In refractory testing, a dilatometer is primarily used to determine which property related to dimensional change on heating?

Introduction / Context:
Accurate measurement of thermal expansion and dimensional changes is critical in refractory quality control. The dilatometer is a common instrument for these evaluations.

Given Data / Assumptions:

• Dilatometry measures length change versus temperature under a specified heating schedule.
• Permanent linear change (PLC) after firing reflects sintering/shrinkage or expansion.

Concept / Approach:
While modulus of rupture, RUL, and CO attack resistance require different tests, dilatometry directly captures thermal expansion curves and resultant permanent dimensional changes after a prescribed thermal cycle—reported as PLC, a key acceptance criterion.

Step-by-Step Solution:
Identify the instrument capability: length change vs temperature.Relate it to reporting PLC after a cycle.Select “Permanent linear change (PLC).”

Verification / Alternative check:
Standard test methods (e.g., PLC tests) reference dilatometry and post-cycle measurements for specification compliance.

Why Other Options Are Wrong:
MOR, RUL, CO attack, and conductivity involve different rigs and procedures.

Common Pitfalls:
Equating thermal expansion coefficient with PLC; PLC is the permanent net change after cycling, not just instantaneous expansion.

Final Answer:
Permanent linear change (PLC)