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Published byGuillermo Wroe Modified over 8 years ago
Materials Technology Finishing of Materials
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.
Finishing of Materials Wood Many hardwood species have a natural durability as indeed do some softwoods, e.g. larch or red cedar.
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)
Finishing of Materials Protecting Wood Design features – capping, overhangs, sloping surfaces, stanchions and shoes Painting, varnish, etc.
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.
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
Metals Some non-ferrous metals are particularly resistant to corrosion, e.g. Copper 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 and Zinc Copper Cladding Zinc Cladding 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 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 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 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 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 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 Finishing of Materials
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