Materials and Their Properties
Materials and Their Properties tests whether you can name a material, describe how it behaves and justify a selection for a real component. Expect property definitions, timber and manufactured board, metals and alloys, plastics, and simple environmental comparisons.
Core rules
- Hardness resists indentation or scratching; toughness resists impact without fracturing; ductility allows drawing into wire; malleability allows hammering into sheet; elasticity allows recovery after load.
- Hardwood comes from broadleaved trees and softwood from conifers; the terms do not mean hard and soft. Grain direction affects strength and how timber cuts, screws and finishes.
- Ferrous metals contain iron and can rust; non-ferrous metals do not; alloys are mixtures such as brass or stainless steel. Thermoplastics can be remelted; thermosetting plastics char rather than soften.
- Select for the dominant service condition, not just appearance: moisture, heat, wear, weight, cost and fixing method.
Worked example
Choose a kitchen worktop. It needs surface hardness, moisture resistance and hygiene. Solid oak gives warmth and can be refinished, but it needs regular oiling and can stain at the sink. Compact laminate resists water and impact and is easy to clean, but edges must be sealed and it is harder to repair. For a wet kitchen the laminate is the better justified choice; for a feature island with low water exposure, oak may be acceptable if maintained.
Traps
Do not confuse hardness with toughness, or ductility with malleability. Do not claim all plastics are easily recycled, and do not ignore grain when specifying a timber joint.