Inorganic materials 0.000 description 1
- NWFNSTOSIVLCJA-UHFFFAOYSA-L copper;diacetate;hydrate Chemical compound O.[Cu+2].CC([O-])=O.CC([O-])=O NWFNSTOSIVLCJA-UHFFFAOYSA-L 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000011646 cupric carbonate Substances 0.000 description 1
- 235000019854 cupric carbonate Nutrition 0.000 description 1
- 238000005034 decoration Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Landscapes
- Chemical Treatment Of Metals (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は銅又は銅合金の表面、及び銅メッキ面に緑青被
膜を形成する方法に関し、特に被処理面をアンモニア、
水蒸気、及び二酸化炭素の雰囲気中に浸漬することを特
徴とするものである。Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for forming a patina coating on the surface of copper or copper alloy, and on a copper-plated surface.
It is characterized by being immersed in an atmosphere of water vapor and carbon dioxide.
（従来の技術） ゛
神社、仏閣、住宅等の建築物の屋根やエフステリヤ或い
は美術装飾品の多くは銅又は銅合金を用いて形成され、
若しくは表面に銅メッキが施されている。 これは銅が
耐候性にすぐれていて腐蝕されにくく、長期間の使用に
耐えることもあるが、殊に銅は表面に緑青が生じ、これ
が銅製品に重厚で落付いた感じを与えるため、この点が
建築物の屋根材や美術品として好まれているのである。(Prior art) Most of the roofs, efsteria, and artistic decorations of buildings such as shrines, temples, and residences are formed using copper or copper alloys.
Or the surface is copper plated. This is because copper has excellent weather resistance and is resistant to corrosion, and can withstand long-term use, but copper in particular develops a patina on its surface, which gives copper products a solid and solid feel. The dots are popular as roofing materials for buildings and works of art.
ところで緑青は銅製品を大気中に曝しておくことによっ
て自然に発生するが、その成長速度は極めて遅くて所望
の被膜が形成されるまでには数年若しくはそれ以上の長
時間を要するのである。 この様なことから、従来は銅
製品に硫酸、硝酸、或いは塩酸等の無機酸を滌ぎかけて
その表面を一時的に侵蝕したのち、炭酸ナトリウムその
他でこれを処理することによって緑青を人工的に発生さ
せる方法が試みられた。 しかしながらこの方法では緑
青被膜が極めて薄くて色ムラが生じるうえ生産性が低く
、しかも大規模な廃水設備を要する等の欠点があった。By the way, patina occurs naturally when copper products are exposed to the atmosphere, but its growth rate is extremely slow and it takes several years or more for the desired coating to form. For this reason, in the past, copper products were doused with inorganic acids such as sulfuric acid, nitric acid, or hydrochloric acid to temporarily erode the surface, and then treated with sodium carbonate or other substances to artificially remove the patina. Attempts have been made to generate this phenomenon. However, this method has drawbacks such as extremely thin verdigris coating, resulting in color unevenness, low productivity, and the need for large-scale wastewater facilities.
この様な欠点を除去する方策として従来は緑青に替えて
塩基性炭酸銅、硫化鋼、酸化銅等の銅の化合物を顔料と
した塗料を銅製品の表面に塗布する方法も試みられた。As a measure to eliminate such defects, attempts have been made in the past to apply paints containing copper compounds such as basic copper carbonate, steel sulfide, and copper oxide as pigments to the surface of copper products instead of patina.
しかしながらこの方法は、上記した表面処理方法に較
べれば生産性は格段に高いが、反面、耐候性が非常に低
くて、例えばこれを＃！葦き屋根等に使用すると、−年
も経過しないうちに塗装が剥がれてしまい、外観が著し
く醜くなる欠点があった。However, although this method has much higher productivity than the surface treatment methods described above, on the other hand, it has very low weather resistance. When used on reed roofs, etc., the paint peels off within a year, resulting in an extremely ugly appearance.
（発明の目的）
本発明は銅又は銅合金の表面に自然に発生する緑青と同
じく、耐候性が高く、密着性の強い緑青被膜を短時間で
所望の厚さに形成することを目的とする。(Objective of the Invention) The purpose of the present invention is to form a patina coating with high weather resistance and strong adhesion to a desired thickness in a short time, similar to the patina that naturally occurs on the surface of copper or copper alloys. .
（問題点を解決するための手段）
本発明は銅製品、銅合金製品及び、銅メッキを施した金
属製品の被処理面をアンモニア、水蒸気、及び二酸化炭
素の雰囲気中に浸漬して、被処理面に緑青を生成させる
ものであり、殊に水蒸気の濃度を被処理面に水の薄膜が
形成される程度として、被処理面に水が付着した状態に
おいて、これにアンモニア、二酸化炭素及び酸素を作用
させるものである。 即ち、銅製品等に緑青被膜を形成
させるには、先ず銅製品の表面の不要な部分をマスキン
グし、被処理面を露出させて密閉槽にセットし、この密
閉槽にアンモニア、二酸化炭素及び水蒸気を送り込む。(Means for Solving the Problems) The present invention involves immersing the surfaces to be treated of copper products, copper alloy products, and copper-plated metal products in an atmosphere of ammonia, water vapor, and carbon dioxide. This method produces a patina on the surface, and in particular, the concentration of water vapor is set to such a level that a thin film of water is formed on the surface to be treated, and ammonia, carbon dioxide, and oxygen are added to the surface while water is attached to the surface to be treated. It is something that is made to work. That is, in order to form a patina coating on a copper product, etc., first mask off unnecessary parts of the surface of the copper product, expose the surface to be treated, set it in a closed tank, and add ammonia, carbon dioxide, and water vapor to the closed tank. send in.
すると、アンモニアが空気中の酸素の力を借りて被処
理面の表層部の銅を激しく侵蝕し、これを水酸化鋼アン
モニウムに変える。 次いで、この水酸化銅アンモニウ
ムに二酸化炭素が作用して、これを塩基性炭酸銅（緑青
）の緻密な被膜に変えるのである。 尚、このとき、被
処理面には可成の水が付着していて、緑青被膜が濡れた
状態になっているので、これを８０〜４００℃程度の温
度で除々に加熱乾燥すると緑青被膜の一部が分解して塩
基性酸化銅炭酸銅となり、更にこれを乾燥すると塩基性
酸化銅炭酸銅の一部が酸化銅炭酸銅に変り、同時に被膜
は被処理面との密着度の一層強いものとなるのである。Then, the ammonia, with the help of oxygen in the air, violently erodes the copper in the surface layer of the surface to be treated, turning it into ammonium hydroxide steel. Carbon dioxide then acts on this cupric ammonium hydroxide, turning it into a dense coating of basic copper carbonate (green-blue). At this time, there is a considerable amount of water attached to the surface to be treated, and the patina film is in a wet state, so if this is gradually heated and dried at a temperature of about 80 to 400 degrees Celsius, the patina film will be removed. Part of it decomposes into basic copper oxide copper carbonate, and when this is further dried, part of the basic copper oxide copper carbonate changes to copper oxide copper carbonate, and at the same time, the coating has even stronger adhesion to the surface to be treated. It becomes.
上記した反応を化学反応式で示すと、次のようになる。The above reaction can be expressed as a chemical reaction formula as follows.
ＺＣｕ＋８ＮＨ，＋０２＋２Ｈ２０→２（Ｃｕ（ＮＨ，
）Ｊ（ＯＨ）ｚ２［Ｃｕ（Ｎ）１３）、〕（ＯＨ）、
＋ Ｃｏ２−＊ＣｕＣＯ３” Ｃｕ（ＯＨ）ａ ＋８２
０＋８ＮＨ３↑
ＣｕＣ０，−：Ｃｕ（Ｏ）ｌ）、・−ｆ、Ｃｕ０ＥＥＨ
，０
ところで、上記において水蒸気の濃度は被処理面に水の
薄膜が形成される程度以上とし、アンモニア及び二酸化
炭素の濃度は少なくとも３ ＰＰｍ以上とすることが望
ましいのであるが、これらは必ずしも限定されるもので
はない。 緑青被膜の形成速度は、これらのガスの濃度
が高いほど、及び雰囲気温度が高いほど速くなるし、そ
の速度はまたガスを撹拌して被処理面に対する接触条件
を変えることによっても変化するので、これらは、被処
理材料の形状や緑青被膜の厚さ或いは作業方式等に応じ
て適宜法められるのであり、例えばバッチ式の処理方法
ではアンモニアと二酸化炭素の濃度はそれぞれ５〜３０
ＰＰｍ、雰囲気温度は３０〜５０℃とするのが適当であ
る。ZCu+8NH,+02+2H20→2(Cu(NH,
)J(OH)z2[Cu(N)13), ](OH),
+ Co2−*CuCO3” Cu(OH)a +82
0+8NH3↑ CuC0, -: Cu(O)l), -f, Cu0EEH
By the way, in the above, it is desirable that the concentration of water vapor be at least a level that forms a thin film of water on the surface to be treated, and that the concentrations of ammonia and carbon dioxide be at least 3 PPm or higher, but these are not necessarily limited. It's not something you can do. The rate of formation of a patina film increases as the concentration of these gases increases and the ambient temperature increases, and the rate can also be changed by stirring the gas and changing the contact conditions with the surface to be treated. These are determined as appropriate depending on the shape of the material to be treated, the thickness of the patina coating, the working method, etc. For example, in a batch treatment method, the concentrations of ammonia and carbon dioxide are each 5 to 30%.
It is appropriate that PPm and ambient temperature be 30 to 50°C.
以下本発明の実施例を示すが、本発明はこれに限定され
るものではない。Examples of the present invention will be shown below, but the present invention is not limited thereto.
（実施例１）
１５００Ｘ１５００Ｘ１６００ｍｍの密閉槽の上部に厚
さ０５ｍｍの銅板を水平に取付けると共に、槽の底部に
は１４００ｘ１４００ｘ１００ａｍの浅皿状容器を置い
てこれに炭酸アンモニウムの５％水溶液６Ｃ１ｌを容れ
、この水溶液を４０℃に加熱して、炭酸アンモニウムを
分解させると共に水を蒸発させて槽内にアンモニアと二
酸化炭素と水蒸気とを含む雰囲気を現出させ、この状態
を６０分間保ったところ、銅板の表面には緑青の被膜が
形成した。そこでこの銅板を密閉槽から取り出し、直ち
に乾燥機に入れて２００℃の温度で５０秒間加熱し乾燥
した。 その結果、銅板の表面に流水中でブラッシング
しても脱落しない緑青被膜が形成された。(Example 1) A copper plate with a thickness of 05 mm was horizontally attached to the top of a sealed tank measuring 1500 x 1500 x 1600 mm, and a shallow dish-shaped container measuring 1400 x 1400 x 100 mm was placed at the bottom of the tank, and 1 liter of a 5% aqueous solution of ammonium carbonate was placed in it. The aqueous solution was heated to 40°C to decompose the ammonium carbonate and evaporate the water to create an atmosphere containing ammonia, carbon dioxide, and water vapor in the tank. When this state was maintained for 60 minutes, the surface of the copper plate was A green-blue film was formed on the surface. Therefore, this copper plate was taken out from the closed tank, immediately placed in a dryer, and heated at a temperature of 200° C. for 50 seconds to dry it. As a result, a patina film was formed on the surface of the copper plate that did not come off even when brushed under running water.
（実施例２）
浅皿状容器に炭酸水素アンモニウムの５％水溶液６０Ｑ
を容れ、実施例１と同様の条件で銅板を処理した。 そ
の結果、上記したものと同様の緻密で密着力の強い緑青
被膜が得られた。(Example 2) 5% aqueous solution of ammonium hydrogen carbonate 60Q in a shallow dish-shaped container
The copper plate was treated under the same conditions as in Example 1. As a result, a dense patina film with strong adhesion similar to that described above was obtained.
（実施例３）
実施例１と同様の密閉槽の上部に銅板を水平に取付け、
この密閉槽に２０ｐｐｕ＋のアンモニアと２０ｐｐｍの
炭酸ガス及び３０％の水蒸気を含み、１００℃に加熱さ
れた空気を毎秒２Ｑの速度で３０分間送入した。 その
結果、銅板の表面には実施例１と同様の緻密で密着力の
強い緑青被膜が得られた。(Example 3) A copper plate was installed horizontally on the top of the same sealed tank as in Example 1,
Air containing 20 ppu+ ammonia, 20 ppm carbon dioxide, and 30% water vapor and heated to 100° C. was fed into this closed tank at a rate of 2 Q/sec for 30 minutes. As a result, a dense patina coating similar to that of Example 1 with strong adhesion was obtained on the surface of the copper plate.
Claims (1)
ッキを施した製品を、少なくとも３ｐｐｍ以上の濃度の
アンモニア及び二酸化炭素並びに少なくとも銅製品等の
表面に水の薄膜が形成する程度の濃度の水蒸気の雰囲気
中に浸漬することを特徴とする銅製品等の表面に緑青被
膜を形成する方法。Products formed using copper or copper alloys, or products whose surfaces are plated with copper, are exposed to ammonia and carbon dioxide at a concentration of at least 3 ppm or more, and water vapor at a concentration that at least forms a thin film of water on the surface of the copper product, etc. A method for forming a patina film on the surface of a copper product, etc., characterized by immersing it in an atmosphere of
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14729186A JPS634053A (en) | 1986-06-24 | 1986-06-24 | Method for forming patina film on surface of copper product or the like |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14729186A JPS634053A (en) | 1986-06-24 | 1986-06-24 | Method for forming patina film on surface of copper product or the like |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS634053A true JPS634053A (en) | 1988-01-09 |
| JPS6357500B2 JPS6357500B2 (en) | 1988-11-11 |
Family
ID=15426885
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14729186A Granted JPS634053A (en) | 1986-06-24 | 1986-06-24 | Method for forming patina film on surface of copper product or the like |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS634053A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0483568A1 (en) * | 1990-10-27 | 1992-05-06 | KM Europa Metal Aktiengesellschaft | Method of producing brown coating layers on copper |
| US5838099A (en) * | 1996-02-26 | 1998-11-17 | Victor Company Of Japan, Ltd. | Deflection yoke having first coil parts for correction of cross-misconverge and red/blue vertical misconverge |
-
1986
- 1986-06-24 JP JP14729186A patent/JPS634053A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0483568A1 (en) * | 1990-10-27 | 1992-05-06 | KM Europa Metal Aktiengesellschaft | Method of producing brown coating layers on copper |
| US5838099A (en) * | 1996-02-26 | 1998-11-17 | Victor Company Of Japan, Ltd. | Deflection yoke having first coil parts for correction of cross-misconverge and red/blue vertical misconverge |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6357500B2 (en) | 1988-11-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US2499261A (en) | Compositions and methods for depositing amorphous metal-phosphate coatings on metal surfaces | |
| CA1040987A (en) | Process for stripping nickel from articles and composition utilized therein | |
| ES8704141A1 (en) | Improved chemical vapor deposition method of producing fluorine-doped tin oxide coatings. | |
| US3497401A (en) | Patination of copper | |
| CN110408917A (en) | A kind of low cost weathering steel rust plate producing process | |
| US4427499A (en) | Process for surface treatment of stainless steel sheet | |
| JPS634053A (en) | Method for forming patina film on surface of copper product or the like | |
| JP4415449B2 (en) | Method for producing surface-treated steel with excellent weather resistance | |
| CA2188661A1 (en) | Artificial patina | |
| US3752707A (en) | Corrosion resistant composition and method | |
| US1974140A (en) | Production of an adherent patina upon copper or its alloys | |
| Bastidas et al. | Corrosion of bronze by acetic and formic acid vapours, sulphur dioxide and sodium chloride particles | |
| US5714052A (en) | Method for producing brochantite patina on copper | |
| US3669766A (en) | Formation of coating on copper containing materials | |
| US3284249A (en) | Decorative finish for copper | |
| SU1659827A1 (en) | Method of manufacturing silver chloride electrode | |
| JPS6115154B2 (en) | ||
| PT1685273E (en) | Method for covering copper with patina | |
| JP3696139B2 (en) | Cyan blue coloring composition and patina formation method | |
| JPH0348274B2 (en) | ||
| JPH02236286A (en) | Copper product forming patina in early time and production thereof | |
| SU1135804A1 (en) | Aqueous acid solution for chemical nickel plating | |
| US3522109A (en) | Processes for producing decorative and protective coatings on copper metal | |
| JPS6033200B2 (en) | A method of artificially forming a dark green-blue anti-corrosion film on the surface of copper or copper alloys | |
| JPH03236481A (en) | Formation of patina |