ME Ceramics, Glasses, and Electronic Materials

Question 1

The primary bonding type in most ceramic materials is:

Accepted Answer

Ionic and/or covalent bonding

Answer

Ceramics are held together by ionic bonds (in oxides), covalent bonds (in carbides/nitrides), or a combination of both, which explains their high hardness and brittleness.

Question 2

Which defect in a crystalline ceramic consists of a cation vacancy paired with an anion vacancy to maintain electrical neutrality?

Accepted Answer

Schottky defect

Answer

A Schottky defect consists of a paired cation-anion vacancy that maintains charge neutrality in the crystal.

Question 3

The main reason ceramics are brittle compared to metals is:

Accepted Answer

Lack of mobile dislocations due to strong directional bonding and large unit cells

Answer

Ceramics have strong ionic/covalent bonds and complex crystal structures that make dislocation motion energetically very difficult, preventing plastic deformation and causing brittleness.

Question 4

Silica glass (SiO2) has an amorphous structure because:

Accepted Answer

Rapid cooling from the melt prevents long-range atomic ordering

Answer

Silica glass is formed by cooling the melt rapidly enough that the SiO4 tetrahedra cannot arrange into a periodic crystalline lattice, resulting in a random network.

Question 5

Partially stabilized zirconia (PSZ) is toughened by which mechanism?

Accepted Answer

Transformation toughening: stress-induced tetragonal-to-monoclinic phase transformation at a crack tip

Answer

In PSZ, the stress field ahead of a crack tip triggers the tetragonal-to-monoclinic transformation, which involves a volume expansion that closes the crack and absorbs energy.

ME - Materials Engineer Practice Test

ME - Materials Engineer Practice Test

ME Ceramics, Glasses, and Electronic Materials