The selection of materials for a particular application requires knowledge of their physical properties. Engineering materials encompass various substances such as metals, non-metals, polymers, chemicals, and fibers.
Each engineering material possesses a unique set of properties that determine its suitability for specific tasks. These properties can be classified as physical and chemical properties. In this article, we will focus on discussing the physical properties of engineering materials.
Physical properties refer to inherent characteristics that can be observed without altering the material’s identity. Understanding these properties is crucial for selecting appropriate materials for specific purposes. For instance, copper is chosen as an electrical conductor due to its superior conductivity compared to paper, which is a poor conductor.
Physical properties of engineering materials can be further categorized into two types: intensive properties and extensive properties.
Intensive Properties
Intensive properties are independent of the material’s volume or size. They are also referred to as bulk properties. Here are some examples of intensive physical properties:
- Pressure: The force applied per unit area on a material’s surface.
- Temperature: The quantitative expression of the relative hotness or coldness of a material.
- Melting Point: The specific temperature at which a solid material changes into a liquid state.
- Boiling Point: The specific temperature at which a liquid material transforms into a gaseous state.
- Density: The mass per unit volume of a material.
- Ductility: The ability of a material to be drawn into a thin wire.
- Malleability: The ability of a material to be beaten into thin sheets.
- Conductivity: The ability of a material to conduct electricity.
- Toughness: The ability of a material to resist fracture or rupture.
- Thermal Conductivity: The ability of a material to conduct heat.
- Refractive Index: The property that describes how light propagates through a material.
- Specific Heat Capacity: The amount of heat required to raise the temperature of a unit mass of material.
- Thermal Expansion Coefficient: The measure of material’s expansion with a change in temperature.
- Magnetic Susceptibility: The degree to which a material can be magnetized in the presence of a magnetic field.
Extensive Properties
On the other hand, extensive properties depend on the amount of matter present in the material and are influenced by its size and volume. Here are some examples of extensive physical properties:
- Mass: The amount of matter within a material.
- Length: The measurement of the material in one dimension.
- Volume: The amount of space occupied by a material in three dimensions.
- Heat Capacity: The amount of heat required to raise the material’s temperature.
- Entropy: The measure of the disorder or randomness of a material.
- Electric Charge: The property that causes a material to experience a force in an electromagnetic field.
- Momentum: The product of a material’s mass and velocity.
- Energy: The property that allows a material to possess various forms of energy, such as thermal, chemical, or mechanical energy.
Understanding these physical properties helps in comparing and selecting suitable materials for specific engineering applications.