Lecture One

Introduction to Engineering Materials & Applications

Materials science is primarily concerned with the search for basic knowledge about the internal structure, properties, and processing of materials. Materials' engineering is mainly concerned with the use of fundamentals and applied knowledge of materials so that the materials can be converted into products necessary or desired by the society.

Materials in Industry: Industrial applications of materials science include materials design, cost, processing techniques (casting, rolling, welding, ion implantation, crystal growth, thin-film deposition, sintering, etc.) and analytical techniques (electron microscopy, x-ray diffraction, calorimetry, backscattering, neutron diffraction, etc.).

Introduction to Engineering Materials & Applications

General Categories of Engineering Materials Used Today in Manufacturing Industries

Materials Science & Engineering

Properties

ProcessingStructure

Performance

Materials Science

Investigating the relationship between structure and properties of materials.

Materials Engineering

Designing the structure to achieve specific properties of materials.

• Processing

• Structure

• Properties

• Performance

Processing >> Structure >> Properties >> Performance

General Categories of Engineering Materials Used Today in Manufacturing Industries

What is Materials Science and Engineering?

Materials Performance: Strength-to-weight ratio, formability, cost

Processing >>> Structure >>> Properties >>> Performance

• Composition means the chemical make-up of a material.

• Structure means a description of the arrangements of atoms or ions in a material.

• Synthesis is the process by which materials are made from naturally occurring or other chemicals.

• Processing means different ways for shaping materials into useful components or changing their properties.

What is Materials Science & Engineering?

Materials Processing

• Casting• Forging• Extrusion• Stamping• Nanotechnology• Sintering

Materials Characterization: • Diffraction with x-rays, electrons, or neutrons and various forms of spectroscopy and chemical analysis • Energy-dispersive spectroscopy (EDS),• Chromatography,• Thermogravimetric analysis,• Electron microscope analysis

Materials Properties

• Physical behavior, Response to environment

• Mechanical (e.g., stress-strain)• Thermal• Electrical• Magnetic• Optical• Corrosive

Subfields of Materials Science

Biomaterials: Metals for implantation must be corrosion resistant. Three main categories of metals for implants are stainless steels, cobalt-chromium alloys and titanium alloys. Additional metals used for dental implants are amalgam and gold.

Electronic Materials: Semiconductors used to create integrated circuits, storage media, sensors, and other devices. Semiconductors have special electronic properties which allow them to be insulating or conducting depending on their composition. Examples (Silicon and Germanium, III-V Compounds e.g. GaAs)

Main application of semiconductors are transistors, light emitting diodes (LEDs) and diode lasers). Semiconductors are used in computers (45%), consumer products (23%), communications equipment (13%), manufacturing industries (12%), automobiles (5%), and by the military (2%).

Introduction to Engineering Materials & Applications

Subfields of Materials Science

Piezoelectric Materials: Piezoelectric materials are used in acoustic transducers, which convert acoustic (sound) waves into electric fields, and electric fields into acoustic waves. Transducers are found in telephones, stereo music systems, and musical instruments. Quartz, a piezoelectric material, is often found in clocks and watches.

Magnetic Materials: Magnetic materials are used in electrical power applications such as transformers and motors, in video monitor picture tubes to move electron beams, and in computer disks or video or audio tapes to record information. Most materials can be classified as diamagnetic, paramagnetic or ferromagnetic.

Superconductors: A superconductor can conduct electricity without electrical resistance at temperatures above absolute zero. Superconductors are used in medical instruments such as Magnetic Resonance Imaging (MRI) systems.

Introduction to Engineering Materials & Applications

Subfields of Materials Science

Ceramics and Glasses: High temperature materials including structural ceramics such as, polycrystalline SiC and transformed toughed ceramics. Non-crystalline material includes inorganic glasses, vitreous metals and non-oxide glasses.

Composites Materials: Composites are formed from two or more types of materials. Examples include polymer/ceramic and metal/ceramic composites. There are three types of composites; 1) Particulate composites , 2) Laminate composites (Tennis rackets) and 3) Fiber reinforced composites (e.g. fiberglass)

Optical Fibers: An optical fiber contains three layers: 1) a core made of highly pure glass with a high refractive index for the light to travel, 2) a middle layer of glass with a lower refractive index known as the cladding which protects the core glass from scratches and other surface imperfections, and 3) an outer polymer jacket to protect the fiber from damage.

Introduction to Engineering Materials & Applications

Subfields of Materials Science

Fiber-Reinforced Composites are used in some of the most advanced, and therefore most expensive, sports equipment, such as a time-trial racing bicycle frame.

Advanced Materials: Advanced engineered materials are playing a major role in the rapid growth of the global telecommunication network.

Nanotechnology: It is the creation and study of materials whose defining structural properties are anywhere from less than a nanometer to one hundred nanometers in scale.

Crystallography: The study of how atoms in a solid fill space, the defects associated with crystal structures such as grain boundaries and dislocations, and the characterization of these structures and their relation to physical properties.

Introduction to Engineering Materials & Applications

Classification of Materials

Metals and Alloys: Iron and steel, superalloys, intermetallic compounds

Ceramics, Glasses and Glass-ceramics: High temperature materials. Structural ceramics such as, polycrystalline SiC and transformed toughed ceramics, Whitewares (e.g. porcelains). Electrical Ceramics (capacitors, insulators, transducers, etc. Chemically Bonded Ceramics (e.g. cement and concrete). Glass, Non-crystalline material including inorganic glasses, vitreous metals and non-oxide glasses, Glass optical fibers,

Polymers, Thermoplastics and Thermosets Plastics, Liquid crystals and Adhesives.

Electronic, Magnetic and Optical Materials (solid-state lasers, LEDs).

Composite Materials and Biomaterials: Man-made proteins, biosensors, drug-delivery colloids (polymer based)

Introduction to Engineering Materials & Applications

Functional Classification of Materials

• Aerospace (Composites, SiO2-Amorphous silicon, Al-alloys, Super alloys)

• Biomedical ( Titanium alloys, Stainless steels, plastics)

• Electronic Materials (Si, GaAs, BaTiO3, Conducting Polymers)

• Energy and Environmental Technology (Uo2, Ni-Cd, ZrO2, LiCoO2, Amorphous Si-H)

• Magnetic Materials (Fe, Fe-Si, NiZn and MnZn ferrites, Co-Pt-Ta-Cr)

• Optical Materials (SiO2, GaAs, Glasses, Al2O3)

• Smart Materials (NI-Ti shape memory alloys)

• Structural Materials (Steels, concrete, fiberglass, plastics, wood)

Introduction to Engineering Materials & Applications

Periodic Table of Elements

Introduction to Engineering Materials & Applications

Applications, and properties for each category of materials

Example of Applications PropertiesMetals and Alloys Gray cast iron Automobile engine blocks Castable, machinable,

vibration dampingCeramics andGlasses SiO2-Na2O-CaO Window glass Optically transparent,

thermally insulatingPolymers Polyethylene Food packaging Easily formed into thin,

flexible, airtight filmSemiconductors Silicon Transistors and integrated Unique electrical

circuits behaviorComposites Carbide cutting tools for High hardness Tungsten carbide machining good shock resistance-cobalt (WC-Co)

Introduction to Engineering Materials & Applications

Classification of Materials-Based on Structure

1. Crystalline material is a material comprised of one or many crystals. In each crystal, atoms or ions show a long-range periodic arrangement.

2. Single crystal is a crystalline material that is made of only one crystal (there are no grain boundaries).

3. Polycrystalline material is a material comprised of many crystals (as opposed to a single-crystal material that has only one crystal). Grains are the crystals in a polycrystalline material. Grain boundaries are regions between grains of a polycrystalline material.

Introduction to Engineering Materials & Applications

Structure of Materials: Technological Relevance

Level of Structure Example of Technologies

Atomic Structure Diamond – edge of cutting tools

Atomic Arrangements Long-Range Order(LRO)

Lead-zirconium-titanate[Pb(Zrx Ti1-x )]

Atomic Arrangements: Short-Range Order (SRO)

Amorphous silica - fiber optical communications industry

Nanostructure Nano-sized particles of iron oxide – ferrofluids

Microstructure Mechanical strength of metals and alloys

Macrostructure Paints for automobiles for corrosion resistance

Introduction to Engineering Materials & Applications

Properties of Materials

Mechanical properties: Elasticity and stiffness, plasticity, strength, brittleness or toughness, and fatigue.

Electrical properties: Electrical conductivity and resistivity

Magnetic properties: Paramagnetic, diamagnetic, and ferromagnetic properties.

Dielectric properties: Polarizability, capacitance, ferroelectric, piezoelectric, and pyroelectric properties.

Optical properties: Refractive index, absorption, reflection, and transmission, and birefringence (double refraction).

Corrosion, fatigue, and creep properties

Introduction to Engineering Materials & Applications

© 2003 B

rooks/Cole P

ublishing / Thom

son Learning™

Strengths of various categories of materials

Introduction to Engineering Materials & Applications

© 2003 B

rooks/Cole P

ublishing / Thom

son Learning™

Variation of Strengths with Temperature for various categories of materials

Introduction to Engineering Materials & Applications

Materials Design and Selection

1. Density is mass per unit volume of a material, usually expressed in units of g/cm3 or lb/in.3

2. Strength-to-weight ratio is the strength of a material divided by its density; materials with a high strength-to-weight ratio are strong but lightweight.

Introduction to Engineering Materials & Applications

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