Grade 9 Technology: Preserving Metals

Vocabulary flashcards covering metal types, causes of rust, accelerating factors, and methods of metal preservation such as painting.

Ferrous

Refers to the presence of the element iron in a metal such as steel, making the metal more prone to react with oxygen (oxidisation).

Non-ferrous metals

Metals that do not contain iron molecules, such as aluminium, copper, zinc, and gold, which are more expensive than ferrous metals.

Rust

Corrosion of iron and iron alloys caused through oxidation.

Oxidation

The reaction of a metal with oxygen.

Factors accelerating rust on steel objects

Contact with an acid or acidic environment, sea spray in the air, and climates that are misty, have high rainfall, or are very humid (a lot of moisture in the atmosphere).

Methods of preserving metals

Painting, galvanising, and electroplating.

Painting (metal preservation)

The most common and cheap method used to prevent rust by forming a protective barrier between air and the inner metal.

Main limitation of painting metal

Any small area where paint chips off becomes exposed to air containing oxygen and water, leading to rust formation.

Three coats of paint required for metal

A primer, an undercoat, and a topcoat.

Recycling materials and equipment

An action that helps reduce the need for mining, which has a negative impact on the environment.