Nowitzki 發問時間: 科學其他:科學 · 1 0 年前

關於生鏽的英文問題 corrosion?? 急急急 20 點

1.What is corrosion?

A: Corrosion is the reaction to make metal became brown colour, and weak.

2.Why is corrosion an important consideration when using metals?

A: Corrosion can make metal became weak and easy to be broken, so we have to keep the metal away from water, or add some coating.

3.There are many different types of corrosion – Find out all you can about at least four different types of corrosion.

A:

4.What is rusting? What are the chemical and environmental conditions that cause rusting to occur?

A: When the water, oxygen, and metal

5.There are many ways in which corrosion can be minimized, avoided or prevented?

Find out about chrome plating, painting, and wrappings (e.g. Tapes) coatings

(e.g. grease, thick oil, tar product etc), galvanizing, anodizing, tin planting, plastic coating/linings, enameling, alloying, catholic protection, sacrificial anodes. Include examples of the application of each of these methods for extending the usefulness or ‘life’ of objects made from metals.

請用英文回答!!對了20點就是你的

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    最佳解答

    What is corrosion?

    Corrosion is defined as the destruction of a metal by a chemical or electrochemical reaction. Corrosion occurs when a metal in contact with water forms a corrosion cell. The corrosion cell has four components, the aqueous phase (water) which acts as an electrolyte (through which ions migrate), an anode on the metal surface (where the metal is oxidized and goes into solution as metal ions), a cathode (where excess electrons are consumed) and a metallic path connecting the cathode to the anode.

    Why does corrosion occur, and how can it be stopped?

    When found in nature, most engineering metals are generally in their oxidized state. During the smelting and refining processes, they are reduced to an inherently unstable metallic state. Metals corrode to return to their natural form, achieving a lower energy state. Alloys, which contain other elements, may increase the metal's stability and make it more corrosion resistant.

    In order to control corrosion, the current loop must be broken by stopping the electron flow using various means. Some ways to control corrosion include electrical means (cathodic protection), the addition of corrosion inhibitor chemicals, and the application of non-metallic barriers (coatings). Sometimes the metal generates its own barrier from corrosion products (e.g. metal oxide); the metal is then in the "passive condition".

    One of the most important methods of corrosion prevention is to find an economic alloy/environment combination where the alloy is in the passive condition and corrodes at a much slower rate. In production wells, a corrosion rate below 1 mpy (mils per year, 1 mil = 1/1000 in) is acceptable, while in water systems, a rate of 2 mpy is a good target.

    2006-06-12 02:12:49 補充:

    Types of corrosionThe main types of corrosion are - Uniform corrosion - Galvanic corrosion - Intergranular corrosion - Dealloying - Crevice and pitting corrosion - Environmentally induced cracking - Hydrogen damage - Erosion corrosion - Stray current corrosion

    2006-06-12 02:14:58 補充:

    What is rusting?

    The corrosion of iron or iron-based alloys such as steel. Other metals may corrode, but only iron and steel rust.

    2006-06-12 02:15:23 補充:

    What are the chemical and environmental conditions that cause rusting to occur?

    Rust is the substance formed when iron compounds corrode in the presence of oxygen and water. It is a mixture of iron oxides and hydroxides. Rusting is a common term for corrosion, and usually corrosion of steel.

    2006-06-12 02:16:38 補充:

    Iron is found naturally in the ore haematite as iron oxide, and metallic iron tends to return to a similar state when exposed to air, (hydrogen, oxygen, nitrogen, etc.) and water.

    2006-06-12 02:17:03 補充:

    This corrosion is due to the oxidation reaction when iron metal returns to an energetically favourable state. Energy is given off when rust forms.

    2006-06-12 02:17:23 補充:

    The process of rusting can be summarized as three basic stages: The formation of iron(II) ions from the metal; the formation of hydroxide ions; and their reaction together, with the addition of oxygen, to create rust.

    2006-06-12 02:17:39 補充:

    Corrosion control methods include:

    Cathodic Protection

    Protective Coatings

    Chemical Inhibitors

    Plastic or cement liners

    Use of special alloys

    Solids removal

    Removal of corrosive gases

    Dehydration

    參考資料: http://octane.nmt.edu/waterquality/ & Yahoo! Answers.
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