Corrosion 6

Question 1

is also
known as general corrosion. A
type of corrosion where the
corroded areas occur in a
manner evenly distributed
across the material being
attacked.

Answer 1

Uniform corrosion

Question 2

is a primary cause of
uniform corrosion in steels,
alloys, and other metals in
natural environments.

Answer 2

Oxygen

Question 3

is
also known as
intergranular attack (IGA).
This is a specialized type of
attack that takes place at
the grain boundaries of a
metal.

Answer 3

Intergranular corrosion

Question 4

This form of corrosion is
often caused by impurities
in the metal, leading to
chemical or
electrochemical attack on
the grain boundaries.

Answer 4

INTERGRANULAR CORROSION

Question 5

is also known
as dissimilar metal corrosion or
bimetallic corrosion. When two
different metallic
materials are electrically
connected and placed in a
conductive solution (electrolyte),
an electric potential exists.

Answer 5

Galvanic corrosion

Question 6

is a
localized type of corrosion
occurring within or adjacent
to narrow gaps.

Answer 6

Crevice corrosion

Question 7

is
characterized by a highly
localized loss of metal. The
initiation of a pit is associated
with the breakdown of the
protective film on the metal
surface

Answer 7

Pitting corrosion

Question 8

is
usually caused by an
aqueous or gaseous
corrodent flowing over
the metal surface or
impinging upon it.

Answer 8

Erosion corrosion

Question 9

is a phenomenon where cracks
form and propagate in a
material due to the combined
effects of sustained tensile
stress and exposure to a
corrosive environment.

Answer 9

Stress corrosion cracking

Question 10

refers to the
degradation of metals caused
by the activity of living
organisms. This is also referred
to as microbial-induced
corrosion (MIC).

Answer 10

Biologically influenced
corrosion

Question 11

is the term to
describe the leaching of zinc
from brass.

Answer 11

Dezincification

Question 12

is the term
used to describe the selective
leaching of iron from gray cast
iron.

Answer 12

Graphite corrosion

Question 13

When intergranular corrosion
takes place in a metal with a
highly directional grain structure,
it propagates internally, parallel
to the surface of the metal.

Answer 13

EXFOLIATION

Question 14

is the cracking of a
metal or alloy under the combined
action of a corrosive environment and
repeated or fluctuating stress.

Answer 14

Corrosion fatigue

Question 15

is when metals and
alloys fail by cracking when subjected
to cyclic or repetitive stress

Answer 15

Fatigue failure

Question 16

The growth formation is explained by the
formation of a differential aeration cell

Answer 16

FILIFORM CORROSION

Question 17

the process
of a metal returning to
the material’s
thermodynamic stat

Answer 17

Corrosion

Question 18

The measure of the potential
difference between two half
cells in an electrochemical cell

Answer 18

Cell Potential

Question 19

may be formed when two
dissimilar metals are in
contact or due to the
heterogeneity of the
same metal surface

Answer 19

Dissimilar electrode cells

Question 20

are
formed when the
electrodes are identical
but are in contact with
solutions of differing
composition

Answer 20

Concentration cells

Question 21

Formed when electrodes
of the same metal, each of
which is at a different
temperature, are
immersed in an
electrolyte of the same
initial composition

Answer 21

DIFFERENTIAL TEMPERATURE CELL

Question 22

This situation arises when
a significant difference in
metal ion concentration
exists over ametal
surface

Answer 22

METAL ION CONCENTRATION CELLS

Question 23

Also knownas Pourbaix Diagram

Answer 23

Potential-Ph Diagrams

Question 24

Constructed from calculations
based on the Nernst equation and
the solubility data for various
metal compounds

Answer 24

Potential-Ph Diagrams

Question 25

Under these condition of potential and pH, the metal remains in metallic form and is free from corrosion

Answer 25

Immunity Zone

Question 26

Under these condition of potential and pH, the metal corrodes

Answer 26

Corrosion Zone

Question 27

Under these condition of potential and pH, protective layer of the metal's hydroxide or oxide form on iron and further corrosion of metal doesn’t take place

Answer 27

Passive zone

Question 28

The potential change caused by net current to or from an electrode, measured in volts

Answer 28

POLARIZATION

Question 29

is a manifestation of the relative changes in the activation energies for dissolution and deposition, when equilibrium is disturbed.

Answer 29

Activation polarization

Question 30

Polarization of an electrolytic cell resulting from changes in the electrolyte concentration due to the passage of current through the electrode/solution interface

Answer 30

Concentration Polarization

Question 31

The change in voltage associated with effects of the environment and the circuit between the anode and cathode sites. It includes the effects of the resistivity of the media, surface films, corrosion products, etc.

Answer 31

Resistance Polarization

Question 32

is a complicated electrochemical process taking place in corrosion cells consisting of base metal, metallic corrosion products, surface electrolytes, and the atmosphere

Answer 32

Atmospheric corrosion

Question 33

is negligible in climates where the air temperature is below the freezing point of water because ice is a poor conductor and does not function effectively as an electrolyte

Answer 33

Rusting

Question 34

refers to the length of time during which the metal surface is covered by a film of water

Answer 34

Time of wetness

Question 35

The amount of water adsorbed on a metal surface depends on the relative humidity of the atmosphere and on the chemical and physical properties of the corrosion products.

Answer 35

Adsorption Layers

Question 36

Occurs when the temperature of the metal surface is below the dew point of the atmosphere

Answer 36

Dew

Question 37

creates even thicker layers of electrolyte on the surface than dew. It affects corrosion by adding a phase layer of moisture and corrosion stimulators.

Answer 37

Rain

Question 38

high acidity and high concentrations of sulfates and nitrate can be found in fog droplets in areas of high air pollution

Answer 38

Fog

Question 39

can promote corrosion because of their hygroscopic nature

Answer 39

Dust

Question 40

on the surface will contain various species deposited from the atmosphere or originating from the corroding metal.

Answer 40

electrolyte film

Question 41

The metal is covered with a spontaneously formed oxide and aqueous layer

Answer 41

INDUCTION PERIOD

Question 42

The oxide layer transforms into a fully developed layer of corrosion products

Answer 42

TRANSITION PERIOD

Question 43

The surface being fully covered by corrosion product and reach constant corrosion rate

Answer 43

STATIONARY PERIOD

Question 44

defined as the ratio of deposition rate of any gaseous compound and the concentration of that compound in the atmosphere

Answer 44

dry deposition velocity

Question 45

When small amounts of copper, chromium, nickel, etc. are added to carbon steel, low-alloy carbon steel results. These steels are known as

Answer 45

weathering steels