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____ is a localized form of corrosion by which cavities or holes are produced in the material.

• Soil corrosion

• Pitting

• Waterline

• none of the above

Which of the following is not a cause for Corrosion ?

• Exposure to salt and other substances in environment

• Poor surface coating

• Contact with corroded metals

• High temperature and pressure

Which of the following soil components do not affect soil corrosion :

• pH of soil

• Presence of bacteria

• sulphides and carbonates

• vegetation

Correct order of stages in Hot dip galvanization process :

• Inspection > Galvanizing > Surface preparation

• Galvanizing > Surface preparation > Inspection

• Surface preparation > Galvanizing > Inspection

• Inspection > Surface preparation > Galvanixing

Which of the following is not an advantage of galvanizing ?

• Makes the surface abrasion-resistant

• Improves tensile strength of steel

• Creates barrier between steel and environment

• Eco-friendly process

How does Galvanic corrosion occur ? Which metal is typically affected by corrosion process in a Galvanic couple ?

• Due to potential difference between two different metals ; zinc - anode, platinum - cathode

• Due to potential difference between two different metals ; zinc - anode, copper - cathode

• Due to variation in oxygen concentration across the metal surface ; zinc - anode, platinum - cathode

• Due to presence of extraneous impurities (like sand, dust, scales etc) on the surface of metal ; zinc - anode, platinum - cathode

Identify the type of corrosion-protection coating -

Most preferred coating for long term corrosion protection.

The deposition rate of substance is typically faster than other coating processes.

• Metal Cladding

• Cementation

• Electroplating

• Metal spraying

Arrange the following in increasing order of vulnerability to corrosion :

• Li>Al>Mg>Zn>Fe

• Fe<Zn<Al<Mg<Li

• Li<Mg<Al<Zn<Fe

• Zn>Fe>Al>Mg>Li

With respect to Cementation -

• Sherardizing : zinc :: Colorizing : cobalt :: Chromizing : chromium

• Sherardizing : sulphur :: Colorizing : chromium ::

  Chromizing : cobalt

• Sherardizing : zinc :: Colorizing : aluminium :: Chromizing : chromium

• Sherardizing : sulphur :: Colorizing : cobalt :: Chromizing : chromium