This document discusses thermal properties of materials. It begins by introducing the group members and outlines for the document. It then defines key concepts like heat capacity, thermal expansion, and thermal conductivity. It explains that metals generally have high heat capacity and thermal conductivity but low thermal expansion. Ceramics have high heat capacity and melting points but low thermal expansion and thermal conductivity. Polymers typically have low densities, heat capacity, thermal expansion, and thermal conductivity. They also have low melting points.

2. Department: Electrical Engineering.
GROUP NAMES:
1. Abdiwali mohamed salaad
2. Abdihaliim murshid mohamed
3 . Mahdi mohamud Hussein
4. Abdirahman mohamed sheikh khaliif
Hormuud University

4. Outlines
Introduction
Specific Heat
•Heat capacity
•Temperature and Measurements of temperature
•Change State
Thermal Expansion
Heat transfer
•Radiation
•Conduction
•Convection
Thermal Conductivity

5. The study of the response of a material to the
application of heat is very crucial . When a solid
absorbs energy in the form of heat, its temperature
goes up and its dimensions increases. The absorbed
heat energy by the material may be transmitted to
cooler regions if temperature gradient exist, and
eventually, the materials may melt.
Generally solid materials have been conveniently
grouped into three basic categories: metals, ceramics
and polymers.

6. Metals
Normally metallic materials are combinations of
metallic elements. Metallic materials have large
number of non-localized electrons, i.e. electrons are
not bound to particular atoms. Many properties of
metals are directly attributable to these electrons. All
metals are characterized by metallic properties, e.g.
shiny, malleability, ductility ,conduct heat and
electrical conductivity.

7. Cont…
Metallic materials are always crystalline in nature.
Scientists have developed amorphous (non-
crystalline) alloys by very rapid cooling of a melt or by
very high-energy mechanical milling. metals generally
have high melting point so that metals will have
lower thermal expansion also metals have high heat
capacity.
We note that metal like tin has a low melting point
(M.P.) and expands rapidly with rise in temperature.
On the other hand a metal like platinum having high
M.P. has a low rate of thermal expansion.

8. Ceramics
A ceramic is an inorganic non-metallic solid made
up of either metal or metalloid compounds that have
been shaped and then hardened by heating to high
temperatures. In general, they are hard, corrosion-
resistant and brittle.

9. Polymers
Many of these are organic substances and derivatives of carbon and
hydrogen. Polymers include the familiar plastic and rubber materials.
Usually polymers are classified into two categories: thermoplastic
polymers, thermosetting polymers. Polymers have very large
molecular structures. Most plastic polymers are light in weight and
are soft in comparison to metals.
Polymer materials have typically low densities and may be extremely
flexible and widely used as insulators, both thermal and electrical.
the overriding consideration of the selection of a given polymer is
whether or not the material can be processed into the required article
easily and economically.

10. Specific Heat
Heat capacity is the amount of heat required to
raise the temperature of an object or substance
one degree. The temperature change is the
difference between the final temperature ( Tf ) and
the initial temperature ( Ti ).
When heat is transferred to an object, the
temperature of the object increases.
When heat is removed from an object, the
temperature of the object decreases.

11. Temperature
• The atoms and molecules
in a gas are in constant
motion. Temperature is a
measure of the speed with
which they move. (More
exactly it is a measure of
their average kinetic
energy.) The higher the
temperature, the faster the
molecules move.

12. Measurement of temperature
Measurement Of temperature:-
Temperature can be measured by the following devices:-
Mercury Thermometer
Pyrometer
Ideal Gas Thermometer
Electrical Resistance Thermometer

13. Change of state
The change of state from solid to liquid is called
melting and from liquid to solid is called fusion.
The temperature at which the solid and the liquid
states of the substance in thermal equilibrium with
each other is called its melting point.
The melting point of a substance at standard
atmospheric pressure is called its normal melting
point.

14. Some important terms
The change of state from liquid to vapour (or gas) is called
vaporization.
The temperature at which the liquid and the vapour states of
the substance coexist is called its boiling point.
The boiling point of a substance at standard atmospheric
pressure is called its normal boiling point.
The change from solid state to vapour state without passing
through the liquid state is called sublimation, and the
substance is said to sublime.

15. Thermal Expansion
THERMAL EXPANSION refers to the spreading out of
particles in a substance as the thermal energy
increases.
Almost all materials take up more space when
heated (expansion) and less a space when cooled
(contraction).
Some things expand more than others when
heated.

16. Cont,,,

17. Cont…
HEAT TRANSFER refers to HEAT FLOW WITHIN AN OBJECT AND
FROM ONE OBJECT TO ANOTHER due to differences in
temperature.
Transmission of heat to equalize the temperatures is brought about in
three ways.
RADIATION - heat energy travels as electromagnetic waves in the
same manner and speed as light.

18. Cont..
CONDUCTION - heat energy travels when two
objects at different temperatures are in direct
contact with each other.

19. Cont………
CONVECTION - the heat in fluids is transferred to
cooler regions by currents.

20. Cont..

21. Thermal MEANS
“HEAT.”
Conductivity:
Means
“AbiliTy To
convEy”.

22. THERMAL CONDUCTIVITY
Thermal conductivity is the property of a materials
to conduct heat.
Heat moves through a material at a specific rate. The rate
it travels depends on the material itself: some materials
allow heat to move quickly through them, some materials
allow heat to move very slowly through them.

23. Summary
Heat capacity: The ability of a material to absorb heat.
Thermal expansion: s the tendency of matter to change
in shape, area, and volume in response to a change
in temperature through heat transfer.
Thermal conductivity: The ability of a material to transfer
heat.
Polymers:
Heat capacity Low
Thermal expansion High
Thermal conductivity Low
Melting Point Low

24. Cont…
Metals:
Heat capacity High
Thermal expansion Low
Thermal conductivity High
Melting Point High
Ceramics:
Heat capacity High
Thermal expansion Low
Thermal conductivity Low
Melting Point High

25. THANK YOU.
By:Abdiwali Mohamed Salad