ATMIYA INSTITUTE OF TECHNOLOGY & SCIENCEMECHANICAL DEPARTMENT

3rd SEMESTER

Classification of Engineering Materials, Engineering requirements of materials.

(Material Science and Metallurgy - 2131904)

PREPARED BY:Akash Ambaliya (140030119003)Vivek Aghara (140030119001)

What is a material?• A material is defined as a substance (most often a

solid, but other condensed phases can be included) that is intended to be used for certain applications.

•  There are a myriad of materials around us—they can be found in anything from buildings to spacecraft.

• Materials can generally be divided into two classes: – Crystalline and non-crystalline

Fundamentals of materials science

Fundamentals of materials science

• Metal or Metal alloys• Ceramics• Semi – conductors• Organic (Polymer)• Composites

Metal or Metal alloys• The study of metal alloys is a significant part of

materials science.

• Of all the metallic alloys in use today, the alloys of iron (steel, stainless steel, cast iron, tool steel, alloy steels) make up the largest proportion both by quantity and commercial value.

• Iron alloyed with various proportions of carbon gives low, mid and high carbon steels.

Metal or Metal alloys• An iron carbon alloy is only considered steel if

the carbon level is between 0.01% and 2.00%.

• For the steels, the hardness and tensile strength of the steel is related to the amount of carbon present, with increasing carbon levels also leading to lower ductility and toughness.

• Heat treatment processes such as quenching and tempering can significantly change these properties however.

Metal or Metal alloys• Cast Iron is defined as an iron–carbon

alloy with more than 2.00% but less than 6.67% carbon. Stainless steel is defined as a regular steel alloy with greater than 10% by weight alloying content of Chromium.

• Nickel and Molybdenum are typically also found in stainless steels.

Metal or Metal alloys

Ceramics• The most brittle materials.

• Ceramics are as soft as clay or as hard as stone and concrete.

• Usually, they are crystalline in form. Most glasses contain a metal oxide fused with silica.

Ceramics• At high temperatures used to prepare glass,

the material is a viscous liquid.

• The structure of glass forms into an amorphous state upon cooling.

• Windowpanes and eyeglasses are important examples. Diamond and carbon in its graphite form are considered to be ceramics.

Ceramics

Semi – conductors• A semiconductor material has an electrical

conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass.

• Semiconductors are the foundation of modern electronics. Semiconducting materials exist in two types - elemental materials and compound materials. 

• The modern understanding of the properties of a semiconductor relies on quantum physics to explain the movement of electrons and holes in a crystal lattice.

Semi – conductors• The unique arrangement of the crystal

lattice makes silicon and germanium the most commonly used elements in the preparation of semiconducting materials.

• An increased knowledge of semiconductor materials and fabrication processes has made possible continuing increases in the complexity and speed of microprocessors and memory devices.

• Some of the information on this page may be outdated within a year because new discoveries are made in the field frequently.

Silicon crystal (Semi – conductor)

Organic (Polymer)•Polymers are also an important part of materials science.

•Polymers are the raw materials (the resins) used to make what we commonly call plastics.

• Plastics are really the final product, created after one or more polymers or additives have been added to a resin during processing, which is then shaped into a final form.

Organic (Polymer)• Polymers which have been around,

and which are in current widespread use, include polyethylene, polypropylene, PVC, polystyrene, nylons, polyesters, acrylics, polyurethanes, and polycarbonates. Plastics are generally classified as "commodity", "specialty" and "engineering" plastics.

Composite• Composite materials are structured materials

composed of two or more macroscopic phases.

• Applications range from structural elements such as steel-reinforced concrete, to the thermally insulative tiles, which is used to protect the surface of the shuttle from the heat of re-entry into the Earth's atmosphere.

• Other examples can be seen in the "plastic" casings of television sets, cell-phones and so on.

Composite• These plastic casings are usually

a composite material made up of a thermoplastic matrix such as acrylonitrile-butadiene-styrene (ABS) in which calcium carbonate chalk, talc, glass fibers or carbon fibers have been added for added strength, bulk, or electrostatic dispersion.

Composite

Engineering requirements of materials• There’re 3 basic requirements…– Fabrication– Service– Property of a material

Fabrication• It should be able to get shape or joint

with other material without any circumstances.

• The material shouldn’t react with fabricated material in any conditions.

Service• The material selected for the purpose

must stand up to the service.

• Engineering parts should be made up with least initial cost.

Property of a material• Materials exhibit myriad properties. The

important properties of materials are as follows:

- Mechanical properties(stress, elasticity, plasticity, strength, ductility, brittleness.. etc )

- Chemical Properties(compositions, bonding, melting & boiling point.. etc.)

Property of a material- Thermal Properties(thermal conductivity, thermal expansion, specific heat.. etc.)

- Optical Properties(absorbtivity, reflectivity, transitivity)

- Electrical Properties(conductivity, resistivity, semi- conductivity, insulation.. etc.)

Property of a material- Magnetic Properties(permeability, hysteresis)

Thank You…