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Materials - Part II
Materials - Part II
Materials - Part II
Materials - Part II
Materials - Part II
Materials - Part II
Materials - Part II
Materials - Part II
Materials - Part II
Materials - Part II
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Materials - Part II

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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 …

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.

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  • 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 ofEnergy 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 metalsurface 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 themetal’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. FactsAttaching 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 WoodWood 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. FactsCement is made from clay, limestone and sand. Limestone is hard andbrittle, you can crack it into small pieces with a chisel and hammer. Clay is nothard because it only contains small amount of calcium carbonate. Sand is madeof silicon oxide. This is very strong and hard – similar to diamond in atomicstructure.Cement making is where these 3 types of rocks are heated to hightemperature so they react, and then cooled. The further addition ofwater, bonds calcium and silicon together to make a very strong substance, likenatural rock. However, unlike natural rock, you can transport it (cement is lightwhen in dry powdered form), and you can easily shape it when wet, intowhatever is required. +Concrete can be used to make construction bricks. They are cheaper thanfired 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 isrequired to carry tensile loads and prevent cracking and failure of theconcrete.
  • 9. Precautions to take while using Tamping Concrete Curing - enough water to give maximum strength to concreteNo tamping- While working with concrete,poor quality your own safety is equallyconcrete important. Always use:(Honeycombing) Result of not taking safety measures
  • 10. Papercrete + + = Papercrete Cement Paper waterPapercrete is a recent invention, a material under development. It isnot approved by the international code council as a load bearingmaterial, 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.

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