Matakuliah : S0372 – Kimia Teknik Sipil
Tahun
: Ganjil 2007/2008
METAL CORROSION
PERTEMUAN 09
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).
Bina Nusantara
Dampness Relative
Rainfall
Temperature
(%)
( mm )
( oC )
Bandung
70 - 80
2050
21,1 - 26,4
Jakarta
59 - 94
1763
23,5 - 31,6
Medan
60 - 93
1900
22,7 - 31,6
Pontianak
64 - 87
3272
23,6 - 31,8
Manado
66 - 87
3427
22,8 - 30,0
Area
Bina Nusantara
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.
Bina Nusantara
Bina Nusantara
• 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.
Bina Nusantara
Bina Nusantara
•
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 O2 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.
Bina Nusantara
Bina Nusantara
• 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 H2O  8H+ + SOH+
4 Fe + 8H+  4Fe++ + 8H
H2SO4 + 8H  H2S + 4H2O
Fe++ + H2S  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.
Bina Nusantara