英语听力文摘 English Digest 196、不锈钢的秘密

　　Why Stainless¹ Steel Does Not Rust² But Other Metals Do?
不锈钢（Stainless Steel）指耐空气、蒸汽、水等弱腐蚀介质和酸、碱、盐等化学浸蚀性介质腐蚀的钢，又称不锈耐酸钢。实际应用中，常将耐弱腐蚀介质腐蚀的钢称为不锈钢，而将耐化学介质腐蚀的钢称为耐酸钢。由于两者在化学成分上的差异，前者不一定耐化学介质腐蚀，而后者则一般均具有不锈性。不锈钢的耐蚀性取决于钢中所含的合金元素。
所有金属都和大气中的氧气进行反应，在表面形成氧化膜。不幸的是，在普通碳钢上形成的氧化铁继续进行氧化，使锈蚀不断扩大，最终形成孔洞。可以利用油漆或耐氧化的金属（例如，锌，镍和铬）进行电镀来保护碳钢表面，但是，正如人们所知道的那样，这种保护仅是一种薄膜。如果保护层被破坏，下面的钢便开始锈蚀。
铬是使不锈钢获得耐蚀性的基本元素，当钢中含铬量达到12％左右时，铬与腐蚀介质中的氧作用，在钢表面形成一层很薄的氧化膜（ 自钝化膜），可阻止钢的基体进一步腐蚀。除铬外，常用的合金元素还有镍、钼、钛、铌、铜、氮等，以满足各种用途对不锈钢组织和性能的要求。

　　Our modern world, with its skyscrapers³, suspension bridges, and automobiles⁴, relies heavily on steel. If you own an aging car however, you know firsthand that steel has one annoying problem: it rusts⁵. All steel, that is, except stainless steel. What keeps this remarkable⁶ material, used commonly in kitchen sinks and cookware, from rusting⁷?
Rust-Proof
Steel’s main ingredient is iron. When steel rusts, its iron combines with oxygen and reverts⁸ to iron ore, the raw state from which it came. As this happens, the steel turns brown and begins to crumble⁹.
There are many ways to protect steel from corrosion¹⁰. Steel is sometimes painted or greased, or coated with a metal that is less likely to rust.
Sacrificial Metal
Sometimes a metal that is MORE likely to rust is attached. Known as a sacrificial metal, this works by drawing the corrosion process away from the steel. For example, bars of zinc¹¹ are attached to the hulls¹³ of some ships. The zinc rusts heavily, but the steel hull¹² stays relatively¹⁴ safe.
Stainless Steel Avoids Rust
The best way to avoid rust is to use stainless steel. Like all steel, stainless steel is mostly iron, but it also contains nickel and chromium.
These are not just a protective coating, but are melted into the steel itself. The mixture must contain at least ten percent chromium, because it’s the chromium that protects stainless steel from corrosion.
What Happens?
What happens is this: Like a sacrificial metal, the chromium rusts first. Unlike iron however, rusting chromium doesn’t crumble apart. Instead, it forms an invisibly thin layer that protects the iron underneath¹⁵. The nickel in stainless steel helps hold this protective layer of chromium rust in place.
Remember that chromium and nickel are present throughout stainless steel, not just on the surface. Because of this, the microscopic¹⁶ layer will form itself anew, even when the steel is cut or scratched.

1 stainless   

adj.无瑕疵的，不锈的

参考例句：

• I have a set of stainless knives and forks.我有一套不锈钢刀叉。
• Before the recent political scandal,her reputation had been stainless.在最近的政治丑闻之前，她的名声是无懈可击的。

2 rust   

n.锈；v.生锈；(脑子)衰退

参考例句：

• She scraped the rust off the kitchen knife.她擦掉了菜刀上的锈。
• The rain will rust the iron roof.雨水会使铁皮屋顶生锈。

3 skyscrapers   

n.摩天大楼

参考例句：

• A lot of skyscrapers in Manhattan are rising up to the skies. 曼哈顿有许多摩天大楼耸入云霄。
• On all sides, skyscrapers rose like jagged teeth. 四周耸起的摩天大楼参差不齐。

4 automobiles   

n.汽车( automobile的名词复数 )

参考例句：

• When automobiles become popular,the use of the horse and buggy passed away. 汽车普及后，就不再使用马和马车了。 来自《简明英汉词典》
• Automobiles speed in an endless stream along the boulevard. 宽阔的林荫道上，汽车川流不息。 来自《现代汉英综合大词典》

5 rusts   

n.铁锈( rust的名词复数 )；（植物的）锈病，锈菌v.（使）生锈( rust的第三人称单数 )

参考例句：

• Copper nails are better than iron nails because the iron rusts. 铜钉比铁钉好，因为铁会生锈。 来自辞典例句
• The axenic culture of rusts has been achieved on various defined media. 在各种规定的培养基上可得到锈菌的单体纯净培养物。 来自辞典例句

6 remarkable   

adj.显著的，异常的，非凡的，值得注意的

参考例句：

• She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
• These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。

7 rusting   

n.生锈v.（使）生锈( rust的现在分词 )

参考例句：

• There was an old rusting bolt on the door. 门上有一个生锈的旧门闩。 来自辞典例句
• Zinc can be used to cover other metals to stop them rusting. 锌可用来涂在其他金属表面以防锈。 来自辞典例句

8 reverts   

恢复( revert的第三人称单数 )； 重提； 回到…上； 归还

参考例句：

• The mind reverts to the earliest days of colonial history. 我们回想到早期的殖民地历史。
• Macau reverts to Chinese sovereignty at midnight on December19. 澳门主权于十二月十九日零时回归中国。

9 crumble   

vi.碎裂，崩溃；vt.弄碎，摧毁

参考例句：

• Opposition more or less crumbled away.反对势力差不多都瓦解了。
• Even if the seas go dry and rocks crumble,my will will remain firm.纵然海枯石烂，意志永不动摇。

10 corrosion   

n.腐蚀，侵蚀；渐渐毁坏，渐衰

参考例句：

• Corrosion is not covered by the warranty.腐蚀不在保修范围之内。
• Zinc is used to protect other metals from corrosion.锌被用来保护其他金属不受腐蚀。

11 zinc   

n.锌；vt.在...上镀锌

参考例句：

• Brass is formed by the fusion of copper and zinc.黄铜是通过铜和锌的熔合而成的。
• Zinc is used to protect other metals from corrosion.锌被用来保护其他金属不受腐蚀。

12 hull   

n.船身；(果、实等的)外壳；vt.去(谷物等)壳

参考例句：

• The outer surface of ship's hull is very hard.船体的外表面非常坚硬。
• The boat's hull has been staved in by the tremendous seas.小船壳让巨浪打穿了。

13 hulls   

船体( hull的名词复数 )； 船身； 外壳； 豆荚

参考例句：

• Hulls may be removed by aspiration on screens. 脱下的种皮，可由筛子上的气吸装置吸除。
• When their object is attained they fall off like empty hulls from the kernel. 当他们的目的达到以后，他们便凋谢零落，就象脱却果实的空壳一样。

14 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

15 underneath   

adj.在...下面，在...底下；adv.在下面

参考例句：

• Working underneath the car is always a messy job.在汽车底下工作是件脏活。
• She wore a coat with a dress underneath.她穿着一件大衣，里面套着一条连衣裙。

16 microscopic   

adj.微小的，细微的，极小的，显微的

参考例句：

• It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
• A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。