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Chapter 12: Problem 45

Cite one reason why ceramic materials are, in general, harder yet more brittle than metals.

Short Answer

Expert verified
Answer: The main reason ceramics are generally harder yet more brittle than metals is due to the strong, directional ionic and covalent bonds present in ceramics. These bonds result in a rigid lattice structure that does not easily deform under stress, making ceramics harder but more prone to breakage and cracking compared to metals with their non-directional, more deformable metallic bonds.

Step by step solution

01

Understand the properties of ceramics and metals

Ceramic materials are generally composed of inorganic, nonmetallic compounds that are formed by the combination of metallic and nonmetallic elements, like aluminum and oxygen, through ionic and covalent bonds. On the other hand, metals are composed of metallic elements held together by metallic bonds.
02

Discuss the atomic bonding in ceramics and metals

The key difference between ceramics and metals lies in their atomic bonding. Ceramics have ionic and covalent bonds, which are strong, directional bonds responsible for the high hardness of these materials. Metals, on the other hand, have metallic bonds, which are non-directional and involve the sharing of valence electrons among atoms. These metallic bonds are not as strong as ionic and covalent bonds, which makes metals generally less hard than ceramics.
03

Explain the effect of atomic bonding on brittleness

The strong, directional ionic and covalent bonds in ceramics make them hard but also contribute to their brittleness. The directional nature of these bonds results in a more rigid lattice structure, which cannot easily deform when subjected to stress. This is why ceramics tend to break or crack easily under stress. In contrast, the non-directional metallic bonds allow the atoms to slide past one another when subjected to stress, causing the material to deform rather than break or crack. This property of metals is often referred to as their ductility, which makes them more resistant to breakage and less brittle than ceramics.
04

Citing the reason for hardness and brittleness in ceramics

One reason why ceramic materials are, in general, harder yet more brittle than metals is due to the strong, directional ionic and covalent bonds present in ceramics. These bonds result in a rigid lattice structure that does not easily deform under stress, making ceramics harder but more prone to breakage and cracking compared to metals with their non-directional, more deformable metallic bonds.

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Most popular questions from this chapter

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