Raw materials for silicon carbide refractories: the principal raw material actually fed to make SiC shapes and bricks is which of the following?

Introduction / Context:
Silicon carbide (SiC) refractories are valued for high thermal conductivity, excellent thermal-shock resistance, and good corrosion resistance. In practice, most commercial SiC bricks and shapes are manufactured from pre-synthesized SiC grains commonly known by the trade name “carborundum.”

Given Data / Assumptions:

• Modern production uses graded SiC aggregates plus binders.
• Reaction-bonded and nitride-bonded variants exist, but the feed still contains SiC grains.
• Al2O3 (corundum), bauxite, and MgO (periclase) are raw materials for other refractory classes.

Concept / Approach:
Although SiC can be synthesized from silica sand and coke in an Acheson furnace, the refractory plant typically purchases classified SiC grains as the starting aggregate for brickmaking. These are shaped with suitable bonds (e.g., clay, silicon nitride, or oxide binders) and fired or cured to form robust products. Hence, the correct “raw material for manufacture” in a refractory works context is carborundum itself.

Step-by-Step Solution:
Identify the target material class: silicon carbide refractories.Note industrial practice: start from SiC grain feedstock.Select “carborundum (SiC grains)” as the principal raw material.

Verification / Alternative check:
Supplier catalogues and process descriptions list graded SiC as the primary aggregate for SiC bricks; silica and coke are feedstocks for the synthesis of SiC, not the typical brickmaking charge at the plant.

Why Other Options Are Wrong:
Corundum, bauxite, periclase: raw materials for alumina or magnesia bricks, not SiC.Silica flour only: incomplete and not representative of SiC refractory manufacture.

Common Pitfalls:
Confusing SiC synthesis feed (silica + coke) with refractory plant raw materials (SiC grains).Assuming all SiC bricks are identical; bonding systems vary.

Final Answer:
Carborundum (silicon carbide grains)