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The Science And Engineering Of Materials, Instructor's Solution Manual 4Th, Askeland School

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The Science And Engineering Of Materials, Instructor's Solution Manual 4Th, Askeland School Rutgers University Course Title 440 407 Instructors‘ Solution ManualTHE SCIENCEAND ENGINEERINGOF MATE ... RIALSFourth EditionDonald R. AskelandPradeep P. PhuléPrepared by Gregory Lea 11Introduction to Materials Science and Engineering1–5Iron 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? Whatprecautions 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 theiron is completely coated with zinc, the zinc provides a barrier betweenthe iron and the surrounding environment, therefore protecting theunderlying iron. If the zinc coating is scratched to expose the iron, thezinc continues to protect the iron because the zinc corrodes preferentiallyto the iron (see Chapter 22). To be effective, the zinc should bond wellto the iron so that it does not permit reactions to occur at the interfacewith the iron and so that the zinc remains intact during any forming ofthe galvanized material. When the material is recycled, the zinc will belost by oxidation and vaporization, often producing a “zinc dust” thatmay pose an environmental hazard. Special equipment may be requiredto collect and either recycle or dispose of the zinc dust.1–6We would like to produce a transparent canopy for an aircraft. If we were to use aceramic (that is, traditional window glass) canopy, rocks or birds might cause it toshatter. Design a material that would minimize damage or at least keep the canopyfrom breaking into pieces.Solution:We might sandwich a thin sheet of a transparent polymer between twolayers of the glass. This approach, used for windshields of automobiles,will prevent the “safety” glass from completely disintegrating when it fails, with the polymer holding the broken pieces of glass together untilthe canopy can be replaced.Another approach might be to use a transparent, “glassy” polymermaterial such as polycarbonate. Some polymers have reasonably goodimpact 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 energy-absorbing ability of the composite polymer, while being too small tointerfere with the optical properties of the material.1–7Coiled springs ought to be very strong and stiff. Si3N4is a strong, stiff material.Would you select this material for a spring? Explain.Solution:Springs are intended to resist high elastic forces, where only the atomicbonds are stretched when the force is applied. The silicon nitride wouldsatisfy this requirement. However, we would like to also have goodresistance to impact and at least some ductility (in case the spring isoverloaded) to assure that the spring will not fail catastrophically. Wealso would like to be sure that all springs will perform satisfactorily [Show More]

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