Materials Technology

1

• Materials Technology
• Finishing of Materials

2
Overview - Degradation of Materials

• CORE
• The student will learn about
• Finishing materials.
• The student will be able to
• Select suitable finishes for materials, with due
  regard for environmental factors.
• Show an awareness of the effects of environmental
  conditions on materials and the importance of
  suitable finishing techniques.

3
Finishing of Materials

• Wood
• Many hardwood species have a natural durability
  as indeed do some softwoods, e.g. larch

or red cedar.
4
Finishing of Materials

• Wood
• Woods natural durability can be enhanced by
  applying preservatives
• Pressure treatment pre-treated in industrial
  impregnation plants (preventative)
• Spray, brush or dip application can be applied
  with the timber in-situ (curative)

5
Finishing of Materials

• Protecting Wood
• Design features capping, overhangs, sloping
  surfaces, stanchions and shoes
• Painting, varnish, etc.

6
Finishing of Materials

• Wood
• Wood is usually finished by first planeing then
  sanding. It may also require a conditioner
  before either staining or varnishing. A primer
  and undercoat is usually applied before painting.
  

7
Finishing of Materials

• Environmental considerations (Painting)
• Irritation from fumes, odours and vapours
• Contains hazardous materials such as ammonia,
  formaldehyde and volatile organic compounds (VOC)
• Can be harmful to flora and fauna
• Can leech into the water table
• Is considered a hazardous waste - cans and
  leftover paint must be disposed of appropriately

8
Finishing of Materials

• Metals
• Some non-ferrous metals are particularly
  resistant to corrosion, e.g. Copper

and Zinc
Copper Cladding
Zinc Cladding

• They form strong oxides on their surfaces (as
  do aluminium and lead) and these protect the
  metal from further oxidation. Shown as cladding
  on the buildings above

9
Finishing of Materials

• Metals
• Protection and Finishing
• There are various protection and finishing
  treatments applied to metals, they include
• Sacrificial protection
• Design features
• Anodising of aluminium
• Protective coating e.g. paint, plastic, metal
• Electro plating

10
Finishing of Materials

• Metals
• Anodising of Aluminium
• An electrolytic process that increases the
  thickness of aluminium's naturally occurring
  protective oxide film
• Organic acid electrolytes will produce harder
  films and can incorporate dyes to give the
  coating an attractive colour

11
Finishing of Materials

• Metals
• Protective Coating - Paint
• Paint is widely used particularly to protect
  steel. It is not effective over time and under
  certain conditions and must be renewed regularly
  often at considerable expense
• The more effective paints contain lead, zinc or
  aluminium in suspension and part of the
  protection they provide is sacrificial

12
Finishing of Materials

• Metals
• Protective Coating - Plastic
• A variety of plastic coatings exist, they
  include
• Brush on coating
• Electrostatic spraying
• Hot dipping in fluidised tank

13
Finishing of Materials

• Metals
• Protective Coating - Metal
• Metal coatings give the best protection they
  include
• Hot dipping
• Powder cementation
• Metal spraying
• Metal cladding
• Electro-plating

14
Finishing of Materials

• Metals
• Protective Coating Electro-plating
• Uses the chemical effect of an electric current
  to provide a decorative and/or protective metal
  coating to another metal object