The subject of " Engineering Materials " deals with the study of materials in respect of the following : Sources , composition , properties , manufacturing methods and testing , Applying in the varions fields of Engineering and Technology , modern techniques for handling and using materials with economical and safer design of structurs . and machines . Classification of Eng. Materials :

A : 1- civil Eng. Materials : suchas classification According to Application Building stones .bricks and clay products , time, cement , concrete , mortar , timber …..

2- Electrical Eng. materials :

Copper , aluminum , iron , and steel … conductors .

Silicon , germanium ,

Asbestos , Bakelite , mice , varnishes , air…………. In sulators .

Iran , nickel , cobalt , ………… magnetic materials.

3- Mechanical Eng. Materials :

Cast iron , steel , lubricating , materials .

B. 1- Classification according to structure Metals : Iron , Aluminum , copper , Zinc ……….. metals may be subdivided as :.

(1) Ferrous metals ( cast iron , wrought iron and steel ) and alloys ( silicon steel , high speed steel , spring steel ).

(2) Non-Ferrous metals ) copper , Aluminium , Zinc ……. ) and alloys ( brass ,bronze , duralumin a ) .

2- Non metals : Building stones , cement , concrete , plastics , asbestos .

General classification

C. 1- metais and alloys .

2- Ceramics

3- Organic polymers

The Differences between metals and Non-metals

Property / Metals / Non-metals
1- Structure
2- Excitation of Valence electron by E.M.F. ( Electromotive force )
3- State
4- Luster
5- Conductivity
6- Malleability
7- Ductility
8- Hardness
9- Electrolysis
10-  Density / All solid metals have crystalline structure
Easy
Generally solids at room temperature
Possess metallic luster
Good conductor of
heat and electricity
Malleable
Ductile
Generally hard
Form anions
High density / They exist anamorphic or mesomorphic forms
Difficult
Gases and solids at ordinary temperatures
Do not possess metallic luster ( except iodine and graphite )
Bad conductor of heat and electricity
Not Malleable
Not ductile
Hardness Varies
Form anions
Low density

1-  Metals and alloys :

Metals are polycrystalline bodies consisting of a great number of fine crystals differently oriented with respect to one another (10-1 – 10-4 c, size ) . Depending on the mode of crystallization , there are crystals of regular shapes which called crystallites or grains of the metal .

Metals in the solid state , and to same extent in the liqnid state possess high thermal and electrical conductivity . the electrical resistance of pure metals increases with the temperature

Many metals display duper conductivity at temperatures near absolute Zero where their electrical resistance drops abruptly to extremely low values .

All metals are capable of thermionic emission ( the emission of electrons when being heated , they are good reflectors of light and lend them selves to plastic deformation .

Pure metals are of low string the and do not possess the required physiochemical and technological properties for some definite purpose , so they are seldom used in Eng. The majority of metals used are alloys .

Alloys are produced by melting or sintering twoor more metals , or metals and anon-metal together . An Alloy can consist of twoor more components .

Examples : steels , super alloys , brass , bronze

2-  Ceramic Materials : these materials are non-metallic solids made of inorganic compounds such as oxides , nitrides , borides , silicates , carbides .

They are fabricated by first shaping the powder with or without the application of pressure in to a compact , which is subsequently subjected to a high temp . treat ment called sintering . Traditional ceramics have been used in the manufacture of pottery , porcelain , cement and silicate glasses . New ceramics possess exceptional electrical , magnetic , chemical , structural , and thermal properties . such ceramics are now extensively used in the electronic control devices. Computers , nuclear Eng. And aerospace fields .

Examples : silica , soda lime glass . concrete , cement . Ferrites , granite , Mgo , Cds , Zno , Sic .

3-  Organic materials : these materials are derived directly from carbon where carbon is chemically combined with hydrogen , oxygen , or other non-metallic Substances and their structure is complex .

Organic materials are termed polymers be cansee they are formed by polymerization reaction in which simple molecules are chemically combined into massive long chain molecules or three – dimensional structures . Examples : phalstics ( PVC , PE , PTFE ) : Fibers ( nylon , cotton , terylene ) : Natural and synthetic rubbers , leather .

Examples of compsites ;

1-  Metals and alloys with ceramics :

(1) Steel reinforced concrete .

(2) Dispersion hardened alloys .

2-  Metals and alloys with organic polymers :

(1) Vinyl – coated steel

(2) Whisker reinforced plastics

3-  Ceramics and organic polymers :

(1) Fiber – reinforced plastics .

(2) Carbon – reinforced rubber.