Download The subject of " Engineering Materials " deals with the study of

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