1.3 Material Enhancement

Question 1

Quenching

Answer 1

Heating the metal until it is red hot and then cooling it quickly in liquid. Makes it hard but brittle.

Question 2

Case Hardening

Answer 2

A hard layer is created but the core remains soft. Uses carburising and quenching to achieve this.

Question 3

Annealing

Answer 3

Heating it to a high temperature (below the melting point) then cooling it, usually in the air. The process has the effect of toughening by lessening brittleness and reducing internal stresses.

Question 4

Carburising

Answer 4

Changes the chemical composition of steel so it can absorb more carbon to increase surface hardness. Placed in a ceramic box packed with carbon. Heated to around 950C so carbon can diffuse into the surface.

Question 5

Hardening

Answer 5

The process of heating steels to alter the crystalline structure. It is then held at this temperature and finally quenched in water, oils or saltwater baths. It increases its hardness but also its brittleness.

Question 6

Tempering

Answer 6

Heating a metal until red hot and leaving it to cool slowly so it hardens and becomes ductile w/o being brittle.

Question 7

Work hardening

Answer 7

Cold working a metal until it hardens from fatigue and gets more tensile strength.

Question 8

Key Advantage of tempering

Answer 8

Increases hardness without making the metal brittle

Question 9

Disadvantages of Natural Timbers without enhancement

Answer 9

• Not very Durable outside
• Flammable
• Hardness
• Toughness

Question 10

Resins and laminations

Answer 10

• Used in engineer Wood
• Makes use of the useless parts: fibres, sawdust and wood chips.
• E.g Chipboard (made from compressing wood chips from a resin

Question 11

Resins and Fire Retardant

Answer 11

• resins impregnated into the wood with fire retardant cladding
• e.g indoor flooring

Question 12

laminations

Answer 12

Veneers such as natural woods are laminated onto the board to enhance aesthetics

Question 13

Preservatives

Answer 13

• Protect the wood from fungal and insect attack (for outdoor)
• Wood is pre treated with a copper-based preservative -penetrates the wood to protect the whole plank

Question 14

Pigments

Answer 14

• added to preservatives
• Gives different coloured shades to improve aesthetics
• Can also be used to make softwoods look like hardwoods
• e.g Outdoor Decking

Question 15

Fire Retardant Preservatives

Answer 15

Used to pressure treat wood

• can make wood harder and more resistant to high wear situations
• e.g roof joists , cladding , flooring

Question 16

Modified Natural Polysaccharide

Answer 16

wood is impregnated ro cure within the wood cell structure

- results in increased hardness, toughness and stability