The document discusses corrosion of metals, which is the gradual decay or damage of metals through chemical or electrical reactions with their environment. It seeks to explain the causes of corrosion, factors that affect it, and methods of controlling and preventing corrosion, including coatings, inhibitors, and selecting appropriate materials. Some key points covered include the definition of corrosion, its economic and environmental impacts, and electrochemical equations describing corrosion reactions.

1. Reaction of building material (CORROSION)
Reaction of building material
(CORROSION)
Directed by HUSSAM FAEZ ALTARAJI
2010337
Superviser by DR.sayib al khouri

2. Reaction of building material (CORROSION)

3. The essential problem is Corrosion of metals because it has big effect at environment
● Corrosion is damage or gradual decay that affects the metal as a result of its chemical or electrical
reaction with the medium in it to move to a more stable state than it was before corrosion.
● The effect are : 1) Material and economic losses.
2) health related to human health that directly affect him
3) the surrounding environment.
● There are not to stop but we can decreased.
● Minerals in nature are found mostly as ores, usually mineral oxides, carbonates or sulfides.

4. Reaction of building material (CORROSION)
The cause of corrosion
1. The metal in it is in the form of a positive ion, and then it is purified and extracted from the
ore by subjecting the ores to processes of heat or electricity reduction, so that the positive
metal ions become neutral atoms and thus this energy is stored in the metal and is in an
excited state that is contrary to its nature on it in nature.
1. It moves from the atomic state that it became in to the ionic state that it was in. Therefore, it
interacts with the surrounding medium to return to the form of oxide or any other compounds
and the corrosion process is completed when metal is given a chance by being in a suitable
medium; Like humidity, gases, or pressure.

5. Reaction of building material (CORROSION)

6. Reaction of building material (CORROSION)
Factors affecting corrosion
1. Properties of the mineral.
2. The presence of a metal or substance as a negative electrode.
3. Electric potential difference.
4. The purity of the metal.
5. His physical condition.
6. Relative areas of negative and positive poles.
7. The relative size of metal atoms and its oxide or other corrosion products.
8. The solubility of the reaction products.

7. Reaction of building material (CORROSION)
Electrochemical reactions of corrosion
● Anodic reaction of a corrosive metal is the oxidation of the metal to an ion in
an environment. This reaction is sometimes described as a metal melting
reaction or an electron removal reaction.
M M +e
● Cathodic reaction : 1) Acidic nature when the pH is less than 5
2) In near-neutral circles pH = 5-9, as well as in circles
Basal, whose pH is greater than 9 Fe Fe2++ 2 e-

8. Reaction of building material (CORROSION)
The recycle life of corrosion

9. Reaction of building material (CORROSION)
The procedure of corrosion

10. Reaction of building material (CORROSION)

11. Reaction of building material (CORROSION)
Corrosion thermodynamics
The change in free energy ∆G associated with the corrosion reaction, in
order to judge the spontaneity of corrosion or not. Therefore, the
corrosion process is automatic and thermodynamically preferred when G
is negative. And if we take the corrosion of iron in the middle of acidic
HCl

12. Reaction of building material (CORROSION)
Equation of corrosion
Cathode:
O2 +4H+ +4e- 2H2O E = 1.23 V
Anode:
Fe Fe+2 + 2e- E = -0.45 V
4Fe+2 + O2 + H2O 2Fe2O3 + H2O + 4H+ E = 1.65 V

13. Reaction of building material (CORROSION)
Corrosion Control
1. The choice of materials (mineral or non-metallic) should depend on their
chemical properties. And the perimeter (the mean) which is used in it not only
at its cost where should Isolate metallic materials from the more cathodic
minerals if the metal is active.
2. moisture, that, saving mineral parts in plastic impenetrable containing On the
active silica.
3. Control of the acidity or basicity of the ocean; the all-metal less corrosion at
pH Certain, for example, tin will erode rapidly when the pH value is higher.
4. In the design of the equipment, the sharp corners or points of association should be
avoided. Barriers and girders that can form spaces stagnant accumulate dirt And
sediments

14. Reaction of building material (CORROSION)

15. Reaction of building material (CORROSION)
Inhibitors
● A chemical substance is added in small quantities to the corrosive medium to
reduce the speed of corrosion of the metal in it through its action on the
surface of the metal or close to it by removing the corrosive substances from
it.

16. Reaction of building material (CORROSION)
There are two type if Inhibitors
1. Organic inhibitors: such as organic colloids; Where absorbent protective
layers are. Organic bases such as amines and pyridine which form positive
ions attach themselves through the nitrogen atom to the cathodic surface.
2. Inorganic inhibitors: such as Na2SiO3, sodium silicate, are added in low
concentrations to saline solutions transported by pipelines to reduce
corrosion and reduce the problem of leaching from the tubes to a large
extent.

17. Reaction of building material (CORROSION)
Inorganic inhibitors
➔ Sodium Benzoate C6H5COONa, which is also used as steel corrosion inhibitor
1.5% sodium benzoate with 0.1% basic sodium nitrate used in antifreeze
solution as well as calcium hydroxide Ca (OH) 2 which can act as a cathodic
inhibitor to cause CaCO3 to precipitate in acid water containing temporary
hardness or dissolved CO2. As the colloidal fines of positively charged
calcium carbonate are attracted to the cathode regions, causing them to be
deposited there, interrupting the corrosion current.

18. Reaction of building material (CORROSION)
Hinte
❖ Basic metal chlorides are particularly harmful to many metals and alloys,
where they work
The chloride ion breaks down the inert protective film on the surface of the
metal, and on the contrary, some anions can be the product of an insoluble
reaction that protects the metal, which means that they act as an inhibitor of
the corrosion process.

19. Reaction of building material (CORROSION)
The coating
● The coating process is used to protect the tools from damage and corrosion
by coating the outer surfaces of them, and it is a chemical film that works to
resist the factors causing damage and corrosion.
● The coating is a chemical product of opaque solutions of fine particles
suspended in a liquid called a carrier. These particles cover the outer surface,
while the carrier liquid provides a protective layer and a connection between
these particles and the surface.

20. Reaction of building material (CORROSION)
Pigment
● The main action of the dye in the paint is to give the distinctive color
of the paint, and the chemical composition of it, its volumetric
distribution, as well as the shape of its minutes and its ratio to the
holder affect the properties of the coating.

21. Reaction of building material (CORROSION)
Properties of pigment
1. the color.
2. Its ability to hide the painted surface.
3. Oil absorption, which is the amount of oil needed to moisturize a
standard weight of the dye, so that it flows or becomes a suspended
liquid.
4. Its chemical behavior.

22. Reaction of building material (CORROSION)
● Color is affected by light absorption and reflection, as the blue pigment
mainly reflects the blue part of the body
The solar spectrum while absorbing green, yellow and red, and the absorption
and reflection of the light beams may not be limited to one color, for example
the Prussian blue dye reflects some green rays and also separates the yellow
chromium, but it absorbs some green and red and all wave blue is that it
reflects yellow to give a dominant shade

23. Reaction of building material (CORROSION)
WHITE dye
● Lead white pigment is basic lead carbonate. They should not be used in
kitchen paints because they contain lead, and there is also zinc sulfide
ZnS that is produced according to the reactions:
Zn+ 2HCl ZnCl2 + H2
ZnCl2 + BaS ZnS + BaCl2
● This dye has good masking ability and is not affected by hydrogen
sulfide.

24. Reaction of building material (CORROSION)

25. Reaction of building material (CORROSION)
Red dye
● And iron oxides are natural and artificially prepared, such as the red lead dye,
which is prepared from heating white lead:
3pb(OH)2+3pbCO3 +O2 2pb3O4 + 3H2 O+3CO2

26. Reaction of building material (CORROSION)

27. Reaction of building material (CORROSION)
Driers
● Auxiliary factors in the drying process, meaning the absorption of
oxygen, and usually, they are mineral or resin soaps. . Vanadium dryers
are two and a half times faster than manganese dryers and five times as
fast as lead compounds. A large amount of desiccant causes paint to
form hard and shiny films.

28. Reaction of building material (CORROSION)

29. Reaction of building material (CORROSION)
The chemical nature of Dehydrating
● Drying oils are fatty, the chemical composition of which is an asterisk, from
the reaction of glycerol with unsaturated carboxylic acids containing one or
more double packets. When oil is exposed to air, oxygen is absorbed and
organic peroxide is formed like :
Linoleic acid : C17H31COOH

30. Reaction of building material (CORROSION)
Linoleic acid : C17H31COOH
● Structural formula :CH3-(CH2)4-CH=CH-CH2-CH=CH-(CH2)7-COOH
● When exposed to air, it forms an organic peroxide
● :CH3-(CH2)4-CH-CH-CH2-CH-CH-(CH2)7-COOH
O – O O - O
● Organic peroxide oxide as a catalyst to accelerate drying or to form a firm and solid layer of
paint, and the porosity of the film depends on the nature and concentration of the drying oil,
and the films of Tang oil are less permeable than that of flaxseed oil.