7

Materials Engineering

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Objectives

• Define materials engineering.• Identify different types of materials.• Describe a range of material properties.• List examples of material tests.• Describe nanotechnology.

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

About Materials Engineering

• Historical time periods based on materials– Stone Age– Bronze Age– Iron Age– Information Age (silicon and plastics)

• Understanding of science is important• Design and development of new materials• Production using specific materials

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Education Typically Required

• High school courses– Upper-level math (calculus and statistics)– Upper-level science (chemistry and physics)

• College courses– Engineering design– Thermodynamics of materials– Structures of materials– Metallurgy

• Internships

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Professional Organizations

• ASTM– Develops material testing standards– Over 30,000 members worldwide

• Materials Information Society • Materials Research Society• NACE International• Other organizations for ceramics, plastics, and

metals

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Principles of Materials Engineering

• Broad field• Materials are used in every engineering field• All engineers must understand basic principles

– Types of materials– Properties of materials

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Material Types

• Metals• Ceramics• Polymers• Composites

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

The Four Types of Materials

ARENA Creative/Shutterstock.com; kubais/Shutterstock.com; Evgeny Korshenkov/Shutterstock.com; noppharat/Shutterstock.com

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Metals

• Have crystalline atomic structure– High material strength– Good conductors of heat and electricity– Malleable

• Inorganic material• Most pure metals are natural• Many are found in ore• Commonly used in alloys

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Atomic Structure of Crystalline Materials

Goodheart-Willcox Publisher

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Properties of Various Forms of Alloys

Goodheart-Willcox Publisher

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Ceramics

• Most have crystalline structure– Strong in compression– High melting temperature– Can retain heat well

• Brittle• Good insulators• Include clay, cement, many types of abrasives• Some can become magnets

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Polymers

• Organic materials• Noncrystalline• Can be natural or synthetic• Plastics are most common type

– Lightweight but strong– Easy and fairly inexpensive to process– Have some negative environmental impacts– Thermoplastics and thermosets

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Atomic Structure of Noncrystalline Materials

Goodheart-Willcox Publisher

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Thermoplastics and Thermosets

Picsfive/Shutterstock.com; Barghest/Shutterstock.com; Claudio Divizia/Shutterstock.com; Big Pants Production/Shutterstock.com; Kletr/Shutterstock.com; Santhosh Kumar/Shutterstock.com

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Recycling Plastics

• Saves use of oil and natural gas• Less plastics take up space in landfills• Society of Plastics Industry created codes

– Include recycling symbol, number, and abbreviation– Useful to consumers who recycle

• Over 82 million tons of materials are recycled per year in U.S.

Going Green

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Composites

• Utilize advantages of several materials• Each material can be identified• Can be natural or synthetic• Most consist of matrix and fiber

– Matrix is main material– Fiber is strengthening material

• Include wood, concrete, plywood, and fiberglass

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Other Materials

• Fluids– Air and water– Many products rely on their use

• Semiconductors– Can act as insulators or conductors– Used to create electronic components

• Biomaterials– Can interact safely with human body– Used in medical applications

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Materials Symbols

• Used in architectural design• Symbols for common building materials

– Brick– Concrete– Cinder block

• Symbols for insulation, glass, and metal• Allow designers and architects to include graphics

of types of materials to be used

Design

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Examples of Materials Symbols

Goodheart-Willcox Publisher

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Material Properties

• Physical• Mechanical• Electrical• Magnetic

• Chemical• Thermal• Optical • Acoustical

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Physical Properties

• Can often be obtained using senses• Include size, shape, look, feel, taste, and smell• Some cannot be determined by senses• Most commonly used is density

– Mass per unit of volume– Often used to compare materials

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Mechanical Properties

• How material behaves when force or load is applied• Understanding of stress is important

– Can be applied through axis of material– Shear stress is not applied through axis– Causes strain on material

• Compression strength and tensile strength• Elasticity• Plasticity

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

A Stress/Strain Diagram

Goodheart-Willcox Publisher

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Electrical Properties

• How a material behaves when electrically charged• Materials fall into one of three categories

– Conductors– Insulators– Semiconductors

• Conductivity• Resistivity

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Magnetic Properties

• How a material behaves when within a magnetic field

• Magnetic permeability– Measured in Henrys per meter– Impacted by temperature and distance from

magnetic field– If it is high, material will allow magnetic flow

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Chemical Properties

• Changed by a chemical reaction• Include flammability• Include corrosion• Often need to be controlled because they can be

damaging to material

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Thermal Properties

• How the material responds to heat• Thermal conductivity• Thermal resistance• Thermal expansion• Melting point

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Optical Properties

• How light waves interact with material– How well material absorbs light– How well material reflects light– How well material transmits light

• Reflected light gives material color• Transmission occurs when light is absorbed and

reflected by transparent materials but still passes through materials

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Acoustical Properties

• How sound waves interact with material– How well material absorbs sound– How well material reflects sound– How well material transmits vibration

• Porous materials usually absorb sound• Smooth materials reflect sound in one direction• Rough materials reflect sound in many directions

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Material Engineering Applications

• Material testing– Many companies specialize in specific materials– ASTM develops standards for testing

• Nanotechnology– One nanometer is one billionth of meter– Has potentially exciting impacts

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Material Testing

• Used for new materials when creating new products or improving existing products

• Designer might try different formulation of existing material

• Large industry• Categories of material tests

– Destructive material tests– Nondestructive material tests

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Destructive Tests

• Often used to test mechanical properties– Exert a force on material until it fails– Tensile tests– Compression tests– Fatigue tests

• Often used to test chemical properties– Test material’s reaction to corrosion– Material exposed to saltwater

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Nondestructive Tests

• Used to inspect materials• Used to look for flaws and defects• Visual examinations, sometimes with dyes• Some use waves

– Radiography tests– Ultrasonic tests

• Some use currents– Eddy current testing– Magnetic particle testing

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Potential Uses of Nanotechnology

• For delivery of medicines directly to cancerous tumors

• For creating microscopic computer chips• For manufacturing materials that repair and clean

themselves

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Nanoparticles

• Most basic components at nanoscale• Some materials demonstrate properties at

nanoscale that are not present at larger scales• Products are being designed that utilize these

properties

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Nanostructures

• Nanowires– Designed to transmit light or electricity– Might be useful in computer circuits and lighting

• Nanotubes– Cylindrical fullerenes with honeycomb pattern– Useful in electronics and structural applications

• Buckyballs– Most perfectly round molecules– Useful as lubricants

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Nanotubes

Tyler Boyes/Shutterstock.com

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Buckyballs

Mark Lorch/Shutterstock.com

Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc.

Materials Engineering in Action

• Used to select or create most appropriate materials for engineered solution

• Engineers must consider several key elements– Material function– Manufacturability– Cost– Safety