Chromite refractories: Select the correct combined statements about bonding, thermal fatigue resistance, and slag resistance.

Introduction / Context:Chromite refractories (based on FeO·Cr2O3 spinel compositions) are widely used in metallurgical furnaces where a neutral-to-basic refractory is advantageous. Their behavior against thermal cycling and basic slags influences lining life in steel and nonferrous operations.

Given Data / Assumptions:

• Bonding systems for chromite shapes include lime and clay additions.
• Thermal fatigue (spalling) resistance depends on thermal expansion, thermal conductivity, and microstructural stability.
• Basic slag resistance is a key selection criterion for certain vessels.

Concept / Approach:Chromite (especially low-silica grades) exhibits good resistance to basic slags and thermal shock/fatigue relative to some silica and magnesite products in specific operating windows. Traditional manufacturing used lime/clay bonding; modern products may use synthetic spinel or resin bonds, but the statement remains broadly correct in a classical context.

Step-by-Step Solution:

Verification / Alternative check:Handbooks on refractories list chromite as neutral-basic refractory with the cited properties and bonding systems, supporting the combined statement.

Why Other Options Are Wrong:

• Choosing any single option omits the full, correct property set; the combined choice reflects established practice.

Common Pitfalls:Assuming all magnesite bricks outperform chromite in every respect; resistance comparisons depend on grade, impurities, and operating environment.

Final Answer:All of the statements (a), (b) and (c) are correct.