We have learned about 'Iron' in detail in the previous presentation: 'Materials Part I'. In part II, we will study about other metals like Copper, Aluminum, their advantages etc. We will also learn about other materials like wood, cement, their advantages, disadvantages and uses etc.

1. Copper
Copper is more malleable – it is
softer and can be shaped and bent
more easily.
It is a better conductor of
electricity and therefore used in
electrical wires.
When copper corrodes, the rust
creates a waterproof barrier and
therefore used as a roofing
material.
Copper is very easy to recycle, The
copper you see around has not been
manufactured, but is reused.
India is one of the most significant
suppliers of copper.

2. Aluminium
Most common element on
earth
Takes huge amounts of
Energy energy to extract
Once extracted, very easy
to recycle
Is used in manufacturing of
large parts of cars,
aeroplanes
Used in alloys to create
strong but light
structures
Non-corrosive
Is used in construction
field
Shorter lifespan
Comparatively expensive

3. What is Corrosion?
 Degradation of metals’ properties due to the interaction with air
and water, is called Corrosion.
 Atoms on the surface of the metal reacts with Oxygen atoms in
the air.
 This forms an oxide.
 Oxides are weak and brittle, so they damage the material.
 Iron forms iron oxide.
 Copper forms copper oxide.
 Aluminium forms aluminium oxide.
 These are slow processes.
 Corrosion of metals can be controlled by different methods such as
painting the surface or applying a layer of other non-corrosive metal
In case of aluminium, a thin layer of aluminium oxide forms on the metal
surface which protects the inside metal from further corrosion.
In effect, aluminium forms its own protective coating against corrosion.
This behaviour is beneficial for us and different from iron’s which expose the
metal’s surface to further corrosion.
That is why, aluminium is used in many places instead of iron.

4. How corrosion can be stopped?
• Physical Barriers:
Coating a metal by paint Or plastic
• Alloys:
Combination of one metal with another Stainless Steel
metal or non-metal is called alloy.
Stainless Steel is iron alloyed with
chromium and nickel. Chromium forms a
Protective chromium
protective oxide layer, just like oxide layer
aluminium. Galvanic Series
• Galvanic Protection Magnesium
Zinc
Reactivity
Aluminium
Iron/Steel
Brass
Copper
Stainless Steel

5. Facts
Attaching a more reactive metal to a less reactive metal stops the
less reactive metal from corroding. Zinc is more reactive than
steel, so when attached to steel, the zinc corrodes faster than it
would on its own. The steel corrodes (rusts) much slower than it
would on its own.
Cars are ‘galvanised’. The chassis parts are passed through molten
zinc to produce a zinc coating. This is better than simple paint
because even when the coating is scratched the car won’t rust.
Same with roofs – this is what is meant by ‘GI’ roof (galvanised
iron).
You can see the zinc plates on this steel ships hull. They prevent it
from rusting. However, after a few years the zinc will be used up,
and the item will continue to rust unless repainted/new zinc block
is attached.

6. Wood
Wood is made up of long carbon chains (cellulose and lignin).
Toughness of wood comes from fibrous quality of wood.
Softwood – coniferous Hardwood - deciduous
Jackfruit Tree
Umbar Tree Mango Tree
Eucalyptus Tree
Wood expands and shrinks according to humidity. It is Flammable.
There is danger of damages by termites/rot.
Damage of wood because of termites can be controlled by Chemical Treatment
on the wood. It must be applied before seasoning.

7. Seasoning Of Wood
Wood is stored out in the open, out of direct sunlight. Wind and Sun dry wood
naturally over 6-12 months. This is inexpensive but time consuming method
of seasoning the wood.
Kiln – It takes 2-3 weeks to dry the wood but it is expensive process.
Advantages of seasoning of wood: Removes moisture, prevent rotting, wood
becomes lighter and hence cheaper to transport, more receptive to
preservatives/paint/glue, better insulating qualities, stronger.
Disadvantages of seasoning of wood: As moisture leaves wood, it shrinks. Can
cause warping and cracking and weakening of the timber in hardwoods, as
the ends dry faster than middle part of the wood.
Air dried – natural way
of wood seasoning Kiln dried

8. Facts
Cement is made from clay, limestone and sand. Limestone is hard and
brittle, you can crack it into small pieces with a chisel and hammer. Clay is not
hard because it only contains small amount of calcium carbonate. Sand is made
of silicon oxide. This is very strong and hard – similar to diamond in atomic
structure.
Cement making is where these 3 types of rocks are heated to high
temperature so they react, and then cooled. The further addition of
water, bonds calcium and silicon together to make a very strong substance, like
natural rock. However, unlike natural rock, you can transport it (cement is light
when in dry powdered form), and you can easily shape it when wet, into
whatever is required.
+
Concrete can be used to make construction bricks. They are cheaper than
fired bricks, and also more insulating as they contain air gaps.
Concrete may be used for non load bearing walls and foundations.
Concrete may be used to bear large loads, though it should be reinforced.
Under load, concrete may bend putting it into tension. Reinforcement is
required to carry tensile loads and prevent cracking and failure of the
concrete.

9. Precautions to take while using
Tamping
Concrete
Curing - enough water
to give maximum
strength to concrete
No tamping- While working with concrete,
poor quality your own safety is equally
concrete important. Always use:
(Honeycombing)
Result of not taking safety measures

10. Papercrete
+ + = Papercrete
Cement Paper water
Papercrete is a recent invention, a material under development. It is
not approved by the international code council as a load bearing
material, but many people are experimenting with its uses.
Advantages: Disadvantages
It is strong for its weight, as Tendency to absorb huge
it is an incredibly light amounts of water
material. from rain and from
the ground if
It is an outstanding insulator.
directly in contact.
It resists fire to a good It becomes soft because of
extent. moisture.
It is simple to produce. If placed in wet areas, it
It is very cheap. grows mould.