Materials and Their Properties
Categories and properties
Candidates must classify materials as hardwoods (oak, ash, beech), softwoods (pine, spruce), manufactured boards (plywood, MDF, chipboard), ferrous metals (steel, cast iron), non-ferrous metals (aluminium, copper, brass), thermoplastics (acrylic, HDPE, polystyrene), thermosetting plastics (epoxy, melamine), composites (GRP, carbon fibre) and smart/modern materials (shape-memory alloys, photochromic pigments).
Linking property to use
Understand mechanical properties - strength, stiffness, toughness, hardness, ductility, malleability, elasticity - and physical properties such as density, thermal and electrical conductivity, and resistance to corrosion. Be able to justify a material choice by matching properties to function: aluminium for lightweight corrosion-resistant frames, mild steel for strength and weldability, MDF for smooth stable panels, HDPE for weather-resistant outdoor products.
Common traps
Questions often test the difference between strength (resists load without breaking) and stiffness (resists deflection), or between thermoplastic (reformable on heating) and thermoset (cannot be remelted). Another trap is assuming hardwood is always stronger than softwood, or forgetting that composites are anisotropic - strong along the fibre direction only.
Worked rule of thumb
Use a property-matching sentence: 'Material X is chosen because property Y meets requirement Z.' Example: HDPE is chosen for a garden chair because it is weather-resistant and tough, whereas MDF would swell and fail outdoors.