Classification of Engineering Materials PDF

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MATERIAL SCIENCE Branch of applied science concerned with investigating the relationship between structure of materials and their properties

Classification of Engineering Materials “Because without materials, there is no engineering.”

Six Major Classes of Materials • Some of these have descriptive subclasses. • Classes have overlap, so some materials fit into more than one class.

• Metals • Iron and Steel • Alloys and Superalloys (e.g. aerospace applications) • Intermetallic Compounds (high-T structural materials)

Ceramics • Structural Ceramics (high-temperature load bearing) • Refractories (corrosion-resistant, insulating) • Whitewares (e.g. porcelains) • Glass • Electrical Ceramics (capacitors, insulators, transducers, etc.) • Chemically Bonded Ceramics (e.g. cement and concrete)

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Six Major Classes of Materials • Polymers • Plastics • Liquid crystals • Adhesives

• Electronic Materials • Silicon and Germanium • III-V Compounds (e.g. GaAs) • Photonic materials (solid-state lasers, LEDs)

• Composites • Particulate composites (small particles embedded in a different material) • Laminate composites (golf club shafts, tennis rackets, Damaskus swords) • Fiber reinforced composites (e.g. fiberglass)

• Biomaterials • Man-made proteins (cytoskeletal protein rods or “artificial bacterium”) • Biosensors (Au-nanoparticles stabilized by encoded DNA for anthrax detection) • Drug-delivery colloids (polymer based) 3

Classification of Materials • Materials used in the design and manufacture of products • • • • • •

Plastics Wood Composites Ceramics Metals Fabrics

Linen, cotton, nylon, Layers of polycarbonate, Tungsten Steel, aluminium carbide toolKevlar bit Balsa Acrylic wood lens model aluminium & acrylic

Classification of Materials (Plastics) •Plastics can be further classified as; •Thermoplastic •Thermoset •Elastomers Thermoplastics Acrylics Nylons PVC Polyethylene

Thermos Epoxy re Phenolic Urea Phenol formaldehyde formaldehyde Polyester PVC Polyethylene gutters Rubber

Classification of Materials (Wood) • • • •

Wood can be further categorised as; Hardwood Softwood Manufactured board Beech Ash Oak Mahogany Plywood Chipboard Cedar with Veneer

Hardwood

ed

Soft

Oak Ash Beech Sycamore

board

Classification of Materials (Composites)

• A composite is a combination of two or more chemically distinct materials whose physical characteristics are superior to its constituents acting independently. • Because of their high strength/stiffne ratio they are widely us • Aerospace industry • Offshore structures • Boats • Sporting goods

Classification of Materials (Composites)

• • • • •

Examples of composites i Reinforced Plastics Ceramic-matrix Metal-Matrix Laminates

Cylinder linings Carbon Outer Combustion reinforced Kevlar, skin Thrust Cylinder Glass panels taffeta chamber plastic reinforced chamber linings & polyester fuselage for of plastic rocket jet A380 sails engine hull

Classification of Materials (Ceramics)

• Ceramics are compounds of metallic and nonmetallic elements, examples include; • Oxides (alumina – insulation and abras zirconia – dies for metal extrusion and abrasives) • Carbides (tungsten-carbide tools) • Nitrides (cubic boron nitride, 2nd in ha to diamond)

Classification of Materials (Metals) •Metals can be further classified as Ferrous & Non-Ferrous, some examples include; Stainless Brass Copper Aluminium Speed Steel steel Non-Ferrous Ferrous High

Steels Stainless S High Speed Cast Irons

The difference between 304 and 316 stainless steel!  304 contains 18% chromium and 8% nickel  316 contains 16% chromium, 10% nickel and 2% molybdenum. The molybdenum is added to help resist corrosion to chlorides (like sea water and de- icing salts)

Classification of Materials (Fabrics) •Fabrics can be further classified as natural and synthetic

Na

hetic

Cotton Canvas Materials used in Colourful space suits include aluminized Mylar, neoprene Cotton T-shirt (design & print projects) Polyester Canvas Polyester deck marine chair nylon kite ropespinnaker less coated nylon,stretch dacron, urethane nylon, than nylon- coated resists UV lighttricot and spandex. The outer layer is a blend of Gortex, Kevlar and Nomex

Properties of Materials Electrical properties A. Electrical conductivity and resistivity

Dielectric properties A. Polarizability B. Capacitance C. Ferroelectric properties D. Piezoelectric properties E. Pyroelectric properties

Magnetic properties A. Paramagnetic properties B. Diamagnetic properties C. Ferromagnetic properties

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Properties of Materials Optical properties A. Refractive index B. Absorption, reflection, and transmission C. Birefringence (double refraction)

Corrosion properties Deteriorative properties Biological properties A. Toxicity B. bio-compatibility

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Materials Science & Engineering in a Nutshell Performance Materials Engineering Designing the structure to achieve specific properties of materials.

Processing

Structure

• Processing Properties

• Structure

Materials Science Investigating the relationship between structure and properties of materials.

•Properties

• Performance 15

SOLIDS

• A solid consists of atoms, ions, or molecules packed closely together and the forces that hold together in place give rise to the distinctive properties

ORDERS OF REGULARITY

No order of regularity

Amorphous solid

Short range in water

Long range order

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ATOMIC ORDER & CLASSIFICATION

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 Sharp peaks are obtained from crystalline materials (using parallel, monochromatic radiation), while typically a broad peak is obtained from an amorphous material. The sharp peak is referred to as a Bragg peak.

In contrast sharp peaks are obtained from crystals

Note the broad peak

SAD the

XRD pattern showing the formation of amorphous structure...