Niquel

Instructors‘ Solution Manual

THE SCIENCE
AND ENGINEERING
OF MATERIALS
Fourth Edition

Instructors‘ Solution Manual

THE SCIENCE
AND ENGINEERING
OF MATERIALS
Fourth Edition

Donald R. Askeland
Pradeep P. Phulé
Prepared by Gregory Lea

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Introduction to Materials Science
and Engineering

1–5

Iron is often coated with a thin layer of zinc if it is to be used outside.What characteristics do you think the zinc provides to this coated, or galvanized, steel? What
precautions should be considered in producing this product? How will the recyclability of the product be affected?
Solution:

1–6

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 thesurrounding 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 intactduring 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.

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 whenit

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The Science and Engineering of Materials

Instructor’s Solution Manual

fails, with the polymer holding the broken pieces of glass together until
the canopy can be replaced.
Another approach might be to use a transparent, “glassy” polymer
material such as polycarbonate. Some polymers have reasonably good
impact properties and may resist failure. The polymers can also betoughened to resist impact by introducing tiny globules of a rubber,
or elastomer, into the polymer; these globules improve the energyabsorbing ability of the composite polymer, while being too small to
interfere with the optical properties of the material.
1–7

Coiled springs ought to be very strong and stiff. Si3N4 is a strong, stiff material.
Would you select this material for a spring?Explain.
Solution:

1–8

Temperature indicators are sometimes produced from a coiled metal strip that
uncoils a specific amount when the temperature increases. How does this work;
from what kind of material would the indicator be made; and what are the important
properties that the material in the indicator must possess?
Solution:

1–9

Springs are intended to resist high elasticforces, where only the atomic
bonds are stretched when the force is applied. The silicon nitride would
satisfy this requirement. However, we would like to also have good
resistance to impact and at least some ductility (in case the spring is
overloaded) to assure that the spring will not fail catastrophically. We
also would like to be sure that all springs will perform satisfactorily.
Ceramicmaterials such as silicon nitride have virtually no ductility,
poor impact properties, and often are difficult to manufacture without
introducing at least some small flaws that cause to fail even for
relatively low forces. The silicon nitride is NOT recommended.

Bimetallic materials are produced by bonding two materials having
different coefficients of thermal expansion to one another,...