Materials and their Properties

Basics of Material Properties

• Understanding material properties is fundamental for successful product design and production.

• Every material has specific characteristics that make it suitable or unsuitable for certain applications.

• The four basic categories of material properties include physical, mechanical, electrical, and thermal properties.

Physical Properties

• Physical properties determine a material's observable characteristics.

• Include colour, density, size, and shape. An understanding of these properties is important when selecting materials for aesthetic or practical reasons.

• Density is the mass per unit volume of a material. This property can significantly affect the weight and cost of a product.

Mechanical Properties

• Mechanical properties define a material's behaviour under different stresses and strains, including hardness, tensile strength, and elasticity.

• Hardness refers to the resistance of a material to indentation or abrasion. Hard materials are often used in products required to withstand wear and tear.

• Tensile strength is the maximum amount of tensile stress a material can take before failure, such as breaking or permanent deformation.

• Elasticity describes how much a material will return to its original shape after being deformed. Elastic materials like rubber can be stretched significantly without permanent deformation.

Electrical Properties

• Electrical properties of materials like conductivity and resistivity dictate their usage in electrical applications.

• Conductivity is a measure of a material’s ability to conduct electric current. Materials with high conductivity such as copper are often used in electric wires.

• Resistivity, the inverse of conductivity, is a measure of how strongly a material opposes the flow of electric current. High-resistivity materials like plastic are used for insulation.

Thermal Properties

• Thermal properties determine how a material responds to changes in temperature and heat, critical in many manufacturing processes.

• Include thermal conductivity, specific heat capacity, and coefficient of thermal expansion.

• Thermal conductivity measures a material's ability to conduct heat. For example, metals generally have high thermal conductivity and are often used for heat sinks and cooking utensils.

• Specific heat capacity is the measure of the energy required to raise the temperature of a unit mass of a substance by one degree Celsius. This property can be important in products that must resist changes in temperature.

• The coefficient of thermal expansion describes how the size of a material changes with a change in temperature. Understanding this property is crucial for products that may be exposed to a range of temperatures.