ME Ceramics, Glasses, and Electronic Materials 3

Question 1

The sintering process in ceramics densifies the material by:

Accepted Answer

Diffusion-driven elimination of porosity and grain boundary migration at elevated temperature

Answer

Melting the powder and resolidifying it in a mold

Answer

Chemical vapor deposition onto a substrate

Answer

Mechanical compression without any heat

Question 2

Which of the following ceramic materials is used as a thermal barrier coating (TBC) in gas turbine blades?

Accepted Answer

Yttria-stabilized zirconia (YSZ)

Answer

Silicon carbide (SiC)

Answer

Alumina (Al2O3)

Answer

Boron nitride (BN)

Question 3

Ferroelectric materials differ from piezoelectric materials in that ferroelectrics:

Accepted Answer

Have spontaneous electric polarization that can be reversed by an applied electric field

Answer

Show piezoelectricity only at temperatures above their Curie point

Answer

Are non-centrosymmetric only under mechanical stress

Answer

Cannot be poled to align domains

Question 4

Chemically strengthened glass (e.g., Gorilla Glass) achieves high strength by:

Accepted Answer

Ion exchange: replacing smaller Na+ ions with larger K+ ions in the surface layer to create compressive stress

Answer

Rapid cooling to create residual compressive surface stresses

Answer

Adding alumina to the glass composition to increase covalent bonding

Answer

Laminating two glass layers with a polymer interlayer

Question 5

The dielectric constant (relative permittivity) of a material is important in capacitor design because:

Accepted Answer

Higher dielectric constant allows a capacitor to store more charge at a given voltage and size

Answer

Higher dielectric constant reduces the capacitor's breakdown voltage

Answer

It determines the resistance of the dielectric layer

Answer

It controls the inductance of the capacitor

Question 6

Galvanic corrosion occurs when:

Accepted Answer

Two dissimilar metals are in electrical contact in an electrolyte, causing the less noble metal to corrode preferentially

Answer

A metal is exposed to an oxidizing acid solution

Answer

A single metal undergoes uniform dissolution in saline water

Answer

Stray electrical currents pass through a metal structure