,
, I
THE SCIENCE AND ENGINEERING OF MATERIALS, INSTRUCTORS SOLUTION
MANUAL 4TH, ASKELAND
THE SCIENCE AND ENGINEERING OF MATERIALS, INSTRUCTORS SOLUTION
MANUAL 4TH, ASKELAND
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1–5 Iron is often coated with a thin layer of zinc if it is to be used outside.
What charac- teristics do you think the zinc provides to this coated, or
galvanized, steel? What precautions should be considered in producing
this product? How will the recycla- bility of the product be affected?
Solution: The zinc provides corrosion resistance to the iron in two
ways. If the iron is completely coated with zinc, the zinc
provides a barrier between the iron and the surrounding
environment, therefore protecting the underlying iron. If
the zinc coating is scratched to expose the iron, the zinc
continues to protect the iron because the zinc corrodes
preferentially to the iron (see Chapter 22). To be effective,
the zinc should bond well to the iron so that it does not
permit reactions to occur at the interface with the iron and
so that the zinc remains intact during any forming of the
galvanized material. When the material is recycled, the zinc
will be lost by oxidation and vaporization, often producing
a “zinc dust” that may pose an environmental hazard.
Special equipment may be required to collect and either
recycle or dispose of the zinc dust.
1–6 We would like to produce a transparent canopy for an aircraft. If we
were to use a ceramic (that is, traditional window glass) canopy,
rocks or birds might cause it to shatter. Design a material that would
minimize damage or at least keep the canopy from breaking into
pieces.
Solution: We might sandwich a thin sheet of a transparent polymer
between two layers of the glass. This approach, used for
windshields of automobiles, will prevent the “safety” glass
from completely disintegrating when it
, I
THE SCIENCE AND ENGINEERING OF MATERIALS, INSTRUCTORS SOLUTION
MANUAL 4TH, ASKELAND
THE SCIENCE AND ENGINEERING OF MATERIALS, INSTRUCTORS SOLUTION
MANUAL 4TH, ASKELAND
, 1
iM
c
u
d
tro
In
S
ls
e
a
g
E
1–5 Iron is often coated with a thin layer of zinc if it is to be used outside.
What charac- teristics do you think the zinc provides to this coated, or
galvanized, steel? What precautions should be considered in producing
this product? How will the recycla- bility of the product be affected?
Solution: The zinc provides corrosion resistance to the iron in two
ways. If the iron is completely coated with zinc, the zinc
provides a barrier between the iron and the surrounding
environment, therefore protecting the underlying iron. If
the zinc coating is scratched to expose the iron, the zinc
continues to protect the iron because the zinc corrodes
preferentially to the iron (see Chapter 22). To be effective,
the zinc should bond well to the iron so that it does not
permit reactions to occur at the interface with the iron and
so that the zinc remains intact during any forming of the
galvanized material. When the material is recycled, the zinc
will be lost by oxidation and vaporization, often producing
a “zinc dust” that may pose an environmental hazard.
Special equipment may be required to collect and either
recycle or dispose of the zinc dust.
1–6 We would like to produce a transparent canopy for an aircraft. If we
were to use a ceramic (that is, traditional window glass) canopy,
rocks or birds might cause it to shatter. Design a material that would
minimize damage or at least keep the canopy from breaking into
pieces.
Solution: We might sandwich a thin sheet of a transparent polymer
between two layers of the glass. This approach, used for
windshields of automobiles, will prevent the “safety” glass
from completely disintegrating when it
