Rate of slag attack on refractories typically increases with temperature primarily because of what change in slag behavior?

Introduction / Context:
Slag corrosion is a major wear mechanism. Understanding why higher temperature accelerates attack helps in choosing compositions and operating windows that extend lining life.

Given Data / Assumptions:

• As temperature rises, slags become more fluid (viscosity decreases).
• Mass transfer and reaction rates increase with fluidity and temperature.

Concept / Approach:
Lower viscosity promotes infiltration and dissolution of refractory components by the slag. This, combined with faster reaction kinetics at higher temperature, raises corrosion rates. While thermal conductivity of bricks may change with temperature, it is not the primary reason slag attack increases.

Step-by-Step Solution:
Relate T ↑ to slag viscosity ↓.Infer increased slag mobility and penetration.Select “Decreased viscosity of slag.”

Verification / Alternative check:
Corrosion tests show stronger dissolution rates at higher temperatures due to enhanced fluidity and diffusion.

Why Other Options Are Wrong:
Brick conductivity or oxidising conditions are secondary/context-specific, not the main universal cause.

Common Pitfalls:
Over-attributing wear to atmosphere alone; slag fluidity is central.

Final Answer:
Decreased viscosity of slag