METAL CORROSION PERTEMUAN 09 Matakuliah: S0372 – Kimia Teknik Sipil Tahun: Ganjil 2007/2008

Bina Nusantara ANTECEDENT Corrosion come from Latin Ianguage “ Corrodere “ with the meaning mutilation of metal or rust. Corrosion : process degradation / deteorisasi / ruining of material that happened because caused by environmental influence around (air with sunshine, dew, freshwater, sea water, lake water, river water and land; ground which in the form of farmland, bog, land; ground calcify and sand stone).

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CAUSE OF CORROSION : Environmental Influence Natural Process. Operation of corrosion have to start from planning, environmental data collecting, process, equipments weared by raw material and way of conservancy to be executed.

Bina Nusantara Type of Corrosion Corrotion Flatten Example : At plate become militant or profile, its surface of cleanness and its homogeneous metal, if let ordinary on the air some month;moon hence will be formed by corrosion flatten at all its surface. Its operation : 1.Is given to endue pregnant covert of inhibitor. 2.For the wall of boat which is wide of to be given by katodic protection. 3.Is given by metal unite copper 0,4%

Bina Nusantara Korosi in form of Well. Happened because metal composition is not homogeneous and can generate korosi which in at some place. Earn also caused by contact between different metal and metal less august, hence at boundary area arise corrosion in form of well

Bina Nusantara Operation of Korosi in form of well : 1.Choose homogeneous materials. 2.Protect against aggresive element. 3.Give inhibitor.

Bina Nusantara Corrosion Erosion. Metal which have hit erosion effect of happened friction and generate part of harsh and keen. This shares is easy to attacked by corrosion and if happened friction will generate heavier abrasi again and so on. Effort operation: 1.Choose homogeneous materials. 2.Protect against aggresive element. 3.Give inhibitor. 4.Surface attenuated.

Bina Nusantara Erosion corrosion earn also happened because corrosion impingment, that is effect of very rapid fluid and can erod protector film at metal. Effort operation: 1.Avoid too rapid fluid flow. 2.Lessen fluid turn.

Bina Nusantara Galvanik Corrosion When direct contact iron with copper where copper more august, hence iron will have the character of anodik and will sacrifice its self so that will happened heavy corrosion at iron while its copper remain to be intact. Effort Operation: Isolator berry which is thick enough till there no electron stream.

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Tension of Corrosion. When metal have been formed to be to be chilled (to be stretched, to be bended, etcetera) hence although do not broken or is barst, but its metal item metamorphose till arise tension in. Tense Metal item easy to once react with its environment, till in a moment that object will be barst or break by itself. Operation effort: Degrading burden, protect against corrosive compound, giving inhibitor, and is existing of stress have to be stretched.

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Gap Corrosion Happened at metal which nearby other metal or non metal and among others there is gap able to arrest; detain water and dirt which become the source of corrosion. Concentration of O 2 at richer mouth compared to at interior, inner so that more mouth shares and anodik become katodik, hence arising current direction from within to mouth. Effort Operation: 1.Gap isolator. 2.Drying. 3.Cleaning dirt.

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Microbiology Corrosion. Micro-Organisme for its life conduct metabolism directly or indirectly with metal so that final reaction will generate korosi. Or earn also result of its reaction make corrosive environment. Example : Microbe of Reduktor sulphate of anaerobik = Desulfofibrio desulfuricans 8 H 2 O  8H + + SOH + 4 Fe + 8H +  4Fe H H 2 SO 4 + 8H  H 2 S + 4H 2 O Fe ++ + H 2 S  FeS + 2H +

Bina Nusantara Kavitasi Corrosion Happened caused by air bubble and aqueous vapour bubble which brought by current. At the time of that bubble break will result the happening of kavitasi [at] metal. After happened kavitasi happened reaction of with water hence emerging event of korosi, both interconnected is till referred as by kavitasi corrosion. Preventive Effort: 1. Finish Surface which is good to be (Made is slippery) 2. Covert Laminated like type plastic or rubber of epoksi. 3. Minimize hydrodynamic pressure. 4. Degrading fibrasi.