Corrosion

Electrochemical corrosion must have

• Cathode, anode and electrolyte

• Cathode ,anode and aluminium

• Anode , cathode and nickel

• Anode ,cathode and magnesium

Fretting corrosion occurs when there is

• Deep scratch

• Cut on the metal

• Small movement between two materials against each other

• Pitting corrosion

Corrosion on magnesium can be identified as

• Reddish - brown oxide

• Blue - greenish powdery deposit

• Grey colour deposits

• White spots on the surface

The corrosion caused, when two dissimilar metals touch each other

• Fatigue corrosion

• Galvanic corrosion

• Fretting corrosion

• Surface corrosion

Anodising treatment of aluminium

• produces a coating of aluminium oxide on the surface

• produces a coating of iron oxide on the surface

• produces a coating of magnesium oxide on the surface

• produces a coating of titanium dioxide on the surface

Corrosion at the grain boundaries is called

• Fretting corrosion

• Filiform corrosion

• Surface corrosion

• Intergranular corrosion

Black marks from a rivet on engine cowling and wing skins are due to

• Filiform corrosion

• Pitting corrosion

• Fretting corrosion

• Intergranular corrosion

Corrosion on brass or bronze appears as

• Reddish-brown oxide

• White spots on the surface

• Dark spots on the surface

• Blue-green powdery deposit

Which of these is a common cause of corrosion?

• Untreated metal

• Spilled battery acid

• Incorrect alloying

• Water in fuel

Lead-acid battery acid deposits can be cleaned with

• Sulphuric acid

• Sulphur and Lime

• Hot distilled water

• Sodium bicarbonate