Question

Which combination of mechanical properties is typically shown by Ceramics?

• A. \( \text{High ductility and low toughness} \)
• B. \( \text{High hardness and high brittleness} \)
• C. \( \text{Low hardness and high ductility} \)
• D. \( \text{High tensile strength and high toughness} \)

Hint:

Ceramics = High hardness, excellent compressive strength, but highly brittle (very prone to cracking under sudden impact or tension).

Answer 1

The Correct Option is B

Concept: Ceramics are inorganic, non-metallic compounds featuring strong ionic and covalent bonding networks. These highly localized directional bonds require immense energy to disrupt, making dislocation motion (plastic slip) nearly impossible.

Step 1: Translating Bond Architecture to Mechanical Properties
- Due to tight ionic/covalent networks, ceramics resist localized surface deformation exceptionally well, which translates into high hardness. - Because dislocations cannot easily glide to dissipate stress concentrates, stress accumulates at cracks or structural defects. When the load exceeds a critical threshold, these cracks propagate instantly through the crystal structure, resulting in catastrophic failure without warning. This is high brittleness.

Step 2: Reviewing Alternate Options
Ceramics are notorious for lacking ductility and fracture toughness under tensile configurations, which rules out options (1), (3), and (4).