Engineering Materials : Introduction

 Engineering Materials Introduction: Part 1

Classification of Engineering Materials

METALS

Bonding: Metallic Bonding – Nonlocalized Electron

Structure: Crystalline

Advantages :

·         Relatively stiff and strong

·         Ductile

·         Good Conductor

·         Polished metal has a lustrous appearance

·         Ferromagnetic

Disadvantages :

·         Corrosion and oxidation

·         Failure by fatigue

·         Not transparent

 

Familiar Object Made of Metals (Callister, 2018)

POLYMERS

Bonding: Covalent bonding

Structure: Amorphous

Advantages :

·         Lightweight

·         Ductile

·         Easy to form

·         Low coefficient of friction

·         Corrosion resistant

Disadvantages :

·        Low modulus elasticity

·        Low melting point

·        Not strong as metals and ceramics

·        Difficult to recycle

 

Several Common Objects Made of Polymers (Callister, 2018)

CERAMICS

Bonding: Ionic and covalent bonding

Structure: Crystalline or Amorphous

Advantages :

·         Relatively stiff

·         High Strength

·         Good insulator

·         Heat resistant

·         Corrosion and oxidation resistant

Disadvantages :

·        Brittle

·        Difficult to design

·        Highly susceptible to fracture

Common Objects Made of Ceramics (Callisters, 2018)

Material Engineering Comparison

Density

Bar Chart of Room Temperature Density Values for Various Materials (Callister, 2018)

Stiffness

Bar Chart of Room Temperature Stiffness Values for Various Materials (Callister, 2018)

Strength

Bar Chart of Room Temperature Strength Values for Various Materials (Callister, 2018)

Fracture Resistance

Bar Chart of Room Temperature Fracture Resistance Values for Various Materials (Callister, 2018)

Electrical Conductivity

Bar Chart of Room Temperature Electrical Conductivity Values for Various Materials (Callister, 2018)

Reference :

Callister, W, D., and Rethwisch, D, G., 2018, Materials Science and Engineering Introduction, 8th ed, John Wiley & Sons, inc., New Jersey., The US.