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Unformatted text preview: depending on the conditions under
which the bonds were formed. In the case of graphite, the primary bonds exist within a plane; the carbon atoms
lying within a single plane are strongly bonded in a two-dimensional network while the forces holding adjacent
planes together are rather weak. A structure is thus formed in which adjacent planes can easily slide over
one another and the material in this form exhibits good lubricating properties. On the other hand, if high
temperature and pressure are exerted upon this solid, the character of the bonds changes to a three
dimensional structure. The bonds of the carbon atoms take on a shape akin to toy jacks. These “jacks” bond
together in a three-dimensional network to form diamond, the hardest material known to man. It is possible
to produce diamonds commercially and such diamonds are used in drill bits for drilling through very hard
minerals as well as for other kinds of cutting tools.
In this chapter we shall study the basic principles of bonding and examine some of the relationships
between the underlying bond character and material properties. | v v 23 | e-Text Main Menu | Textbook Table of Contents pg024 [V] G2 7-27060 / IRWIN / Schaffer 24 Part I pgm 1-14-98 plm 3-21-98 MP Fundamentals body-centered cubic (BCC) A cubic structure in
which atoms are located in the corners of the unit cell
| e-Text center of | Textbook Table of Contents
plus one in the Main Menu the cubic unit cell.
v a vinyl polymer whose side
ioned during polymerization. v measure of the amount of
athermal Describing a phase transformation that is not
arent material, expressed in
thermally activated. That is, the extent of the reaction is
Have you wondered why metals are good electrical conductors while ceramics and
not a function of time, but depends on temperature. The
plastics are generally good insulators? Why does rubber stretch while metals are relatively
martensite to an applied force? Why is diamond able to cut
urity level within the band gap
rigid in response tran...
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