This set of Ceramics Engineering Multiple Choice Questions & Answers (MCQs) focuses on “General Properties of Ceramics”.
1. Why are most of the ceramics brittle?
a) Because of mixed ionic-covalent bonding
b) Because of metallic bonding
c) Because of ionic bonding
d)Because of covalent bonding
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Explanation: Ceramics contain mixed ionic-covalent bonds. The bonding of atoms in mixed ionic-covalent systems is much stronger than metallic bonding in metals. That is why, metals are ductile and ceramics are brittle.
2. Which of the following ceramics is good conductor of electricity at room temperature?
a) Diamond
b) Rhenium Trioxide
c) Boron Trioxide
d) Gypsum
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Explanation: Rhenium Trioxide has electrical conductivity at room temperature similar to that of copper. As temperature decreases, its resistivity decreases. Diamond, boron trioxide and gypsum are bad conductors of electricity.
3. Ceramics are stronger in compression than in tension.
a) True
b) False
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Explanation: Ceramics possess internal cracks and impurities. Tensile load is applied perpendicular to the direction of cracks, that is why these cracks propagate further and cause failure. Compressive load is applied parallel to the direction of cracks which is why cracks do not propagate. Therefore, ceramics are stronger in compression than in tension.
4. Why are most of the ceramics transparent?
a) Because of metallic bond
b) Because of mixed ionic-covalent bonds
c) Because of large band gap
d) Because of high glass transition temperature
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Explanation: Due to high energy gap in ceramics, photons cannot excite electrons into high energy level. This allows photons to pass through the material unaffected, making it transparent. For example, alumina.
5. What happens to glass when it is heated above its glass transition temperature?
a) It behaves as a viscous fluid
b) It becomes brittle
c) It becomes hard
d) It conducts electricity
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Explanation: Above glass transition temperature, few intermolecular bonds are broken or become loose. This allows movement of atoms around the bonds. Thus glass becomes soft and viscous. This property is helpful in creating intricate shapes in glass.
6. Which of the following ceramics is a High Temperature Superconductor (HTSC)?
a) Feldspar
b) Silica
c) Cryolite
d) Yttrium barium copper oxide
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Explanation: Yttrium barium copper oxide is a High Temperature Superconductor (HTSC). It has zero resistivity below 92 K. Feldspar, silica and Cryolite are examples of non conducting ceramics.
7. Why are ceramics used in structural applications?
a) Due to high compressive strength
b) Due to low coefficient of thermal expansion
c) Due to high strength to weight ratio
d) Due to low fracture toughness
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Explanation: Ceramics tend to resist high temperatures. Therefore, they have low coefficient of thermal expansion. They are used in structural applications like buildings and bridges which require high thermal stability.
8. The following graph shows stress-strain curve of a material. What type of material is it?
a) Polymers
b) Composites
c) Metals
d) Ceramics
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Explanation: Ceramics are highly brittle materials and do not undergo deformation. They tend to fracture when they enter the plastic deformation region. Therefore the given graph represents ceramic materials.
9. Which of the following is in decreasing order of room temperature stiffness (Young’s Modulus)?
a) Ceramics > Metals > Composites > Polymers
b) Polymers > Ceramics > Metals > Composites
c) Metals > Ceramics > Composites > Polymers
d) Composites > Ceramics > Metals > Polymers
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Explanation: Ceramics have the highest stiffness values at room temperature due to strong ionic or covalent bonding. Metals undergo deformation therefore they have lower stiffness values than ceramics. Polymers are highly flexible therefore they have lowest stiffness values.
10. Which of the following has the highest room temperature resistance to fracture?
a) Ceramics
b) Metals
c) Polymers
d) Composites
View Answer
Explanation: Metals have high ductility and undergo ductile fracture. Therefore, they have very high room temperature resistance to fracture. Composites have comparatively lower values of fracture toughness. However, ceramics and polymers have poor resistance to fracture.
Sanfoundry Global Education & Learning Series – Ceramics Engineering.
To practice all areas of Ceramics Engineering, here is complete set of Multiple Choice Questions and Answers.
