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| Steel Corrosion |
Civillery Zone, Corrosion is the degradation of the events due to metal redox reaction between a metal with a variety of substances in the surrounding environment that produce undesirable compounds. In daily language, often called rust corrosion. Common metal is rusted iron. In the event of corrosion, metal is oxidized while oxygen is reduced. Rust usually oxide or carbonate form, a solid colored brownish red. Corrosion causes very harmful, for example a building with structural steel experience corrosion will reduce the strength of the steel. Here is the cause of corrosion :
Metallurgical factors (metal material itself)
- Metals and alloys
- heat treatment
- The nature capable of fabricating and machining
- Morphology and homogeneity
Environmental Factors
- The chemical composition
- biological conditions
- Gas, liquid or solid
- temperature
- The concentration of the electrolyte and the oxygen content
For its prevention are as follows :
Prevent metal, to avoid direct contact with oxygen or water
- Corrosion event need water or oxygen, if one of them is missing, the event corrosion does not occur. Prevent corrosion can be done by coating the metal with paint, oil or other corrosion resistant metals such as zinc or chromium.
Sacrificial anode (cathode protection)
- Iron coated with a more active metal will form an electrochemical cell with iron as the cathode. Here, the iron only serves as the site of oxygen reduction. Other metal acts as the anode, and undergo oxidation reactions. In this case iron, as the cathode, protected by another metal (the anode, sacrificed). Iron will safely protected during the protective metal is still there / have not been exhausted. For the cathode protection on underground pipeline system commonly used magnesium metal. These metals must be controlled periodically and replaced.
- Such as iron mixed with metals Ni and Cr be stainless steel (72% Fe, 19% Cr, 9% Ni).
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