Engineering material

Question

(i) Write short notes on general properties of engineering materials.

(ii) Cite examples from the engineering field where thermal expansion/contraction is put to use in the engineering industry.

(iii) State how expansion of metals is accommodated in the transfer of hot liquids or in high temperature surroundings.

Answer 1

(i) Here are some general properties of engineering materials:

1. Mechanical Properties:
   - Strength: The ability of a material to withstand applied forces without yielding or fracturing.
   - Stiffness: The resistance of a material to deformation under stress.
   - Ductility: The extent to which a material can be deformed plastically without fracture.
   - Hardness: The resistance to indentation or scratching.
   - Toughness: The ability of a material to absorb energy and deform before fracturing.

2. Physical Properties: 
   - Density: Mass per unit volume of a material.
   - Thermal Conductivity: The ability of a material to conduct heat.
   - Electrical Conductivity/Resistivity: Ability to conduct or resist the flow of electricity.
   - Thermal Expansion: The change in size of a material with temperature variations.
   - Optical Properties: Transparency, reflectivity, and absorption of light.

3. Chemical Properties:
   - Corrosion Resistance: Ability to withstand degradation or deterioration by chemical reactions with the environment.
   - Chemical Stability: Resistance to chemical reactions or decomposition.
   - Oxidation Resistance: Ability to resist reactions with oxygen.

4. Environmental Properties:
   - Weathering Resistance: Resistance to degradation due to environmental exposure like sunlight, moisture, or chemicals.
   - Fatigue Resistance: Ability to resist failure under repeated or cyclic loading.

5. Manufacturing Properties:
   - Machinability: Ease with which a material can be cut, shaped, or formed.
   - Weldability: Ability to be welded without losing integrity.
   - Castability: Capability of a material to be shaped through casting processes.

Engineering materials often possess a combination of these properties, and the choice of material for a specific application depends on the desired characteristics and performance requirements in that particular context.