1. Metals
2. Ceramics
3. Polymers
4. Composites
Metals
In manufacturing metals are used usually in the form of alloys, which are composed of two or more elements,
at least one of which is metal
Metals used in manufacturing are classified into Two basic groups:
1.
Ferrous metals - based on iron, comprise 75% of
metal tonnage in the world:
- Steel = iron-carbon alloy with 0.02 to 2.11% C
- Cast iron = alloy with 2% to 4% C
Ceramics
A
compound containing metallic (or semi-metallic) and non metallic
elements. Typical nonmetallic elements are
oxygen, nitrogen, and carbon
For manufacturing processing purposes, ceramics divide into:
1.
Crystalline ceramics –includes:
- Traditional ceramics, such as clay (hydrous aluminium silicates)
- Modern ceramics, such as alumina (Al2O3)
2. Glasses –mostly
based on silica (SiO2)
Polymers
A
compound formed of repeating structural units called mers, whose atoms share
electrons to form very large
molecules
For manufacturing processes polymers are classified in Three
categories:
1. Thermoplastic polymers - can be subjected to multiple
heating and cooling cycles without altering
their molecular structure
2. Thermosetting polymers - molecules chemically transform
(cure) into a rigid structure upon cooling
from a heated plastic condition
3 Elastomers - exhibit
significant elastic behavior
Composites
A
material consisting of two or more phases that are processed
separately and then bonded together to achieve
properties superior to its constituents
- A phase = a homogeneous mass of material, such as grains of identical unit cell structure in a solid metal
- Usual structure consists of particles or fibers of one phase mixed in a second phase
- Properties depend on components, physical shapes of components, and the way they are combined to form the final material