KINDS OF METAL CORROSION PERTEMUAN 10

1. KINDS OF METAL CORROSION PERTEMUAN 10 Matakuliah : S0372 – Kimia Teknik Sipil Tahun : Ganjil 2007/2008

2. KINDS OF METAL CORROSION Corrosion in water Atmosphere Corrosion Corrosion in Limited place.

3. CORROSION IN WATER • Corrosion by Freshwater. • Korosi by clean water. At metal which not glorify will be formed by the following reaction: L + 2H2O  L(OH)2 + H2 • Corrosion by clean water andO2 Hence reaction of above will mount to higher level valence because earning oxidation on the. 2L + 3H2O + 3/2 O2  2L(OH)3 This reaction take place at water near by surface becauseO2 diffusion can into water.. To water which in henceO2 will very minimum more than anything else its silent water, so that only formedL(OH)2. For Example Fe(OH)2

4. Corrotion by Sea Water • Factor influencing incidence of corrosion by water go out to sea to metal: • Dampness of air • Oxygen • sea water pH • Speed of sea current • Existence of difference of metal humanity potency or structure which is not homogeneous • Existence of other sea animal or microbe • Temperature • Dissolve element rate in sea water • Imperfect metal connected • Less precise painting.

5. Place – attacked sea water corrosion. All metal able to have an effect on direct like : which is sink or hit sprayer also when hitting influence of sea atmosfir. • Effect of sea water corrosion. • Go down strength him of materials and goods till can endanger. Flimsy Ship wall and in a moment will leak. • Nature of seeing ugly. • Can generate damage related to. • Required by defrayal of big conservancy.

6. Control of water corrosion go out to sea which during the time often conducted: • With painting of and the like. Paint anti korosi, used by paint marine which generally have the nature of holding up to : reaction of chemistry, weather, dampness, dirts and easy to doing it. Part and parcel of painting is sweeping of surface to all kinds of rust pickings dirt, scale mill, sea dirts, oil, dirt and others.

7. Other ways besides paint • Metallic Coating Arranging in layers with protector of other metal, both for more august from is metal of base and also less august. • By using two nearby metal in galvanic line of him, so that not happened galvanic corrosion. • Labouring equivalent surface possible. Link of two metal which not stick correctness often represent beginning dot of corrosion also result of connected, what not flatten.

8. ATMOSPHERE CORROSION Seen from facet of aggresive corrosion, hence atmosphere earn us to the: • Mountain atmosphere or hinterland. • Atmosphere go out to sea and coastal edge (marine) • Industrial area and urban • Industrial area in coastal periphery. Mountain atmosphere which there no cauldron of mount have fire to hence only containing aqueous vapour, O2, and CO2, which is have cauldron usually contain H2S very corrosive and poisonous at metal.

9. Atmosfir go out to sea and coastal very aggresive caused by sprinkling of aeolian sea water into the air and pregnant sprinkling of NaCl and very corrosive other salts because will form strong electrolyte. • Industrial Area Atmosfir releasing many gas CO2, SO2, NO2,HCl, Cl2, if there are any water very corrosive at metal.

10. CORROTION IN LIMITED PLACE Because limited place its certain volume, in fact environment can be arranged so that is not aggresive, its way for example passing draining dismayed etcetera. But on the contrary when not be controlled, room corrosion will generate the problem of which complicated enough. If there are any wet shares, hence when heat, water will condense and when again chilled of dew. The condensation will become the source of continuous korosi. For this event, is needed by good ventilation till if (there are) any which condensing castaway of exit.