Industrial applications of silicon carbide (SiC) refractories: in which of the following are SiC refractories commonly employed?

Introduction / Context:
Silicon carbide (SiC) refractories are valued for their high thermal conductivity, excellent thermal-shock resistance, good abrasion resistance, and strong mechanical strength at elevated temperatures. Because of this unique property set, they are chosen in furnace components that must transfer heat efficiently, withstand cycling, and resist corrosive environments. The question checks familiarity with typical end uses.

Given Data / Assumptions:

• Applications include muffles, non-ferrous smelting gear, and recuperators.
• SiC may be reaction-bonded, nitride-bonded, or recrystallized; all retain high conductivity.
• Service involves high temperature and/or rapid heating–cooling cycles.

Concept / Approach:
Muffle furnaces benefit from SiC’s high thermal conductivity for rapid, uniform heat transfer to the charge through the muffle wall. Zinc smelting furnaces face corrosive vapors and high temperatures where SiC’s corrosion and thermal-shock resistances pay off. Ceramic recuperators require robust heat-exchange surfaces resistant to thermal gradients—again a natural fit for SiC. Therefore, all listed applications are legitimate uses.

Step-by-Step Solution:
Evaluate muffle service: needs high k and thermal-shock resistance → SiC suitable.Evaluate zinc smelting: corrosive, hot environment → SiC durable.Evaluate recuperators: heat-exchange efficiency and cycling → SiC excels.Conclude: all three are correct.

Verification / Alternative check:
Product catalogs and plant case studies document SiC muffles, SiC lining blocks in non-ferrous furnaces, and SiC-based heat-exchanger elements for energy recovery.

Why Other Options Are Wrong:
Individual picks (a), (b), or (c) alone understate SiC’s broad applicability.“None of the above” contradicts widespread industrial practice.

Common Pitfalls:
Assuming all ceramics are thermal insulators; SiC is notably conductive.Overlooking chemical corrosion factors in non-ferrous operations.

Final Answer:
All of (a), (b), and (c)