Metal, heal thyself

　　金屬，自己愈合吧

　　Materials science: Researchers have devised aningenious way for the damaged surfaces of metalsto repair themselves when they come to harm

　　材料科學：研究人員構想出了一種新穎獨特的方法，使得金屬在表面受損時可以自我修復。

　　SADLY for engineers, inanimate objects cannot yetrepair themselves. But work by Claudia dos Santosat the Fraunhofer Institute for ManufacturingEngineering and Automation, and Christian Mayer atDuisburg-Essen University in Stuttgart, has brought the day when they will be able to do so alittle nearer. They and their colleagues have invented a way for damaged metals to healthemselves.

　　對工程師來說悲哀的一面是，沒有生命的物體還無法實現自我修復。但是在德國弗勞恩霍夫制造工程和自動化學會的Claudia dos Santos和斯圖加特杜伊斯堡艾森大學的Christian Mayer的共同研究下，無生命物體實現自我修復那一天的到來被拉近了一點。他們與同事研發出了一種能讓受損金屬自我愈合的方法。

　　The surfaces of many metal objects are coated with other metals for protection. Iron, forinstance, is frequently galvanised with zinc. The basic idea of the new technology is to infiltratethis coating with tiny, fluid-filled capsules. When the metal coating is punctured or scratched,the capsules in the damaged area burst and ooze restorative liquids, in the form of compoundscalled trivalent chromates. These react with nearby metal atoms and form tough, protectivefilms a few molecules thick to ameliorate the damage.

　　許多金屬物體的表面都覆蓋著其他金屬層來保護自己。例如，鐵就通常會鍍上鋅。而這種新技術的基本構想就是在金屬覆蓋層中加入微小并且充滿液體的膠囊。當金屬的覆蓋層受到扎刺或劃損時，受損區域的膠囊將會破裂并滲出具有恢復性的液體---三價鉻鈍化化合物。這些液體將與周圍金屬原子發生反應，形成幾個分子厚、堅固且具有保護性的膜，以修復表面的損害。

　　The idea of doing this has been around for years, but it has proved difficult in practice becausethe capsules used were too big. Surface coatings tend to be about 20 microns thick. The capsules were 10-15 microns acrosslarge enough to disrupt the coatings,and thus do more harm than good. The trick worked out by Dr dos Santos and Dr Mayer is howto create capsules a few hundredths of this size.

　　這種構想已經現世好幾年了，但是由于過去所使用的膠囊太大，在實踐中應用起來難度很大。金屬表面的覆蓋層厚度趨近于20微米，而過去用的膠囊跨度為10到15微米，這種跨度足以打亂覆蓋層的結構，因此對金屬造成的弊大于利。dos Santos 博士和Mayer博士想出來的訣竅就是如何創造跨度僅為過去的百分之幾的膠囊。

　　The capsules the researchers have come up with are made by mixing butylcyanoacrylate, achemical found in superglue, with an oil carrying the healing compounds. This mixture is thenmixed with dilute hydrochloric acid. The result is an emulsion of droplets between 100 and 300nanometres across. Each droplet has an oil core surrounded by a thinlayer of butylcyanoacrylate. To make the droplets stable, phosphate is added to the emulsion.This triggers the polymerisation of the butylcyanoacrylate into a tough plastic, which forms theoutside of the capsule.

　　如今研究人員創造的膠囊是通過把氰基丙烯酸正丁酯和有愈合功效的化合物懸浮其中的油類混合而制的。氰基丙烯酸正丁酯是在超強力膠中發現的一種化學物質。這種混合物再跟稀釋的鹽酸混合，結果會產生一種乳狀液， 其微滴直徑在100到300納米之間。每個微滴都有一顆油核，周圍包裹著一層薄薄的氰基丙烯酸正丁酯。為了穩定這些微滴，研究人員在膠狀液中添加了磷酸鹽，這就促使氰基丙烯酸正丁酯進行聚合反應轉變成一種堅固的塑料。這種塑料就形成了膠囊的外殼。

　　The greatest challenge for the team, however, was not making the capsules in the first place,but stabilising them during the plating process. Though galvanisation is often done by dippingsteel in liquid zinc, it is sometimes done by electrolysisnickel and copper plating are normallydone this way. The capsules, though, tend to stick together in the liquids used as electrolytesduring electroplating, and are also destroyed by the extreme acidity or alkalinity that is ofteninvolved in the process. To overcome these problems, Dr dos Santos and Dr Mayer usedspecial detergents that stick to the polymerised butylcyanoacrylate shell around each capsule,which stops them sticking together and protects them from the electrolytes.

　　然而，對于這組研究人員來說，最大的挑戰并不是開始時膠囊的制造過程，而是在電解過程中如何穩定這些膠囊。盡管一般是通過液態鋅蘸洗鋼鐵來鍍鋅，有時候也會用電解的方法，在電鍍鎳和銅時就通常使用電鍍。在電鍍過程中，不過，膠囊容易在使用的電解質液體中黏在一起，而且也會由于這一過程中通常出現的極酸性和極堿性而受到破壞。為了克服這些問題， dos Santos博士 和Mayer博士使用了一種特殊的去污劑，這種去污劑可以粘附在每個膠囊周圍聚合氰基丙烯酸正丁酯的外殼上，阻止這些膠囊黏在一起，并保護它們免受電解液的破壞。

　　The researchers have now proved their techniques in electroplated layers of copper, nickel andzinc, and believe that self-repairing metals should commonly be available in the years ahead.Moreover, their nanocapsules may have other applications. Lubricants such as silicone oils canbe included in them, to make the damaged surfaces of ball-bearings that have run out of oilmore slippery, so that they are not scratched too rapidly. Anti-fouling compounds can beplaced in capsules on the surfaces of metals intended for use in marine environments. And, ina nod to butylcyanoacrylates origins in superglue, capsules containing chemicals that will reactto form adhesives when two surfaces are put together are also on the horizon.

　　研究人員現在已經在電鍍銅層，鎳層和鋅層上證實了這種技術，同時他們相信在未來的幾年里將會普遍實現金屬的自我修復技術。此外，他們所研發的納米囊也可能應用到其他領域，比如硅系列油等潤滑劑，可以使耗盡了油的滾珠軸承的受損表面更加光滑，避免過快摩擦。還可以在用于海洋環境的金屬表面膠囊中植入防污化合物，以保護環境。而且，由于氰基丙烯酸正丁酯來自超強力膠水，當兩種金屬表面放在一起時，膠囊內含的化學物質能夠反應生成粘合劑，這種新型膠囊的問世也將指日可待。

　　Metal, heal thyself

　　金屬，自己愈合吧

　　Materials science: Researchers have devised aningenious way for the damaged surfaces of metalsto repair themselves when they come to harm

　　材料科學：研究人員構想出了一種新穎獨特的方法，使得金屬在表面受損時可以自我修復。

　　SADLY for engineers, inanimate objects cannot yetrepair themselves. But work by Claudia dos Santosat the Fraunhofer Institute for ManufacturingEngineering and Automation, and Christian Mayer atDuisburg-Essen University in Stuttgart, has brought the day when they will be able to do so alittle nearer. They and their colleagues have invented a way for damaged metals to healthemselves.

　　對工程師來說悲哀的一面是，沒有生命的物體還無法實現自我修復。但是在德國弗勞恩霍夫制造工程和自動化學會的Claudia dos Santos和斯圖加特杜伊斯堡艾森大學的Christian Mayer的共同研究下，無生命物體實現自我修復那一天的到來被拉近了一點。他們與同事研發出了一種能讓受損金屬自我愈合的方法。

　　The surfaces of many metal objects are coated with other metals for protection. Iron, forinstance, is frequently galvanised with zinc. The basic idea of the new technology is to infiltratethis coating with tiny, fluid-filled capsules. When the metal coating is punctured or scratched,the capsules in the damaged area burst and ooze restorative liquids, in the form of compoundscalled trivalent chromates. These react with nearby metal atoms and form tough, protectivefilms a few molecules thick to ameliorate the damage.

　　許多金屬物體的表面都覆蓋著其他金屬層來保護自己。例如，鐵就通常會鍍上鋅。而這種新技術的基本構想就是在金屬覆蓋層中加入微小并且充滿液體的膠囊。當金屬的覆蓋層受到扎刺或劃損時，受損區域的膠囊將會破裂并滲出具有恢復性的液體---三價鉻鈍化化合物。這些液體將與周圍金屬原子發生反應，形成幾個分子厚、堅固且具有保護性的膜，以修復表面的損害。

　　The idea of doing this has been around for years, but it has proved difficult in practice becausethe capsules used were too big. Surface coatings tend to be about 20 microns thick. The capsules were 10-15 microns acrosslarge enough to disrupt the coatings,and thus do more harm than good. The trick worked out by Dr dos Santos and Dr Mayer is howto create capsules a few hundredths of this size.

　　這種構想已經現世好幾年了，但是由于過去所使用的膠囊太大，在實踐中應用起來難度很大。金屬表面的覆蓋層厚度趨近于20微米，而過去用的膠囊跨度為10到15微米，這種跨度足以打亂覆蓋層的結構，因此對金屬造成的弊大于利。dos Santos 博士和Mayer博士想出來的訣竅就是如何創造跨度僅為過去的百分之幾的膠囊。

　　The capsules the researchers have come up with are made by mixing butylcyanoacrylate, achemical found in superglue, with an oil carrying the healing compounds. This mixture is thenmixed with dilute hydrochloric acid. The result is an emulsion of droplets between 100 and 300nanometres across. Each droplet has an oil core surrounded by a thinlayer of butylcyanoacrylate. To make the droplets stable, phosphate is added to the emulsion.This triggers the polymerisation of the butylcyanoacrylate into a tough plastic, which forms theoutside of the capsule.

　　如今研究人員創造的膠囊是通過把氰基丙烯酸正丁酯和有愈合功效的化合物懸浮其中的油類混合而制的。氰基丙烯酸正丁酯是在超強力膠中發現的一種化學物質。這種混合物再跟稀釋的鹽酸混合，結果會產生一種乳狀液， 其微滴直徑在100到300納米之間。每個微滴都有一顆油核，周圍包裹著一層薄薄的氰基丙烯酸正丁酯。為了穩定這些微滴，研究人員在膠狀液中添加了磷酸鹽，這就促使氰基丙烯酸正丁酯進行聚合反應轉變成一種堅固的塑料。這種塑料就形成了膠囊的外殼。

　　The greatest challenge for the team, however, was not making the capsules in the first place,but stabilising them during the plating process. Though galvanisation is often done by dippingsteel in liquid zinc, it is sometimes done by electrolysisnickel and copper plating are normallydone this way. The capsules, though, tend to stick together in the liquids used as electrolytesduring electroplating, and are also destroyed by the extreme acidity or alkalinity that is ofteninvolved in the process. To overcome these problems, Dr dos Santos and Dr Mayer usedspecial detergents that stick to the polymerised butylcyanoacrylate shell around each capsule,which stops them sticking together and protects them from the electrolytes.

　　然而，對于這組研究人員來說，最大的挑戰并不是開始時膠囊的制造過程，而是在電解過程中如何穩定這些膠囊。盡管一般是通過液態鋅蘸洗鋼鐵來鍍鋅，有時候也會用電解的方法，在電鍍鎳和銅時就通常使用電鍍。在電鍍過程中，不過，膠囊容易在使用的電解質液體中黏在一起，而且也會由于這一過程中通常出現的極酸性和極堿性而受到破壞。為了克服這些問題， dos Santos博士 和Mayer博士使用了一種特殊的去污劑，這種去污劑可以粘附在每個膠囊周圍聚合氰基丙烯酸正丁酯的外殼上，阻止這些膠囊黏在一起，并保護它們免受電解液的破壞。

　　The researchers have now proved their techniques in electroplated layers of copper, nickel andzinc, and believe that self-repairing metals should commonly be available in the years ahead.Moreover, their nanocapsules may have other applications. Lubricants such as silicone oils canbe included in them, to make the damaged surfaces of ball-bearings that have run out of oilmore slippery, so that they are not scratched too rapidly. Anti-fouling compounds can beplaced in capsules on the surfaces of metals intended for use in marine environments. And, ina nod to butylcyanoacrylates origins in superglue, capsules containing chemicals that will reactto form adhesives when two surfaces are put together are also on the horizon.

　　研究人員現在已經在電鍍銅層，鎳層和鋅層上證實了這種技術，同時他們相信在未來的幾年里將會普遍實現金屬的自我修復技術。此外，他們所研發的納米囊也可能應用到其他領域，比如硅系列油等潤滑劑，可以使耗盡了油的滾珠軸承的受損表面更加光滑，避免過快摩擦。還可以在用于海洋環境的金屬表面膠囊中植入防污化合物，以保護環境。而且，由于氰基丙烯酸正丁酯來自超強力膠水，當兩種金屬表面放在一起時，膠囊內含的化學物質能夠反應生成粘合劑，這種新型膠囊的問世也將指日可待。