- Definition of corrosion
Corrosion is
v redox reaction between a metal with a variety of substances in the environment that produces a compound - a compound that is not desired.
v oxidation reaction of a metal which forms rust with Fe2O3.xH2O formula.
- Factors - factors that support berlangsugnya corrosion:
v Oxygen
v Water
v Acidity
v Contact with other metals
v Lead
v Air Humidity
- Prevention of corrosion:
v Changing iron into stainless steel (stainless steel).
v Painting.
Paint can avoid contact with air and water. Paint containing lead and zinc (zinc) will be better, because they protect the metal against corrosion.
v Pelumuran with oil and grease.
This method is applied to a variety of tools and machinery. Oil and grease to prevent contact with water.
v dressing with plastic.
Plastics can prevent contact with water and air.
v Tin plating (coating with tin)
Cans tyerbuat packaging of iron coated with tin by electrolysis. Tin metal that resists rust classified. However, the tin coating protects the iron during the coating was intact (without paint). If the tin layer is broken, such as scratches, then lead it to encourage or accelerate the corrosion of iron. It happens because the reduction potential is more negative than the tin iron (Fe E0 = -0.44 V, E0sn2 + I sn = - 0.14 V). Therefore, iron coated with tin to form an electrochemical cell with iron as the anode. Thus, pushing tin corrosion of iron. But this is precisely what is expected, so the tin - tin cans quickly destroyed.
v Galvanization (with a zinc coating).
In contrast to tin, zinc can protect iron from corrosion even if the lining is intact. This happens because of a protection mechanism called the cathode. Because iron reduction potential more positive than zinc, iron mak contact with zinc to form an electrochemical cell with iron as the cathode. With that case, unprotected iron and zinc which is oxidized.
v Cromium Plating (with a chromium coating).
Iron or steel can also be coated with chromium to a glossy protective coating member, for example for automobile bumpers. Cromium Plating is also done by electrolysis. Just like zinc, chromium can be member protection and chromium layer was damaged.
v Sacrificial Protection (sacrificial anode).
Magnesium is a metal that is much more active (meaning more easily corroded) dariapada iron. If metallic magnesium is contacted with iron, magnesium then it will not rust, but iron. This method is used to protect steel pipes are planted in soil or marine hull. Periodically, magnesium rod must be replaced.
v Modification of the environment
Because oxygen and air moisture is a major factor in the corrosion process, it reduces oxygen levels and lowers the humidity can slow the rusting process. For example, the humidity in the warehouse can be reduced by cooling the warehouse using the AC.
v Modification of Iron
When menbentuk iron alloys with elements - certain elements of iron would be more resistant to corrosion. Steel (alloys of iron) containing 11-12% chromium and low in carbon, so-called stainless steel, stainless steel and is often used in industry, for chemicals, and in the household.
v Cathodic Protection
v If ferrous metal associated with zinc, iron would be difficult to experience corrosion. This is because zinc is more easily oxidized than iron (zinc reduction potential E0zn2 + I zn = - 0.76 V) is more negative than the reduction potential of iron (Fe E0Fe2 + I = - 0.44 V). Zinc will react with oxygen and water in an environment containing carbon dioxide and form zinc carbonate compound. Zinc carbonate formed itself serve to protect zinc from corrosion. How to protect metal like this is called the way Cathodic Protection (cathode protector). In addition to zinc (Zn), metal magnesium (Mg) which includes an alkaline earth is widely used for this purpose.
- Given: metals iron, zinc, aluminum, and chrome
a) Metals are the most rapidly oxidized
v aluminum (Al E0Al3 + I = - 1.66 V)
v Zinc (E0zn2 + I zn = - 0.76 V)
v Chromium (Cr E0Cr3 + I = - 0.74 V)
v Iron (Fe E0Fe2 + I = - 0.44 V)
- Tins is a tin-coated steel, while the roof is zinc coated steel
a) Zinc (E0zn2 + I zn = - 0.76 V)
Tin (E0sn2 + I sn = - 0.14 V)
So the cans are more resistant to rust than the roof, because the roof is less than E0 E0 cans.
b) Canned easier than rusty tin roof because if the layer is broken, such as peeling, then lead it to encourage or accelerate the corrosion of iron. It happens because the reduction potential of iron is more negativ than tin (E0 = -0.44 V Fe, E0sn2 + I sn = - 0.14 V). Therefore, iron coated with tin to form an electrochemical cell with iron as the anode. Thus, pushing tin corrosion of iron.
Corrosion is
v redox reaction between a metal with a variety of substances in the environment that produces a compound - a compound that is not desired.
v oxidation reaction of a metal which forms rust with Fe2O3.xH2O formula.
- Factors - factors that support berlangsugnya corrosion:
v Oxygen
v Water
v Acidity
v Contact with other metals
v Lead
v Air Humidity
- Prevention of corrosion:
v Changing iron into stainless steel (stainless steel).
v Painting.
Paint can avoid contact with air and water. Paint containing lead and zinc (zinc) will be better, because they protect the metal against corrosion.
v Pelumuran with oil and grease.
This method is applied to a variety of tools and machinery. Oil and grease to prevent contact with water.
v dressing with plastic.
Plastics can prevent contact with water and air.
v Tin plating (coating with tin)
Cans tyerbuat packaging of iron coated with tin by electrolysis. Tin metal that resists rust classified. However, the tin coating protects the iron during the coating was intact (without paint). If the tin layer is broken, such as scratches, then lead it to encourage or accelerate the corrosion of iron. It happens because the reduction potential is more negative than the tin iron (Fe E0 = -0.44 V, E0sn2 + I sn = - 0.14 V). Therefore, iron coated with tin to form an electrochemical cell with iron as the anode. Thus, pushing tin corrosion of iron. But this is precisely what is expected, so the tin - tin cans quickly destroyed.
v Galvanization (with a zinc coating).
In contrast to tin, zinc can protect iron from corrosion even if the lining is intact. This happens because of a protection mechanism called the cathode. Because iron reduction potential more positive than zinc, iron mak contact with zinc to form an electrochemical cell with iron as the cathode. With that case, unprotected iron and zinc which is oxidized.
v Cromium Plating (with a chromium coating).
Iron or steel can also be coated with chromium to a glossy protective coating member, for example for automobile bumpers. Cromium Plating is also done by electrolysis. Just like zinc, chromium can be member protection and chromium layer was damaged.
v Sacrificial Protection (sacrificial anode).
Magnesium is a metal that is much more active (meaning more easily corroded) dariapada iron. If metallic magnesium is contacted with iron, magnesium then it will not rust, but iron. This method is used to protect steel pipes are planted in soil or marine hull. Periodically, magnesium rod must be replaced.
v Modification of the environment
Because oxygen and air moisture is a major factor in the corrosion process, it reduces oxygen levels and lowers the humidity can slow the rusting process. For example, the humidity in the warehouse can be reduced by cooling the warehouse using the AC.
v Modification of Iron
When menbentuk iron alloys with elements - certain elements of iron would be more resistant to corrosion. Steel (alloys of iron) containing 11-12% chromium and low in carbon, so-called stainless steel, stainless steel and is often used in industry, for chemicals, and in the household.
v Cathodic Protection
v If ferrous metal associated with zinc, iron would be difficult to experience corrosion. This is because zinc is more easily oxidized than iron (zinc reduction potential E0zn2 + I zn = - 0.76 V) is more negative than the reduction potential of iron (Fe E0Fe2 + I = - 0.44 V). Zinc will react with oxygen and water in an environment containing carbon dioxide and form zinc carbonate compound. Zinc carbonate formed itself serve to protect zinc from corrosion. How to protect metal like this is called the way Cathodic Protection (cathode protector). In addition to zinc (Zn), metal magnesium (Mg) which includes an alkaline earth is widely used for this purpose.
- Given: metals iron, zinc, aluminum, and chrome
a) Metals are the most rapidly oxidized
v aluminum (Al E0Al3 + I = - 1.66 V)
v Zinc (E0zn2 + I zn = - 0.76 V)
v Chromium (Cr E0Cr3 + I = - 0.74 V)
v Iron (Fe E0Fe2 + I = - 0.44 V)
- Tins is a tin-coated steel, while the roof is zinc coated steel
a) Zinc (E0zn2 + I zn = - 0.76 V)
Tin (E0sn2 + I sn = - 0.14 V)
So the cans are more resistant to rust than the roof, because the roof is less than E0 E0 cans.
b) Canned easier than rusty tin roof because if the layer is broken, such as peeling, then lead it to encourage or accelerate the corrosion of iron. It happens because the reduction potential of iron is more negativ than tin (E0 = -0.44 V Fe, E0sn2 + I sn = - 0.14 V). Therefore, iron coated with tin to form an electrochemical cell with iron as the anode. Thus, pushing tin corrosion of iron.
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